Guidance
on Controlling
Agricultural Sources
of Nonpoint Source
Pollution
Draft 9/30/98
Prepared for
Steve Dressing
Nonpoint Source Control Branch
Office of Water, U.S. Environmental Protection Agency
by
NCSU Water Quality Group
North Carolina State University
Raleigh, NC
as Subcontractor to
Tetra Tech, Inc.
Fairfax, VA
George Townsend, Work Assignment Leader
U.S. EPA Contract # 68-C7-0014
Work Assignment # 0-16
-------
Acknowledgments
Steven A. Dressing of the Nonpoint Source Control Branch, Office of Water, U.S.
Environmental Protection Agency, Washington, DC, is the primary author of this guidance
document. Many individuals assisted in this effort, including the following:
John Kosco, Municipal Support Division, Office of Water, U.S. EPA, Washington, DC
Thomas Davenport, Region 5, U.S. EPA, Chicago, IL
David Rathke, Region 8, U.S. EPA, Denver, CO
Don Meals, consultant, Burlington, VT
Tommy C. Daniel, Department of Agronomy, University of Arkansas, Fayetteville, AR
Brent Hallock, Soil Science Department, California Polytechnic State University, San Luis
Obispo, CA
Ray Knighton, Soil Science Department, North Dakota State University, Fargo, ND
Jerry Hatfield, USDA-ARS, Washington, DC
Robert Goo, Nonpoint Source Control Branch, Office of Water, U.S. EPA, Washington, DC
Roger Dean, Region 8, U.S. EPA, Denver, CO
Amy Sosin, Watershed Branch, Office of Water, U.S. EPA, Washington, DC
Chris Laabs, Watershed Branch, Office of Water, U.S. EPA, Washington, DC
Joan Warren, Watershed Branch, Office of Water, U.S. EPA, Washington, DC
Kristen Martin, Nonpoint Source Control Branch, Office of Water, U.S. EPA
Steven W. Coffey, Division of Soil and Water Conservation, NC Department of Environment
and Natural Resources, Raleigh, NC
Judith A. Gale, Galeforce Consulting, Raleigh, NC
Richard E. Phillips, retired, Biological and Agricultural Engineering Department, North
Carolina State University, Raleigh, NC
Ron Marlow, USDA-NRCS, Washington, DC
The following team from North Carolina State University, Raleigh, NC, contributed as
subcontractors to Terra Tech, Inc., providing much of the writing and editing:
Laura Lombardo, Daniel £. Line, Garry L. Grabow, Jean Spooner, Janet M. Young, Terry
W. Pollard of the NCSU Water Quality Group
Deanna L. Osmond and Rich McLaughlin of the Soil Science Department
Frank J. Humenik, Animal Waste Management Programs, College of Agriculture and Life
Sciences
In addition, the.following team from Tetra Tech, Incorporated, provided valuable contributions:
George Townsend, Leslie Shoemaker, etc.
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Table of Contents
Chapter 1: Introduction 1
The Purpose and Scope of this Guidance 1
What is Nonpoint Source Pollution? '..;: : 2
National Efforts to Control Nonpoint Source Pollution 4
Nonpoint Source Program — Section 319 Clean Water Act 4
National Estuary Program 5
Pesticides Program 5
Coastal Nonpoint Pollution Control Program 5
Rural Clean Water Program (RCWP) 6
Farm Bill Conservation Provisions 7
Chapter 2: Overview 9
Agricultural Sources of Water Pollution 9
Nutrients ; 9
Sediment '. 13
Animal Wastes 15
Salts .' 17
Pesticides '. 18
Habitat Impacts 21
Mechanisms to Control Agricultural Nonpoint Pollution 23
Management Measures 24
Management Practices 25
Resource Management Planning Concepts , 25
Chapter 3: Management Practices : 27
How Management Practices Work to Prevent Nonpoint Source Pollution 27
Summary of USDA-NRCS Practices -. 28
Management Practice Systems 33
Types of Management Practice Systems 34
Site-Specific Design of Management Practice Systems 34
Practices Must Fit Together for Systems to Perform Effectively 35
Chapter 4: Management Measures 37
4A: Nutrient Management 37
Management Measure for Nutrient Management 37
Management Measure for Nutrient Management: Description 38
Sources of Nutrients 38
Nutrient Movement into Surface and Ground Water 50
Nutrient Management Practices and Their Effectiveness 53
Factors in the Selection of Management Practices 63
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Cost of Practices '. 64
4B: Pesticide Management 67
Management Measure for Pesticide Management.. 67
Management Measure for Pesticide Management: Description 67
Pesticides: An Overview :. 69
Pesticide Movement into Surface and Ground Water 70
Pesticide Management Practices and Their Effectiveness 75
Factors in the Selection of Management Practices 79
Relationship of Pesticide Management Measures to Other Programs 80
Cost of Practices 81
4C: Erosion and Sediment Control 85
Management Measure for Erosion and Sediment Control 85
Management Measures for Erosion and Sediment Control: Description 85
Sediment Movement into Surface and Ground Water 86
Erosion and Sediment Control Practices and Their Effectiveness 90
. Factors in the Selection of Management Practices 102
Cost of Practices 103
4D: Facility Wastewater and Runoff from Animal Feeding Operations 107
Management Measure for Facility Wastewater and
Runoff from Animal Feeding Operations ; 107
AFOs, CAFOs, and CZARA 108
Management Measure for Facility Wastewater and Runoff from Animal
Feeding Operations: Description 112
Containment Movement from Animal Feeding Operations into Surface
and Ground Water 113
Animal Feeding Operation Management Practices and Their Effectiveness 117
Factors in the Selection of Management Practices 122
Cost of Practices 124
4E: Grazing Management 127
Management Measure for Grazing Management 127
Management Measure for Grazing Management: Description 127
Grazing and Pasture: An Overview 129
Grazing Impacts on Surface and Ground Water 136
Grazing Management Practices and Their Effectiveness .137
Factors in the Selection of Management Practices 145
Cost of Practices 146
4F: Irrigation Water Management 155
Management Measure for Irrigation Water Management 155
Management Measure for Irrigation Water Management: Description 156
Irrigation and Irrigation Systems: An Overview 156
Irrigation Water Management Practices and Their Effectiveness 181
Factors in Selection of Management Practices 191
Cost of Practices 192
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Chapter 5: Using Management Measures to
Prevent and Solve Nonpoint Source Problems in Watersheds 195
Watershed Approach 195
Implementing Management Measures in Watersheds 196
Technology-Based Implementation 197
Water Quality-Based Implementation 197
Chapter 6: Monitoring and Tracking Techniques 205
Water Quality Monitoring 205
Tracking Implementation of Management Measures 2Q9
Determining Effectivness of Implemented Management Measures 210
Quality Assurance and Quality Control 212
Chapter 7: Load Estimation Techniques 215
Estimating Pollutant Loads through Monitoring 217
Components of a Load 217
Measuring Water Discharge 217
Measuring Pollutant Concentration 218
Calculating Pollutant Loads '. 221
Estimating Pollutant Loads Through Modeling ,. ; 223
Types of Models Available ...: 223
Watershed Loading Models 223
Planning and Selection of Models 228
Model Calibration and Validation 229
Unit Loads... 230
Addressing Uncertainty in Modeling Predictions T 231
Model Applications Using GIS Technology 231
ChapterS: Glossary 233
Chapter 9: References -. 237
Appendix : 263
Appendix A: Best Management Practices — Definitions and Descriptions : 263
Appendix B: SCS Field Office Technical Guide Policy 284
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Introduction
Agriculture is listed
as a source of
pollution for 60% of
the impaired river
miles in the United
States.
The Nation's aquatic resources are among its most valuable assets. While
environmental protection programs in the United States have successfully im-
proved water quality during the past 25 years, many challenges still remain. Al-
though significant strides have been made in reducing the impacts of discrete
pollutant sources, aquatic ecosystems remain impaired, primarily due to complex
pollution problems caused by nonpoint source (NFS) pollution.
The most recent national water quality inventory shows that, as of 1994,
nearly 40% of surveyed waters in the United States remain too polluted for fish-
ing, swimming, and other uses. The leading causes of impairment are sediment,
nutrients, toxic metals, oxygen-depleting materials, disease-causing bacteria, oil,
and grease (EPA, 1995a). Habitat alterations, such as hydromodification, dredg-
ing, and streambank destabilization, may also degrade water quality. Agriculture
is listed as a source of pollution for 60% of the impaired river miles in the U.S.
The Purpose and Scope of this Guidance
This guidance is
designed to provide
current information
to State program
managers on
controlling agricultural
nonpoint source
pollution.
This guidance document is intended to provide technical assistance to State
program managers and others on the best available, most economically achiev-
able means of reducing NFS pollution of surface and ground water from agricul-
ture. The guidance provides background information about agricultural NFS
pollution, where it comes from and how it enters the Nation's waters, discusses
the broad concept of assessing and addressing water quality problems on a water-
shed level, and presents up-to-date technical information about how to reduce
agricultural NFS pollution.
The causes of agricultural NFS pollution, specific pollutants of concern, and
general approaches to reducing the impact of such pollutants on aquatic re-
sources are discussed in the Overview (Chapter 2). A general discussion of best
management practices (BMPs) and the use of combinations of individual prac-
tices (BMP systems) to protect surface and ground water is given in Chapter 3.
Management measures for nutrient management, pesticide management, erosion
and sediment control, facility wastewater and runoff from confined animal facili-
ties, grazing management, and irrigation water management are described in
Chapter 4. Also in Chapter 4 are discussions of BMPs that can be used to achieve
the management measures, including cost and effectiveness information. Chapter
5 summarizes watershed planning principles, and Chapters 6 and 7 give over-
views of nonpoint source monitoring and pollutant load estimation, respectively.
While the scope of this guidance is broad, covering diverse agricultural NFS
pollutants from a range of sources, there are a number of issues that are not cov-
ered. Such issues include nutrient transfer over long distances (e.g., the shipping
of feed from one state to another in which the resulting animal waste is then
applied to fields), animal nutrition (e.g., changing the nutrient mix fed to live-
stock as an approach to managing nutrients in animal waste), alternatives for
manure (such as composting or regional distribution of manure from farms that
Chapter 1-1: 10/98
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2 Chapter 1: Introduction
do not need it to farms that can use it), odor control, and methane production.
Furthermore, because it is national in scope, this document cannot address all
practices or techniques specific to local or regional soils, climate, or agronomic
conditions. In addition, new BMPs are being developed as a result of ongoing
agricultural research. Readers should consult with State or local agencies includ-
ing the United States Department of Agriculture (USDA)-Natural Resources
Conservation Service (NRCS), Cooperative Extension Service, land grant univer-
sities, conservation districts, and agricultural organizations for additional infor-
mation on agricultural nonpoint source pollution controls applicable to their local
area.
This guidance does
NOT replace the 1993
Guidance Specifying
Management
Measures for Sources
of Nonpoint Pollution
in Coastal Waters.
Readers should note that this guidance is entirely consistent with the Guid-
ance Specifying Management Measures for Sources of Nonpoint Pollution in
Coastal Waters (EPA, 1993) published under Section 6217 of the Coastal Zone
Act Reauthorization Amendments of 1990 (CZARA). This guidance, however,
does not supplant or replace the 1993 coastal management measures guidance for
the purpose of implementing programs under Section 6217. This document modi-
fies and expands upon supplementary technical information contained in the
Coastal Management Measures Guidance both to reflect circumstances relevant
to differing inland conditions and to provide current technical information.
Under CZARA, States that participate in the Coastal Zone Management
Program under the Coastal Zone Management Act are required to develop coastal
nonpoint pollution control programs that ensure the implementation of EPA's
management measures in their coastal management area. In contrast, Section 319
of the Clean Water Act contains no language that requires States to implement
EPA's coastal management measures as part of their Section 319 programs. This
document does not set new or additional standards for either Section 6217 or
Section 319 programs.
What is Nonpoint Source Pollution?
Nonpoint source pollution generally results from precipitation, atmospheric
deposition, land runoff, infiltration, drainage, seepage, orhydrologic modifica-
tion. As runoff from rainfall or snowmelt moves, it picks up and transports natu-
ral pollutants and pollutants resulting from human activity, ultimately depositing
them into rivers, lakes, wetlands, coastal waters, and ground water. Technically,
the term nonpoint source is defined to mean any source of water pollution that
does not meet the legal definition of point source in Section 502(14) of the Clean
Water Act of 1987:
The term point source means any discernible, confined
and discrete conveyance, including but not limited to any pipe,
ditch, channel, tunnel, conduit, well, discrete fissure, container,
rolling stock, concentrated animal feeding operation, or vessel
or other floating craft from which pollutants are or may be
discharged. This term does not include agricultural stormwater
discharges and return flows from irrigated agriculture.
Chapter 1-2:10/98
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Chapter V. Introduction 3
Although diffuse runoff is generally treated as nonpoint source pollution,
runoff that enters and is discharged from conveyances such as those described
above is treated as a point source discharge and hence is subject to the permit
requirements of the Clean Water Act. In contrast, nonpoint sources are not sub-
ject to federal permit requirements. Point sources generally enter receiving water
bodies at some identifiable site(s) and carry pollutants whose generation is con-
trolled by some internal process or activity, rather than weather. Point source
discharges such as municipal and industrial waste waters, runoff or leachate from
solid waste disposal sites and concentrated animal feeding operations, and storm
sewer outfalls from large urban centers are regulated and permitted under the
Clean Water Act.
Nonpoint sources, i.e. sources not defined by statute as
point sources as described above, include return flow from
irrigated agriculture, other agricultural and silvicultural runoff and
infiltration, urban runoff from small or unsewered urban areas,
flow from abandoned mines, and hydrologic modification.
While it is imperative that water program managers understand and manage
in accordance with legal definitions and requirements, the non-legal community
often characterizes nonpoint sources in the following ways:
O Nonpoint source discharges enter surface and/or ground waters in a diffuse
manner at intermittent intervals related mostly to meteorological events.
G Pollutant generation arises over an extensive land area and moves overland
before it reaches surface waters or infiltrates into ground waters.
O The extent of NPS pollution is related to uncontrollable climatic events and
to geographic and geologic conditions and varies greatly from place to place
and from year to year.
O Nonpoint sources are often more difficult or expensive to monitor at their
point(s) of origin, as compared to monitoring of point sources.
O Abatement of nonpoint sources is focused on land and runoff management
practices, rather than on effluent treatment.
O Nonpoint source pollutants may be transported and/or deposited as airborne
contaminants.
Nonpoint source pollutants that cause the greatest impacts are sediments,
nutrients, toxic compounds, organic matter, and pathogens. Hydrologic modifica-
tion can also cause adverse effects on biological and physical integrity of surface
and ground waters.
Chapter 1-3:10/98
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4 Chapter 1: Introduction
National Efforts to
Control Nonpoint Source Pollution
Section 319
requires States to
assess NFS pollution
and implement
management
programs.
Section 319
authorizes EPA to
provide grants to
assist State NPS
pollution control
programs.
Nonpoint Source Program — Section 319 of the
Clean Water Act
During the first 15 years of the national program to abate and control water
pollution (1972-1987), EPA and the States focused most of their water pollution
control activities on traditional point sources. These point sources have been
regulated by EPA and the States through the National Pollutant Discharge Elimi-
nation System (NPDES) permit program established by Section 402 of the 1972
Federal Water Pollution Control Act (Clean Water Act). Discharges of dredged
and fill materials into wetlands have also been regulated by the U.S. Army Corps
of Engineers and EPA under Section 404 of the Clean Water Act.
As a result of the above activities, the Nation has greatly reduced pollutant
loads from point source discharges and has made considerable progress in restor-
ing and maintaining water quality. However, the gains in controlling point
sources have not solved all of the Nation's water quality problems. Recent stud-
ies and surveys by EPA and by State water quality agencies indicate that the
majority of the remaining water quality impairments in our Nation's rivers,
streams, lakes, estuaries, coastal waters, and wetlands result from NPS pollution
and other nontraditional sources, such as urban storm water discharges and com-
bined sewer overflows.
In 1987, in view of the progress achieved in controlling point sources and
the growing national awareness of the increasingly dominant influence of NPS
pollution on water quality, Congress amended the Clean Water Act to focus
greater national efforts on nonpoint sources. Under this amended version, re-
ferred to as the 1987 Water Quality Act, Congress revised Section 101, "Declara-
tion of Goals and Policy," to add the following fundamental principle:
It is the national policy that programs for the
control of nonpoint sources of pollution be developed
and implemented in an expeditious manner so as to
enable the goals of this Act to be met through the
control of both point and nonpoint sources of pollution.
More importantly, Congress enacted Section 319 of the 1987 Water Quality
Act, which established a national program to control nonpoint sources of water
pollution. Under Section 319, States address NPS pollution by assessing NPS
pollution problems and causes within the State and implementing management
programs to control the NPS pollution. Section 319 authorizes EPA to issue
grants to States to assist them in implementing management programs or portions
of management programs which have been approved by EPA.
Chapter 1-4:10/98
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Chapter 1: Introduction 5
The Federal Coastal
Nonpoint Pollution
Control Program
(6217) is designed
to enhance State
and local efforts to
manage land use
activities that
degrade coastal
habitats and waters.
National Estuary Program
EPA also administers the National Estuary Program under Section 320 of
the Clean Water Act. This program focuses on point and NPS pollution in geo-
graphically targeted, high-priority estuarine waters. In this program, EPA assists
State, regional, and local governments in developing comprehensive conservation
and management plans that recommend priority corrective actions to restore
estuarine water quality, fish populations, and other designated uses of the waters.
Pesticides Program
Another program administered by EPA that controls some forms of NPS
pollution is the pesticides program under the Federal Insecticide, Fungicide, and
Rodenticide Act (FIFRA). Among other provisions, this program authorizes EPA
to control pesticides that may threaten ground and surface water. FIFRA provides
for the registration of pesticides and enforceable label requirements, which may
include maximum rates of application, restrictions on use practices, and classifi-
cation of pesticides as "restricted use" pesticides (which restricts use to certified
applicators trained to handle toxic chemicals).
Coastal Nonpoint Pollution Control Program
In November 1990, Congress enacted the Coastal Zone ActKeauthorization
Amendments (CZARA). These amendments were intended to address several
concerns, including the impact of NPS pollution on coastal waters.
To more specifically address the impacts of NPS pollution on coastal water
quality, Congress enacted Section 6217, Protecting Coastal Waters (codified as
16 U.S.C. Section 1455b). Section 6217 provides that each State with an ap-
proved Coastal Zone Management Program must develop and submit to EPA and
the National Oceanic and Atmospheric Administration (NOAA) for approval a
Coastal Nonpoint Pollution Control Program. The purpose of the program "shall
be to develop and implement management measures for nonpoint source pollu-
tion to restore and protect coastal waters, working in close conjunction with
other State and local authorities."
Coastal Nonpoint Pollution Control Programs are not intended to supplant
existing coastal zone management programs and NPS management programs.
Rather, they are intended to serve as an update and expansion of existing NPS
management programs and are to be coordinated closely with the coastal zone
management programs that States and Territories are already implementing pur-
suant to the Coastal Zone Management Act of 1972. The legislative history indi-
cates that the central purpose of Section 6217 is to strengthen the links between
Federal and State Coastal Zone Management and Water Quality Programs and to
enhance State and local efforts to manage land use activities that degrade coastal
waters and habitats.
Chapter 1-5: 1.0/98
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6 Chapter 1: Introduction
Section 6217(g) of CZARA requires EPA to publish, in consultation with
NOAA, the U.S. Fish and Wildlife Service, and other Federal agencies, "guid-
ance for specifying management measures for sources of nonpoint pollution in
coastal waters." Management measures are defined in Section 6217(g)(5) as
economically achievable measures for the control
of the addition of pollutants from existing and new
categories and classes of nonpoint sources of pollution,
which reflect the greatest degree of pollutant reduction
achievable through the application of the best available
nonpoint source control practices, technologies,
processes, siting criteria, operating methods, or other
alternatives.
In selected
watersheds, the
RCWP showed that
implementation of
agricultural BMPs
improved water
quality.
EPA published Guidance Specifying Management Measures for Sources of
Nonpoint Source Pollution in Coastal Waters (EPA, 1993b). In EPA's (1993b)
document, management measures for urban areas; agricultural sources; forestry;
marinas and recreational boating; hydromodification (channelization and channel
modification, dams, and streambank and shoreline erosion); and wetlands, ripar-
ian areas, and vegetated treatment systems were defined and described. The man-
agement measures for controlling agricultural NPS pollution discussed in
Chapter 4 of this document are based on those outlined by EPA (1993b).
Rural Clean Water Program (RCWP)
The Rural Clean Water Program (RCWP), a Federally sponsored NPS pollu-
tion control program, was initiated in 1980 as an experimental effort to address
agricultural NPS pollution in watersheds across the country.
The objectives of the RCWP were to:
O Achieve improved water quality in the approved project area in the most
cost-effective manner possible while providing food, fiber, and a quality
environment;
O Assist agricultural landowners and farm operators in reducing agricultural
NPS water pollutants and improving water quality in rural areas to meet
water quality standards or goals; and
O Develop and test programs, policies, and procedures for the control of agri-
cultural NPS pollution.
The RCWP was administered by the USDA-Agricultural Stabilization and
Conservation Service (now called USDAFarrn Service Agency) in consultation
with EPA. The Soil Conservation Service (now the NRCS), Extension Service,
Economic Research Service, U.S. Geological Survey (USGS), Forest Service,
and many other Federal, State, and local agencies also participated in the RCWP.
Programmatic and project-level decisions were made by national, State, and local
RCWP interagency coordinating committees.
Chapter 1-6:10/98
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Chapter 1: Introduction 7
Many Farm Bill
programs provide
funds for land
treatment. Please
contact your State
or local USDA
office for details.
Twenty-one experimental projects were funded across the United States.
The projects represented a wide range of pollution problems and impaired water
uses. Projects were located in Alabama, Delaware, Florida, Idaho, Illinois, Iowa,
Kansas, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Nebraska,
Oregon, Pennsylvania, South Dakota, Tennessee/Kentucky, Utah, Vermont, Vir-
ginia, and Wisconsin.
Each project included implementation of BMPs to reduce NPS pollution and
water quality monitoring to evaluate the effects of BMPs. The BMPs were tar-
geted to critical areas in each project — sources of NPS pollutants identified as
having significant impacts on the impaired water resource. Landowner participa-
tion was voluntary, with cost-sharing and technical assistance offered as incen-
tives for implementing BMPs.
The linkage of water quality monitoring to land treatment efforts in the
RCWP helped improve targeting of BMPs to sources most in need of treatment.
Water quality findings from the RCWP projects were also used to adjust.and
refine BMPs.
Farm Bill Conservation Provisions
Technical and financial assistance for landowners seeking to preserve soil
and other natural resources is authorized by the Federal government under provi-
sions of the Food Security Act (Farm Bill). 1996 provisions relating directly to
installation and maintenance of BMPs are summarized in the following sections.
Environmental Conservation Acreage Reserve Program (ECARP) —?
This is an umbrella program established by the 1996 Farm Bill which contains
the Conservation Reserve Program (CRP), Wetlands Reserve Program (WRP),
and Environmental Quality Incentives Program (EQIP). It authorizes the Secre-
tary of Agriculture to designate watersheds, multi-state areas, or regions of spe-
cial environmental sensitivity as conservation priority areas which are eligible for
enhanced Federal assistance. Assistance in priority areas is to be used to help
agricultural producers comply with NPS pollution requirements of the Clean
Water Act and other State or Federal environmental laws. The ECARP is autho-
rized through 2002.
Conservation Reserve Program (CRP) — First authorized by the Food
Security Act of 1985 (Farm Bill), this is a voluntary program that offers annual
rental payments, incentive payments, and cost-share assistance for establishing
long-term, resource-conserving cover crops on highly erodible land. Conserva-
tion Reserve Program contracts are issued for a duration of 10 to 15 years for up
to 36.4 million acres of cropland and marginal pasture. Land can be accepted into
the CRP through a competitive bidding process where all offers are ranked using
an environmental benefits index, or through continuous sign-up for eligible lands
where certain special conservation practices will be implemented.
Wetlands Reserve Program (WRP) — The WRP is a voluntary program
to restore and protect wetlands and associated lands. Participants may sell a per-
manent or 30-year conservation easement or enter into a 10-year cost-share
agreement with USDA to restore and protect wetlands. The landowner voluntar-
ily limits future use of the land, yet retains private ownership. The NRCS pro-
vides technical assistance in developing a plan for restoration and maintenance of
Chapter 1-7:10/98
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8 Chapter 1: Introduction
the land. The landowner retains the right to control access to the land and may
lease the land for hunting, fishing, and other undeveloped recreational activities.
Environmental Quality Incentives Program (EQIP) — The EQIP was
established by the 1996 Farm Bill to provide a voluntary conservation program
for farmers and ranchers who face serious threats to soil, water, and related natu-
ral resources. EQIP offers financial, technical, and educational help to install or
implement structural, vegetative, and management practices designed to conserve.
soil and other natural resources. Current priorities for these funds dictate that one
half of the available monies be directed to livestock-related concerns. Cost-shar-
ing may pay up to 75% of the costs for certain conservation practices. Incentive
payments may be made to encourage producers to perform land management
practices such as nutrient management, manure management, integrated pest
management, irrigation water management, and wildlife habitat management.
Cost-share for construction of animal waste management facilities is prohibited
for livestock operations over 1,000 animal units or as otherwise approved by the
Chief of NRCS, but such units are eligible for incentive payments and technical
and educational assistance.
Wildlife Habitat Incentives Program (WHIP) — This program is de-
signed for people who want to develop and improve wildlife habitat on private
lands. Plans are developed in consultation with the NRCS and local Conservation
District. USDA will provide technical assistance and cost-share up to 75% of the
cost of installing the wildlife practices. Participants generally must sign a 5- to
10-year contract with USDA which requires that they maintain the practices.
Forestry Incentives Program (FIP) — Originally authorized in 1978, the
FTP allows cost sharing up to 65% (up to a maximum of $10,000 per person per
year) for tree planting, timber stand improvement, and related practices on nonin-
dustrial private forest land. The FIP is administered by the NRCS and the U.S.
Forest Service. Cost share funds are restricted to individuals who own no more
than 1,000 acres of eligible forest land.
Conservation of Private Grazing Land — This program was authorized
by the 1996 Farm Bill for the purpose of providing technical and educational
assistance to owners of private grazing lands. It offers opportunities for better
land management, erosion reduction, water conservation, wildlife habitat, and
improving soil structure.
Chapter 1-8:10/98
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Overview
Agricultural Sources of Water Pollution
Commercial
fertilizers and
manure are the
primary sources
of crop nutrients
for agriculture.
Most of the contamination of surface waters in the United States is due to
nonpoint sources of pollution. In its 1994 National Water Quality Inventory:
Report to Congress, the U.S. Environmental Protection Agency (EPA) noted that
the leading source of water quality impairment of rivers and lakes was agricul-
ture. Based on data collected by the States and Territories, EPA estimated that
60% of the impaired river miles, 50% of the impaired lake acres, and 34% of the
impaired estuarine square miles are polluted due to agricultural nonpoint sources
of pollutants (EPA, 1995a).
The primary agriculturalnonpoint source (NFS) pollutants are nutrients,
sediment, animal wastes, salts, and pesticides. The effects of these pollutants are
discussed below. Agricultural activities also have the potential to directly impact
the habitat of aquatic species through physical disturbances caused by livestock
or equipment.
Although agricultural NPS pollution is a serious problem nationally, a great
deal has been learned in the recent past about effective ways to prevent and re-
duce NPS pollution from agricultural activities. The purpose of this chapter is to
describe the general causes of agricultural NPS pollution, the specific pollutants
and problems of concern, and the general approaches to reducing the impact of
such pollutants and problems on aquatic resources.
Nutrients
Nitrogen (N) and phosphorus (P) are the two major nutrients from agricul-
tural land that degrade water quality. Nutrients are applied to agricultural land in
several different forms and come from various sources, including:
O Commercial fertilizer in a dry or fluid form, containing nitrogen, phosphorus,
potassium (K), secondary nutrients, and micfonutrients;
O Manure from animal production facilities including bedding and other wastes
added to the manure, containing N, P, K, secondary nutrients, micronutrients,
salts, some metals, and organics;
O 'Municipal and industrial treatment plant sludge, containing N, P, K, second-
ary nutrients, micronutrients, salts, metals, and organic solids;
O Municipal and industrial treatment plant effluent, containing N, P, K, second-
ary nutrients, micronutrients, salts, metals, and organics;
O' Legumes and crop residues containing N, P, K, secondary nutrients, and
micronutrients;
O Irrigation water; and
O Atmospheric deposition of nutrients such as nitrogen and sulphur.
Chapter 2-9: 10/98
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10 Chapter 2: Overview
Overloading with
nitrogen and
phosphorus
causes eutro-
phication which
reduces the
suitability of
waterways for
beneficial uses.
In addition, decomposition of organic matter and crop residue may be a
source of mobile forms of nitrogen, phosphorus, and other essential crop nutrients.
Surface water runoff from agricultural lands to which nutrients have been
applied may transport the following pollutants:
O Particulate-bound nutrients, chemicals, and metals, such as phosphorus, or-
ganic nitrogen, and metals applied with some organic wastes;
D Soluble nutrients and chemicals, such as nitrogen, phosphorus, metals, and
many other major and minor nutrients;
O Paniculate organic solids, oxygen-demanding material, and bacteria, viruses,
and other microorganisms applied with some organic waste; and
O Salts.
Ground water infiltration from agricultural lands to which nutrients have
been applied may transport the folio wing pollutants:
D Soluble nutrients and chemicals, such as nitrogen, phosphorus, metals;
D Other major and minor nutrients; and
D Salts.
All plants require nutrients for growth. In aquatic environments, nutrient
availability usually limits plant growth. Nitrogen and phosphorus generally are
present at background or natural levels below 0.3 and 0.05 mg/L, respectively.
When these nutrients are introduced into a stream, lake, or estuary at higher
rates, aquatic plant productivity may increase dramatically. This process, referred
to as cultural eutrophication, may adversely affect the suitability of the water for •
other uses.
Increased aquatic plant productivity results in the addition to the system of
more organic material, which eventually dies and decays. The decaying organic
matter produces unpleasant odors and depletes the oxygen supply required by
aquatic organisms. Depleted oxygen levels, especially in colder bottom waters
where dead organic matter tends to accumulate, can reduce the quality of fish •
habitat and encourage the propagation offish that are adapted to less oxygen or
to warmer surface waters. Highly enriched waters will stimulate algae produc-
tion, consequently increasing turbidity and color. Excess plant growth may also
interfere with recreational activities such as swimming and boating. Algae
growth is also believed to be harmful to coral reefs (e.g., Florida coast). Further-
more, the increased turbidity results in less sunlight penetration and availability
to submerged aquatic vegetation (SAV). Since SAV provides habitat for small or
juvenile fish, the loss of SAV has severe consequences for the food chain. Chesa-
peake Bay is an example in which nutrients are believed to have contributed to
SAV loss.
Nitrogen
All forms of transported nitrogen are potential contributors to eutrophication
in lakes, estuaries, and some coastal waters. In general, though not in all cases,
nitrogen availability is the limiting factor for plant growth in marine ecosystems.
Thus, the addition of nitrogen can have a significant effect on the natural func-
tioning of marine ecosystems.
Chapter 2-10:10/98
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Chapter 2: Overview 11
Excessive
ammonia can be
toxic to fish.
The safe limit for
nitrate nitrogen in
drinking water is
10 mg/L.
The Gulf of Mexico has a hypoxic (low dissolved oxygen) area that covers
almost 7,000 square miles, having doubled in size over the past ten years (Inter-
agency Interim Working Group on Hypoxia, 1997). Increased loads of nitrate and
phosphorus, coupled with decreased riverine silica loading, are believed to have
caused shifts in off-shore phytoplankton species and increased primary produc-
tion (Rabalais et al., 1996). Related research links increased nutrient loads from
rivers to increased eutrophication in coastal waters, as evidenced by increasing
incidence of noxious algal blooms and hypoxia in bottom waters (Justic et al.,
1995).
The toxic dinoflagellate Pfiesteriapiscicida, implicated in causing about
50% of the major fish kills in North Carolina's estuaries and coastal waters from
1991 to 1993, has been linked to conditions of over-enrichment of nutrients such
as nitrogen and phosphorus (Burkholder, 1996). Pfiesteria-like species have also
been tracked to eutrophic sudden-death fish kill sites in estuaries, coastal waters,
and aquaculture facilities from the mid-Atlantic through the Gulf Coast
XBurkholder et al., 1995).
In addition to eutrophication, excessive nitrogen causes other water quality
problems. Dissolved ammonia at concentrations above 0.2 mg/L may be toxic to
fish, especially trout. Also, nitrates in drinking water are potentially dangerous,
especially to newborn infants. Nitrate is converted to nitrite in the digestive tract,
which reduces the oxygen-carrying capacity of the blood (methemoglobinemia),
resulting in brain damage or even death. The U.S. Environmental Protection
Agency has set a limit df 10 mg/L nitrate-nitrogen in water used for human con-
sumption (EPA, 1989a).
Data collected within the first 20 National Water Quality Assessment
(NAWQA) Program sites showed that nitrate concentrations in ground water
were highest in samples from wells in agricultural areas, with concentrations
exceeding the drinking water standard of 10 mg/L in about 12% of domestic
wells (Mueller and Helsel, 1996). Nitrate concentrations in surface waters were
highest downstream from agricultural or urban areas, but concentrations rarely
exceeded the drinking water standard.
Nitrogen is naturally present in soils but must be added to increase crop
production. Nitrogen is added to the soil primarily by applying commercial fertil-
izers and manure, but also by growing legumes (biological nitrogen fixation) and
incorporating crop residues. Not all nitrogen that is present in or on the soil is
available for plant use at any one time. For example, in the eastern Corn Belt, it
is normally assumed that about 507o of applied nitrogen is assimilated by crops
during the year of application (Nelson, 1985). Organic nitrogen normally consti-
tutes the majority of the soil nitrogen. It is slowly converted (2 to 3% per year) to
the more readily plant-available inorganic ammonium or nitrate.
The chemical form of nitrogen affects its impact on water quality. The most
biologically important inorganic forms of nitrogen are ammonium (NH4-N), ni-
trate (NO3-N), and nitrite (NO,-N). Organic nitrogen occurs as paniculate matter,
in living organisms, and as detritus. It occurs in dissolved form in compounds
such as amino acids, amines, purines, and urea.
Chapter 2-11: 10/98
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12 Chapter 2: Overview
Nitrate-nitrogen can
readily leach below
the root zone into
shallow ground
water and can
threaten water
supplies.
Phosphorus
Most often,
phosphorus is
sediment-attached.
Phosphorus may
also be dissolved.
Either form can
contribute to
eutrophication.
Nitrate-nitrogen is highly mobile and can move readily below the crop root
zone, especially in sandy soils. It can also be transported with surface runoff, but
not usually in large quantities. Ammonium, on the other hand, becomes adsorbed
through the soil and is lost primarily with eroding sediment. Even if nitrogen is
not in a readily available form as it leaves the Field, it can be converted to an
available form either during transport or after delivery to water bodies.
Mean nitrate concentrations in three Wisconsin streams with watersheds
ranging from 5,960 to 10,510 acres in size have increased from the 1960s and
1970s to 1988 and 1989 (Mason etal., 1990). Increases are attributed to the con-
version of land to row crops and the increased application of commercial fertil-
izer and animal manure.
Studies in Walnut Creek, Iowa, showed that nitrate levels in the stream
draining this corn-soybean watershed ranged from 10 to 20 mg/L (Hatfield et al.,
1995). It was concluded that nitrate concentration was largely determined by
stream discharge.
Over the period 1986-1992, annual flow-weighted mean nitrate concentra-
tions in ground water in the highly agricultural Big Spring basin of Iowa ranged
from 5.7 mg/L in the very dry water year 1989 to 12.5 mg/L in the very wet wa-
ter year 1991 (Rowdenetal., 1995).
Phosphorus can also contribute to the eutrophication of both freshwater and
estuarine systems. Studies on the Cannonsville Reservoir, New York, showed
that eutrophication was accelerated by phosphorus loading (Brown et al., 1986).
The low dissolved oxygen levels associated with eutrophication impacted fish
populations, and use of the lake for recreational fishing was much less than at
nearby Pepacton Reservoir. Also, nutrients are the major cause of use impairment
in Lake Champlain, Vermont, with phosphorus the main culprit (Vermont Agency
of Natural Resources, 1996). It is estimated that 71% of the NPS phosphorus load
is derived from agricultural activities.
While phosphorus typically plays the controlling role in freshwater systems,
in some estuarine systems both nitrogen and phosphorus can limit plant growth.
Algae consume dissolved inorganic phosphorus and convert it to the organic
form. Phosphorus is rarely found in concentrations high enough to be toxic to
higher-level organisms.
Phosphorus can be found in the soil in dissolved, colloidal, or particulate
forms. Although the phosphorus content of most soils in their natural condition is
low (between 0.01 and 0.2% by weight), recent soil test results show that the
phosphorus content of most cropped soils in the Northeast has climbed to the
high or very high range (Sims, 1992). Manure and fertilizers.increase the level of
available phosphorus in the soil to promote plant growth, but many soils now
contain higher phosphorus levels than plants need (Killorn, 1980; Novais and
Kamprath, 1978). Manures are normally applied at rates needed to meet crop
nitrogen needs, yet the ratio of nitrogen to phosphorus in most manures results in
over-application of phosphorus (Sharpley et al., 1996).
Chapter 2-12:10/98
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Chapter 2: Overview 13
Sediment
threatens water
supplies and
recreation, and
causes harm to
plant and fish
communities.
Relationships between soil phosphorus levels and phosphorus loss in runoff
have been established for a few soils and crops, with soil test results able to ex-
plain from 58 to 98% of the variations in concentration of dissolved phosphorus
in runoff (Sharpley et al., 1996). It was concluded, however, that the relationship
between soil test phosphorus levels and runoff concentration of phosphorus var-
ies across soil type, while the load of phosphorus in runoff is more related to
variability in runoff volume than to soil test results.
Lemunyon and Gilbert (1993) described an index for identifying soils, land-
forms, and management practices that could cause phosphorus problems in water
bodies. The index uses soil erosion rates, runoff, soil test values of available
phosphorus, and fertilizeY and organic phosphorus application rates to assess the
potential for phosphorus movement from the site. Sharpley (1995) applied the
Lemunyon and Gilbert phosphorus index to 30 watersheds in the Southern
Plains, and concluded that the index is a valuable tool for identifying sources
where phosphorus management was most needed. Several recommendations
were made for improving the accuracy and utility of the index.
Runoff and erosion can carry some phosphorus to nearby water bodies.
Dissolved inorganic phosphorus (orthophosphate phosphorus) is probably the
only form directly available to algae, but eutrophication can be stimulated by the
bioavailable phosphorus derived from the upper 5 cm of agricultural soils
(Sharpley, 1985). Bioavailable phosphorus consists of dissolved phosphorus and
a portion of paniculate phosphorus that varies from site to site. Sharpley (1993)
developed a method using iron-oxide impregnated paper to estimate the amount
of phosphorus in soil that is available for algal growth. This method covers both
dissolved and adsorbed phosphorus. Paniculate and organic phosphorus deliv-
ered to water bodies may later be released as dissolved phosphorus and made
available to algae when the bottom sediment of a stream becomes anaerobic,
causing water quality problems.
Sediment
Sediment is the result of erosion. It is the solid material, both mineral and
organic, that is in suspension, is being transported, or has been moved from its ,
site of origin by wind, water, gravity, or ice. The types of erosion associated with
agriculture that produce sediment are (1) sheet and rill erosion, (2) gully erosion,
and (3) streambank erosion. Soil erosion can be characterized as the transport of
particles that are detached by rainfall, flowing water, or wind. Eroded soil is
either redeposited on the same field or transported from the field in runoff.
Soil loss reduces nutrients and deteriorates soil structure, causing a decrease
in the productive capacity of the land. Wind erosion may cause abrasion of crops
and structures by flying soil particles, air pollution by particles in suspension,
transport of sediment-attached nutrients and pesticides, and burial of structures
and crops by drifting soil.
Sediment affects the use of water in many ways. Suspended solids reduce the
amount of sunlight available to aquatic plants, cover fish spawning areas and food
supplies, smother coral reefs, clog the filtering capacity of filter feeders, and clog
and harm the gills of fish. Turbidity interferes with the feeding habits offish.
These effects combine to reduce fish, shellfish, coral, and plant populations and
decrease the overall productivity of lakes, streams, estuaries, and coastal waters.
Chapter 2-13:10/98
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14 Chapter 2: Overview
Sediment from
topsoil, often
containing higher
levels of nutrients
and pesticides, can
be a greater threat
to water quality
compared to subsoil
sediment.
Recreation is limited because of the decreased fish population and the water's
unappealing, turbid appearance. Turbidity also reduces visibility, making swim-
ming less safe.
The use of Highland Silver Lake, Illinois, as a public water supply was im-
paired by high turbidity levels and sedimentation (EPA, 1990b). Similarly, sedi-
ment surveys revealed that Lake Pittsfield, also in Illinois, was losing storage
capacity at a rate of 1.08%, which would cause the lake to fill in with sediment in
92 years if no efforts had been made to control erosion (Davenport and Clarke,
1984). Due to erosion control efforts the rate of storage capacity loss has been
reduced from 15% over 13 years to 10% over the subsequent 18 years (EPA,
1996a). In addition, a water supply intake on Long Creek, North Carolina, was
clogged due to erosion from surrounding lands, necessitating annual dredging of
the water supply intake pool (EPA, 1996a).
At current rates of sedimentation, Morro Bay, California, could be lost as an
open water estuary within 300 years unless erosion control efforts are stepped up
(EPA, 1996a). Sedimentation has been associated with the lack of ocean-run trout
in tributary streams, as well as significant economic losses to the oyster industry
in the bay. Also, a trout fishery in Long Pine Creek, Nebraska, was impaired by
high sediment loadings from streambank erosion and irrigation discharge
(Hermsmeyer, 1991). Irrigation return flows and streambank erosion caused
negative impacts to salmonid spawning and recreational uses of Rock Creek,
Idaho (Yankey et al., 1991).
Chemicals such as some pesticides, phosphorus, and ammonium are trans-
ported with sediment in an adsorbed state. Changes in the aquatic environment,
such as decreased oxygen concentrations in the overlying waters or the develop-
ment of anaerobic conditions in the bottom sediments, can cause these chemicals
to be released from the sediment. Adsorbed phosphorus transported by the sedi-
ment may not be immediately available for aquatic plant growth but does serve
as a long-term contributor to eutrophication.
Sediments from different sources vary in the kinds and amounts of pollut-
ants that are adsorbed to the particles. For example, sheet and rill erosion mainly
move soil particles from the surface or plow layer of the soil. Sediment that origi-
nates from surface soil has a higher pollution potential than that from subsurface
soils. The topsoil of a field is usually richer in nutrients and other chemicals
because of past fertilizer and pesticide applications, as well as nutrient cycling
and biological activity. Topsoil is also more likely to have a greater percentage of
organic matter. Sediment from gullies and streambanks usually carries less
adsorbed pollutants than sediment from surface soils.
Soil eroded and delivered from cropland as sediment usually contains a
higher percentage of finer and less dense particles than the parent soil on the
cropland. This change in composition of eroded soil is due to the selective nature
of the erosion process. For example, larger particles are more readily detached
from the soil surface because they are less cohesive, but they also settle out of
suspension more quickly because of their size. Organic matter is not easily de-
tached because of its cohesive properties, but once detached it is easily trans-
ported because of its low density. Clay particles and organic residues will remain
suspended for longer periods and at slower flow velocities than will larger or
more dense particles. This selective erosion can increase overall pollutant delivery
per ton of sediment delivered because small particles have a much greater adsorp-
Chapter2-14:10/98
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Chapter 2: Overview 15
Runoff of animal
waste to surface
water can result in
oxygen depletion
and fish kills.
tion capacity than larger particles. As a result, eroding sediments generally contain
higher concentrations of phosphorus, nitrogen, and pesticides than the parent soil
(i.e., they are enriched).
Animal Wastes
Animal waste (manure) includes the fecal and urinary wastes of livestock and
poultry; process water (such as from a milking parlor); and the feed, bedding,
litter, and soil with which they become intermixed. The following pollutants may
be contained in manure and associated bedding materials and could be trans-
ported by runoff water and process wastewater from confined animal facilities:
O Oxygen-demanding substances;
•»
O Nitrogen, phosphorus, and many other major and minor nutrients or other
deleterious materials;
O Organic solids;
O Salts;
O Bacteria, viruses, and other microorganisms;
O Metals; and
O Sediments.
When such runoff, process waste water or manure enters surface waters, ex-
, cess nutrients are added. The decomposition of these nutrients depletes the oxygen
supply.in the water, creating anoxic or anaerobic conditions which could lead to
fish kills. Methane, amines, and sulfide are produced in anaerobic waters, causing
the water to acquire an unpleasant odor, taste, and appearance. Such waters can
be unsuitable for drinking, fishing, and other recreational uses. Investigations in
Illinois have demonstrated the impacts of animal waste on water quality, including
fish kills associated with a hog facility, a cattle feeding operation, and surface
application of liquid waste on frozen or snow-covered ground (Ackerman and
Taylor, 1995). In addition, North Carolina experienced six spills from animal
waste lagoons in the summer of 1995, totaling almost 30 million gallons. This
included a spill of 22 million gallons of swine waste into the New River, which
killed fish along a 19-mile downstream area (EPA Office of Inspector General,
1997).
Solids deposited in water bodies can accelerate eutrophication through the
release of nutrients over extended periods of time. Because of the high nutrient
and salt content of manure and runoff from manure-covered areas, contamination
of ground water can be a problem if storage structures are not built to minimize
seepage. A study of Herrings Marsh Run in the coastal plain of North Carolina
showed that nitrate levels in stream and ground water were highest in areas with
the greatest concentration of swine and poultry production (Hunt et al., 1995).
Orthophosphate levels were affected only slightly by animal waste applications
since most of the phosphorus was bound by the soil. In addition, runoff from feed-
lots has long been associated with severe stream pollution. Feedlots, which are
devoid of vegetation and subjected to sever hoof action, generate runoff containing
large amounts of bacteria, exceeding water quality standards (Baxter-Potter and
Gilliland, 1988).
Chapter 2-15:10/98
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16 Chapter 2: Overview
Diseases can be transmitted to humans through contact with animal or human
feces. Runoff from fields receivi ng manure will contain extremely high numbers of
bacteria if the manure has not been incorporated or the bacteria have not been
subject to stress. Shellfishing and beach closures can result from high fecal
coliform counts. Although not the only source of pathogens, animal waste has
been responsible for shellfish contamination in some coastal waters.
The pathogen Cryptosporidium, a protozoan parasite, is common in surface
waters, especially those containing high amounts of sewage contamination or ani-
mal waste. Cryptosporidium may pass through water treatment filtration and
disinfection processes in sufficient numbers to cause health problems, such as the
gastrointestinal disease cryptosporidiosis.The most serious consequences of
cryptosporidiosis tend to be focused on people with severely weakened immune
systems. In 1993, Milwaukee, Wisconsin, which draws its water from Lake
Michigan, experienced an outbreak of cryptosporidiosis, affecting 400,000 people,
with more than 4,000 hospitalized and over 50 deaths attributed to the disease
,(EPA, 1997c). While the source of contamination is uncertain, the problem was
linked to suboptimal performance of the water treatment plant, together with un-
usually heavy rainfall and runoff. The watersheds of two rivers which discharge
into Lake Michigan contain slaughterhouses, human sewage discharges, and cattle
grazing ranges (Lisle and Rose, 1995).
In a review of literature regarding the impacts of long-term animal waste
applications on soil characteristics, it was concluded that positive impacts include
buildup of soil organic matter, increased soil fertility, and improvement of soil
physical properties (Wood and Hattey, 1995). Negative impacts include nitrate
pollution of ground water, phosphorus contamination of surface water, and unfa-
vorably high soil concentrations of copper and zinc when poultry litter and pig
manure are applied.
The method, ti ming, and rate of manure application are significant factors in
determining the likelihood that water quality contamination will result. Manure is
generally more likely to be transported in runoff when applied to the soil surface
than when incorporated into the soil. Spreading manure on frozen ground or snow
can result in high concentrations of nutrients being transported from the field dur-
ing rainfall or snowmelt, especially when the snowmelt or rainfall events occur
soon after spreading (Robillard and Walter, 1986). Winter spreading of manure
onto com fields in Vermont increased phosphorus export by up to 1500%, with up
to 15% of the applied phosphorus lost in runoff (Meals, 1996).
When application rates of manure for crop production are based on N, the P
and K rates applied normally exceed plant requirements (Westerman et al.,
1985). The soil generally has the capacity to adsorb much of the phosphorus
from manure applied on land, but this capacity is not unlimited. As previously
mentioned, however, nitrates are easily leached through soil into ground water or
to return flows, and phosphorus can be transported by eroded soil.
Animal wastes contain large numbers of bacteria and other microorganisms,
although many of these tend to die rapidly outside the animal. Conditions that
cause a rapid die-off of bacteria after hind application include low soil moisture,
low pH, high temperatures, and direct solar radiation. Manure storage generally
promotes die-off, although pathogens can remain dormant at certain tempera-
tures. Composting the wastes can be quite effective in decreasing the number of
pathogens.
Chapter 2-16: 10/98
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Chapter 2: Overview 17
Accumulation of
excess sodium
reduces irrigated
agricultural
production and
runoff of saline
water harms aquatic
ecosystems.
Salts
Salts are a product of the natural weathering process of soil and geologic
material. They are present in varying degrees in all soils and in fresh water,
coastal waters, estuarine waters, and ground waters.
In soils that have poor subsurface drainage, high salt concentrations are cre-
ated within the root zone where most water extraction occurs. The accumulation
of soluble and exchangeable sodium leads to soil dispersion, structure breakdown,
decreased infiltration, and possible toxicity; thus, salts often become a serious
problem on irrigated land, both for continued agricultural production and for wa-
ter quality considerations. High salt concentrations in streams can harm freshwa-
ter aquatic plants just as excess soil salinity damages agricultural crops. While
salts are generally a more significant pollutant for freshwater ecosystems than for
saline ecosystems, they may also adversely affect anadromous fish. Although they
live in coastal and estuarine waters most of their lives, anadromous fish depend on
freshwater systems near the coast for crucial portions of their life cycles.
The movement and deposition of salts depend on the amount and distribution
of rainfall and irrigation, the soil and underlying strata, evapotranspiration rates,
and other environmental factors. In humid areas, dissolved mineral salts have been
naturally leached from the soil and substrata by rainfall. In arid and semi-arid
regions, salts have not been removed by natural leaching and are concentrated in
the soil. Soluble salts in saline and sodic soils consist of calcium, magnesium,
sodium, potassium, carbonate, bicarbonate, sulfate, and chloride ions. They are
fairly easily leached from the soil. Sparingly soluble gypsum and lime also occur
in amounts ranging from traces to more than 50% of the soil mass.
Irrigation water, whether from ground or surface water sources, has a natural
base load of dissolved mineral salts. As the water is consumed by plants or lost to
the atmosphere by evaporation, the salts remain and become concentrated in the
soil. This is referred to as the "concentrating effect."
The total salt load carried by irrigation return flow is the sum of the salt
remaining in the applied water plus any salt picked up from the irrigated land.
Irrigation return flows provide the means for conveying the salts to the receiving
streams or ground water reservoirs. If the amount of salt in the return flow is low
in comparison to the total stream flow, water quality may not be degraded to the
extent that use is impaired. However, if the process of water diversion for irriga-
tion and the return of saline drainage water is repeated many times along a
stream or river, water quality will be progressively degraded for downstream
irrigation use as well as for other uses. "
Another related issue is selenium toxicity. Selenium is a natural element in
soil, found in a variety of geologic formations, including Cretaceous sediments in
the western U.S. Selenium is essential to human and animal health in very small
amounts, but is toxic to some organisms when ingested in excessive quantities
(Letey et al., 1986). The major threat posed by selenium is the leaching of its
soluble, oxidized form (selenate) from seleniferous soils and movement of leachate
to shallow ground water and ultimately surface waters. It is in the aquatic environ-
ment where selenium enters the food chain through plants, which then become the
food base for higher organisms such as insects, fish or birds. Accumulation and
concentration of selenium as it moves up the food chain can become toxic (Letey
etal., 1986).
Chapter 2-17: 10/98
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18 Chapter 2: Overview
Some pesticides
are resistant to
degradation and
may persist and
accumulate in
aquatic
ecosystems.
Pesticides may
negatively affect
fish behavior and
reproduction.
In the western U.S., irrigation of soils from seleniferous parent materials can
accelerate the natural leaching process. In the early 1980's, irrigation drainage
water laden with high concentrations of selenium caused congenital deformities
and mortality of waterfowl at Kesterson Reservoir, a National Wildlife Refuge in
central California (Long et al., 1990). Concern over this incident prompted the
U.S. Department of Interior to establish the National Irrigation Water Quality
Program in 1985, to evaluate the potential for toxic effects of selenium in other
irrigated areas of the west (Nolan and Clark 1997).
Pesticides
The term pesticide includes any substance or mixture of substances intended
for preventing, destroying, repelling, or mitigating any pest or intended for use as
a plant regulator, defoliant, or desiccant. The principal pesticidal pollutants that
may be detected in surface water and in ground water are the active and inert
ingredients and any persistent degradation products. Pesticides and their degrada-
tion products may enter ground and surface water in solution,' in emulsion, or
bound to soil colloids. A study of 303 wells from across the Midwest showed
that pesticide metabolites were found more frequently than the parent compounds
(Kolpin et al., 1996). For example, the metabolite alachlor ethanesulfonic acid
was detected nearly 10 times more frequently than alachlor in the 153 wells
where both chemicals were analyzed. For simplicity, the term pesticides will be
used to represent "pesticides and their degradation products" in the following
sections.
Despite the documented benefits of using pesticides (insecticides, herbi-
cides, fungicides, miticides, nematicides, etc.) to control plant pests and enhance
production, these chemicals may, in some instances, cause impairments to the
uses of surface water and ground water. Some types of pesticides are resistant to
degradation and may persist and accumulate in aquatic ecosystems.
Maximum atrazine concentrations were 2.7 mg/L in base flow and 30 mg/L
in stormflow in Little Conestoga Creek, Pennsylvania (Koerkle et al., 1996).
Annual flow-weighted mean concentrations of atrazine for the period 1986-
1992 ranged from 0.13 ug/L to 1.17 ug/L in the Big Spring basin in Iowa
(Rowden et al., 1995). Alachlor, cyanazine, and metolachlor were also detected
at most monitoring sites in the basin during that period.
Monitoring of seven Lake Erie tributaries from 1983 to 1993 detected maxi-
mum atrazine concentrations of 6.80 to 68.40 ug/L, and maximum concentrations
of alachlor, metolachlor, metribuzin, cyanazine, and linuron ranging of 1.16 to
64.94, 5.39 to 96.92, 1.49 to 25.15, 1.36 to 24.77, and 1.92 to 15.5 ug/L, respec-
tively (Baker, 1993). The long-term time-weighted mean concentrations, how-
ever, were all below EPA's maximum contaminant levels and lifetime health
advisory levels for drinking water. In a related study, it was determined that
alachlor and atrazine posed the bulk of the total pesticide threat to drinking water
supplies in Ohio (Baker and Richards, 1991). Although chronic health standards
were not exceeded, public water supplies derived from rivers or reservoirs drain-
ing agricultural watersheds delivered the greatest quantities of pesticides to con-
sumers.
Chapter 2-18: 10/98
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Chapter 2: Overview 19
Pesticides may harm the environment by eliminating or reducing populations
of desirable organisms, including endangered species. Sublethal effects include the
behavioral and structural changes of an organism that jeopardize its survival. For
example, certain pesticides have been found to inhibit bone development in young
fish or to affect fertility, behavior, and embryo development.
Herbicides in the aquatic environment can destroy the food source for higher
organisms, which may then starve. Herbicides can also reduce the amount of veg-
etation available for protective cover and the laying of eggs by aquatic species.
Also, the decay of plant matter exposed to herbicide-containing water can cause
reductions in dissolved oxygen concentration (Maas, 1984).
Sometimes a pesticide is not toxic by itself but is lethal in the presence of
other pesticides. This is referred to as a synergistic effect, and it may be difficult
to predict or evaluate. Bioconcentration is a phenomenon that occurs if an organ-
ism ingests more of a pesticide than it excretes. During its lifetime, the organism
will accumulate a higher concentration of that pesticide than is present in the
surrounding environment. When the organism is eaten by another animal, the
pesticide will then be passed to that animal, and on up the food chain. As a result
of this biomagiiification process, aquatic organisms at higher trophic levels, such
as predatory fish, may contain high levels of pesticides or other toxics, even if
the compounds are undetectable in the water itself.
A major source of contamination from pesticide use is the result of normal
application of pesticides. Other sources of pesticide contamination are atmo-
spheric deposition, spray drift during the application process, misuse, and spills,
leaks, and discharges that may be associated with pesticide storage, handling, and
waste disposal.
The primary routes of pesticide transport to aquatic systems are through
(Maas, 1984):
O Direct application;
O Runoff;
O Aerial drift;
O Leaching;
D Volatilization and subsequent atmospheric deposition; and
D Uptake by biota and subsequent movement in the food web.
The amount of field-applied pesticide that leaves a field in the runoff (either
dissolved or attached to sediment) and enters a stream primarily depends on:
O The intensity and duration of rainfall or irrigation;
• D The length of time between pesticide application and rainfall occurrence;
O The amount of pesticide applied and its soil/water partition coefficient; \
O . The length and degree of slope and soil composition;
O The extent of exposure to bare (vs. residue or crop-covered) soil;
O Proximity to streams;
Chapter 2-19: 10/98
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20 Chapter 2: Overview
O Soil loss/erosion rate;
n The method of application; and
D The extent to which runoff and erosion are controlled with agronomic and
structural practices.
Pesticide losses are generally greatest when rainfall is intense and occurs
shortly after pesticide application, a condition for which water runoff and erosion
losses are also greatest.
A study of herbicides and nutrients in storm runoff from nine stream basins
in the Midwestern states from 1990-1992 showed sharp increases in triazine
herbicides (e.g., atrazine) in the post-planting period (Scribner etal., 1994). Atra-
zine levels increased from 1.0 ug/L to more than EPA's maximum contaminant
level (MCL) of 3.0 ug/L, with peaks of 10-75 ug/L. It was concluded that trans-
port of herbicides to streams was seasonal, with peaks from early May to early
July. In a related study of 76 Midwestern reservoirs from April 1992 through
September 1993, atrazine was the most frequently detected and persistent herbi-
cide, followed by alachlor ethane sulfonic acid, deethylatrazine,
deisopropylatrazine, metolachlor, cyanazine amide, and cyanazine (Scribner et
al., 1996). Eight reservoirs had concentrations of one or more herbicides exceed-
ing EPA's maximum contaminant levels or health advisory levels for drinking
water during late April through mid-May, 1992, while 16 reservoirs had these
high contaminant levels in late June through July, 1992.
Research at the 5,600-ha Walnut Creek watershed in Iowa also showed that
atrazine levels in runoff increased to above the MCL with heavy rains after
chemical application (Hatfield et al., 1995). The total loss of atrazine and
metolachlor in stream flow was about 1 % of the amount applied each year. Her-
bicide concentrations in tile drains were often near the detection limit of 0.2 ug/
L, while only atrazine and metolachlor exceeded 3.0 ug/L once in more than
1,700 ground water samples. Water balance studies indicated that the predomi-
nant flow path in the prairie-pothole watershed is from the bottom of the root
zone into the stream through tile drains.
Concentrations of atrazine, alachlor, cyanazine, and metolachlor in Mid-
western streams and reservoirs increased suddenly during rainstorms following
herbicide applications (Goolsby et al., 1995). Atrazine levels less than 0.2 ug/L
also persist year-round in Midwestern streams, partly due to the discharge of
contaminated waters from surface and ground water reservoirs.
Elevated monthly average pesticide concentrations in Lake Erie tributaries
usually occur in May to August, and smaller tributaries had higher maximum
concentrations, more frequent concentrations below the detection limit, and
fewer intermediate concentrations than larger tributaries (Richards and Baker,
1993).
The rate of pesticide movement through the soil profile to ground water is
inversely proportional to the pesticide adsorption partition coefficient or Kd (a
measure of the degree to which a pesticide is adsorbed by the soil versus dissolved
in the water). The larger the KJ5 the slower the movement and the greater the
quantity of water required to leach the pesticide to a given depth.
Chapter 2-20:10/98
-------
Chapter 2: Overview 2
Pesticides can be transported to receiving waters either in dissolved form or
attached to sediment. Dissolved pesticides may be leached to ground water sup-
plies. Both the degradation and adsorption characteristics of pesticides are highly
variable.
From calculations combining estimated pesticide use data with measured
load data, it was estimated that less than 2% of applied pesticides reached surface
waters in the Mississippi River basin (Larson et al., 1995). Since the relative
percentages of specific pesticides reaching the rivers were often not in agreement
with projected runoff potentials, it was concluded that soil characteristics,
weather, and agricultural management practices are more important than chemi-
cal properties in the delivery of pesticides to surface waters. Richards and Baker
(1993) concluded that average pesticide concentrations in Lake Erie tributaries
are correlated with amount applied, but are also affected by chemical properties
and modes of application of the pesticides. •
Habitat Impacts
The functioning condition of riparian-wetland areas is a result of interaction
among geology, soil, water, and vegetation. Riparian-wetland areas are function-
ing properly when adequate vegetation is present to
O Dissipate stream energy associated with high water flows, thereby reducing
erosion and improving water quality;
O Filter sediment and aid floodplain development;
O Support denitrification of nitrate-contaminated ground water as it is dis-
charged into streams;
O Improve floodwater retention and ground water recharge;
O Develop root masses that stabilize banks against cutting action;
D Develop diverse ponding and channel characteristics to provide the habitat
and the water depth, duration, and temperature necessary for fish production,
waterfowl breeding, and other uses; and
O Support biodiversity.
Improper livestock grazing affects all four components of the water-riparian
system: banks and shores, water column, channel, and aquatic and bordering
vegetation (Plaits, 1990). The potential effects of grazing include:
Shore/banks
O Shear or sloughing of streambank soils by hoof or head action.
D Water, ice, and wind erosion of exposed streambank and channel soils be-
cause of loss of vegetative cover.
D Elimination or loss of streambank vegetation.
O Reduction of the quality and quantity of streambank undercuts.
O Increasing streambank angle (laying back of streambanks), which increases
water width, decreases stream depth, and alters or eliminates fish habitat.
Chapter 2-21:10/98
-------
22 Chapter 2: Overview
Riparian-wettand
vegetation is
essential for
stable aquatic
ecosystems.
Water Column
O Withdrawal from streams to irrigate grazing lands.
D Drainage of wet meadows or lowering of the ground water table to facilitate
grazing access.
CD Pollutants (e.g., sediments) in return water from grazed lands, which are
detrimental to the designated uses such as fisheries.
D Changes in magnitude and timing of organic and inorganic energy (i.e., solar
radiation, debris, nutrients) inputs to the stream.
O Increase in fecal contamination.
D Changes in stream morphology, such as increases in stream width and de-
creases in stream depth, including reduction of stream shore water depth.
D Changes in timing and magnitude of stream flow events from changes in
watershed vegetative cover.
CD Increase in stream temperature.
Channel
D< Changes in channel morphology.
O Altered sediment transport processes.
Riparian Vegetation
D Changes in plant species composition (e.g., shrubs to grass to forbs).
D Reduction of floodplain and strearnbank vegetation including vegetation
hanging over or entering into the water column.
O Decrease in plant vigor.
O Changes in timing and amounts of organic energy leaving the riparian zone.
O Elimination of riparian plant communities (i.e., lowering of the water table
allowing xeric plants to replace riparian plants).
Water temperature plays a key role in the life of fish and other aquatic or-
ganisms by influencing their distribution, growth rate, and survival (Barthalow
1989; Holmes and Regier, 1990; Armour 1991), as well as migration patterns,
egg maturation, incubation success, competitive ability, and resistance to para-
sites, diseases, and pollutants (Armour 1991). In addition, water temperature
affects the rates of in-stream chemical reactions, the self-purification capacity of
streams, and their aesthetic and sanitary qualities (Feller 1981). Changes in chan-
nel morphology leading to an increased stream width, as well as loss of riparian
vegetation, have the potential to alter stream temperature (LeBlanc et al. 1997).
A wider stream has a greater surface area and a greater air-water interface, where
most energy exchanges occur; hence, the surface area of the stream is directly
related to water temperature changes. Also, losses in riparian vegetation expose
the stream to greater temperature fluctuations, resulting in potentially higher tem-
peratures during the day and cooler temperatures at night. Riparian vegetation acts
to moderate stream temperatures by absorbing short-wave radiation during the day
and insulating the stream from loss of long-wave radiation at night.
Chapter 2-22:10/98
-------
Chapter 2: Overview 23
Livestock grazing is a significant contributor to streambank erosion and ri-
parian habitat degradation. In a study of 60 streams in the Intermountain West, it
was found that grazed stream habitats were substantially degraded with poor ri-
parian conditions (Robinson and Minshall, 1995). Problems associated with graz-
ing included reduced riparian cover, exposed streambanks, high sediment levels,
elevated water temperatures, higher nutrient levels, and a shifting to more stress-
tolerant invertebrates.
Soil erosion, primarily from poor grazing management and poorly maintained
riparian areas, is causing excessive sedimentation to the Missouri River in South
Dakota (Osmond et al., 1997). This sedimentation has impaired recreational uses
and hydropower generation, and has increased flooding in the cities of Pierre and
Ft. Pierre. Grazing has also contributed to declines in anadromous fish popula-
tions in the Upper Grande Ronde Basin in Oregon (Osmond et al., 1997). In-
creased stream water temperature and loss of habitat, caused largely by the loss in
Improper livestock riparian vegetation, are key factors in the decline (Hafele, 1996). Grazing in the
grazing can have Morro Bay, California, watershed has stripped riparian areas of their vegetation
devastating impacts ancj decreased streambank stability, contributing to the excessive erosion in the
on streambanks, watershed (Osmond et al., 1997). Sedimentation has caused negative impacts to
hydrology, water both the oyster industry and anadromous fish species. Streambank erosion in
quality, and aquatic Peacheater Creek, Oklahoma, has impaired aquatic habitat (Osmond et al., 1997).
habitat.
Mechanisms to Control
Agricultural Nonpoint Pollution
There exists a considerable amount of jargon associated with the mecha-
nisms to control nonpoint source pollution. Terms include best management
practices (BMPs), management practices, accepted agricultural practices, man-
agement measures, BMP systems, management practice systems, resource man-
agement systems, total resource management systems, and the like. Some of
these terms are based in legislation or regulations such as the management mea-
sures specified by EPA for the section 6217 coastal nonpoint pollution control ,
program (EPA, 1993) and Vermont's, accepted agricultural practices (Vermont
Department of Agriculture, 1995), while other terms are found in technical
manuals, journal articles, and informational materials.
The meanings of the terms also vary. Most practitioners consider BMPs to
be individual practices such as a fence or diversion that serve specific functions
such as excluding livestock or routing water safely away from eroding or con-
taminated areas. Management measures are generally groups of affordable man-
agement practices that are used together in a system to achieve more
comprehensive goals such as minimizing the delivery of sediment from a farm to
receiving waters or maximizing the efficiency with which nutrients are applied to
croplands to achieve reasonable yields. Resource management systems (RMS)
generally go beyond management measures in that they are systems of BMPs that
meet criteria for soiK water, air, and related plant and animal resources (USDA,
1990). Since the focus of this guidance is confined to water quality issues, the full
complement of issues addressed in a typical resource management system is not
addressed. For example, water quality performance expectations are contained in
the management measures, but criteria for animal resources are absent. Resource
management planning concepts are discussed briefly in this chapter, however.
Chapter 2-23: 10/98
-------
24 Chapter 2: Overview
Because definitions of terms overlap, there is no clear hierarchy or levels of
control that can be adopted for this guidance and agreed upon by all readers, but
the following statements apply:
O Complete resource management systems are not presented in this guidance,
but resource management planning concepts are discussed. The water quality
aspects and some of the soil, air, and plant criteria of an RMS are addressed
through the management measures.
O Management practices are the building blocks for management practice sys-
tems and management measures.
O Implementation of all six management measures, as appropriate, will result
in a comprehensive, technology-based water quality protection plan on most1
farms.
Management Measures
Management measures are defined under section 6217 of CZARA as:
economically achievable measures for the control of
the addition of pollutants from existing and new categories
and classes of nonpoint sources of pollution, which reflect
the greatest degree of pollutant reduction achievable
through the application of the best available nonpoint
source control practices, technologies, processes, siting
criteria, operating methods, or other alternatives.
The management measures specified by EPA for section 6217 contain per-
formance expectations and, in many cases, specific actions that are to be taken to
prevent or minimize nonpoint source pollution (EPA, 1993). For example, the
performance expectations for erosion and sediment control for agriculture are "to
minimize the delivery of sediment from agricultural lands to surface waters" or
"to settle the settleable solids and associated pollutants in runoff delivered from
the contributing area for storms up to and including a 10-year, 24-hour fre-
quency." Individual management practices or specific actions to take to achieve
these performance expectations are not included in the management measure
statement. The management measure for pesticides, however, includes both per-
formance expectations ("reduce contamination of surface water and ground water
from pesticides") and specific practices and actions such as anti-backflow de-
vices on hoses, and calibration of pesticide spray equipment. Thus, in most cases,
there is considerable flexibility to determine how to best achieve the performance
expectations for EPA's section 6217 management measures.
EPA's six management measures for agriculture are described in Chapter 4.
'In some cases, additional control practices may be needed to address problems that are not
anticipated by the management measures. ^_
Chapter 2-24: 10/98
-------
Chapter 2: Overview 25
Management Practices
"Best" management practices, BMPs, are designed to reduce the quantities of
pollutants that are generated at and/or delivered from a source to a receiving water
body. In EPA's guidance for section 6217, the term management practice is used
in lieu of BMPs since "best" can be a highly subjective and site-specific label. For
example, the BMP manuals used by States to implement the Clean Water Act
section 319 program are not identical although much consistency exists across
States. Even within States, a practice may be considered best in one area (e.g.,
coastal plain) but inappropriate in another area (e.g.,.mountains). Criteria for
determining what is best may include extent of pollution prevention or pollutant
removal, ease of implementation, ease of maintenance and operation, durability,
attractiveness to landowner (e.g., how willing will farmers be to implement the
practice in a voluntary program?), cost, and cost-effectiveness. The relative im-
portance assigned these and other criteria in judging what is best varies across
States, within States, and among landowners, often for very good reasons (e.g.,
irrigation water management considerations are very different in western States
with low rainfall and water rights laws, versus midwestern States with diminishing
ground-water reserves, versus eastern States with plentiful rainfall and surface
waters). For these reasons, this guidance is consistent with the section 6217 man-
agement measures guidance in its use of the term "management practice" rather
than "BMP."
Management practices can'be structural (e.g., waste treatment lagoons, ter-
races, or sediment basins) or managerial (e.g., rotational grazing, nutrient man-
agement, pesticide management, or conservation tillage). Management practices
generally do not stand alone in solving water quality problems, but are used in
combinations to build management practice systems. For example, soil testing is
a good practice for nutrient management, but without estimates of realistic yield;
good water management; appropriate planting techniques and timing; and proper
nutrient selection, rates, and placement; the performance expectations for nutri-
ent management cannot be achieved.
Each practice, in turn, must be selected, designed, implemented, and main-
tained in accordance with site-specific considerations to ensure that the practices
function together to achieve the overall management goals. For example, a
grassed waterway must be designed to handle all of the water that will be con-
veyed to it from upland areas, including all water re-routed with diversions and
drainage pipes. Design standards and specifications must be compatible for prac-
tices to work together as effective systems.
A summary of agricultural management practices and how they function in
systems is given in Chapter 3. Management practices that can be used to achieve
each of the six agricultural management measures are described in Chapter 4.
Resource Management Planning Concepts
Resource management planning is a relatively new tool that enables farmers
to more fully assess the potential impact of management decisions on their farm
operation. It is a voluntary process that involves setting of personal, environmen-
tal, economic, and production goals for the farm. Potential changes in practices
are then evaluated in terms of their potential impact on these goals. Follow-up
Chapter 2-25: 10/98
-------
26 Chapter 2: Overview
A resource
management plan
for the farm serves
to maintain quality of
life while achieving
goals for profitability
and water quality.
evaluation provides active feedback that is used to "fine tune" the decisions that
are made.
Resource management planning is evolving partially because of a growing
negative reaction to "single purpose plans" that have traditionally been used to
address individual economic or natural resource issues. Essential goals for a
whole farm planning process include:
D Improving farm profitability by finding solutions that save money, increase
sales, or simplify/reduce the work;
D Reducing water pollution through application of appropriate systems of man-
agement practices;
O Coordinating regulatory input so that implementation of the final plan will
assure compliance with all applicable regulations impacting the farm opera-
tion; and
D Incorporating the farm family's personal goals for quality of life.
Public institutions and private organizations are currently involved in devel-
oping and using resource management plans. For example, the United States
Department of Agriculture (USDA)-Natural Resources Conservation Service
(NRCS) has recently finished their Resource Management Planning guide. This
guide was developed by national- and State-agency personnel, farmers, and rep-
resentatives of commodity groups.
Many states are developing their own resource management planning proto-
cols. An example of one of these plans is the Idaho One Plan. The Idaho pro-
gram was developed to reduce diverse agency requirements and to produce a
user-friendly product that allows farmers and ranchers to develop farm plans
unique to their operations. Farmers in Ontario, Canada, in conjunction with
Ontario Ministries, developed the Ontario Environmental Farm Plan. Every farm
family in Ontario is encouraged to complete an Environmental Farm Plan, which
is reviewed and certified by a committee comprised of local farmers. Individuals
interested in resource management planning should contact their Cooperative
Extension Service, local NRCS Office, land grant university, or appropriate State
agency to learn more about locally available materials.
.Chapter 2-26:10/98
-------
Management Practices
Management practices are implemented on agricultural lands for a variety of
purposes, including protecting water resources, protecting terrestrial or aquatic
wildlife habitat, and protecting the land resource from degradation by wind, salt,
and toxic levels of metals. The primary focus of this guidance is on agricultural
management practices that control the generation and delivery of pollutants into
water resources or remediate or intercept pollutants before they enter water re-
sources.
NRCS maintains a National Handbook of Conservation Practices (1977),
updated continuously, which details numerous management practices. In addition
to the NRCS standards, many States use locally determined management practices
that are not reflected in the NRCS handbook. Readers interested in obtaining in-
formation on management practices used in their area should contact their local
Soil and Water Conservation District or local USD A office. A very helpful hand-
book for farmers in the Midwest is 60 Ways Farmers Can Protect Surface Water
(Hirschi et al., 1997).
How Management Practices Work
to Prevent Nonpoint Source Pollution
Management
practices can
minimize the
delivery and
transport of
agriculturally derived
pollutants to surface
and ground waters.
Although a wide
variety of BMPs are
available, all require
regular inspection
and maintenance.
Management practices control the delivery of nonpoint source (NFS) pollut-
ants to receiving water resources by (see Figure 3-1 - illustration needed):
O minimizing pollutants available (source reduction);
O retarding the transport and/or delivery of pollutants, either by reducing water
transported, and thus the amount of the pollutant transported, or through
deposition of the pollutant; or
O remediating or intercepting the pollutant before or after it is delivered to the
water resource through chemical or biological transformation.
Management practices are generally designed to control a particular pollut-
ant type from specific land uses. For example, conservation tillage is used to
control erosion from irrigated or non-irrigated cropland. Management practices
may also provide secondary benefits by controlling other pollutants, depending
on how the pollutants are generated or transported. For example, practices which
reduce erosion and sediment delivery often reduce phosphorus losses since phos-
phorus is strongly adsorbed to silt and clay particles. Thus, conservation tillage
not only reduces erosion, but also reduces transport of paniculate phosphorus.
In some cases, a management practice may provide environmental benefits
beyond those linked to water quality. For example, riparian buffers, which reduce
nitrogen and sediment delivery to water bodies, also serve as habitat for many
species of birds and plants.
Chapter 3-27:10/98
-------
28 Chapter 3: Management Practices
Sometimes, however, management practices used to control one pollutant
may inadvertently increase the generation, transport, or delivery of another pollut-
ant. Conservation tillage, because it creates increased soil porosity (i.e., large pore
Control of surface spaces), often increases nitrate leaching through the soil. Tile drains, used to re-
transport may juce runoff and increase soil drainage, can also have the undesirable effect of
increase leaching concentrating and delivering nitrogen directly to streams (Hirschi et al., 1997).-In
Of pollutants. order to reduce the nitrogen pollution caused by tile drains, other management
practices, such as nutrient management for source reduction and biofilters that
are attached to the outflow of the tile drains for interception, may be needed.
Summary of USDA-NRCS Practices
As discussed in Chapter 2, management practices can be structural (e.g.,
waste treatment lagoons, terraces, sediment basins, or fences) or managerial (e.g.,
rotational grazing, nutrient management, pesticide management, or conservation
tillage). A list containing both structural and managerial conservation practices
used by the USDA-Natural Resources Conservation Service (NRCS) is pre-
sented in Table 3-1. The table contains the practice (in alphabetical order), NRCS
practice code, the pollutants that can be controlled with the practice (denoted by
**), and the pollutant sources for which the information is applicable. Source
codes and abbreviations for pollutants are provided in the table legend. For ex-
ample, NRCS practice 580, streambank and shoreline protection, can be used to
control total phosphorus, paniculate phosphorus, Kjeldahl nitrogen, ammonia,
and sediment derived from streambanks.
Chapter 3-28: 10/98
-------
Chapter 3: Management Practices 29
Table 3-1. NRCS conservation practices, pollutants potentially controlled, and
sources of pollutants (cite).
NRCS
CODE
560
575
310
314
317
327
322
324
328
330
335
340
342
352
362
382
386
393A
400
410
412
548
561
422
PRACTICE
Access Road
Animal Trails and
Walkwavs
Beddine
Brush Management
Comoost facility
Conservation
Cover
Channel Vegetation
Chisel Tillage
Conservation Crop
Rotation
Contour Farm
Controlled Drainage
Cover and Green
Manure Croo
Critical Area Planting
Deferred Grazing
Diversion
Fencing
Field Border
Filter Strips
Floodwav Diversion
Grade Stabilization
Structure
Grass Waterway
Grazing Land
Mechanical
Treatment
Heavy Use Area
Protection
Hedgerow Planting
POLLUTANT TO BE CONT
TP
**
#*
**
**
**
**
**
**
**
**
**
**
#*
**
**
**
**
**
PP
**
**
**
**
*+
**
**
**
**
**
**
**
**
**
**
**
OP
**
**
**
**
**
**
**
**
TN
**
**
**
**
**
**
**
**
**
**
**
**
**
**
**
**
TKN
**
**
**
**
**
**
**
**
**
**
##
**
ON
**
**
**
**
**
**
**
**
**
NI
**
**
«*
**
**
**
**
**
ROLLED
AM
**
*+
**
**
**
**
**
**
**
**
**
**
SE
**
**
»*
**
**
«*
**
**
**
**
**
**
**
**
**
**
4*
**
**
**
**
**
BOD
FC
%^
**
**
*^c
**
*^
**
**
SOURCE
CD, CI, PA,
RG. FO
PA, RG
CD.CI
RG
CA
CD.CI
CD.CI.PA,
RG. GU
CD.CI
CD.CI
CD
CD.CI
CD, Cl
GU.CD,
PA. RG
PA. RG
CD. Cl. CA
CA, PA,
RG
CD.CI
CA, CD, CI,
FO, PA, RG,
CONSTR
GU.ST
CD.CI
PA.RG
CA, PA, RG
CA. PA
Chapter 3-29:10/98
-------
30 Chapter 3: Management Practices
Table 3-1 (Continued)
NRCS
CODE
423
320
388
464
552A
552B
436
443
441
428B
428C
428A
430AA
430DD
430EE
PRACTICE
Hillside Ditch
Irrigation Canal or
Lateral
Irrigation Field Ditch
Irrigation Land
Leveline
Irrigation Pit or
Regulating Reservoir,
Irrieation Pit
Irrigation Pit or
Regulating Reservoir,
Reeulatine Reservoir
Irrigation Storage
Reservoir
Irrigation System,
Surface and
Subsurface
Irrigation System,
Trickle
Irrigation Water
Conveyance, Ditch
and Canal Lining,
Flexible Membrane
Irrigation Water
Conveyance, Ditch
and Canal Lining,
Galvanized Steel
Irrigation Water
Conveyance, Ditch
and Canal Lining,
Nonreinforced
Concrete
Irrigation Water
Conveyance,
Pipeline, Aluminum
Tubing
Irrigation Water
Conveyance,
Pipeline, High-
Pressure,
Underground, Plastic
Irrigation Water
Conveyance,
Pipeline, Low-
Pressure,
Underground. Plastic
POLLUTANT TO BE CONTROLLED
TP
**
**
**
**
**
**
**
**
**
»*
»*
**
**
**
**
PP
OP
**
**
*#
**
»*
**
**
**
**
**
**
**
**
**
TN
**
**
**
**
**
**
**
»*
**
**
**
+*
**
**
**
TKN
ON
MI
AM
SE
**
**
**
**
**
**
**
**
**
**
**
** '
**
**
**
BOD
FC
SOURCE
GU
CI
CI
CI
CI
CI
CI
CI, PA
ci
CI
CI
CI
CI
CI
CI
Chapter 3-30:10/98
-------
Chapter 3: Management Practices 31
Table 3-1 (Continued)
NRCS
CODE
430CC
430HH
430FF
447
449
472
482
484
329
590
512
378
462
528A
532
550
554
344
391A
555
558
570
PRACTICE
Irrigation Water
Conveyance,
Pipeline,
Nonreinforced
Concrete
Irrigation Water
Conveyance,
Pipeline, Rigid Gated
Pipeline
Irrigation Water
Conveyance,
Pipeline. Steel
Irrigation System,
Tailwater Recovery
Irrigation Water
Management
Livestock Exclusion
Mole Drain
Mulching
NoTill
Nutrient Management
Pasture and Hay
Planting
Pond
Precision Land
Forming
Prescribed Grazing
Pumoed Well Drain
Range Planting
Regulating Water in
Drainage Systems
Residue
Management,
Seasonal
Riparian Forest
Buffer
Rock Barrier
Roof Runoff
Management
Runoff Management
Svstem
POLLUX ANT TO BE CONTROLLED
TP
»*
**
**
**
**
**
**
**
*.*
**
**
**
**
**
**
**
**
** •
PP
**
**
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**
**
**
**
•
**
**
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OP
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**
**
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**
**
TN
**
#*
**
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*#
**
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**
**
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**
TKN
**
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ON
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**
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NI
**
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**
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AM
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SE
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**
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**
»*
**
**
+*
**
**
BOD
-
FC
**
**
**
**
I
SOURCE
CI
CI
CI
CI
CI.PA
PA.RG
CA
CD.CI
CD, CI
CA, CI, CD
CD, PA
CD, CI, RG,
CONSTR,
PA
CD.CI
RG.PA
CA.CI
RG
C1,CA
CD.CI
CA.CD
CD
CA
Const
Chapter 3-31: 10/98
-------
32 Chapter 3: Management Practices
Table 3-1 (Continued)
NRCS
CODE
350
574
442
580
585
587
586
606
607
608
600
612
614
3I2
313
359
633
638
640
PRACTICE
Sediment Basin
Soring Development
Irrigation System,
Sprinkler
Streambank &
Shoreline Protection
Stripcropping,
Contour
Structure for Water
Control
StripcroDDine. Field
Subsurface Drain
Surface
Drainage. Field Ditch
Surface Drainage,
Main or Lateral
Terrace
Tree Shrub
Establishment
Trough or Tank
Waste Management
System
Waste Storage
Facility
Waste Treatment
Lagoon
Waste Utilization
Water & Sediment
Control Basin
Waterspreading
POLLUTANT TO BE CONT
TP
**
**
**
**
**
*»
**
**
**
**
**
PP
* *
**
**
**
**
**
**
**
OP
* 4
* *
**
TN
**
**
#*
**
* *
**
**
**
**
**
TKN
**
* *
**
* *
**
* *
* *
* *
ON
**
NI
**
#*
**
**
**
**
POLLED
AM
**
**
**
**
**
4*
**
**
SE
**
**
* *
* «
* *
* *
* *
* *
* *
* *
* *
* *
BOD
FC
**
**
4t«
**
**
**
**
**
SOURCE
CD.CI.CA,
CONSTR
NA
CI
Stream-
banks
CD.C1
CI.GU
CD
CD.CI
CD.CI
CD.CI
CD.CI
CD.CI, FO
CA
CA
CA.PA
CA.CD.CI,
PA
CD.CA,
PA.RG,
GU.IR
CA.CI. PA,
RG
Legend for Table 3-1. Abbreviations for pollutants and pollutant sources.
POLLUTANTS
TP = Total Phosphorus
PP = Paniculate Phosphorus
OP = Orthophosphate
TN = Total Nitrogen
TKN = Kjeldahl Nitrogen
ON = Organic Nitrogen
NI = Nitrate
AM = Ammonia
SE = Sediment
BOD = Biological Oxygen Demand
FC = Fecal Coliform
POLLUTANT SOURCES
CA = Confined Animals
CD = Cropland (Dryland)
CI = Cropland (Irrigated)
Const. = Construction
FO = Forest
GU = Gullies
PA = Pasture
RG = Rangeland
NA = Not Applicable
Chapter 3-32: 10/98
-------
Chapter 3: Management Practices 33
Management Practice Systems
A management
practice system is
any combination
of BMPs that
comprehensively
reduce a pollutant
from the same
source.
If multiple sources
of a pollutant exist,
more than one
management
practice system
will be needed to
provide effective
control.
Water quality problems cannot usually be solved with one management
practice because single practices do not typically provide the full range and ex-
tent of control needed at a site. Multiple practices are combined to build -manage-
ment practice systems that address treatment needs associated with pollutant
generation from one or more sources, transport, and remediation. Management
practice systems are generally more effective in controlling the pollutant since
they can be used at two or more points in the pollutant delivery process. For
example, the objective of" many agricultural NFS pollution projects is to reduce
the delivery of soil from cropland to water bodies. A system of management
practices can be designed to reduce soil detachment, erosion potential, and off-
site transport of eroded soil. Such a system could include conservation tillage to
reduce soil detachment and cropland erosion. Grassed waterways could be in-
cluded to carry concentrated flows from the fields in a non-erosive manner, while
field borders might be used to filter sediment from water leaving the field in
shallow, uniform flow (Hirschi et al., 1997). Sediment retention basins could be
added to trap sediment and runoff from the farm if other practices failed to pro-
vide the level of control needed.
Similarly, if nitrogen is the pollutant of concern, nutrient management can
be used to minimize the availability of nitrogen for transport from cropland. This
can be achieved by matching the application rate with crop needs, based upon
soil testing, analysis of nutrient sources, and realistic yield expectations. Proper
timing of nutrient application will also reduce nitrogen availability since the time
frame over which the applied nitrogen is available but not used by the crop is
minimized. Conservation tillage can help reduce overland transport of nitrogen
by reducing erosion and runoff, and nutrient management will minimize subsur-
face losses due to the resulting increased infiltration. Field borders can be used to
decrease nitrogen transport by increasing infiltration, and through uptake of
available nitrogen by the field border crop. Nitrogen not controlled by nutrient
management, conservation tillage, and field borders can be intercepted and
remediated through denitrification in riparian buffers.
A set of practices does not constitute an effective management practice
system unless the practices are selected and designed to function together to
achieve water quality goals reliably and efficiently. In the Oregon RCWP project
(see Chapter 1 for a discussion of RCWP), dairy farmers installed animal waste
management systems to reduce fecal coliform runoff into an important shellfish-
producing estuary. Although 12 practices (waste storage, guttering, dike, drains,
etc.) initially comprised the animal waste management systems, these systems
were not as effective as needed because the practices addressed manure storage
but not land application of the manure. Utilization of manure was added as a
practice which enabled implementation of complete management practice sys-
tems that successfully addressed the need for managing land application to
achieve water quality goals (Gale et al., 1993).
Chapter 3-33: 10/98
-------
34 Chapter 3: Management Practices
Types of Management Practice Systems
Management practice systems can be separated into three categories:
O treatment redundancy,
O necessary diversification, or
O a combination of the first two.
Systems that combine individual management practices to treat a pollutant
at different points in the pollutant delivery process achieve management objec-
tives through treatment redundancy. The above examples for sediment and nitro-
gen control both employ treatment redundancy. Conservation tillage, grassed
waterways, field borders, and sediment retention basins control soil particles and
runoff at various stages in the pollutant delivery process. Nutrient management,
conservation tillage, field borders, and riparian buffers provide similar treatment
redundancy to control nitrogen losses in the second example.
In some cases a management practice cannot be used without an accompa-
nying practice. For example, if it is necessary to install fence to keep cows from
a stream, watering devices may be needed to provide drinking water for the
cows. This is an example of necessary diversification.
Some management practice systems include both treatment redundancy and
necessary diversification. An example of such a system is ari animal waste man-
agement system in which some components are included to help others function.
For example, diversions and subsurface drains may be necessary to convey run-
off and wastes to a waste treatment lagoon for treatment. While the diversions
and subsurface drains may not provide any measurable pollution control of their
own, they are essential to the overall performance of the animal waste manage-
ment system. Other components, such as lagoons and waste utilization plans, are
added to provide treatment redundancy.
Site-Specific Design of Management Practice Systems
There is no single, ideal management practice system for controlling a par-
ticular pollutant in all situations. Rather, the system should be designed based on
the type of pollutant; the source of the pollutant; the cause of the pollution at the
source; the agricultural,-climatic, and environmental conditions; the pollution
reduction goals; the economic situation of the farm operator; the experience of
the system designers; and the willingness and ability of the producer to imple-
ment and maintain the practices. The relative importance of these and other fac-
tors will vary depending upon other considerations such as whether the
implementation is voluntary (e.g., State cost-sharing program) or mandatory
(e.g., discharge permits).
An example of site-specific design of management practice systems can be
found in the Rural Clean Water Program (RCWP) which was discussed in Chap-
ter 1. A similar water quality problem existed in RCWP projects conducted in
Utah and Florida (Gale et al., 1993). In both projects, eutrophication was caused
partly by excess phosphorus contained in dairy runoff. Animal waste manage-
ment systems were installed in both projects. In the Florida project, seven indi-
vidual management practices (referred to as "BMPs" in the RCWP) were needed
Chapter 3-34:10/98
-------
Chapter 3: Management Practices 35
to control the animal manure in barnyard areas, whereas only five BMPs were
needed in Utah (Table 3-2). Some BMPs were used in both projects, while other
BMPs were used in one but not both projects. Differences existed because the
regions in which the two projects were located have significantly different cli-
matic, ecological, and soil characteristics, requiring different approaches to miti-
gate animal waste problems. In Florida, annual rainfall is approximately 50-
inches per year, whereas annual precipitation in Utah is approximately 16 inches
per year. Surface water is largely derived from snowmelt in Utah. Dikes were
used in the Florida project to prevent runoff and phosphorus from entering the
drainage ditches. These dikes were not needed in Utah due to the lower rainfall
.producing less runoff.
Table 3-2. Animal waste management BMP systems used in two agricultural
pollution control projects (Utah and Florida).
NRCS Code
312
313
356
362
425
428
430
633
Individual Animal Waste Management BMPs
Waste Management System
Waste Storage Structure
Dike
Diversion
Waste Storage Pond
Concrete Lining
Pipeline
Waste Utilization
UT
**
**
**
**
**
FL
**
**
**
**
**
**
**
NRCS = Natural Resource Conservation Service, U.S. Department of Agriculture
Source for NRCS codes: NRCS, 1996
Practices Must Fit Together for Systems to Perform
Effectively
Each practice in a management practice system must be selected, designed,
implemented, and maintained in accordance with site-specific considerations to
ensure that the practices function together to achieve the overall management
goals. If, for example, nutrient management, conservation tillage, field borders,
and riparian buffers are used to .address a nitrogen problem, then planting and
nutrient applications need to be conducted in a manner consistent with conserva-
tion tillage goals and practices (e.g., injecting rather than broadcasting and incor-
porating fertilizer). In addition, runoff from the fields must be conveyed evenly
to the field borders which, in turn, must be capable of delivering the runoff to the
riparian buffers in accordance with design standards and specifications.
Chapter 3-35: 10/98
-------
36 Chapter 3: Management Practices
Chapter 3-36:10/98
-------
Management Measures
To reduce water
pollution caused
by nitrogen and
phosphorus,
develop and
implement a
comprehensive
nutrient
management
plan.
4A: Nutrient Management
Management Measure for Nutrient Management
Develop, implement, and periodically update a nutrient management plan to:
(1) apply nutrients at rates necessary to achieve realistic crop yields, (2) improve
the timing of nutrient application, and (3) use agronomic crop production technol-
ogy to increase nutrient use efficiency. When the source of the nutrients is other
than commercial fertilizer, determine the nutrient value and the rate of availability
of the nutrients. Determine and credit the nitrogen contribution of any legume
crop. Soil and plant tissue testing should be used routinely. Nutrient management
plans contain the following core components:
1. Farm and field maps showing acreage, crops, soils, and waterbodies. The
current and/or planned plant production sequence or crop rotation should be
described.
2. Realistic yield expectations for the crop(s) to be grown, based primarily on the
producer's actual yield history, State Land Grant University yield expectations
for the soil series, or SCS Soils-5 information for the soil series.
3. A summary of the nutrient resources available to the producer, which at a
minimum include:
O Soil test results for pH, phosphorus, nitrogen, and potassium;
O Nutrient analysis of manure, sludge, mortality compost (birds, pigs, etc.),
or effluent (if applicable);
O Nitrogen contribution to the soil from legumes grown in the rotation (if
applicable); and
O Other significant nutrient sources (e.g., irrigation water, atmospheric
deposition).
4. An evaluation of field limitations based on environmental hazards or concerns,
such as:
D Sinkholes, shallow soils over fractured bedrock, and soils with high leach-
ing potential;
D Lands near surface water;
O Highly erodible soils;
D Shallow aquifers;
D Combinations of excessively well drained soils and high rainfall seasons,
resulting in very high potential for surface runoff and leaching; and
D Submarine seeps, where nutrient-laden ground water from upland areas
can directly enter the ocean through tidal pumping (e.g. along the coast-
line of Maui, Hawaii).
Chapter 4A-37:10/98
-------
38 Chapter 4: Management Measures
5. Use of the limiting nutrient concept to establish the mix of nutrient sources
and requirements for the crop based on a realistic yield expectation.
6. Identification of timing and application methods for nutrients to provide nutri-
ents at rates necessary to achieve realistic crop yields, reduce losses to the
environment, and avoid applications as much as possible to frozen soil and
during periods of leaching or runoff.
7. Provisions for the proper calibration and operation of nutrient application
equipment. ,
Management Measure for Nutrient Management:
Description
The goal of this management measure is to minimize nutrient losses from
agricultural lands occurring by edge-of-field runoff and by leaching from the root
zone. Once nitrogen, phosphorus, or other nutrients are applied to the soil, their
movement is largely controlled by the movement of soil and water and must there-
fore be managed through other control systems such as erosion control and irriga-
tion water management. Effective nutrient management abates nutrient movement
. by minimizing the quantity of nutrients available for loss (source reduction). This
is usually achieved by developing a nutrient budget for the crop, applying nutri-
ents at the proper time, applying only the types and amounts of nutrients necessary
to produce a crop, and considering the environmental hazards of the site. In cases
where manure is used as a nutrient source, manure holding areas may be needed to
provide capability to apply manure at optimal times.
The focus of nutrient management is to increase the efficiency with which
applied nutrients are used by crops, thereby reducing the cost of production, as
well as reducing the amount available to be transported to both surface and
ground waters. Application of this management measure may, in some cases, re-
sult in more nutrients being applied where there has not been a balanced use of
nutrients in the past.
The best approach to minimizing nutrient transport to surface and ground
waters depends upon whether the nutrient is in the dissolved phase or is attached
to soil particles. For dissolved nutrients, effective management includes source
reduction and reduction of water runoff or leaching. Erosion and sediment trans-
port controls are necessary to reduce transport of nutrients attached to soil par-
ticles. Practices that focus on controlling the transport of smaller soil particle sizes
(e.g., clays and silts) are most effective because these are the soil fractions that
transport the greatest share of adsorbed nutrients.
While the nutrient
management plan
may have many
components, the
principle is simple:
minimize total
losses.
Sources of Nutrients
Nitrogen (N), phosphorus (P), and potassium (K) are the primary nutrients
applied in most agricultural operations. Nutrient management plans typically fo-
cus mainly on N and P, the nutrients of greatest concern for water quality.
The major sources of nutrients in most crop production include:
O Commercial fertilizers
O Manures, sludges, and other organic materials
Chapter 4A-38:10/98
-------
Chapter 4A: Nutrient Management 39
Nutrient
Cycles
Nutrient management
planning is enhanced
by knowledge of the
nitrogen and
phosphorus cycles.
O Crop residues and legumes in rotation
O Irrigation water
D Soil reserves
Because these two elements behave very differently, basic understanding of
how N and P are cycled in the soil-crop system is an important foundation for
effective nutrient management.
Nitrogen is continually cycled among plants, soil organisms, soil organic
matter, water, and the atmosphere (Figure 4a-1) in a complex series of biochemi-
cal transformations. Some N forms are highly mobile, while others are not. At any
given time, most of the N in the soil is held in soil organic matter (decaying plant
and animal tissue) and the soil humus. Mineralization processes slowly transform
the N in soil organic matter by microbial decomposition to ammonium ions
(NH4+), releasing them into the soil where they can be strongly adsorbed and rela-
tively immobile. Plants can use the ammonium, however, and it may be moved
with sediment or suspended matter. Nitrification by soil microorganisms trans-
forms ammonium ions (either mineralized from soil organic matter or added in
fertilizer) to nitrite (NO2~) and then quickly to nitrate (NO3"), which is easily taken
up by plant roots. Nitrate, the form of N most often associated with water quality
problems, is soluble and mobile in water. Immobilization includes processes by
which ammonium and nitrate ions are converted to organic-N, through uptake by
plants or microorganisms, and bound in the soil. Denitrification converts nitrate
into nitrite and then to gaseous nitrogen (N,) and nitrous oxide (N2O) through
microbial action in an anaerobic environment.
Figure 4a-1. The nitrogen cycle (Kansas State Univ. CES & NAWG Foundation, 1994).
(legume plants) (commercial fertilizer]
Leaching Loss
Chapter 4A-39:10/98
-------
40 Chapter 4: Management Measures
A nitrogen molecule may pass through this cycle many times in the same
field. The processes in the nitrogen cycle can occur simultaneously and are con-
trolled by soil organisms, temperature, and availability of oxygen arid carbon in
the soil. The balance among these processes determines how much N is available
for plant growth and how much may be lost to ground water, surface water, or the
atmosphere.
Phosphorus lacks an atmospheric connection (although it can be transported
via airborne soil particles) and is much less subject to biological transformation,
rendering the P cycle considerably simpler (Figure 4a-2). Most of the P in soil
occurs as a mixture of mineral and organic materials. A large amount of P (50-
75%) is held in soil organic matter which is slowly broken down by soil microor-
ganisms. Some of the organic P is released into soil solution as phosphate ions that
are immediately available to plants. The phosphate ions released by decomposition
or added in fertilizers are strongly adsorbed to soil particles and are rapidly immo-
bilized in forms that are unavailable to plants. The equilibrium level of dissolved P
in the soil solution is controlled by the chemical environment of the soil (e:g. pH,
oxidation-reduction, iron concentration) and by the P content of the soil.
Figure 4a-2. The phosphorus cycle (Buckman and Brad/, 1969).
Available
Soil
Phosphorus
Leaching
losses
Erosion
losses
Fixation
Commercial
Fertilizers
Fertilizers represent the largest single source of N, P, and K applied to most
cropland in the U.S. Major commercial fertilizer N sources include anhydrous
ammonia, urea, ammonium nitrate, and ammonium sulfate. Major P fertilizer
sources include monoammonium phosphate, diammonium phosphate, triple super-
phosphate, ammonium phosphate sulfate, and liquids. The predominant source of
potassium (K) fertilizer is potassium chloride. Descriptions of common fertilizer
materials are given in Table 4a-l. The use of any particular material or blend is
governed by the characteristics of the formulation (such as volatilization potential
Chapter 4A-40:10/98
-------
Chapter 4A: Nutrient Management 41
and availability rate), suitability for the particular crop, crop needs, existing soil
test levels, economics, application timing and equipment, and handling preferences
of the producer. An example of general fertilizer recommendations for com is
shown in Table 4a-2. Commercial fertilizers offer the advantage of allowing exact
formulation and delivery of nutrient quantities specifically tailored to the site,
crop, and time of application in concentrated, readily available forms. —.
Table 4a-1. Common fertilizer minerals.
Common Name
Nitrogen materials
Ammonium nitrate
Ammonium sulfate
Ammonium nitrate-urea
Anhydrous ammonia
Aqua ammonia
Urea
Phosphate materials
Superphosphate
Ammoniated
superphosphate
Monoammonium
phosphate
Diammonium
phosphate
Urea-ammonium
phosphate
Potassium materials
Muriate of potash
Monopotassium phosphate
Potassium hydroxide
Potassium nitrate
Potassium sulfate
Chemical Formula
NH4N03
(NH4)2S04
NH4NO3+(NH2 )2CO
NH3
NH4OH
(NH2)2CO
^
Ca(H2P04)2
Ca(NH4H2P04)2
NH4H2PO4
(NH4)2HP04
(NH2)2CO+(NH4)2HP04
KCI
KH2PO4
KOH
KN03
.K2S04 .
Analysis (%)
N P20S K20
34
21
32
82
20
46
0
5
13
18
28
0
0
0
13
0
Source: Pennsylvania State University. 1997. The Penn State Agronomy Guide,
Park, PA. Cornell Cooperative Extension. 1997. 1997 Cornell Recommendations
Management. Resource Center, Cornell University, Ithaca, NY.
0
0
0
0
0
0
20-46
40
52
46
28
0
50
0
0
0
0
0
0
0
0
0
0
0
0
0
0
60
40
70
45
50
1997-1998, University
for Integrated Field Crop
Chapter 4A-41: 10/98
-------
42 Chapter 4: Management Measures
Precision Farming
A New Era of Production
The Precisely Tailored Practice
Precision farming, also known as site-specific management, is a fairly new practice that has'been attracting
increasing attention both within and outside the agricultural industry over the past few years. It is a
practice concerned with making more educated and well-informed agricultural decisions. Precision farming
provides tools for tailoring production inputs to specific plots within a field. The size of the plots typically
1 range from one acre to three acres, depending on the farmer's preference. By treating each plot as much or
as little as needed, farmers can potentially reduce the costs of seed, water, and chemicals; increase overall
crop yields; and reduce environmental impacts by better matching inputs to specific crop needs. Rather
than applying fertilizer or pesticides to an entire field at a single rate of application, farmers first test the
soil and crop yields of specific sections (or plots) and then apply the appropriate amount of fertilizer, water,
and/or chemicals needed to alleviate the problems in those sections of the field.
Precision farming is changing the way farmers think about their land. They are increasingly concerned not
with the average needs of the entire field, but with the actual needs of specific sections of the field, which
can fluctuate from one square meter to the next. The practice of precision farming acknowledges the fact
that conditions for agricultural production vary across space and overtime. With this in mind, precision
farmers are now making management decisions more specific to time and place rather than regularly
scheduled and uniform applications.
The Computer-Aided Approach
The approach of precision farming involves using a wide range of computer-related information technolo-
gies, many just recently introduced to production agriculture, to precisely match crops and cultivation to the
various growing conditions. The key to successfully using the new technologies available to the precision
farmer to maximize possible benefits associated with this approach is information. Data collection efforts
should occur before crop production and continue until after the harvest. Information-gathering technolo-
gies available prior to crop production include grid soil sampling, past yield monitoring, remote sensing,
and crop scouting. These data collection efforts are even further enhanced by obtaining precise location
coordinates of plot boundaries, roads, wetlands, etc., using a global positioning system (GPS).
Other data collection takes place during production through "local" sensing instruments mounted directly
on farm machinery. Variable rate technology (VRT) uses computerized controllers to change rates of inputs
such as seed, pesticides, and nutrients through planters, sprayers, or irrigation equipment. For example,,
soil probes mounted on the front of fertilizer spreaders can continuously monitor electrical conductivity, soil
moisture, and other variables to predict soil nutrient concentrations and accordingly adjust fertilizer appli-
cation "on-the-fly" at the rear of the spreader. Other direct sensors available include yield monitors, grain
quality sensors, salinity meter sleds, weather monitors, and spectroscopy devices. Optical scanners can be
used to detect soil organic matter, to recognize weeds, and to instantaneously alter the amount or applica-
tion of herbicides applied.
The precision farmer can then take the information gathered in the field and analyze it on a personal
computer. The personal computer can help today's farmer organize and manage the information collected
more effectively. Computer programs, including spreadsheets, databases, geographic information systems
(GIS), and other types of application software, are readily available. By tying specific location coordinates
obtained from the GPS in with the other field data obtained, the farmer can use the GIS capability to create
overlays and draw analytical relationships for site-specific patterns of soils, crop yields, input applications,
drainage patterns, and other variables of interest over a particular distance or time period.
Chapter 4A-42: 10/98
-------
Chapter 4A: Nutrient Management 43
GIS can also be integrated with other decision support systems (DSS), such as process models and artifi-
cial intelligence systems, to simulate anything from crop growth and financial expectations to the genera-
tion and movement of nutrients and pesticides through the environment. Today's precision farmer can also
use expert systems, information systems based on input from human experts, to retrieve advice on when to
spray for specific pests, when to till, and so forth. These systems are continuously modified for the
farmer's field based on past, current, and expected conditions represented by soil, weather, pest levei^and
other data input from the GIS.
The Technology~Driven Future '
Further technological advances will make the coming years decisive for the precision farming industry.
There's no saying what the future holds for this new era of agricultural production. Listed below are just a
few of the technological advances projected to hit this industry in the years to come.
O Onboard grain quality analyzers will check both physical and chemical
attributes (including smell).
O High-precision soil testing will move from the lab to the field, with
fiberoptic spectrometers attached to real-time onboard computers.
n Micro-ecology will be tested along with water runoff and air samples.
D Tmmunochemical assays will measure chemical residues on leaf surfaces
or monitor plant health and productivity.
O "•"'•• A wide range of sensors, monitors, and controllers such as shaft monitors,
pressure transducers, and servo motors will be used to collect accurate
': ;,, ;. •".' •;•.. •• .'••' • ./'--.data.
O Weather monitors will be mounted on sprayers, or "talk" directly to local
: weather station networks as they simultaneously change droplet size or
spray patterns, as well as rates and products, on the go.
O' Remote imaging technologies will look over the farmer's shoulder to
guarantee approved application procedures.
O Guidance on control systems will guarantee straight rows, control depth,
and optimize inputs.
D Crop models will optimize economic and environmental variables. Farm
ers will buy insurance directly from the underwriter, who will also rely on
remote sensing and risk modeling.
n Wearable computers with voice recognition and head-mounted displays
will guide farmers through equipment maintenance and crop scouting.
Although precision farming has not yet been widely adopted to date, this practice continues to attract
increasing attention both on and off the farm. Much of the off-the-farm enthusiasm for precision farming
can be attributed to the eminent good sense of matching input application to plant needs. Precision farm-
ing is simply a more broken-up version of the kinds of best management practices (BMPs) already recom-
mended at the field level. Because this technology is still somewhat new to the industry, there is much
more to learn about the potential overall impact of precision farming on water and air quality relative to
conventional techniques. But one thing is certain: precision farming has the potential to enhance economic
return (by cutting costs and raising yields) and to ease environmental concerns (by reducing the impacts of
fertilizers, pesticides, and erosion).
Chapter 4A-43: 10/98
-------
Table 4a-2. Fertilizer recommendations for corn (Cornell Cooperative Extension, 1997). |
Soil
Management
Croup
Soil group 1-Clayey soils, fine-textured
soils in northern New York, near lakes
and along Ihe Hudson River. Examples:
Vergennes, Kingsbury, Hudson,
Rhinebeck, Schoharie, Odessa.
Soil group ll-Silty soils, medium- to
moderately fine-textured soils of the
central region. Examples: Cazenovia,
Hilton, Honeoye. Lima. Ontario.
Lansing. Mohawk, Chagrin, Teel.
Soil group Ill-Sill loam soils,
moderately coarse-textured acid soils of
the Southern Tier, glacial outwash.
Examples: Barbour, Chenango, Palmyra.
Tioga, Mardin, Langfoi, Tunkhannock.
Soil group IV-Loamy soils, coarse- to
medium-loomed soils of northern New
York and the Hudson Valley. Examples:
Bombay. Broadalbin. Copake.
Empeyville, Madrid, Sotlus, Worth.
Soil group V-Sandy soils, very coarse-
textured soils on beach ridges, deltas, and
sandy or gravelly outwush near
mountains and the Hudson Valley.
Examples: Alton. Cotton, Windsor,
Colonie, Elmwood, Junius, Suncook.
Years
Following Sod
\
2
3
4 or more
1
2
3
4 or more
1
2
3
4 or more
1
2
3
4 or more
1
2
3
4 or more
Fertilizer Nutrients to Be Added (lb/A)[4\
NITROGEN (MSI. |6|. |7|
Type of Plowed Sod
Grass
No
Manure Manure
10-30 10-30
50-100 10-40
70-110 10-50
80-120 20-60
10-30 10-30
60-100 10-40
80-120 10-60
90-130 30-70
10-30 10-30
60-100 10-40
80-120 20-60
90-130 30-70
10-30 10-30
60-110 10-50
80-120 I0-«0
90-130 30-70
10-30 10-30
40-100 10-40
60-110 10-50
70-120 20-60
Less than
50% Legume
No
Manure Manure
10-30 10-30
30-80 10-20
60-100 I(MO
80-120 20-60
10-30 10-30
50-90 10-30
70-110 10-50
90-130 30-70
10-30 10-30
40-90 10-30
70-110 10-50
90-130 30-70
10-30 10-30
50-90 10-30
70-120 10-60
90-130 30-70
10-30 10-30
20-80 10-20
50-100 10-40
70-120 10-60
Greater than
50% Legume
No
Manure Manure
10-30 10-30
20-70 10-30
60-100 10-40
80-120 20-60
10-30 10-30
40-80 10-30
70-110 10-50
90-130 30-70
10-30 10-30
30-80 10-30
70-110 10-50
90-130 30-70
10-30 10-30
40-90 10-30
70-110 10-50
90-130 30-70
10-30 10-30
20-70 10-30
50-100 10-40
70-120 10-60
PHOSPHORUS (Pfl,)
Soil Test Phosphorus Levels (8)
Very Very
Low Low Medium High High
70 60 40 20 0
70 60 40 20 0
70 60 40 20 0
70 60 40 20 0
70 60 40 20 0
POTASSIUM (Kfl)
Soil Tea Potassium Levels |8|
Very Very
Low Low Medium High High
50 40 30 20 0
60 60 40 20 0
80 70 50 25 0
120 80 50 25 0
120 90 60 30 0
[1]A more specific recommendation will be obtained from a complete Soil test analysis.
[2]For sorghum, sudan-sorghum hybrids, and milets, use 2/3 to 3/4 of the nitrogen rate in the table. Nitrogen may be applied preplan! or as a postemergence application if planted after June 1 .
(3]The nitrogen recommendations are based on a broad range of soils. A more accurate recommendation for a specific soil can be obtained from the Cornell soil testing program.
(4]Do not use more than 80-100 Ib/A of N + K2O in the fertilizer band at planting.
[5]For nitrogen recommendations greater than SOIb/A, apply a lower rate in the starter fertilizer (such as 1 0-30 Ib in the band at planting), and sidedress the remaining nitrogen when the corn is 6-15
in. high.
[6]Use the lower nitrogen rate for soils with a low yield potential.
(7]For a more accurate estimate of the nitrogen contribution from manure, see the Cornell Field Crops and Soils Handbook. ' !
o
-------
Chapter 4A: Nutrient Management 45
Organic —
Nutrient Sources
Organic nutrient sources, such as manure, sludge, and compost, can supply
all or part of the N, P, and K needs for crop production. Organic nutrient sources
offer additional advantages because they also contain secondary nutrients and
micronutrients (e.g. iron, boron), add organic matter to the soil, provide nutrients
to crops for several years after application, and provide a practical outlet to re-
cycle manure and other farm organic materials. The use of manure is particularly
important on livestock and poultry farms because nutrients can build up on such
farms as more are brought into the farm than leave in products sold. Table 4a-3
shows examples of estimated N and P mass balances for several New York dairy
farms.
Table 4a-3. N and P mass balances on several New York dairy farms.
INPUT
purchased fertilizer
purchased feed
legume N fixation
Total:
OUTPUT
milk
meat
crops sold
Total:
REMAINDER
remaining on farm
Source: Klausner, S.
95CUWFP1, Cornell
Nitrogen
Size (#of cows)
45 85 120
—tons of N/yr —
1.0 2.2 4.6
3.8 9.7 21.4
UJ U. 3.2
6.1 13.0 29.2
2.0 3.8 6.3
0.1 0.4 0.6
OJ. O5 .=
2.2 4.7 6.9
3.9 8.3 22.3
64% 64% 76%
1995. Nutrient Management:
University, Ithaca, NY.
Phosphorus
Size (ft of cows)
45
85
120
— tons of P/yr —
1.2
1.0
2^2
0.4
<0.1
-------
46 Chapter 4: Management Measures
Table 4a-4. Representative values for nutrients in manure, sludge, and whey, as applied.
SOLID MANURE
Species
Dairy cattle
Beef cattle
Swine
Poultry
Sheep
Horse
LIQUID MANURE
Species
Dairy cattle
Beef cattle
Veal calf
Swine
Poultry
DIGESTED SLUDGE
WHEY
% dry matter
18-22
15-50
18
22-76
28
46
% dry matter
1-8
1-11
3
1-4
13
Total N
6-17
11-21
8-10
20-68
14-18
14
lb/1000 gal-
4-32
4-40
24
4-36
69-80
20
12
4-18
9-27
25
2-27
36-69
5-30
5-34
51
4-22
33-96
lb/1000 gal
12 1
-lb/1000 gal
9 18
'Convert values for P2O5 and KjO to P and K by multiplying by 0.43 and 0.83, respectively.
Sources: Midwest Plan Service. 1985. Livestock Waste Facilities Handbook. Iowa State University,
1991a. Ames, IA. Klausner, S. 1995. Nutrient Management: Crop Production and WaterQuality.
95CUWFP1, Cornell University, Ithaca, NY. University of Wisconsin-Extension and Wisconsin Dept. of
Agriculture, Trade, and Consumer Protection. 1989. Nutrient and Pesticide Best Management Practices
for Wisconsin Farms. WDATCP Technical Bulletin ARM-, Madison, Wl. University of Vermont. 1996.
Agricultural Testing Laboratory-Manure Analysis Averages, 1992-1996. Dept..of Plant & Soil Science,
University of Vermont, Burlington, VT.
Credits for previous
year manure
applications and
nitrogen-fixing crops
should be
considered in the
plan for nitrogen
management.
Another difficulty in efficient use of manure nutrients involves nutrient avail-
ability. Not all nutrients in manure are immediately available for crop uptake. The
organic N in manure, for example, must be mineralized before it can be used by
plants, a process that may take 3 or more years to complete. An example of nutri-
ents available for crop growth in the first year of application is shown in Table 4a-
5. Failure to account for this slow availability can result in under-supply of
nutrients in a given year of manure application. Perhaps more critically, it must be
recognized that when manure is applied to the same field over the years, each
succeeding year requires the addition of less N to maintain an adequate supply of
plant available N (Table 4a-6). Failure to consider this N carryover could lead to
excessive application of N.
Chapter 4A-46:10/98 . .
-------
Chapter 4A: Nutrient Management 47
Table 4a-5. Nutrients available for crop use in the first year after spreading manure.
Animal
Dairy
Beef
Swine
Poultry
N
incorp.
4
4
5
15
SOLID
Ibs/ton
3
4
4
13
P.O.
not incorp.
3
5
3
14
Sources: Dept. of Soil Science, College of Agricultural and
sin-Madison, University of Wisconsin Extension.
N
incorp.
. 10
.12
28
41
UQUID
not
-lbs/1000 gal-
8
10.
22
35
Life Sciences, University of
P2°5
incorp.
8
14
15
38
Wiscon-
Table 4a-6. Quantity of livestock or poultry manure needed to supply 100 kg of Nitrogen
over the cropping year with repeated applications of manure (Schepers and Fox, 1989).
Number of
years applied
1
2
3
4
5
10
15
20
Quantity
0.25
154
79
54
41
33
17
12
9
(metric tons) needed
1.0
22
16
13
11
10
7
6
5
for manure
2.0
7
6
5
5
4
3.7
3.3
3.0
with these percent N
4.0
1.4
1.4
1.4
1.3
1.3
1.3
1.2
1.2
Since organic nutrient sources contain valuable nutrients and have soil-condi-
tioning properties, application to land should never be considered disposal. In
cases where organic nutrient sources are disposed of as waste with no regard given
to their N and P content, excessive levels of available nutrients and losses to sur-
face or ground waters are likely to occur.
Because of their ability to "fix" atmospheric nitrogen, legumes grown in
rotation can represent a significant input of N into the soil of a crop field. Alfalfa
has been reported to fix from 60 to 530 Ib N/ac (pounds of nitrogen per acre);
soybeans may fix from 13 to 275 Ib N/ac. Some of this fixed N is removed in
harvest, but some remains in crop residue or in the soil and is available for subse-
quent crops. Table 4a-7 shows representative values for residual N contributions
from legume crops. Failure to account for such added N could result in excessive
application of N from other sources.
Chapter 4A-47:10/98
-------
48 Chapter 4: Management Measures
Table 4a-7. Representative values for first-year nitrogen credits for previous legume crops.
Crop
Forages
Alfalfa
>50%
25-50%
<25%
Nitrogen Credit (Ib N/acl
80 - 120
50-80
0-40
Red Clover and Trefoil
>50% .
25-50%
<25%
Soybeans
60-90
40-60
0 -30
• 1 Ib N/ac for each bu/ac harvested
up to 40 Ib N/ac
Green Manure Crops (plowed down after growing season of seeding year)
Sweet clover 80 - 120
Alfalfa 60-100
Red clover . 50-80
Vegetable Crops (residue not removed)
Peas, snap beans,
lima beans 10-20
Sources: Pennsylvania State University. 1997. The Penn State Agronomy Guide, 1997-1998, University
Park, PA. University of Wisconsin-Extension and Wisconsin Dept. of Agriculture, Trade, and Consumer
Protection. 1989. Nutrient and Pesticide Best Management Practices for Wisconsin Farms. WDATCP
Technical Bulletin ARM-1, Madison, Wl.
Irrigation
Water
Irrigation water, if drawn from already nutrient-enriched sources, can supply
significant amounts of N. In the Central Platte River Valley in Nebraska, ground
water used to irrigate corn contributed an average of 41 Ib N/ac, nearly one-third
of the N fertilizer requirement (Schepers et al., 1986). Ground water used to irri-
gate potatoes in Wisconsin contributed an average of 51 Ib N/ac, or 25% of the N
added as fertilizer (Saffigna and Keeney, 1977). Table 4a-8 shows guidelines for
calculating the N contribution from irrigation water.
Table 4a-8. Calculating N contributions from irrigation water.
N in water (mg/l)
2
4
6
8
10
Water Application Rate (acre-feet)
0.5 1.0 1.5 2.0
Ib N/ac
3
5
8
11
13
5
11
16
13
27
8
16
24
32
40
11
22
32
43
54
Source: Kansas State University Cooperative Extension System and The National
Association of Wheat Growers Foundation. 1994. Best Management Practices for
Wheat. NAWG Foundation, Washington, D.C.
Chapter 4A-48: 10/98
-------
Chapter 4A: Nutrient Management 49
Soil Nutrients
Atmospheric
Sources
The release of N, P, K, and micronutrients from soil reserves provides an
additional source of plant-available nutrients. The amount of nutrient release de-
pends on soil moisture, aeration, temperature, pH, and the amount of organic mat-
ter in the soil. The magnitude of this source can be assessed accurately only
through soil testing.
Finally, atmospheric deposition of nutrients, especially N, should be consid-
ered. Because of the atmospheric linkages of the N cycle and industrial additions
of N to the atmosphere, N loading from atmospheric deposition can be significant.
From 1983-1994, average annual inorganic N deposition over the Chesapeake
Basin ranged from 3.5 to 7.7 kg N/ha; average annual NO3+NH4 atmospheric
deposition loading rates ranged from 6.7 to 7.8 kg N/ha (Wang et al., 1997).
McMahon and Woodside (1997) cite wet NO3 and NH4 deposition rates of 9.8 kg
N/ha/yr and 2.8 kg N/ha/yr, respectively, for the Albemarle-Pamlico Drainage
Basin in North Carolina and Virginia. Examples of atmospheric deposition rates
for various forms of N across the U.S. are given in Table 4a-9.
Atmospheric deposition of P is generally very small. Ahl (1988) cited atmo-
spheric deposition of 0.05-0.5 kg P/ha/yr in Canada. Annual P loading rates to
the Chesapeake Basin have been estimated at 0.16 to 0.47 kg/ha (Wang et al.,
1997). A similar P deposition rate of 0.16 kg/ha/yr has been measured in the Lake
Champlain basin (VTDEC and NYS DEC, 1997). An estimated annual load of
0.66 kg P/ha by atmospheric deposition has been cited for the Albemarle-Pamlico
Basin (McMahon and Woodside, 1997).
Table 4a-9. N loading in atmospheric deposition, NADP/NTN data, 1996.
Location
Vermont
North Carolina
Florida
Wisconsin
Indiana
Arkansas
Nebraska
California
Alaska
Hawaii1
Station
Mt. Mansfield (VT99)
Mt. Mitchell (NC45)
Quincy (FL14)
Popple River (WI09)
Purdue Ag ResCtr(IN41)
Fayetteville (AR27)
North Platte Ag Exp Sta (NE99)
Davis (CA88)
Poker Creek (AK01)
Mauna Loa (HIOO)
NH4-N
2.29
3.08
1.37
2.49
4.24
3.29
3.27
2.81
0.06
0.07
NOa-N
-kg N/r
13.07
12.92
7.08
9.58
16.11
9.90
6.99
3.62
0.47
0.21
Inorganic
4.73
5.31
2.66
4.10
6.94
4.80
4.12
3.00
0.16
0.10
N
'1993
Source: National Atmospheric Deposition Program (NRSP-3)/National Trends Network (June 24, 1 998).
NADP/NTN Coord. Office, Illinois State Water Survey, 2204 Griffith Dr., Champaign, IL 61820.
Chapter 4A-49: 10/98
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50 Chapter 4: Management Measures
Some general
principles govern
nutrient movement.
Site specific crop
history, climate,
soils, watershed,
and farming
characteristics result
in specific local
nutrient pathways
and transformations.
Nutrient Movement into Surface and Ground Water
Nutrients in harvested crops typically represent the largest single component
of nutrient output from agricultural land. Table 4a-10 gives representative values
for annual crop nutrient removal. However, crop uptake of added N and P is by no
means complete. A mass balance of 1987 inputs and outputs of N and P on all
U.S. croplands showed that 33 to 40 percent of N inputs (6.7 to 9.1 million metric
tons) and 63 percent of P inputs (2.9 million metric tons) remained after nutrients
in harvested crops and crop residues were accounted for (NRC, 1993). Accumula-
tion of P in cropland soils may be especially high if the N requirement of the crop
is met with animal waste, adding P in excess of crop P uptake (Figure 4a-3). The
magnitude of potential loss of nutrients to surface and ground waters is directly
related to accumulation of excessive nutrient levels in soils.
Table 4a-10. Crop nutrient removal.
Crop
Corn
Corn silage
Grain sorghum
Soybeans
Wheat/rye
Oats
Barley
Alfalfa
Orchardgrass
Tall fescue
Sugar beets
Yield
/ac
125 bu
21 t
125 bu
40 bu
60 bu
80 bu
75 bu
5 t
6t
3.5 1
30 1
N P
Ib/ac
95 22
190 46
65 33
130 18
90 ' 26
90 31
105 20
250 33
300 44
135 29
275 37
Sources: Pennsylvania State University. 1997. The Penn State Agronomy Guide 1997-1998,
University Park, PA; Midwest Plan Service. 1 985. Livestock Waste Facilities Handbook. Iowa
State University, Ames, IA.
N and P not removed in the harvested crop can become available for trans-
port to surface and ground waters. The movement of applied nutrients is primarily
driven by the movement of water and eroded soil, but the specific transport path-
ways are largely determined by the characteristics of the nutrient source, soil char-
acteristics, and related environmental conditions (e.g., soil temperature). As noted
in the earlier discussion of nutrient cycles, readily soluble nitrate moves easily in
the liquid phase. Due to its strong affinity for soil particles, phosphorus usually
moves primarily with eroding soil particles. Nitrogen can volatilize directly from
fertilizers such as urea and ammonia and from surface-applied manure; N lost to
the atmosphere in this way may be washed from the atmosphere by rain a great
distance away. Nitrogen can also be lost to the atmosphere as harmless nitrogen
gas through denitrification. Other factors influencing nutrient movement include
topography, precipitation patterns, and, of course, land use and management.
Chapter 4A-50: 10/98
-------
Chapter 4A: Nutrient Management 51
Figure 4a-3. P added in poultry litter compared with crop requirements
(Sharpley et at., 1994).
CROP
Bermuda
grass
Com
Sorghum
WhMt
AMOUNT OF P (kgPha-'yr1)
YIELD 0 20 _ 40 60 80 100 120
Mg lw/1
22
12
I Utter P
dJCropP
requirement
60 £»•** P
Movement to -
Surface Waters
Transport of nutrients to surface waters depends on the availability of nutri-
ents in the upper soil zone, how easily the nutrients and/or associated soil particles
are detached, whether the chemical is transported in the dissolved form or attached
to soil, and any deposition that may occur before delivery to a waterway. Nutrients
are most susceptible to runoff loss while they are in a thin (<3 cm) layer at the soil
surface where overland flow, chemicals, and soil intermix during runoff. Once
nutrients are below this mixing zone, they are usually less vulnerable to ordinary
runoff losses. Nitrate is an exception, as it can be readily leached through the soil.
Nitrogen can be delivered to surface waters through runoff, erosion, and
subsurface flow. Some N in the form of ammonium can be lost by erosion along
with organic N attached to soil particles. Soluble N can be carried in surface run-
off, but most soluble nitrate is lost via leaching through the soil. Leached nitrate
may move into surface waters through shallow subsurface flow or be transported
to deeper ground water. Drainage tiles may provide an important short circuit for
delivery of N from shallow subsurface flow to surface waters. Concentrations of
nitrate in tile drain flow are normally higher than levels found in surface runoff.
The majority of phosphorus lost from agricultural land is transported via
surface runoff, mostly in paniculate form attached to eroded soil particles. Be-
cause P is so strongly adsorbed to soil particles, the P level in the soil is a critical
factor in determining loads of P delivered to surface waters (Daniel et al., 1998).
Increased residual P levels in the surface soil can lead to increased P loadings to
surface water, both attached to soil particles and in dissolved form. Soluble P
losses from cropland can also be significant if runoff occurs very soon after heavy
addition of phosphate fertilizer.
Chapter 4A-51:10/98
-------
52 Chapter 4: Management Measures
Runoff of Dissolved P
Phosphorus can be exported from agricultural land in paniculate and
dissolved forms. In most cases, the majority of P loss occurs in surface
runoff in particulate form. However, dissolved P carried in surface runoff or
subsurface flow may be a critical consideration because dissolved P tends
to be immediately available to stimulate growth in receiving waters.
• Loss of dissolved P in runoff is directly related to the P
content of the surface soil — linear relationships have been
observed between dissolved P concentration in runoff and P
content (Mehlich 3) of surface soils in cropped and grassed
watersheds (Daniel et al., 1998).
• P losses from grassland may be high, particularly because
fertilizers and animal waste are not usually incorporated into
the soil. Significant phosphorus export has been measured
in surface runoff and interflow from grazed grassland, with
losses of over 0.5 kg P/ha during major storm events,
especially when events closely followed inorganic fertilizer
application (Haygarth and Jarvis, 1997).
• Soluble P losses may be greater from pasturelands than
from croplands due to the presence of animal waste on the
land surface, P release from plant decomposition, and low
amounts of suspended sediment to sorb dissolved P (Baker
et al., 1978; Sharpley and Menzel, 1987; Sharpley et al.,
1992).
• In the Chesapeake Basin, dissolved P concentrations in
storm runoff were higher from pastureland than from either
cropland or forest (Correll et al., 1995).
Movement to
Ground Water
Leaching of phosphorus to ground water is generally not a significant prob-
lem. Organic soils and sandy soils, which lack the iron and aluminum oxides im-
portant for P adsorption, are exceptions; P losses in leaching from intensive
cropping on such soils can be large. The degree of leaching will vary with soil
structure, geologic conditions, climate, and management practices. Recent reports
document phosphorus leaching in areas of intensive manure application to highly
enriched soils over shallow water tables (Breeuwsma et al., 1995).
The magnitude of nutrient loss to ground water, especially through leaching,
depends on the availability of the chemical in the soil profile, the ease with which
the nutrient form is detached from the soil, the rate and path of dowrm arc! trans-
Chapter 4A-52:10/98
-------
Chapter 4A: Nutrient Management 53
. . „. . port or percolation of water and chemicals, and any possible removal or deposition
Increasing efficiency r u u • i L r • u j XT • u • jj
... 7 of the chemical before it reaches ground water. Nutrients may be introduced to
and reducing . ... ° L -> .. .. • • • u • i u •
. . . . a . ground water by direct routes such as abandoned wells, irrigation wells, sinkholes,
nutrient losses is , . . , . r . , ..... . c , f ...
, . . ' or back-siphoning of nutrients when filling tanks. Such pathways are especially
founded upon the • -r fu uu-i-u ., r • • •
. . . , significant because transport through soil is bypassed, eliminating any opportunity
development OT r \ \
,r .. . for adsorption or uptake. —
sound soil and water v v
conservation Leaching of soluble nutrients to ground water can occur as chemicals are
principles. carried with precipitation or irrigation water moving downward past the root zone
to the ground water table. Over-application of irrigation water can enhance leach-
ing of nutrients to ground water by carrying dissolved nutrients quickly below the
root zone. Ponded water in surface depressions due to large runoff events can be a
significant source of nutrient transport to ground water, as ground water mounds
underneath the depression (Zebarth and DeJong, 1989). Summerfallow may have
a higher ground water contamination risk than continuous cropping because of the
increased water storage in soil profiles that may increase deep percolation
(Campbell et al.,. 1984; Bauder et al., 1993). Finally, idling of cropland either due
to normal rotations or to commodity or conservation programs can in some cases
initially increase nutrient leaching to ground water as nutrients are not taken up by
growing plants and are available for leaching loss (Webster and Goulding, 1995).
Nutrient Management Practices
and Their Effectiveness
Nutrient
Management Principles
There are several fundamental principles that should be applied to managing
nutrients for both crop production and water quality protection. These principles
focus on improving the efficiency of nutrient use and thereby reducing the poten-
tial for nutrient loss to surface or ground waters:
CD Determine realistic yield goals, preferably on a field-by-field basis
D Account for nutrients from all sources before making supplemental applica-
tions
O Synchronize nutrient applications with crop needs; N is needed most during
active crop growth and N applied at other times is easily lost
O Reduce excessive soil-P levels by balancing P inputs and outputs
Because of the complex cycling and multiple sources of N in the soil-crop
system, careful accounting for all sources is often the most critical step in improv-
ing N management. Since the level of P in the soil is a major factor determining
the amount of P lost from agricultural land, reducing soil P levels will ultimately
reduce P delivery to surface and ground waters.
Additional practices may be needed to reduce detachment and transport of N
and P and delivery to surface or ground waters. Erosion control practices are par-
ticularly critical to reduce losses of P and sediment-bound forms of N. Efficient
water management can reduce leaching of soluble N from irrigated cropland, and
improved irrigation practices can reduce water, sediment, and nutrient transport in
tailwaters. Crop failure due to a lack of water leaves nutrients in the soil, render-
ing them vulnerable to leaching or runoff loss.
Chapter 4A-53: 10/98
-------
54 Chapter 4: Management Measures
Nutrient —•—
Management Practices
Numerous practices are available to address the above principles. Many of
these are specific to the cropping system, soils, climate, and management activities
associated with particular crops and regions of the country. Readers are encour^
aged to contact their State Land Grant universities, cooperative extension offices,
State agriculture departments, or producer organizations for more site specific
practices.
The district soil
and water
conservation or
extension office
can assist growers
with the selection
of nutrient
management
practices.
Soil, tissue, and
manure testing
provide useful
information for
nutrient
management
planning.
Following are practices, components, and sources of information that should
be considered in the development of a nutrient management plan:
(1) Use of soil surveys in determining soil productivity and identifying environ-
mentally sensitive sites. Aerial site photographs or maps and a soil map
should be used. If the agricultural lands lie within a watershed that has been
designated as having impaired water quality associated with nutrients, then
nutrient management plans should include an assessment of the potential for N
or P from the agricultural lands to be contributing, to the impairment.
(2) Use of producer-documented yield history and other relevant information to
determine realistic crop yield expectations. Appropriate methods include aver-
aging the three highest yields in five consecutive crop years for the planning
site or other methods based on criteria used in developing the State Land
Grant University's nutrient recommendations. Increased yields due to im-
proved management and/or the use of new and improved varieties and hybrids
should be considered when yield goals are set for a specific site.
(3) Application of N and P at recommended rates for realistic yield goals.
Through remote sensing and precision farming techniques, yield and fertiliza-
tion can be optimized. Accurately located (e.g. via Global Positioning System,
GPS) soil testing can help evaluate soil variability between and within fields,
and use of on-the-go yield monitors and GPS-driven variable rate application
can match inputs to soil and field variations and place nutrients where in-
creased yield potential exists. Limit manure and sludge applications to phos-
phorus crop needs, supplying any additional nitrogen needs with nitrogen
fertilizers or legumes.
It may be necessary in some cases to route excess phosphorus in manures or
sludge to fields that will be rotated into legumes, to other fields that will not
receive manure applications the following year, or to sites with low runoff and
low soil erosion potential.
USD A has proposed P application guidelines for situations where animal
manure or other agricultural by-products are applied (Federal Register,
April 22, 1998). The guidelines for the Resource Management System (RMS)
level of treatment (Table 4a-ll) should be followed whenever possible for
existing agricultural lands and organic by-products used on those lands, and
in. all cases on new agricultural lands and/or agricultural lands to which
new or additional organic by-products are applied. Progressive plans can be
developed and implemented in accordance with USDA guidelines by produc-
ers who cannot meet the P application requirements of an RMS level of treat-
ment due to constraints associated with existing agricultural lands and
organic by-products.
Chapter 4A-54:10/98
-------
Chapter 4A: Nutrient Management 55
Table 4a-11. Allowable P Application Rates for Organic By-products (e.g., manure).
The following guidelines are contained in USDA's proposed guidelines for nutrient management. These will
be updated upon finalization of USDA's guidelines.
For phosphorus, one of the following options may be used to establish acceptable phosphorus application
rates for an RMS:
a) When soil specific phosphorus threshold (TH) data is available that identifies the soil phosphorus
level at which soluble losses of phosphorus in runoff become significant, the phosphorus
application may be based upon the following guidance: Soil Test P Level, Allowed P Application
Rates; <3/4TH Value, Nitrogen Based Application; =>3/4TH <1 1/2TH, Crop Removal; =>1 1/2TH
<2TH, 1/2 Crop Removal; =>2TH, No Application;
b) When soil specific phosphorus threshold (TH) data is not available, the phosphorus application
shall be based upon the following guidance: Soil Test P Level, Allowed P Application Rates; Low,
Nitrogen Based Application; Medium, Nitrogen Based Application; High, 1.5 times Crop Removal;
Very High, Crop Removal; Excessive, No Application.
(4) Soil testing for pH, phosphorus (Figure 4a-4), potassium, and nitrogen (Fig-
ure 4a-5). Preplant or midseason soil profile nitrate testing (e.g., a pre-
sidedress nitrate test) should be used when appropriate. Sub-soil sampling for
residual nitrate may be needed for irrigated croplands. Surface layer sampling
(0-2 inches) for elevated soil P and soil acidity may be needed when there is
permanent vegetation, non-inversion tillage, or when animal manure or other
organic by-products are broadcast or surface-applied.
(5) Plant tissue testing, e.g. chlorophyll testing in corn.
(6) Manure, sludge, mortality compost, and effluent testing.
(7) Quantification of nutrient impacts from irrigation water, atmospheric deposi-
tion, and other important nutrient sources.
(8) Use of proper timing, formulation, and application methods for nutrients that
maximize plant utilization of nutrients and minimize the loss to the environ-
ment: This includes split applications and banding of the nutrients, use of
nitrification inhibitors and slow-release fertilizers, and incorporation or injec-
tion of fertilizers, manures, and other organic sources. In addition, fall appli-
cation of N fertilizer on coarse-textured soils should be avoided. Manure
should be applied uniformly in accordance with crop needs, but surface appli-
cation to no-till cropland should be avoided.
(9) Coordination of irrigation water management with nutrient management. For
example, in-field measurement of crop and soil N status during the growing
season can be coupled with high-frequency irrigation to match N applications
with crop needs and reduce N losses (Onken et al., 1995). Irrigation should
also be managed to minimize leaching and runoff.
(10) Use of small grain cover crops or deeply-rooted legumes to scavenge nutrients
remaining in the soil after harvest of the principal crop, particularly on highly
leachable soils. Consideration should be given to establishing a cover crop on
land receiving sludge or animal waste if there is a high leaching potential.
. Sludge and animal waste should be incorporated or subsurface injected.
Chapter 4A-55:10/98
-------
56 Chapter 4: Management Measures
Figure 4a-4. Example of soil test report (Pennsylvania State University, 1992a).
07/31/84
DATE
0004
LAB HO.
700234
SERIAL HO.
SOMERSET
COUNTY
25
ACRES
MPBUU1
FIELD
UXD:NSTOM
COIL.
SOIL TEST flEPOHT FOR
P.A. PENH
RD1
AH Y. TOW. PA
THE PENSYLVAXXA STATE UIXVEUXTY
COLLEGE 07 ASHZCUITUW
MXRKLE LABORATORY - SOIL I FORASX TttTXIS
OTIVEASXTY PARK, PA 16802
COPY SEVT rot
10000
ACHE TERTILZZER CO.
XAXM STREET
, PA
10000
SOIL NUTRIENT LEVELS
SOU pH
Phosphate (P*0,)'
Potash (X»0)
Magnesium (MgO)
RECOMME^ATIQNS fOR
YIELD GOAL
LXKESTOKEs
lb/A
xxxxxxxxxxxxxx
xxxxxxbuQcxxx
xxxxxxxxxxx
:«IXW*::
FOR GRAIN (for ouw &w u« sr 2
125.0 BUSHELS (PER ACRE)
Carbonatt Cquivtlent
PLART IUTRXEHT mTUOCEK (H PHOSPHATE {>fO»> POTASH (X,O) MASHESXOM (MgO)
lb/A
• USE A STABTER rcRTlklZCR
• LIMESTONE RECOMMENDATION. IF ANY. IS TO BRING THf SOIL PH TO 4.0 - «.S-
MULTIPLY THE (XCHANOAILE ACIDITY IV 1OOO TO ESTIMATI THE LIME RSOUIIISUMT fOR
PH t.S • 7.0.
. RECOMMENDED LIMESTONE CONTAINING .Tt MOO HILL MtlT TNI MC *E«JI«IltINT .
• IF MANURE MILL BE APPLIED. SEC ST-1O *VJSI OF MANURE*
tar
i.a
LABORATQRV RESULTS
6.2
SOIL pM
50
P lb/A
4.1
ACXDXTY
0.19
0.6
1.8
12.6
CXC
EXCHA»CEAILE CAT! PUS (tieq/lOO 9>
1.5
4-'
«*•*
OTHEK TESTS. ORCAHJC KATrER - 2.2
Chapter 4A-56:10/98
-------
Chapter 4A: Nutrient Management 57
Figure 4a-5. Example of Penn State's soil quicktest form (Pennsylvania State University, 1992a).
PENNSWE
PRE-SIDEDRESS SOIL NITROGEN TEST FOR CORN
QUICKTEST EVALUATION PROJECT
- SOIL TEST INFORMATION AND REPORT FORM -
tnUT CHILD. N0.t
torr.iuri.AM> apt
I ANALYZED §Tl
B««t lint* to call (8 urn • 4 30 pen):
Please answer til o< the following questions about this Held:
1. What is (he field ID (name or number)? . Com Height in.
2. What is the expected yield of the com crop (bu/A or torvA) in this field?
3. What was the previous crop?
If this was a forage legume what was the % stand?
(check one): Q 0-25% D 25-50% Q 50-100%
4. Was manure applied to this field? Q Yes Q No II-yes'answer the following questions:
When? Q Fall Q Spring Q] Both Q Daily
Type? ncattte n p°u||ry n Swin« n *>«• o shee»>
Estimate manure rate: tons/acre - OH - gallons/acre
If incorporated how many days were there between spreading and incorporation?
5. What is the tillage program on this field? Q Conventional Tillage Q Minimum Tillage Q No-till
6. What would be your normal N fertilizer application rate lor this field? fcs. N/acra
Quicktest Analysis Result & Recommendation
individual Avarage Soil
M«tar R«iding« Average meter Conversion standard Nltrate-N
reading factor reading (ppm)
20
Sidedress N Fertilizer
Recommendation
(See table and guideline* on back of form)
Ibs. N/acre
If you h«v« «ny qumtlon* about thl* te«* contact your Pvnn 3t»t» Coep«r>ttv» Extension Office
White copy- Grower
Yellow copy- Analytt
Pink copy- Agronomy Extension
Chapter 4A-57: 10/98
-------
58 Chapter 4: Management Measures
(11) Use of buffer areas or intensive nutrient management practices to address
concerns on fields where the risk of environmental contamination is high, such
as:
O Karst topographic areas containing sinkholes and shallow soils over frac-
tured bedrock, .
O Lands near surface water,
O High leaching index soils,
O Irrigated land in humid regions,
O Highly credible soils,
D Lands prone to surface loss of nutrients, and
D Shallow aquifers.
For example, nitrification inhibitors may be needed when conditions promote
leaching, and banding or ridge application may render applied N or P less
susceptible to leaching. Manure should not be applied to frozen or saturated
soils, to shallow soils over fractured bedrock, or to excessively drained soils.
12) Use soil erosion control practices to minimize runoff and soil loss.
13) Calibrate nutrient application equipment regularly.
(14) A narrative accounting of the nutrient management plan that explains the plan
and its use.
The best means for implementing and coordinating many of the above activi-
ties is through a comprehensive, site-specific nutrient management plan. Nutrient
management plans should be reviewed annually to determine if modifications are
needed for the next crop, and a thorough review of the plan should be done at least
once every 5 years or once per crop rotation period. Application equipment should
be calibrated and inspected for wear and damage periodically and repaired when
necessary; Records of nutrient use and sources should be maintained along with
other management records for each field. This information will be useful when it is
necessary to update or modify the management plan.
A list of the required nutrient management plan elements for confined animal
operations in the Pequea-Mill Creek (PA) National Monitoring Program project is
shown Table 4a-12. Table 4a-13 shows a set of nutrient recommendations from a
Vermont Crop Management Association. Table 4a-14 shows two summary tables
from a sample plan.
Practice .
Effectiveness
Following is a summary of information regarding pollution reductions that
can be expected from installation of nutrient management practices.
O The State of Maryland estimates that average reductions of 34 pounds of
nitrogen and 41 pounds of phosphorus per acre can be achieved through the
implementation of nutrient management plans (Maryland Department of Agri-
culture, 1990). These average reductions may be high because they apply
mostly to farms that use animal wastes; average reductions for farms that use
only commercial fertilizer may be lower.
Chapter 4A-58: 10/98
-------
Chapter 4A: Nutrient Management 59
Table 4a-12. Required nutrient management plan elements for confined animal operations in the
Pequea-Mill Creek National Monitoring Program project, Pennsylvania.
A. Farm Identification
including location, receiving waters, size of operation, and farm maps of fields, soils, and slopes_
6. Summary of Plan
Manure summary, including annual manure generation, use, and export
Nutrient application rates by field or crop
Summary of excess manure utilization procedures
Implementation schedule
Manure management and stormwater BMPs
C. Nutrient Application
Inventory of nutrient sources
Animal populations
Acreage and expected crop yields for each crop group
. Nutrients necessary to meet expected crop yields
Nutrient content of manure
Nitrogen available from manure
Residual N from legumes and past manure applications
Planned manure application rate
Target spreading rates for manure application
Nitrogen balance calculation
Winter manure spreading procedures (if applicable)
D. Alternative Manure Use
Amount, destination, and use of manure exported to other landowners, brokers, markets, or used
in other than agricultural application
E. Barnyard Management
F. Storm Water Runoff Control
Source: Penn State Cooperative Extension. 1997. Pequea-Mill Creek Information Series. Smoketown, PA.
Table 4a-13. Missisquoi Crop Management Association 1997 nutrient recommendations.
Crop
Manure
Field Applied Recom.
Name Acres In Fall Manure
Loads
/Field
Rate 3375 gal Ib/A
Corn
Alfalfa
New
Seeding
Grass
1st Cut
Grass
2nd Cut
#7
#9A
#11
Spooner 3
#1
#3
#1
#3
9.7 9742
11.3 2000
20.0 5625
4.3
10.0
10.8 7986
10.0
10.8
0
or 3737
5226
8798
3333
orO
4135
or 0
0
0
3755
0 150
11 150
17 150
52 250
300
12
200
200
12
After Manure & Fertilizer
—Recommended Fertilizer — Remaining Need — Lime
N
10
10
10
10
5
23
23
P205
20
20
20
20
NONE
10
NONE
0
NONE
0
NONE
K20 Micronutrients
20 with 1.33% Zinc
20 with 1.33% Zinc
20 with 1.33% Zinc
20 with 0.8% Zinc
30 with 0.6% Boron
30
30
N
47
0
0
0
0
0
0
0
6
0
0
P205 K20
0
0
0
0
o s
0
0
0
0
0
0
0
0.
0
0
0
. 0
26
40
0
0
0
Mg Need
0
0
0
0 .2.0
0 2.0
0 2.0
0 1.0
0
0
0
0
Chapter 4A-59:10/98
-------
60 Chapter 4: Management Measures
Table 4a-14. Plan Summary from a Sample Plan (Pennsylvania State University
Cooperative Extension, 1997).
Manure Summary Table
Manure Source
liquid dairy
uncollected solid dairy
collected solid dairy
solid poultry
Generated
on the Farm
523,000 gal
263 tons
175 tons
1,860 tons
Used on the Farm
523,000 gal
263 tons
175 tons
0 tons
Nutrient Application Rates by Crop Group
Starter Fertilizer
Nutrients
(Ibs per acre)
N P205 K20
Crop Group
Corn, grain
(liquid manure)
Com, grain
(liquid manure)
Corn, silage
(liquid manure)
Corn, silage
(solid manure)
Alfalfa (new)
Alfalfa .
Acres
32
18
12
9
21
53
10 20
10
20
20 20
20
10
0
20
20
0
10
10
10
10
10
0
Planned
Manure
Application
Rate/ac.
9,000 gal
9,000 gal
6,000 gal
20 tons
0
0
When
Manure
Applied
(incorp. time)
spring
(2-4 days)
fall
(2-4 days)
fall
(2-4 days)
fall/spring
(2-4 days)
Exported
from the Farm
0 gal
0 tons
0 tons
1,860 tons
Additional Chemical
Fertilizer Nutrients
Applied
P205 K20
N
50
0
0
0
0
40
120
20
230
200
- All numbers rounded off recognizing the built-in variation in figures used.
- Manure application is restricted in the following areas:
a) within 100 feet of the farm well (field A-13) and the neighbor's well (field A-7), where surface
flow is towards the well (unless the manure is incorporated within 24 hours of application, in
which case manure application rates and supplemental fertilizer needs may need to be adjusted)
b) within 100 feet of Little Fishing Creek when the ground is frozen, snow-covered, or saturated
(fields A-2 and A-3)
c) within the grassed waterway when the ground is frozen, snow-covered, or saturated (fields A-1
and A-2)
As of July 1990, the Chesapeake Bay drainage basin states of Pennsylvania,
Maryland, and Virginia had reported that approximately 114,300 acres (1.4%
of eligible cropland in the basin) had nutrient management plans in place
(EPA, 199la). The average nutrient reductions of TN and TP were 31.5 and
37.5 pounds per acre, respectively. The States initially focused nutrient man-
agement efforts on animal waste utilization. Because initial planning was
focused on animal wastes (which have a relatively high total nitrogen and
phosphorus loading factor), estimates of nutrient reductions attributed to nu-
trient management may decrease as more cropland using only commercial
fertilizer is enrolled in the program.
In Iowa, average corn yields remained constant while nitrogen use dropped
from 145 pounds per acre in 1985 to less than 130 pounds per acre in 1989
and 1990 as a result of improved nutrient management (Iowa State University,
Chapter 4A-60:10/98
-------
Chapter 4A: Nutrient Management 61
1991b). In addition, data supplied from nitrate soil tests indicated that at least
32% of the soils sampled did not need additional nitrogen for optimal yields
(Iowa State University, 1991b).
O Data from the 66,640-acre Big Spring ground water basin in northeastern Iowa
indicate that reduced application of nitrogen fertilizer associated with the_1983
payment-in-kind set-aside program resulted in reduced nitrate levels in ground
water two years later (Hallberg et al., 1993). Based upon this analysis, it is
postulated that water quality improvements at the watershed level will be defin-
able over time in responsive ground water systems if significant changes in
nitrogen application are accomplished across the watershed.
O In a pilot program in Butler County, Iowa, 48 farms managing 25,000 acres
reduced fertilizer nitrogen use by 240,000 pounds by setting realistic yield goals
based on soils, giving appropriate crop rotation and manure credits, and some
use of the pre-sidedress soil nitrate test (Hallberg et al., 1991). Other data from
Iowa showed that in some areas fields had enough potassium and phosphorus to
last for at least another decade (Iowa State University, 1991b).
O In Garvin Brook, Minnesota, fertilizer management on com resulted in nitrogen
savings of 29 to 49 pounds per acre from 1985 to 1988 (Wall et al., 1989). In
this Rural Clean Water Program (RCWP) project, fertilizer management con-
sisted of split applications and rates based upon previous yields, manure appli-
cation, previous crops, and soil test results.
P Baker (1993) concluded that the downward trends in total and soluble phospho-
rus loads from Lake Erie tributaries for the period from the late 1970s to 1993
indicate that agricultural controls have been effective in reducing soluble phos-
phorus export. Tributary nitrate concentrations increased, however, possibly
due to adoption of conservation tillage.
O Berry and Hargett (1984) showed a 40% reduction in statewide nitrogen use
over 8 years following introduction of improved fertilizer recommendations in
Pennsylvania. Findings from the RCWP project in Pennsylvania indicated that,
for 340 nutrient management plans, overall recommended reductions (corn, hay,
and other crops) were 27% for nitrogen, 14% for phosphorus, and 12% for
potash (USDA-ASCS, 1992a). Producers achieved 79% of the recommended
nitrogen reductions and 45% of the recommended phosphorus reductions. In the
same project area, Hall (1992) documented 8 to 32% decreases in median ni-
trate concentrations in ground water samples following decreases of 39-67% in
N application rates under nutrient management.
O Base flow concentrations of dissolved nitrate-nitrite from a 909-acre
subwatershed under nutrient management decreased slightly relative to a 915-
acre paired subwatershed in the Little Conestoga Creek watershed in Pennsyl-
vania, suggesting that nutrient management had a positive impact on water
quality (Koerkle et al., 1996). Nutrient applications in the 909-acre treated
subwatershed (study site) decreased in the period 1986-1989 by about 30%
versus the period 1984-1986 (pre-implementation) as 85% of the land was
placed under nutrient management. Less than 10% of the land was under nutri-
ent management in the 915-acre untreated subwatershed (control site). The
study was extended for two years to improve upon the findings, but implemen-
tation at the control site resulted in nutrient management on 40% of agricultural
land, while implementation for the study site stood at 90% (Koerkle and
Chapter 4A-61:10/98
-------
62 Chapter 4: Management Measures
Gustafson-Minnich, 1997). Nitrogen applications for the period 1989-1991
were about 7% less than for the period 1984-1986 at the study site, a much
smaller decrease than the 30% decrease reported for the period 1986-1989.
^Nutrient application data were not available for the control site. The lack of
statistically significant reductions in dissolved nitrate-nitrite for the period
1989-1991 versus 1984-1986 is interpreted as an indication that a reduction in
nitrogen input of 30% (as achieved in 1986-1989) is needed to cause a 0.5
mg/L decrease in dissolved nitrate-nitrite.
A related study in the Conestoga River headwaters, Pennsylvania, showed that
nutrient management caused statistically significant decreases in nitrate con-
centrations in ground water (Hall et al., 1997). Changes in nitrogen applica-
tions to the contributing areas of five wells were correlated with nitrate
concentrations in the well water on a 55-acre crop and livestock farm in car-
bonate terrain. Lietman et al. (1997) showed that terracing decreased sus-
pended-sediment yield as a function of runoff, but also increased nitrate-nitrite
yields in runoff, and increased nitrate concentrations in ground water at 4 of
the wells on a 23.1 -acre site.
A 6-year study in the 403-acre Brush Run Creek watershed in Pennsylvania
showed that monthly and annual base flow loads of total nitrogen, dissolved
nitrite-nitrate, total ammonia plus organic nitrogen, and total and dissolved
phosphorus and orthophosphorus decreased during the 3-year period when
nutrient management was implemented (Langland and Fishel, 1996). How-
ever, stormflow discharges of total nitrogen and total phosphorus increased by
14 and 44%, respectively, while nitrogen and phosphorus applications were
reduced by 25 and 61 %. Fewer storms were sampled during two of the three
years under nutrient management due to a significant decrease in precipitation
during the growing seasons. Maximum total nitrogen concentrations were 21
mg/L above the tile drains before nutrient management, and 2,400 mg/L in the
tile drains before nutrient management (Langland and Fishel, 1996). Median
concentrations of total nitrogen and dissolved nitrite-nitrate were reduced from
3.3 and 1.2 mg/L, respectively, to 2.5 and 0.90 mg/L when nutrient manage-
ment was applied above the tile drains. Nutrient management in this tile-
drained watershed resulted in a 14% decrease in nitrogen and 57% decrease in
phosphorus applied as commercial and manure fertilizer.
In Vermont, research suggested that a newly introduced, late spring soil test
resulted in about a 50% reduction in the nitrogen recommendation compared
to conventional technologies (Magdoff et al., 1984). Research in New York
and other areas of the nation documented fertilizer use reductions of 30 to
50% for late spring versus preplant and fall applications, with yields compa-
• rable to those of the preplant and fall applications (Bouldin et al., 1971).
Improved nutrient management on a case-study group of 8 United States De-
partment of Agriculture (USDA) Demonstration Projects (DP) and 8 Hydro-
logic Unit Area (HUA) Projects resulted in reported nitrogen application
reductions ranging from 14 to 129 Ib/acand phosphorus application reduc-
tions of 0 to 106 Ib/ac (Table 4a-l 5). The case study group included both
animal and crop agriculture and both irrigated and non-irrigated cropland.
A summary of the literature findings regarding the effectiveness of nutrient
management in controlling nitrogen and phosphorus is given in Table 4a-16.
Chapter 4A-62: 10/98
-------
Chapter 4A: Nutrient Management 63
Table 4a-15. Reported Changes in average annual nutrient application rates on land with practice
adoption in 19 USDA Demonstration and Hydrologic Unit Area Projects, 1991-1995.
Project
ALHUA
INHUA
MIHUA
NYHUA
UT HUA
DEHUA
IL HUA
OR HUA
MDDP
NCDP
Wl DP
FLOP
MNDP
NEDP
TXDP
CADP
Nitrogen Reductions
Purpose1 (Ib/ac)
N, P 129
N, P 21
N, P 41
N,P 14
P —
N, P 118
N, P 117
N 52
N, P 43
N, P 72
N, P 78
N,P 14
N, P 30
N ' 21
N, P 21
N, P 47
Phosphorus Reductions
(Ib/acl
106
30
18
21
0
96
36
42
n/a
18
3
21
18
11
1 Nutrients to be controlled as project objective: N=nitrogen, P=phosphorus
— = data not applicable
n/a = data not available
Source: Meals, D.W., J.D. Sutton, and R.H. Griggs. 1996. Assessment of Progress of Selected
Water Quality Projects of USDA and State Cooperators. USDA-NRCS, Washington, D.C.
Table 4a-1G. Relative effectiveness3 of nutrient management (Pennsylvania State
University, 1992b).
Practice
Nutrient Management"
Percent Change in Total
Phosphorus Loads
-35
Percent Change in Total
Nitrogen Loads
-15
• Most observations from reported computer modeling studies
"An agronomic practice related to source management; actual change in contaminant load to surface and
ground water is highly variable.
Factors in Selection of Management Practices
The movement of available nutrients to surface and/or ground waters
depends on the properties of the nutrients involved, climate, soil and geologic
characteristics, and land management practices such as crops grown, fertilizer
applications, erosion control, and irrigation water management. These factors
determine which specific strategies and practices should be selected to reduce
nutrient movement in a given situation. Land management practices such as selec-
tion of fertilizer formulation or rate and method of application can be controlled,
while environmental factors such as climate cannot. Other factors, such as crop
selection and farming equipment, are governed to varying degrees by economic
considerations and may therefore limit nutrient management options in some
cases.
Chapter 4A-63:. 10/98
-------
64 Chapter 4: Management Measures
Care should be taken that practices to control surface runoff do not increase
the risk of ground water contamination, and vice versa. In general, practices that
increase the efficiency of nutrient use and thereby reduce availability of nutrients
for loss are the first line of defense in nutrient management. Control of detachment
and transport of nutrients in the particulate phase and of runoff and leaching of
soluble forms may be achieved with other practices or management.measures,
including erosion and sediment control and irrigation water management.
The characteristics of the agricultural operation are critical considerations in
selection of appropriate practices for nutrient management. Specific nutrient man-
agement practices will differ markedly, for example, between a large grain farm,
where all nutrients are supplied by purchased fertilizer and can be applied by pre-
cision farming methods, and a small dairy farm, where nutrients are supplied by
animal waste, legumes, and purchased fertilizer, and exact nutrient balance is
difficult to achieve. The equipment and facilities available to the producer, such as
manure or fertilizer application equipment and the type of waste storage system
influence both the form of the nutrients and the producer's ability to efficiently
'manage the nutrients.
Effective nutrient
management will
not transfer
problems from
surface to ground
water, or vice versa.
Climatic and other environmental conditions such as soils and geology are
key determinants in the selection of practices. For example, the need for irrigation
to grow crops in the Columbia Basin of Washington places a premium on careful
scheduling of fertigation to protect ground water below sandy soils (Annandale
and Mulla, 1995), whereas the yield variability in midwestern clay pan soils makes
"on-the-go" changes in fertilizer application rates essential to maximizing the
efficiency of N uptake (Kitchen et al., 1995). In addition, local environmental
factors, such as the presence of sensitive or protected waterbodies, may require
additional practices such as buffer strips or vegetative filter strips to reduce deliv-
ery of nutrients lost from agricultural land.
Local and regional agricultural economies and land use mix can also be im-
portant factors in selecting nutrient management practices. In livestock agricul-
ture, the available land base with respect to animal populations may limit the
potential for full use of manure nutrients on farm land and require efforts to export
manure from an area in order to follow a nutrient management plan. Proximity to
residential and urban centers can offer opportunities for exporting manure nutri-
ents, but may also limit some forms of nutrient management due to odor problems
or other perceived nuisances.
Finally, a range of issues such as the availability of soil, manure, and plant
testing services; the availability of nutrient management consultants; the opportu-
nity for producer training; the availability of rental equipment for specialized op-
erations; and State, Tribal, and local laws and regulations may all affect the
selection of best management practices for any given location.
Cost of Practices
In general, most of the costs for this management measure are associated
with technical assistance to landowners to develop nutrient management plans.
Some costs are also involved in ongoing nutrient management activities such as
soil, manure, and plant tissue testing. Technical assistance in nutrient management
is typically offered by universities, farm service dealers, and independent crop
consultants. Rates vary widely depending on the extent of the service and type and
Chapter 4A-64: 10/98
-------
Chapter 4A: Nutrient Management 65
value of the crop. Fees can range from about $5 per acre for basic service up to
$30 per acre for extensive consultation on high-value crops (NAIGC, 1998).
Typical nutrient management costs for Vermont dairy farms begin with a
$150 fixed charge for a nutrient management plan. There is an additional $6 per
acre for corn land, which includes record-keeping for manure, fertilizer, and pesti-
cide applications, soil analysis for each field, manure test, and a PSNT; cost for
grassland is $4 per acre, which includes the same services as for corn fields except
the PSNT (Stanley, 1998).
In Pennsylvania, where state law requires extensive nutrient management
planning, charges for development of a plan range from $400 to $900. Specific
costs vary from around $3 to $4 per acre for a "generic" plan without soil sam-
pling or weed and insect control recommendations, up to $8 to $12 per acre for a
complete plan with full scouting (Craig, 1998).
In Maryland, again subject to a recent state law requiring all farms to have
nutrient management plans, average costs across the state are about $3 per acre,
which includes writing the plan, technical recommendations on fertilization and
waste management, maps, and record-keeping (MDA, 1998). Soil and manure
testing are additional costs, at $2 to $5 per analysis.
Charges listed by an Illinois crop consultant range from $5 to $15 per acre
for services including scaled maps, manure analysis, soil testing, and site specific
recommendations for fertilizer and manure applications (Cochran, 1998).
A Wisconsin agronomic service charges $5 to $8 per acre for nutrient man-
agement services that include farm aerial maps; identification of fields with ma-
nure spreading restrictions; soil test reports; animal inventory with manure
analysis; written plans for each field specifying crop to be grown, previous crop
grown, fertilizer recommendations, legume and manure credits, manure applica-
tion rates, and record-keeping sheets; and regular field scouting (Polenske, 1998).
In Nebraska, a crop consulting service charges $5 per acre for basic soil
fertility and pest and water management, another $4 per acre for precision-farming
GPS grid samples, plus a separate soil analysis charge (Michels, 1998).
»,
In many instances landowners can actually save money by implementing
nutrient management plans. For example, Maryland estimated (based on the over
750 nutrient management plans that were completed prior to September 30,1990)
that plan recommendations would save the landowners an average of $23 per acre
per year (Maryland Dept. of Agriculture, 1990). This average savings may be
high because most of the 750 plans were for farms using animal waste. Savings
for farms using commercial fertilizer may be less.
In the South Dakota RCWP project, the total cost (1982-1991) for imple-
menting fertilizer management on 46,571 acres was $50,109, or $1.08 per acre
(USDA-ASCS, 199la). In the Minnesota RCWP project, the average cost for
fertilizer management for 1982-1988 was $20 per acre (Wall et al., 1989). As-
suming a cost of $0.15 per pound of nitrogen, the savings in fertilizer cost due to
improved nutrient management on Iowa com was about $2.25 per acre as rates
dropped from 145 pounds per acre in 1985 to about 130 pounds per acre in 1989
and 1990 (Iowa State University, 199la).
Chapter 4A-65: 10/98
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66 Chapter 4: Management Measures
Chapter 4A-66:10/98
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Chapter 4B: Pesticide Management 67
4B: Pesticide Management
Six general
principles guide
safe pesticide
management.
Pesticide
management
consistent with this
management
measure is based on
pesticide application
only when an
economic benefit is
anticipated.
Management Measure for Pesticide Management:
To reduce contamination of ground and surface water from pesticides:
1. Evaluate the pest problems, previous pest control measures, and cropping
history.
2. Evaluate the soil and physical characteristics of the site including mixing,
loading, and storage areas for potential leaching or runoff of pesticides. If
leaching or runoff is found to occur, steps should be taken to prevent further
contamination.
3. Use integrated pest management (IPM) strategies that
D apply pesticides only when an economic benefit to the producer will be
achieved (i.e., applications based on economic thresholds), and
D apply pesticides efficiently and at times when runoff losses are least likely.
4. When pesticide applications are necessary and a choice of registered materials
exists, consider the persistence, toxicity, runoff potential, and leaching poten-
tial of products in making a selection.
5. Periodically calibrate pesticide spray equipment.
i
6. Use anti-backflow devices on the water supply hose, and other safe mixing
and loading practices such as a solid pad for mixing and loading, and various
new technologies for reducing mix and load risks.
Management Measure for Pesticide Management:
Description
The goal of this management measure is to reduce contamination of ground
and surface water from pesticides. The basic concept of the pesticide management
measure is to foster effective and safe use of pesticides without causing degrada-
tion to the environment. The most effective approach to reducing pesticide pollu-
tion of waters is, first, to release a lesser quantity of and/or less toxic pesticides
into the environment and, second, to use practices that minimize the movement of
pesticides to ground and surface water (Figure 4b-l). In addition, pesticides
should be applied only when an economic benefit to the producer will be achieved.
This usually results in some reduction in the amount of pesticides being applied to
the land, plants, or animals, thereby enhancing the protection of water quality and
possibly reducing production costs as well.
The pesticide management measure identifies a series of steps or thought
processes that producers should use in managing pesticides. First, the pest prob-
lems, previous pest control measures, and cropping history should be evaluated for
pesticide use and water contamination potential. Second, the physical characteris-
tics of the soil and the site, including mixing, loading, and storage areas, should be
evaluated for leaching and/or runoff potential. Integrated pest management (IPM)
strategies should be used to minimize the amount of pesticides applied. In rare
cases, IPM practices may not be available for some commodities or in certain
Chapter 46-67:10/98
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Chapter 4B: Pesticide Management 67
regions. An effective IPM strategy should call for pesticide applications only when
an economic benefit to the producer will be achieved. In addition, pesticides
should be applied efficiently and at times when runoff losses are unlikely.
Figure 4b-1.
Pesticide labels
must be followed.
Calibrating
equipment saves
money and reduces
damage to the
environment.
Pesticide Fate: Major Pathways
When pesticide applications are necessary and a choice of materials exists,
producers are encouraged to choose the most environmentally benign pesticide
products. State Cooperative Extension Service specialists may be able to assist
producers in this selection process.
Users must apply pesticides in accordance with the requirements on the label
of each pesticide product. Label instructions include the following: allowable use
rates; whether the pesticide is classified as "restricted use" for application only by
certified and trained applicators; safe handling, storage, and disposal require-
ments; whether the pesticide can be used only under the provisions of an approved
Pesticide State Management Plan; and other requirements.
At a minimum, effective pest management requires evaluating past and cur-
rent pest problems and cropping history; evaluating the physical characteristics of
the site; applying pesticides only when an economic benefit to the producer will be
achieved; applying pesticides efficiently and at times when runoff losses are un-
likely; selecting pesticides (when a choice exists) that are the most environmentally
benign; using anti-backflow devices on hoses used for filling tank mixtures; and
providing suitable mixing, loading, and storage areas.
Pest management practices should be updated whenever the crop rotation is
changed, pest problems change, or the type of pesticide used is changed. Applica-
tion equipment should be calibrated and inspected for wear and damage each
spray season and repaired when necessary. Anti-backflow devices should also be
inspected and repaired each spray season.
Chapter 46-67:10/98
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Chapter 4B: Pesticide Management 69
Pesticides: An Overview
Why are :
pesticides used in agriculture?
Pests have affected crop production since man first started planting seeds.
Crop damage from insects, fungi, and weeds can reduce yields or even kill the
crop in some cases. As a result, farmers have aways sought ways to reduce this
damage. Pest control using chemicals such as sulfur or plant extracts has been
around for thousands of years. The first synthetic pesticides were discovered in
the late 1930s and early 1940s and thousands have been developed since.
Pesticide use became widespread in part because the early results were so
promising. Pests which farmers had battled for centuries seemed to be eliminated
quickly and easily with these sprays. In many cases, less labor was required to
produce a crop since hand or mechanical weeding was no longer necessary. As a
result, yields increased and more acres could be managed by a farmer.
One problem which turned up very quickly was pest resistance to the chemi-
cals. When large areas are regularly sprayed with a pesticide, sooner or later
target pests can develop a resistance and are no longer controlled by the chemical.
This resulted in disastrous levels of pests which devastated crops. It was learned
later that this problem can be reduced by spraying only when necessary and using
different pesticides when possible.
Another problem was the effect of pesticides on non-target organisms, which
were inadvertantly exposed through the food chain. Many of the first pesticides
were persistent in the environment and accumulated in animals which consumed
contaminated insects or fish. As a result of this problem, most modem pesticides
are much less persistent and do not accumulate in the food chain.
What are •_.
pesticides?
Pesticides are chemicals which are used to protect crops against damaging
organisms. They are generally divided into four categories according to the target
pests:
Insecticides are targeted at insect pests. There are many kinds of insecticides
in use today. They may be applied to the soil to protect roots, seeds, or seedlings.
They may also be applied to the crop to protect stems, leaves, or fruit. Some of
the most common insecticides include chlorpyrifos, diazinon, and carbaryl. Many
insecticides kill the insects by disrupting their nervous system, resulting in paraly-
sis and death. Unfortunately, they can have the same effect on non-target insects
or fish and animals if enough of the applied product drifts or washes from the
field.
Herbicides are used to control weeds in crops. Up to 80% of all pesticides
sold are herbicides and they are used in most crop production systems. Weed
control is usually the single most effective practice to increase yields. Herbicides
can be selective, killing the weeds but not the crop, such as atrazine in com or
trifluralin in soybeans. Other herbicides are non-selective/killing all plants they
contact, such as glyphosate or paraquat. Most herbicides are relatively non-toxic
to insects, fish, or animals because only plants have the systems which are af-
fected.
Chapter 4B-69:10/98
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70 Chapter 4: Management Measures
Fungicides are used to control fungi which cause disease in crops. They are
applied to seeds, to soil, or to the crop to prevent or slow disease when conditions
are favorable for the fungus. Fungicides are used primarily on high-value food
crops and in turf and ornamental plant maintenance. They generally kill the fun-
gal spores before they can germinate and infect the plant. Fungicides such as
benomyl, metalaxyl, and chlbrothalonil are used for a wide variety of crops, turf;
and ornamental plants. They are generally non-toxic to insects, fish, or animals.
Nematicides are targeted at nematodes which infect plant roots and stunt or
kill the crop. They are always applied to the soil as that is where the target oc-
curs. Nematicides are generally non-selective, killing most everything they contact
in the soil.
What are the '
risks to water quality?
o
There are several potential problems caused by pesticides reaching surface or
ground water. The most severe case would be when enough of the pesticide
reaches (a body of water to kill fish or other organisms in the water. This is called
acute toxicity as it causes an effect very quickly, in a matter of hours or days.
Most of these cases are caused by insecticides which drift or wash from fields
soon after application. As noted above, insecticides tend to be much more acutely
toxic than other pesticides.
The most widespread problem is the occurrence of pesticides in surface and
ground water used for drinking water. Because this may result in many people
being exposed to the pesticide through their drinking water, there are concerns
about chronic toxicity in these groups. This is when the exposure occurs over
many years at concentrations which cause no outward effects, but which may
increase cancer or other disease risks. Studies have shown that it is highly im-
probable that the types and concentrations of pesticides found in drinking water
pose significant risks. However, most agree that it is prudent to minimize or
eliminate pesticide occurrence in drinking water supplies.
Pesticide Movement into Surface and Ground Water
Pesticides can reach ground and surface water in a number of ways. Surveys
of ground and surface water have found pesticides in many areas of the country.
The extent of the contamination is often well defined, but the source or sources of
contamination can be quite elusive in some cases. Figures 4b-2 to 4b-4 illustrate
the major environmental fates of pesticides and are indicative of how difficult it is
to quantitatively assess pesticide fate. However, the sources and problems associ-
ated with ground and surface water contamination are described in the following
section.
Movement to
Surface Water
Importance of pesticide contamination of surface water: About half of the
population in the United States gets its water from surface sources. Therefore,
pesticide contamination of surface water is of great concern to many. Several
studies have shown that water supply reservoirs in the Midwest routinely exceed
the health limits for pesticides, although these levels often only occur briefly in
Chapter 48-70:10/98
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Chapter 4B: Pesticide Management 71
late spring after the main application season. Typical treatment systems will not
remove most pesticides from water, and the costs of systems that will remove
pesticides is substantial.
Losses of pesticides to runoff generally range from <1 to 5% of applied
amounts, depending on various factors. Losses are usually greatest in the 1-to 2
weeks after application, and are highly dependent on storm events. Often, pesticide
residues are only detectable in the first storm event after application.
Pesticides can enter surface water from the atmosphere in the form of drift or
rainfall. Drift into surface waters can be serious locally if the pesticide is highly
toxic to aquatic organisms, as in the case of many insecticides. Rain and fog have
been shown to contain pesticide residues, particularly during the spring planting
season. However, neither drift nor rain are major contributors to surface water
contamination when compared to runoff.
Figure 4b-2.
Pesticide Fate-
Losses To The Atmosphere: 0-30%
Depends On:
• weather (wind, temperature)
• formulation and additives that
affect droplet size
•pesticide properties
•application equipment
Volatilizing Into Air
Good soil and water
management are
also essential for
effective pesticide
management.
Most pesticide contamination of streams, lakes, and estuaries occurs as a
result of runoff from agricultural and urban areas. Runoff carries with it a mix of
suspended soil particles and any pesticides which were either attached to the par-
ticles or dissolved in surface moisture just before runoff began. The amount of
pesticide loss due to runoff is affected by the following factors:
Rain Intensity — Heavy downpours result in minimal infiltration and maxi-
mum runoff. If soil is already moist prior to a rainfall event, then runoff will be
greater since the soil's capacity to store additional water is reduced.
Surface Conditions — Recently tilled soil and soil with good ground cover
have the most resistance to runoff, since water infiltrates relatively easily and the
surface is "rough", enough to impede the flow of water. Maximum runoff potential
occurs during the month after planting, since the soil is exposed and the crop has
Chapter 46-71:10/98
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72 Chapter 4: Management Measures
not grown large enough to intercept rain and reduce its ability to detach and trans-
port soil particles. Reduced tillage practices will decrease runoff relative to con-
ventional tillage practices that leave the soil bare at planting.
Figure 4b-3.
Pesticide Fate: Plant
Depends On:
•spray timing (plant size and cover)
•pesticide properties/formulation and
additives
•application equipment
•crop properties
•foliar applied materials often just remain on
plant surface and degrade or are washed off
Foliar uptake impeded by leaf hairs anil cuticle
Much of the spray misses the plant or is washed off
Root uptake is low because roots
do not penetrate most of the soil.
Figure 4b-4.
Pesticide Fate: Soil 50-100%
Majority of Applied Material Ends Up In Soil
•Directly applied to soil such as with
preemergent herbicides and fumigants
•Spray that misses target or washes off
(?) (ft
Major Pathways:
•adsorbtion to clay and/or organic matter
•chemical or microbial degradation
o-
•leaching or runoff: usually <1% of applied but
this can still produce measurable residues in
water.
Chapter 46-72:10/98
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Chapter 4B: Pesticide Management 73
Length of Slope — Longer field slopes increase runoff energy, and the trans-
port of soil and pesticides.
Method of Application — Pesticides tilled or injected into the soil are less
likely to be lost in runoff, although the disturbance of the soil by tilling or injection
may increase soil (and attached pesticides) losses. Large losses of foliar pesticides
in runoff can result if a heavy downpour occurs soon after application.
Timing — If a runoff event occurs soon after the pesticide is applied, sub-
stantial losses can occur.
Vegetated Borders and Buffers — The beneficial effects of grassed borders
can be quite substantial, with reductions of pesticide movement into adjoining
streams ranging from 80 to 90%. The combination of infiltration, reduced over-
land flow rates, and adsorption in these zones can be quite effective in keeping
pollutants in field runoff from being delivered to waterways.
It is important to emphasize that buffers function only under conditions of
overland or sheet flow. Pesticides in runoff which moves through a buffer in a
ditch or channel have little opportunity to degrade or adsorb before delivery to
surface water.
Pesticide Degradation in Surface Waters — Once pesticides enter surface
water, their rate of degradation slows considerably compared to degradation rates
in soils. A portion of the pesticide will adsorb onto the sediment and remain there
until a flood event moves the sediment back into the moving water. This cycle of
deposition and re-suspension is one of the mechanisms responsible for the pres-
ence of low levels of pesticides long after the application season.
Movement to •_ ._
Ground Water
Importance of pesticides in ground water: Since approximately half of the
people in the U.S. drink water from wells, ground water protection is very impor-
tant. Once a pesticide reaches ground water, it is very slow to degrade or flush
out, so prevention is very important.
Movement of pesticides into ground water can occur through leaching after
normal applications or by more direct pathways not related to normal uses (i.e.
spills and direct contamination):
O Leaching — Pesticides can be moved downward toward ground water as rain
or irrigation water percolates through the soiL Such a leaching process is
controlled by the properties of the pesticide, the properties of the soil, and the
weather.
Pesticide Properties: There are hundreds of pesticides and each one has a
unique set of properties which determine if it is more or less likely to con-
taminate ground water. The most important are:
Persistence: measured in amount of time require for 50% to be de-
graded (half-life). The more persistent a chemical, the more likely it
will find its way into ground water.
Adsorption: measured by how much of the chemical binds to soil
when shaken in water. The greater the adsorption ability of a pesti-
Chapter 46-73:10/98
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74 Chapter 4: Management Measures
cide, the less likely it will leach through the soil.
Application Rate and Method: measured in amount of active ingredi-
ent applied per acre. Pesticides requiring higher application rates may
have an increased chance of leaching into ground water. Pesticides
applied to growing crops are less likely to have the opportunity to
leach than those applied to the soil.
Soil Properties: Pesticides often are applied to, or wash into, soils, where
they may be adsorbed, degraded, or leached into shallow ground water.
The properties of the soil that most influence these processes are:
Organic Matter: measured as a fraction of the soil by weight. Most
pesticides bind tightly to organic matter in soil so higher organic mat-
ter contents reduce the risk of leaching.
Clav: measured as a fraction of the soil by weight. Clay can bind
many pesticides and it tends to reduce or slow the movement of perco-
lating water. These two effects combined result in lower leaching risk
with increasing clay content.
pH: measured on a scale of 0-14, with most soils falling in the 5-8
range. Generally, lower pH values will reduce leaching of pesticides
and increase their rate of degradation.
Depth to Ground Water: not exactly a soil property but often closely
related. The farther pesticide residues have to leach to reach ground
water, the greater the chance of biological or chemical degradation.
Although degradation rates decline rapidly below the root zone, most
pesticides will degrade slowly as they move toward the ground water
table.
Weather: The degradation and movement of pesticides in soil is highly
influenced by the weather. Warmer or cooler temperatures will speed up or
slow down degradation, respectively. Wet weather after application can
move pesticides deeper in the soil profile and increase the chance of leach-
ing into ground water.
D Spills — Although soils are very good at adsorbing and degrading applied
pesticides, high concentrations of pesticides which result from spills over-
whelm all these processes. Highly contaminated soils are a long-term source
of contamination because percolating water will continue to carry the pesticide
into the ground water. Although the movement of pesticide residues is through
leaching, a spill is still considered a point source.
O Direct Contamination — Ground water can be contaminated directly in
many ways. Some of the most serious include backsiphoning, surface water
movement into wells, or drainage into limestone channels or sinkholes. These
contamination problems can almost always be prevented. Once they occur,
however, the point of entry becomes a point source for contamination. A
plume of contamination moves slowly away from the source and can spread to
contaminate many downgradient wells.
Chapter 46-74:10/98
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Chapter 4B: Pesticide Management 75
Well contamination is often the result of poor well construction.
Problems such as a poor or absent casing, lack of grouting, location
in a low spot where water accumulates, or capping below the soil
surface are all invitations for contaminated surface water to enter the
well. High nitrates and bacterial contamination are often associated
with these problems.
Pesticide Management Practices and Their
Effectiveness
The practices set forth below have been found by EPA to be representative
of the types of practices that can be applied successfully to achieve the manage-
ment measure described above. Additional information about individual practices,
their purpose, and how they work is presented in Appendix A.
(1) Inventory current and historical pest problems, cropping patterns, and use
of pesticides for each field.
The purpose of this procedure is to assist the grower in evaluating the poten-
tial for water contamination at the site and to determine IPM strategies which
may be applied to the operation. Much of this information is important for
many aspects of farm operation beyond pollution prevention. This can be
accomplished by using a farm and field map, and by compiling the following
information for each field:
O Crops to be grown and a history of crop production. Certain IPM strate-
gies, such as crop rotation, require this information.
O Information on soil types. Different soils can have very different suscepti-
bility to either runoff or leaching losses of applied pesticides.
D The exact acreage of each field. This information can be used to check
application rates as well as yields.
D Records on past pest problems, pesticide use, and other information for
each field. By keeping these records, the grower can evaluate options for
pest management such as crop rotations and alternative pesticides.
(2) Evaluate the soil and physical characteristics of the farm including mixing,
loading, and storage areas for potential for the leaching and/or runoff of
pesticides. The most important types of features for evaluation include:
O Sinkholes, drainage wells, abandoned wells, and karst topography which
allow direct access to ground water. These allow surface water carrying
sediment, bacteria, and pesticides to quickly enter and contaminate the
ground water table.
O Proximity to surface water. Pesticides should not be used directly adjacent
to surface water because of the high potential for pesticide contamination
from runoff and drift. An untreated buffer around the surface water will
provide a measure of protection.
O Runoff potential. Steeper slopes, heavier soils, and conventional tillage all
increase the runoff potential for a field. Greater amounts of organic matter
and clay increase the ability of the soil to bind the pesticide. Conservation
tillage tends to increase infiltration and decrease the amount of runoff,
further reducing potential pesticide losses.
Chapter 46-75:10/98
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76 Chapter 4: Management Measures
O Aerial drift. Fields with their longer dimension at 90 degrees to the pre-
vailing wind direction will have lower drift potential than those parallel to
,the wind.
O Soils with a high risk of erosion. Cropping practices such as no-till can
greatly reduce the runoff potential for pesticides on steep slopes with
heavy soils. ~"
O Soils with poor adsorptive capacity. Low organic matter (<1%) and clay
content reduces the ability of the soil to bind applied pesticides and pre-
vent them from leaching through to ground water.
O Highly permeable soils. Often the same soils as above have high sand
contents which allow water to percolate rapidly through them. This allows
any pesticides present to move quickly downward before they are de-
graded by the more abundant microbes in the surface horizons.
D Shallow aquifers. A shorter distance between the application zone in the
surface soil to the aquifer means less opportunity for binding and degrada-
tion of the pesticide.
O Wellhead protection areas. Private wells should have a 100-foot buffer in
which no pesticides or fertilizers are applied. Public water supply wells
may require a larger buffer. The buffer minimizes the risk of agricultural
chemicals leaching into the ground water immediately adjacent.
(3) Use IPM strategies to minimize the amount of pesticides applied, including:
O Scouting fields for pest problems. Most universities have scouting guides
for farmers which will provide guidance for procedures appropriate to
their area. Often county extension staff provide training for scouting, or a
farmer may be able to hire a consultant to provide this service. The key is
to know how and where to look for pests and their correct identification. •
For weeds, a farmer may rely on problems from the previous year or he
may walk a specified length of row to count weed seedlings. For insects,
a sweep net may be brushed through the crop and the insects identified
and counted to estimate crop damage.
O Determine the economic threshold for pests. This is also information that
is usually available from local extension offices. The expected value of
the crop and the anticipated losses caused by the pest are estimated
against the cost of an application before any sprays occur.
O Use varieties of crops resistant to pests. Resistant varieties usually re-
quire fewer pesticide applications.
O Use crop rotation. Crop rotations interrupt pest buildup by eliminating
the host plants or by allowing the application of pesticides which reduce
pest populations. An example is a corn-soybean rotation, in which broad-
leaf weeds are more easily controlled in the corn crop and grass weeds are
more easily controlled in the soybean crop.
O Foster biological controls. Identifying the pest properly and recognizing
beneficial insects is key. If a spray is necessary, select a pesticide which
is the most specific to the pest and least toxic to non-target species. Natu-
ral enemies can be introduced and their habitats preserved. Pheromones
can be used to monitor populations, disrupt mating, or attract predators or
parasites.
Chapter 46-76:10/98
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Chapter 4B: Pesticide Management 77
O Use of improved tillage practices such as ridge tillage.
O Use of cover crops in the system to promote water use and reduce deep
percolation of water that contributes to leaching of pesticides into ground
water.
O Destruction of pest breeding, refuge, and overwintering sites (this may
result in loss of crop residue cover and an increased potential for erosion).
O Use of mechanical destruction of weed seed.
O Diversification of habitat.
O Use of allelopathic characteristics of crops. There is evidence that some
crops can reduce pest populations in subsequent crops. For example, a rye
cover crop may reduce weed populations in subsequent crops.
O Use of timing of field operations (planting, cultivating, irrigation, and
harvesting) to minimize application and/or runoff of pesticides.
O Use of efficient application methods, e.g., spot spraying and banding of
pesticides. Often pest problems occur primarily in one portion of the field,
allowing for targeted pesticide application. Banding may provide protec-
tion of the crop without the entire area being sprayed.
(4) When pesticide applications are necessary and a choice of material exists,
consider the persistence, toxicity, and runoff and leaching potential of
products along with other factors, including current label requirements, in
making a selection. This is a complex area and most pesticide users will not
have much of the information necessary to make such judgements. The leach-
ing potential for many pesticides has been estimated in several ways and are in
general agreement with each other. One example is the PLP, or Pesticide
Leaching Potential, which is an index of persistence and leaching characteris-
tics of each chemical (Table 4b-l).
Table 4b-1. Typical pesticide leaching potential (PLP) index values calculated using commonly
reported Koc,T1/2, and R values, and estimated fraction hitting the soil for six example herbicides.
Common Name
Herbicides:
Acifluorfen
Alachlor
Ametryn
Amitrole
Asulam
Atrazine
Trade Name
Blazer
Lasso
Evik
Amitrole-T
Asulox
AAtrex
Application Method
PLP Index"
F
S
S
F
F
F
f.ph?
s, ph7
s,ph5
s, ph7, noncrop
s, ph5, noncrop
40
52
50
46
53
51
56
60
52
66
57
a s = soil application and f = foliar appliation of pesticide. pH is given where differences have a known effect
and data are available. 'Noncrop indicates difference in rates, usually higher than crop uses. ,
b PLP values range from 0 (no leaching potential) to 100 (maximum leaching potential).
Chapter 46-77:10/98
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78 Chapter 4: Management Measures
Table 4b-l may be useful as a starting point, but other information may be
available from State agencies or universities.
Users must apply pesticides in accordance with the instructions on the label of
each pesticide product and, when required, must be trained and certified in the
proper use of the pesticide. Labels include a number of requirements including
allowable use rates; classification of pesticides as "restricted use" for applica-
tion only by certified applicators; safe handling, storage, and disposal require-
ments; restrictions required by State Pesticide Management Plans* to protect
ground water; and other requirements. If label requirements include use only
under an approved State Pesticide Management Plan, pesticide management
measures and practices under the State Coastal Nonpoint Program should be
consistent with and/or complement those in approved State Pesticide Manage-
ment Plans.
Grower practices can have significant impact on the movement of pesticides
into surface water. Tillage practices, incorporation, and filter strips all provide
significant reductions in pesticide movement from fields to surface water in
most cases (Table 4b-2). Generally, practices which slow water and trap sedi-
ment tend to reduce pesticide losses.
Table 4b-2. Effect of BMPs on pesticide losses compared to conventional tillage or no filter strips.
Practice Range of Reductions
Ridge Till -33 - 65
No-Till -98 - 9
29-100
64-100
85-99
6-41
41
100
Contour Ridges 53-100
Incorporation 26-75
24-36
7-79
Filter Strips 28-31
4-14
9-35
40-72
50-74
15-72
Average
30
51
77
86
92
21
—
—
79
—
30
52
—
—
22
56
63
45
Reference
Baker and Johnson, 1979
Baker and Johnson, 1979
Glenn and Angle, 1 987
Hall et al., 1991
Hall et al., 1984
Franti et al., 1 995
Setaet al., 1993
Isensee and Sadeghi, 1993
Ritter et al., 1974
Hall et al., 1983
Baker and Laflen, 1979
Franti et al., 1995
Asmussen etal., 1977.
Rhode et al., 1980
Hall etal., 1983
Mickelson and Baker, 1993
Misra et al., 1994
Misra, 1994
(5) Maintain records of application of restricted use pesticides (product name,
amount, approximate date of application, and location of application of
each such pesticide used) for a 2-year period after use, pursuant to the
requirements in section 1491 of the 1990 Farm Bill.
State Pesticide Management Plans may be required by EPA for certain pesticides to go into effect in the year 2001.
These plans are designed by each State as a method to protect ground water.
Chapter 48-78:10/98
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Chapter 4B: Pesticide Management 79
Section 1491 requires that such pesticide records shall be made available to
any Federal or State agency that deals with pesticide use or any health or
environmental issue related to the use of pesticides, on the request of such
agency. Section 1491 also provides that Federal or State agencies may con-
duct surveys and record the data from individual applicators to facilitate sta-
tistical analysis for environmental and agronomic purposes; however,-in no
case may a government agency release data, including the location from which
the data was derived, that would directly or indirectly reveal the identity of
individual producers. Section 1491 provides that in the case of Federal agen-
cies, access to records maintained under section 1491 shall be through the
Secretary of Agriculture or the Secretary's designee. This section also pro-
vides that State agency requests for access to records maintained under section
1491 shall be through the lead State agency so designated by the State.
Section 1491 includes special access provisions for health care personnel.
Specifically, when a health professional determines that pesticide information
maintained under this section is necessary to provide medical treatment or first
aid to an individual who may have been exposed to pesticides for which the
information is maintained, upon request persons required to maintain records
under section 1491 shall promptly provide records and available label infor-
mation to that health professional. In the case of an emergency, such record
information shall be provided immediately.
Operators may consider maintaining records beyond those required by section
1491 of the 1990 Farm Bill. For example, operators may want to maintain
records of all pesticides used for each field, i.e., not just restricted use pesti-
cides. These records will be useful in setting up IPM programs and in crop
rotation and management decisions. In addition, operators may want to main-
tain records of other pesticide management activities such as scouting records
or other IPM techniques used and procedures used for disposal of remaining
pesticides after application.
(6) Use the lowest pesticide application rates which control the pest problem.
(7) Recalibrate and repair spray equipment each spray season and use anti-
backflow devices on hoses used for filling tank mixtures.
Purchase new, more precise application equipment and other related farm
equipment (including improved nozzles, computer sensing to control flow
rates, radar speed determination, electrostatic applicators, and precision
equipment for banding and cultivating) as replacement equipment is needed.
(8) Solid pad for mixing and loading pesticides.
Factors in the Selection of Management Practices
The best way to control pests in crops is to know the crop and pest well
enough to determine a control plan which maximizes crop production while mini-
mizing environmental impacts. This is often a combination of cultural, biological,
and chemical practices. Cultural controls include tillage, crop rotations, resistant
varieties, and varying planting or harvest dates. Biological controls involve en-
couraging or introducing natural enemies of the pest and managing the crop envi-
ronment to the disadvantage of the pest. Chemical controls should involve a
selection process.which selects a pesticide which results in the greatest economic
benefit for the least environmental cost. Such a determination requires knowledge
Chapter 46-79:10/98
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80 Chapter 4: Management Measures
and information which are beyond the average grower. However, many states
have guides to assist in pesticide selection.
Relationship of Pesticide Management Measures to
Other Programs
Under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), EPA
registers pesticides on the basis of evaluation of test data showing whether a pesti-
cide has the potential to cause unreasonable adverse effects on humans, animals,
or the environment. Data requirements include environmental fate data showing
how the pesticide behaves in the environment, which are used to determine
whether the pesticide poses a threat to ground water or surface water. If the pesti-
cide is registered, EPA imposes enforceable label requirements, which can include,
among other things, maximum rates of application, classification of the pesticide
as a "restricted use" pesticide (which restricts use to certified applicators trained
to handle toxic chemicals), or restrictions on use practices, including requiring
compliance with EPA-approved Pesticide State Management Plans (described
below). FIFRA allows States to develop more stringent pesticide requirements
than those required under FIFRA, and some States have chosen to do this. The
EPA and the U.S. Department of Agriculture Cooperative Extension Service pro-
vide assistance for pesticide applicator and certification training in each State.
The Pesticides and Ground Water Strategy published by EPA (EPA, 199 Ic)
describes the policies and regulatory approaches EPA will use to protect the
Nation's ground water resources from risks of contamination by pesticides under
FIFRA. The objective of the strategy is the prevention of ground water contamina-
tion by regulating the use of certain pesticides (i.e., use according to EPA-ap-
proved labeling) in order to reduce and, if necessary, eliminate releases of the
pesticide in areas vulnerable to contamination. Priority for protection will be
based on currently used and reasonably expected sources of drinking water sup-
plies, and ground water that is closely hydrogeologically connected to surface
waters. The EPA will use maximum contaminant levels (MCLs) under the Safe
Drinking Water Act as "reference points" for water resource protection efforts
when the ground water in question is a current or reasonably expected source of
drinking water.
The Strategy describes a significant new role for States in managing the use
of pesticides to protect ground water from pesticides. In certain cases, when there
is sufficient evidence that a particular use of a pesticide has the potential for
groundwater contamination to the extent that it might cause unreasonable adverse
effects, EPA may (through the use of existing statutory authority and regulations)
limit legal use of the product to those States with an acceptable Pesticide State
Management Plan, approved by EPA. Plans would tailor use to local hydrologic
conditions and would address:
D State philosophy;
D Roles and responsibilities of State and local agencies;
O Legal and en forcement authority;
O Basis for assessment and planning;
D Prevention measures;
Chapter 48-80:10/98
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Chapter 4B: Pesticide Management 81
O Ground water monitoring;
D Response to detections;
D Information dissemination; and
O Public participation.
In the absence of such an approved plan, affected pesticides could not be
legally used in the State.
Since areas to be managed under Pesticide State Management Plans, State
nonpoint source programs, and Coastal Nonpoint Pollution Control Programs can
overlap, State coastal zone and nonpoint source agencies should work with the
State lead agency for pesticides (or the State agency that has the lead role in the
Pesticide State Management Plan) in the development and implementation of pesti-
cide management measures and practices under each program. This is necessary to
avoid duplication of effort and conflicting pesticide management requirements
among programs. Further, ongoing coordination will be necessary since each pro-
gram and its management measures will evolve and change with increasing tech-
nology and data.
Cost of Practices
In general, most of the costs of implementing the pesticide management mea-
sure are program costs associated with providing additional educational programs
and technical assistance to producers to evaluate pest management needs and for
field scouting during the growing season.
One of the most important IPM practices is scouting, which carries with it a
cost to the producer. High and low scouting costs are given for major crops in
each of the coastal regions (Table 4b-3). These costs reflect variations in the level
of service provided by various crop consultants. For example, in the Great Lakes
region, the relatively low cost of $4.95 per acre is based on five visits per season
at the request of the producer. Higher cost services include scouting and weekly
written reports during the growing seasons. Cost differences may also reflect dif-
ferences in the size of farms (i.e., number of acres) and distance between farms.
The variations in scouting costs between regions and within regions also
occur because of differences in the provider of the service. For example, in some
states the Cooperative Extension Service provides scouting services and training at
no cost or for a nominal fee. In other areas of the coastal zone, farmer coopera-
tives have formed crop management associations to provide scouting and crop
fertility/pest management recommendations.
Scouting costs also vary by crop type. Scouting services for high-value cash
crops, such as fruits and vegetables, must be very intensive given that pest damage
is permanent and may make the crop unmarketable.
The use of IPM usually reduces the amount of pesticides used and also in-
creases the profitability of the crop. In a review of 61 studies of IPM impacts on
crop yield, pesticide use, and economics, pesticide use declined in seven of the
eight commodities evaluated (Norton and Mullen, 1994; Table 4b-4). Some stud-
ies found increased use of pesticides with IPM due to increased awareness of pest
problems, but the majority found reductions.
Chapter 46-81:10/98
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82 Chapter 4: Management Measures
Another issue regarding the cost of pesticide management practices is selec-
tion of the tillage system and direct and indirect costs associated with that system.
Conservation tillage or no-till practices often rely on the use of herbicides to con-
trol weeds rather than multiple passes with a cultivator employed in conventional
tillage, which mechanically destroy the weeds. When deciding between conserva-
tion versus conventional tillage, the direct costs of buying more pesticides (and
specific pesticides) for no-till must be weighed against the cost of running more
equipment in the field for conventional tillage. Com produced using conventional
tillage averages more than three cultivation passes each season, while no-till corn
requires about one. Since each cultivation pass costs nearly seven dollars per
acre, production costs may increase by more than $ 14/acre for conventional tillage
compared to no-till, minus any additional costs of herbicides.
Indirect costs of each tillage system must also be considered. Soil losses are
reduced by up to 90% in no-till compared to conventional tillage, reducing both
the indirect costs of erosion and consequent crop yield losses and also adverse
environmental impacts of sedimentation of surface water bodies. Yields with con-
servation tillage are often reduced when a farmer first experiments with it, as it is
a new practice which requires new skills and equipment. However, this situation
usually changes with time. An added benefit of no-till is that considerable time is
saved by only needing to work the field once instead of three or more times.
Table 4b-3. Estimated scouting costs (dollars/acre) by coastal region and crop in the coastal zone
in 1992 (EPA, 1992).
COASTAL
REGION
Northeast
Low
High
Southeast
Low
High
Gulf Coast
Low
High
Great Lakes
Low
High
West Coast
Low
High
NA = not available
Corn
5.50
6.25
5.00
6.00
6.00
8.00
4.95
5.50
NA
NA
Soybean
NA
NA
3.25
4.00.
4.50
6.50
4.25
5.00
NA
NA
Wheat
3.75
4.50
3.00
3
50
CROP
Rice Cotton
8.00
12.00
5.00
9.00
6
8
6
9
00
00
00
00
Fresh Market
Vegetables*
25.00
28.00
30
35
35
40
00
00
00
00
3.75 — — —
4.00 — — —
3.50
5.50
NA
NA
6
9
75
30
32.00
38
00
Hay"
2.50
2.75
2.00
3.00
—
—
4.75
5.25
NA
NA
— = not applicable
• Most fresh market vegetables are produced under a regular spraying schedule.
"Scouting costs for hay are based on alfalfa insect inspection. The higher cost in the Great Lakes region includes
pesticide and soil sampling.
Chapter 46-82:10/98
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Chapter 4B: Pesticide Management 83
Table 4b-4. Summary of results of farm-level economic evaluations of IPM programs.
Commodity
Cotton
Soybeans
Com
Vegetables
and
Flowers
Fruits
Peanuts
Tobacco
Alfalfa
Unweighted
Average6
States
TX.GA, MS,
NC. SC.LA,
MO, TN, AZ,
NM, CA, AR
NC, VA, MD
GA, IN
IN, IL, and 10
other states
CT, CA, MA,
TX, FL, OH.
NY, HI
NY, MA, WA,
NJ, CA, CT
GA, TX, OK,
NC
NC
OK, Wl,
Northwest
Number
of
Studies
18
7
3
15
6
5
2
3
Average
Percent
Change in
Pesticide
Use*
-15
-35
+20
-43
-20
-5
-19
-2
-14.9
Percent
Change in
Production
Percent
Yield
Cost with Change with
IPM' IPM'
-7
-5
+3
+29
+6
+7
Percent
Change
in Net
Returns
Per Acre1
+79
+45
+54
Level of
Risk with
IPM
decreased
decreased
Quality increased in 4 studies and remained the
same in others
0
•5
-2.8
+12
+13
0
+13
+11.4
+19
+100
+1
•+37
+47.8
decreased
decreased
• For those producers that adopted the specified IPM practices compared to those that did not.
6 Weighting is not possible without an accurate accounting of the acreage affected for each commodity in each state.
Source: Norton, G.W. and J. Mullen. 1994. Economic evaluation of integrated pest management programs: a literature review.
Va. Coop. Ext. Pub. 448-120, Virginia Tech, Blacksburg, VA 24061.
Chapter 46-83:10/98
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84 Chapter 4: Management Measures
Chapter 46-84:10/98
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Chapter 4C: Erosion and Sediment Control 85
4C: Erosion and Sediment Control
Management Measure for Erosion and Sediment
Control:
Apply the erosion component of a Conservation Management System (CMS)
as defined in the Field Office Technical Guide of the U.S. Department of Agricul-
ture-Soil Conservation Service (see Appendix B) to minimize the delivery of sedi-
ment from agricultural lands to surface waters, or
Design and install a combination of management and physical practices to
settle the settleable solids and associated pollutants in runoff delivered from the
contributing area for storms of up to and including a 10-year, 24-hour frequency.
Management Measures for Erosion and Sediment
Control: Description
Application of this management measure will preserve soil and reduce the
mass of sediment reaching a water body, protecting both agricultural land and
water quality.
This management measure can be implemented by using one of two general
strategies, or a combination of both. The first, and most desirable, strategy is to
implement practices on the field to minimize soil detachment, erosion, and trans-
port of sediment from the field. Effective practices include those that maintain
crop residue or vegetative cover on the soil; improve soil properties; reduce slope
length, steepness, or unsheltered distance; and reduce effective water and/or wind
velocities. The second strategy is to route field runoff through practices that filter,
trap, or settle soil particles. Examples of effective management strategies include
vegetated filter strips, field borders, sediment retention ponds, and terraces. Site
conditions will dictate the appropriate combination of practices for any given
situation. The United States Department of Agriculture (USDA)-Natural Re-
sources Conservation Service (NRCS) or the local Soil and Water Conservation
District (SWCD) can assist with'planning and application of erosion control prac-
tices. Two useful references are the USDA-NRCS Field Office Technical Guide
(FOTG) and the textbook "Soil and Water Conservation Engineering" by Schwab
etal. (1993)/
Sedimentation
causes widespread
damage to our
waterways. Water
supplies and wildlife
resources can be
lost, lakes and
reservoirs can be
filled in, and
streambeds can be
blanketed with soil
lost from cropland.
Conservation management systems (CMS) include any combination of con-
servation practices and management that achieves a level of treatment of the five
natural resources (i.e., soil, water, air, plants, and animals) that satisfies criteria
contained in the Natural Resources Conservation Service (NRCS) Field Office
Technical Guide (FOTG), such as a resource management system (RMS) or an
acceptable management system (AMS). These criteria are developed at the State
level, with concurrence by the appropriate NRCS National Technical Center
(NTC). The criteria are then applied in the provision of field office technical assis-
tance, under the direction of the District Conservationist of NRCS. In-state coor-
dination of FOTG use is provided by the Area Conservationist and State
Conservationist of NRCS.
Chapter 4C-85:10/98
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86 Chapter 4: Management Measures
Water Erosion
Sheet, rill, and gully
erosion can occur
on cropland fields.
Streambank and
streambed erosion
can occur in
intermittent and
perennial streams.
The erosion component of a CMS addresses sheet and rill erosion, wind ero-
sion, concentrated flow, streambank erosion, soil mass movements, road bank
erosion, construction site erosion, and irrigation-induced erosion. National (mini-
mum) criteria pertaining.to erosion and sediment control under an RMS will be
applied to prevent long-term soil degradation and to resolve existing or potential
off-site deposition problems. National criteria pertain ing to the water resource will
be applied to control sediment movement to minimize contamination of receiving
waters. The combined effects of these criteria will be to both reduce upland soil
erosion and minimize sediment delivery to receiving waters.
The practical limits of resource protection under a CMS within any given
area are determined through the application of national social, cultural, and eco-
nomic criteria. With respect to economics, landowners will not be required to
implement an RMS if the system is generally too costly for landowners. Instead,
landowners may be required to implement a less costly, and less protective, AMS.
In some cases, landowner constraints may be such that an RMS or AMS cannot
be implemented quickly. In these situations, a "progressive planning approach"
may be used to ultimately achieve planning and application of an RMS or AMS.
Progressive planning is the incremental process of building a plan on part or all of
the planning unit over a period of time. For additional details regarding CMS,
RMS, and AMS, see Appendix B.
Sediment Movement into Surface and Ground Water
Soil erosion is the process of detachment, transport, and deposition of soil
particles and surficial sediments by the action of moving water or wind. Move-
ment of soil by water occurs in three stages. First, particles or aggregates are
detached from the soil or sediment surface. Second, the detached particles are
transported by moving water or wind. Third, when the water velocity slows or the
wind velocity decreases, the soil particles are deposited as sediment at a new site.
It is not possible to completely prevent all erosion, but erosion can be reduced
to tolerable rates. In general terms, tolerable soil loss is the maximum rate of soil
erosion that will permit indefinite maintenance of soil productivity, i.e., erosion
less than or equal to the rate of soil development. The USDA-NRCS uses five
levels of erosion tolerance ("T") based on factors such as soil depth and texture,
parent material, productivity, and previous erosion rates. These T levels are
equivalent to annual losses of about 1-5 tons/acre/year (2-11 mt/ha/year), with
minimum rates for shallow soils with unfavorable subsoils and maximum rates for
deep, well-drained productive soils.
Water erosion is generally recognized in several different forms. Sheet ero-
sion is a process in which detached soil is moved across the soil surface by sheet
flow, often in the early stages of runoff. Rill erosion occurs as runoff water begins
to concentrate in small channels or streamlets. Sheet and rill erosion carry mostly
fine-textured, small particles and aggregates. These sediments will contain higher
proportions of nutrients, pesticides, or other adsorbed pollutants than are con-
tained in the surface soil as a whole. This process of preferential movement of fine
particulates carrying high concentrations of adsorbed pollutants is called sediment
enrichment. Gully erosion results from water moving in rills which concentrate to
form larger and more persistent erosion channels. Gully and streambank erosion
can move and carry large soil particles that often contain a much lower proportion
Chapter 40-86:10/98 .
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Chapter 4C: Erosion and Sediment Control 87
Headcutting
irrigation waters can
detach and transport
soil particles.
of adsorbed pollutants than the finer sediments from sheet .and rill erosion. Sheet,
rill, and gully erosion are active only during or immediately after rainstorms or
snowmelt. Streambank and streambed erosion typically increase in streams during
runoff events. Within a stream, the force of moving water on bare or undercut
banks causes streambank erosion. Streambank erosion is usually most intense
along outside bends of streams, although inside meanders can be scoured during
severe floods. Stream power can detach, move, and carry large soil particles,
gravel, and small rocks. Streambank and shoreline erosion are addressed in greater
detail in EPA's guidance for the coastal nonpoint source pollution control program
(EPA, 1993).
Irrigation may also contribute to erosion if water application rates are exces-
sive. Erosion may also occur from water transport through unlined earthen
ditches. See the Irrigation Water Management Measure discussion in Chapter 4F
for additional information regarding erosion from irrigation.
Water erosion rates are affected by rainfall energy, soil properties, slope,
slope length, vegetative and residue cover, and land management practices. Rain-
fall impacts provide the energy that causes initial detachment of soil particles. Soil
properties like particle size distribution, texture, and composition influence the
susceptibility of soil particles to be moved by flowing water. Vegetative cover and
residue may protect the soil surface from rainfall impact or the force of moving
water. These factors are used in the Revised Universal Soil Loss Equation
(RUSLE), an empirical formula widely used to predict soil loss in sheet and rill
erosion from agricultural fields, idle land, woodland, and construction sites:
Revised Universal Soil Loss Equation
A = R • K * LS * C * P
where
A = estimated average annual soil loss (tons/acre/year)
R = rainfall/runoff factor, quantifying the effect of raindrop impact and the
amount and rate of runoff associated with the rain, based on long
term rainfall record
K = soil erodibility factor based on the combined effects of soil properties
influencing erosion rates
LS = slope length factor, a combination of slope gradient and continuous
extent
C = cover and management factor, incorporating influences of crop
sequence, residue management, and tillage
P = practice factor, incorporating influences of conservation practices
such as contouring or terraces
Chapter 40-87:10/98
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88 Chapter 4: Management Measures
Prediction
equations such as
the RUSLE and
WEQ help planners
make quantitative
assessments of soil
loss and BMP
effectiveness.
Wind Erosion
Wind can erode
and transport soil
particles of various
sizes causing
damage to land
and waterways.
-The RUSLE may be used as a framework for considering the principal fac-
tors affecting sheet and rill erosion: climate(R), soil characteristics (K), topogra-
phy (LS), and land use and management (C and P). Except for climate, these
factors suggest areas where changes in management can influence soil loss from
water erosion.
It is important to note that the RUSLE predicts soil loss, not sediment deliv-
ery to receiving waters. Even without erosion control practices, delivery of soil
lost from a field to surface water is usually substantially less than 100%. Sedi-
ment delivery ratios (percent of gross soil erosion delivered to a watershed outlet)
are often on the order of 15-40% (Novotny and Olern, 1994). Numerous factors
influence the sediment delivery ratio, including watershed size, hydrology, and
topography.
Erosion control in humid tropical areas like Hawaii and Puerto Rico may
present special problems. Soil loss by water erosion may be drastically higher
than in temperate regions, especially in areas of steep slopes (El-Swaify and
Cooley, 1980). High annual rainfall and the energy of intense storms often result
in high erosion rates. Sediment yields of up to 3000 tons/sq km/yr from montane
basins in Puerto Rico have been reported, where mass wasting contributed most of
the sediment to the receiving streams (Simon and Guzman-Rios, 1990). Land
clearing and changes in soil characteristics (e.g. exhaustion of soil organic matter)
can result in catastrophic soil erosion in tropical regions.
Erosion control practices that succeed in temperate regions are often less
effective in the tropics. Engineered practices like terracing, contour ridging, diver-
sions, terraces, and grassed waterways are frequently overwhelmed by torrential
rains (Troeh et al., 1980; Lai, 1983). Agronomic practices that conserve the soil,
such as mulch farming, reduced tillage, mixed cropping with multistorey canopy
structure, and strip cropping with perennial sod crops are more likely to be suc-
cessful (Troeh et al., 1980; Lai, 1983). El-Swaify and Cooley (1980) reported
that pineapple and sugarcane provided adequate protection from soil erosion only
a few months after planting.
Wind detaches soil particles when, at one foot above the ground surface,
wind velocity exceeds 12 mph. Detached soil is moved by wind in one of three
ways (Figure 4c-1):
1. Soil particles and aggregates smaller than 0.05 mm in diameter may be picked
up by wind and carried in suspension. Suspended dust may be moved great
distances, but does not drop out of the air unless rain washes it out or the
velocity of the wind is dramatically reduced.
2. Intermediate sized grains — 0.05 to 0.5 mm (very fine to medium sand) —
move in the wind in a series of steps, rising into the air and falling after a
short flight in a motion called saltation.
3. Soil grains larger than 0.5 mm cannot be lifted into the wind stream, but par-
ticles up to about 1 mm may be pushed along the soil surface by saltating
grains or by direct wind action. This type of movement is called surface
creep.
Chapter 4C-88:10/98
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Chapter 4C: Erosion and Sediment Control 89
Figure 4c-1. The different ways soil can move during wind erosion.
Source: So// Erosion by Wind. USDA^ Agriculture Information Bulleting
Number 555.
Wind erosion rates are determined by factors similar to those affecting water
erosion rates, including the detachment and transport capacity of the wind, soil
cloddiness, soil stability, surface roughness, residue or vegetative cover, and length
of exposed area. These factors are expressed in the Wind Erosion Equation
(WEQ). The WEQ is an empirical wind erosion prediction equation that is cur-
rently the most widely used method for estimating average annual soil Ipss by
wind for agricultural fields. The equation is expressed in the general form of:
Wind Erosion Equation
E = f(l, K, C, L, V)
where E is the potential average annual soil loss (tons/acre/
year), a function of:
I, the soil erodibility index;
K, the soil ridge roughness factor;
C, the climate factor;
L, the unsheltered distance across the field; and
V. the vegetative cover.
Chapter 4C-89:10/98
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90 Chapter 4: Management Measures
Ground Water
Protection
Although sediment movement into ground water is generally not an issue in
most locations, there are places, such as areas of karst topography, where sedi-
ment and sediment-borne pollutants can enter ground water through direct links to
the surface. More important from a national perspective, however, is the potential
for increased movement of water and soluble pollutants through the soil profile to
ground water as a result of implementing erosion and sediment control practices.
It is not the intent of this measure to correct a surface water problem at the
expense of ground water. Erosion and sediment control systems can and should be
designed to protect against the contamination of ground water. Ground water pro-
tection will also be provided through implementation of the nutrient and pesticide
management measures.
Erosion and Sediment Control Practices and Their
Effectiveness
The strategies for controlling erosion involve reducing soil detachment, re-
ducing sediment transport, and trapping sediment before it reaches water. Combi-
nations of the following practices can be used to satisfy the requirements of this
management measure. The NRCS practice number and definition are provided for
each management practice, where available. Additional information about the
purpose and function of individual practices is provided in Appendix A.
Practices to
Reduce Detachment
Source area
stabilization is
fundamental to
.erosion and
sediment control.
For both water and wind erosion, the first objective is to keep soil on the
field; the easiest and often most effective strategy to accomplish this is to reduce
soil detachment. Detachment occurs when water splashes onto the soil surface and
dislodges soil particles, or when wind reaches sufficient velocity to dislodge soil
particles on the surface.
Crop residues (e.g. straw) or living vegetative cover (e.g. grasses) on the soil
surface protect against detachment by intercepting and/or dissipating the energy of
falling raindrops. A layer of plant material also creates a thick layer of still air
next to the soil to buffer against wind erosion. Keeping sufficient cover on the
soil is therefore a key erosion control practice.
The implementation of practices such as conservation tillage also preserves
or increases organic matter and soil structure, resulting in improved water infiltra-
tion and surface stability. In addition, creation of a rough soil surface through
practices such as surface roughening will break the force of raindrops and trap
water, reducing runoff velocity and erosive forces. Reducing effective wind veloci-
ties through increased surface roughness or the use of barriers or changes in field
topography will reduce the potential of wind to detach soil particles. Practices
which increase the size of soil aggregates increase a soil's resistance to wind ero-
sion.
O Chiseling and subsoiling (324): Loosening the soil without inverting and with
a minimum of mixing of the surface soil to improve water and root penetration
and aeration.
Chapter 4C-90:10/98
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Chapter 4C: Erosion and Sediment Control 91
O Conservation cover (327): Establishing and maintaining perennial vegetative
cover to protect soil and water resources on land retired from agricultural
production.
O Conservation cropping sequence (328): An adapted sequence of crops de-
signed to provide adequate organic residue for maintenance or improvement of
soil tilth. . .
O Conservation tillage (329): Any tillage or planting system that maintains at
least 30% of the soil surface covered by residue after planting to reduce soil
. erosion by water; or, where soil erosion by wind is the primary concern, main-
tains at least 1,000 pounds of flat, small-grain residue equivalent on the sur-
face during the critical erosion period.
O Contour orchard and other fruit area (331): Planting orchards, vineyards,
or small fruits so that all cultural operations are done on the contour.
D Cover and green manure crop (340): A crop of close-growing grasses, le-
gumes, or small grain grown primarily for seasonal protection and soil im-
provement. It usually is grown for 1 year or less, except where there is
permanent cover as in orchards.
O Critical area planting (342): Planting vegetation, such as trees, shrubs, vines,
grasses, or legumes, on highly erodible or critically eroding areas (does not
include tree planting mainly for wood products).
O Crop residue use (344): Using plant residues to protect cultivated fields dur-
ing critical erosion periods.
' O Delayed seed bed. preparation (354): Any cropping system in which all of
the crop residue and volunteer vegetation are maintained on the soil surface
until approximately 3 weeks before the succeeding crop is planted, thus short-
ening the bare seedbed period on fields during critical erosion periods.
n Diversion (362): A channel constructed across the slope with a supporting
ridge on the lower side (Figure 4c-2).
Figure 4c-2. Diversion (USDA-SCS, 1984).
Chapter 4C-91:10/98
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92 Chapter 4: Management Measures
n Windbreak/shelterbelt establishment (380): Linear plantings of single or
multiple rows of trees or shrubs established next to farmstead, feedlots, and
rural residences as a barrier to wind.
O Windbreak/shelterbelt renovation (650): Restoration or preservation of an
existing windbreak, including widening, replanting, or replacing trees.
G Grasses and legumes in rotation (411): Establishing grasses and legumes or
a mixture of them and maintaining the stand for a definite number of years as
part of a conservation cropping system.
O Mulching (484): Applying plant residue or other suitable material to the soil
surface.
O Irrigation water management (449): Effective use of available irrigation
water to manage soil moisture, reduce erosion, and protect water quality.
O Proper Grazing Use (528): Grazing at an intensity that will maintain enough
cover to protect the soil and maintain or improve the quantity and quality of
desirable vegetation.
D Planned grazing systems (556): A practice in which two or more grazing
units are alternately rested and grazed in a planned sequence.
D Cross wind ridges/stripcropping/trap strips (589): Ridges formed by tillage
or planting, crops grown in strips, or herbaceous cover aligned perpendicular
to the prevailing wind direction.
O Surface roughening (609): Roughening the soil surface by ridge or clod-
forming tillage.
O Tree planting (612): Establishing woody plants by planting or seeding.
O Waste utilization (633): Using agricultural or other wastes on land in an envi-
ronmentally acceptable manner while maintaining or improving soil and plant
resources.
O Wildlife upland habitat management (645): Creating, maintaining, or en-
hancing upland habitat for desired wildlife species.
The following additional practices, although typically applied for a different
primary purpose, may have significant secondary benefits in erosion control:
O Brush management (314): The management of undesirable brush species
through use of living organisms, herbicides, prescribed burning, or mechanical
methods.
O Irrigation system - sprinkler (442): Distribution of water by means of sprin-
klers or spray nozzles to efficiently and uniformly apply irrigation water to
maintain adequate soil moisture.
O Pasture and hayland management (510): Proper treatment and use of pas-
ture or hayland.
O Pasture and hayland planting (512): Establishing and re-establishing long-
term stands of adapted species of perennial, biannual, or reseeding forage
plants.
Chapter 4C-92:10/98
-------
Chapter 4C: Erosion and Sediment Control 93
Practices to
Reduce Transport within the Field
Where conditions
and opportunities
permit, install
practices that
prevent edge-of-
field sediment
loss.
Sediment transport can be reduced in several ways, including the use of crop
residues and vegetative cover. Vegetation slows runoff, increases infiltration, re-
duces wind velocity, and traps sediment. Reductions in slope length and steepness
reduce runoff velocity, thereby reducing sediment carrying capacity as well.-Ter-
races and diversions are common techniques for reducing slope length. Runoff can
be slowed or even stopped by placing furrows perpendicular to the slope, through
practices such as contour farming that act as collection basins to slow runoff and
settle sediment particles. By decreasing the distance across a field that is
unsheltered from wind and by creating soil ridges or other barriers, sediment
transport by wind will be reduced.
O Contour farming (330): Farming sloping land in such a way that preparing
land, planting, and cultivating are done on the contour. This includes follow-
ing established grades of terraces or diversions.
D Field windbreak (392): Establishment of trees in or adjacent to a field as a
barrier to wind.
O Grassed waterway (412): A natural or constructed channel that is shaped or
graded to required dimensions and established in suitable vegetation for the
stable conveyance of runoff.
O Contour stripcropping (585): Growing crops in a systematic arrangement of
strips or bands on the contour to reduce water erosion. The crops are arranged
so that a strip of grass or close-growing crop is alternated with a strip of
clean-tilled crop or fallow or a strip of grass is alternated with a close-grow-
ing crop (Figure 4c-3).
O Field strip-cropping (586): Growing crops in a systematic arrangement of
strips or bands across the general slope (not on the contour) to reduce water
erosion. The crops are arranged so that a strip of grass or a close-growing
crop is alternated with a clean-tilled crop or fallow.
D Terrace (600): An earthen embankment, a channel, or combination ridge and
channel constructed across the slope (Figures 4c-4 and 4c-5).
Practices to
Trap Sediment Below the Field or Critical Area
Practices are also typically needed to trap sediment leaving the field before it
reaches a wetland or riparian area. Deposition of sediment is achieved by practices
that slow water velocity or increase infiltration.
O Sediment basins (350): Basins constructed to collect and store debris or sedi-
ment.
CJ Field border (386): A strip of perennial vegetation established at the edge of
a field by planting or by converting it from trees to herbaceous vegetation or
shrubs.
O Filter strip (393): A strip or area of vegetation for removing sediment, or-
. ganic matter, and other pollutants from runoff and wastewater.
O Water and sediment control basin (638): An earthen embankment or a com-
bination ridge and channel generally constructed across the slope and minor
watercourses to form a sediment trap and water detention basin.
Trap sediment
before it reaches
riparian areas.
Chapter 4C-93:10/98
-------
94 Chapter 4: Management Measures
Figure 4c-3. Stripcropping and rotations (USDA-ARS, 1987).
Contour strip cropping systems can involve up to 10 strips in a field. A strip cropping
system could involve the following:
Com (either for grain and/or silage}
Soybeans
1st year Meadow
Established Meadow (2-4 years)
Oats
Grassed waterway or diversion
Tillage systems may include two kinds in the same year such as chisel plowing for the lor
crop and moidboard plowing for the oats.
See the following figure showing typical patterns of Stripcropping.
NT • Mo-Tai
MT- »«ICf» Tit
CT • CunveiMional
C - Corn
SB - Soybean*
O - Small Gt»irt
M • Rotiti«n Meadow
Down flkjge
Chapter 40-94:10/98
-------
Chapter 4C: Erosion and Sediment Control 95
Figure 4c-4. Gradient terraces with tile outlets (USDA-SCS, 1984).
Figure 4c-5. Gradient terraces with waterway outlet (USDA-SCS, 1984).
Chapter 4C-95:10/98
-------
96 Chapter 4: Management Measures
Healthy Wetland
and Riparian Areas Help Reduce Sediment Transport and Delivery
Riparian area
practices can serve
to repair damaged
stream corridors.
Assessment and
remediation of
runoff and
sedimentation
problems enhances
riparian area
restoration.
Properly functioning natural wetlands and riparian areas can significantly
reduce nonpoint source pollution by intercepting surface runoff and subsurface—
flow and by settling, filtering, or storing sediment and associated pollutants. Wet-
lands and riparian areas typically occur as natural buffers between uplands and
adjacent water bodies. Loss of these systems allows a more direct contribution of
nonpoint source pollutants to receiving waters; degraded wetlands and riparian
areas may even become pollutant sources. Thus, natural wetlands and riparian
areas should be protected and should not be used as designated erosion control
practices. Their nonpoint source control functions are most effective as part of an
integrated land management system focusing on nutrient, sediment, and erosion
control practices applied to upland areas.
Management measures for protection of the full range of functions for wet-
lands and riparian areas are discussed in Nonpoint Source Pollution Guidance for
Wetlands, Riparian Areas, and Vegetated Treatment Systems (EPA, 1998). Pro-
tection of wetlands and riparian areas should allow for both nonpoint source pol-
lution control and maintenance of other benefits of these natural aquatic systems,
e.g. wildlife habitat. The Management Measure for Protection of Wetlands
and Riparian Areas states:
Protect from adverse effects wetlands and riparian areas that are serving a
significant NPS abatement function and maintain this function while pro-
tecting other existing functions of these wetlands and riparian areas as
measured by characteristics such as vegetative composition and cover,
hydrology of surface water and ground water, geochemistry of the sub- ,
strate, and species composition.
Examples of implementation practices for protecting wetlands and riparian
areas include:
Identify existing functions of those wetlands and riparian areas with sig-
nificant NPS control potential when implementing NPS management
practices. Do not alter wetlands or riparian areas to improve their water
quality functions at the expense of their other functions.
Use appropriate preliminary treatment practices such as vegetated treat-
ment systems or detention or retention basins to prevent adverse impacts to
wetland functions that affect NPS pollutant abatement from hydrologic
changes, sedimentation, or contaminants.
Practices specifically designed to repair or protect wetlands and streambanks
from erosion include:
D Wildlife wetland habitat management (644): Creating, maintaining, or en-
hancing wetland habitat for desired wildlife species.
O Grade stabilization structure (410): A structure used to control the grade
and head cutting in natural or artificial channels.
D Streambank and Shoreline Protection (580): Using vegetation or structures
to stabilize and protect banks of streams, lakes, estuaries, or excavated chan-
nels against scour and erosion. - - , ...
Chapter 4C-96: 10/98
-------
Chapter 4C: Erosion and Sediment Control 97
O Stream Channel Stabilization (584): Stabilizing the channel of a stream with
suitable structures.
O Livestock exclusion (472): Excluding all types of livestock from a particular
area, primarily by means of fencing:
O Control of streambank erosion on agricultural land requires techniques dif-
ferent from those used to treat upland sheet and rill erosion. The force of flow-
ing water in a river or stream is the most important process causing
streambank erosion. Protection of the slope faces on channel banks, especially
those already undergoing active erosion, from the force of flowing water is the
key control principle. Techniques may be divided into two general categories:
bioengineering (vegetative) and structural. Vegetative methods are generally
preferred, unless structural methods are more cost-effective.
Bioengineering measures use live or dead plant parts and establishment of
woody vegetation to increase channel roughness and slow water velocity near
the slope face, provide armoring and reinforcement of streambanks, and bind
streambanks with roots of living vegetation. It should be noted that bioengi-
neering measures depending on growth of living vegetation also require live-
stock exclusion to protect the growing plants from grazing and trampling.
Specific bioengineering practices include:
• Live staking: The insertion and tamping of live, rootable vegetative cut-
tings into the ground to create a living root mat that stabilizes the soil.
• Live fascines and brushlayering: Placement of bundles of branch cuttings
(usually of willow) in shallow trenches or benches on bare streambanks to
rapidly establish protective vegetation.
• Tree/shrub planting: planting of rooted cuttings and tree or shrub seed-
lings on shaped streambanks and in the riparian zone.
• Trench packing: filling of a gully with woody brush to provide a barrier to
retard water flow and accumulate sediment.
• Brushrolls. brushmattresses. brush boxes: bundles of brush of varying
configurations staked against the base of an eroding streambank as a bar-
rier to slow water flow and to settle and accumulate sediment.
Structural practices protect streambank soils from the erosive force of
streamflow, help retain eroding soil, or influence the direction or velocity of
streamflow with durable nonliving materials:
• Riprap: rock dumped or placed along a sloped streambank to armor the
bank against the force of flowing water.
• Revetments: structures such as timber cribbing backfilled with gravel,
anchored trees, gabions, or bulkheads applied to the streambank to hold
back eroding material as well as to protect from flowing water.
• Streamflow deflectors: sills, bars, or groins of logs, rock, or concrete
projecting out from the bank into the stream to redirect the streamflow
away from an eroding bank.
For further information on controlling streambank erosion, refer to Chapter
6: "Management Measures for Hydromodification: Channelization and Channel
Modification, Dams, and Streambank and Shoreline Erosion," in Guidance Speci-
fying Management Measures for Sources ofNonpoint Pollution in Coastal Wa-
ters, EPA 840-B-92-002, 1993.
Chapter 4C-97:10/98
-------
98 Chapter 4: Management Measures
Practice
Effectiveness
Although some sites
are challenging,
detailed local
information
combined with
sound erosion
control knowledge
and experience
should result in an
effective system
plan for erosion and
sediment control.
The available information shows that erosion control practices can be used to
greatly reduce the quantity of eroding soil on agricultural land, and that edge-of-
field practices can effectively reduce sediment transport. The benefits of this man-
agement measure include preservation of productive agricultural soils and
significant reductions in the mass of sediment and associated pollutants (e.g.,
phosphorus, some pesticides) entering water bodies.
The effectiveness of sediment control practices depends on several factors,
including:
O The contaminant (e.g. sediment, phosphorus) to be controlled;
D The nature of the soil particles to be controlled;
The types of practices or controls being considered;
O
O
Site-specific conditions (e.g. crop rotation, topography, tillage, harvesting
method); and
O 'Operation and maintenance.
Management practices or systems of practices must be designed for site-
specific conditions to achieve desired effectiveness levels. Management practice
systems include combinations of practices that provide source control of the
contaminant(s) as well as control or reductions in edge-of-field losses and delivery
to receiving waters. Table 4c-l provides a gross estimate of practice effectiveness
(i.e., "average" changes in runoff and pollutant loads due to the addition of the
practice(s) at sites where erosion control practices are generally lacking) as re-
ported in research literature. Even within relatively small watersheds, extreme
spatial and temporal variations are common. Because of this variation, the actual
effectiveness of practices at a specific site may differ considerably from the gross
estimates given in Table 4c-1.
Table 4c-1. Relative Gross Effectiveness3 of Sediment" Control Measures (Pennsylvania
State University, 1992b).
Practice Category'
Reduced Tillage Systems0
Diversion, Systems'
Terrace Systems9
Filter Strips'1
Runoff Total" Phosphorus Total' Nitrogen Sediment
Volume (% reduction)
reduced 45 55 75
reduced 30 10 35
reduced 70 .20 85
reduced 75 70 . 65
• Actual effectiveness depends on site-specific conditions. Values are not cumulative between practice categories.
b Includes data where land application of manure has occurred.
c Each category includes several specific types of practices.
" Total phosphorus includes total and dissolved phosphorus; total nitrogen includes organic-N, ammonia-N, and nitrate-N.
• Includes practices such as conservation tillage, no-till, and crop residue use.
1 Includes practices such as grassed waterways and grade stabilization structures.
9 Includes several types of terraces with safe outlet structures where appropriate.
h Includes all practices that reduce contaminant losses using vegetative control methods.
Chapter 40-98:10/98
-------
Chapter 4C: Erosion and Sediment Control 99
The variability in the effectiveness of selected conservation practices that are
frequently recommended by NRCS in resource planning is illustrated in Table 4c-
2. This table can be used as a general guide for estimating the effects of these
practices on water quality and quantity. The table references include additional
site-specific information. Practice effects shown include changes in the water bud-
get, sediment yield, and the movement of pesticides and nutrients. The impacts of
variations in climate and soil conditions are accounted for to some extent through
the presentation of effectiveness data for different soil-climate combinations. Data
were not available for all soils and climates.
Data for Table 4c-2 were obtained from the research literature and include
computer model simulation results. Values are reported as the percentage of
change in the mass load of a given parameter that can be expected from installing
the practice. Changes are determined versus a base condition of a rain-fed, non-
leguminous, continuous, row crop (usually corn) that has been cultivated under
conventional tillage.
Data from model studies are marked with an "M." For example, -27'M indi-
cates that the load reduction estimate of 27% is derived from a model simulation.
Data obtained from plot studies using rainfall simulators are marked with an "S."
For example, +755 indicates that the estimated load increase of 15% is based on a
rainfall simulation study.
The range is reported in parentheses, followed by other reported values
within the range, set off by commas. For example, (-32 to +10), -15, +5.denotes a
range from a decrease of 32% to an increase of 10%, with intermediate reported
changes of a 15% decrease and 5% increase. Some practices have a relatively
wide range of values because of the variability in climate, soils, and management
that occurs with these practices. Although some of the ranges are large, they can
usually be attributed to small changes in very small quantities (thus the percentage
change is great, yet the magnitude of change is small) or to the variability of site-
specific conditions.
Table 4c-2 contains the following information:
O Column (a) lists the practice and its NRCS reporting code number.
"O Column (b) lists the climate and a generalized soil classification for the site
under consideration.
O Column (c) is the percentage change in surface runoff and deep percolation,
components of the water budget, caused by the applied practice.
O Column (d) is the percentage change in sediment load caused by the applied
practice.
O Column (e) is the percentage change in the phosphorus load. Two phases of
phosphorus are considered: adsorbed and dissolved.
O Column (f) is the percentage change in the load of nitrogen in the adsorbed
phase, nitrate in surface runoff, and nitrate in the leachate.
O Column (g) is the percentage change in the pesticide load. The phases of the
pesticide listed are (1) strongly adsorbed in surface water, (2) weakly
adsorbed in surface water, and (3) weakly adsorbed in the leachate.
Chapter 4C-99:10/98
-------
100 Chapter 4: Management Measures
Table 4c-2. Effects of conservation practices on water resource parameters (USDA-SCS, 1988a).
NOTE: Valuoi in me tables are. taken trom published research model simublfans. and results ol stmjlatw rairtaJI Btol*. Butt ifo range [in parentheses) and
additional values wttrun II-,B range (after parentheses, separated by comma) ire proseriled. The values describe lh« parcentatjo change w mass loads cavsad
byithe use of ihe practice on a ronirrigated, nentegjite. contlntous row ctop mat tai been grown under conventional taiage. Values intde fie range are
shown behind: BIB range values and are separated by commas t-30.-90>. -78. Values from model simulation ore marked by an U, e.g.. -30M, and vahas from a
ra'.rdall sinrutalor ara narked wilh an S, 0.9.. -29S. Pew daU a*e svSiteWe lor cad oondfljom and ihart 2ont ii not ineluSed n the vote, rial al soil-ciimato
cnmbinaSans huvn evailabto ralorence data. A minus is a decreased value: a plus is en increase
irt
Prnctrco
and
. Comovr
Farming
330
Strip-
Cropping
Coiitaut
585
Cons.
Tilage-
NoTtll
329
Cons.
Tillage'
(Othor
types)
32S
*>
CUmale
and Soil
H-S4
Sandy
Silly
Clayoy
SA-3-
SBty
Sandy
Silry
dayey
SA*
Clayey
Sllry
Clayey
Sandy
Claye»
SBty
Sand/-
SA-S'
Silly
M-S*
SiRy
H-*1
SBly
Clayey
SA-S'
SHty
Clayey
HP
Sandy
Silty
Clayey
(c)
Water BurJgtH
(% Change)
Surlsca Deep
ftunoft Percolation
(.65..7S) a
(•GO.-40) -10
(•19,.20» 45
(-27.-SO) #
-M »
-30 -10
-18 »
t-17,-29) *
-15 «
-SM tOM
-SJM +3C6rjr*
No change No change
(-91. +38}" No change
(-26M.-8BJ,- •
61
+36 #
1-21,-SO) *
(•1S.-73) +5
•51.-20
-30 +10
-54 e
(-Z9.-89) +10
*
(-40.-SS) +5
(-20.-M) •
(-10.-81),- +10
20
•:c»
Sediment
Yield
(% Ciange)
(-ZO.-50;.
(-B5.-20)
(•a2.-£3)
•26
-60
«
•
s)7JC-U),-4a
-esM
-03M
(-73M.-aZ}
1-7S.-9S}
K6M.-99S)
•96
HH.-93)
(-43,495)
-65.-S5
•70
»
(-49,-BI)
(•29.-88)'
•34-41
(o)
l^aspnorirs
C& Changa)
Sediment Rur.ofl
-2» -10
t-60,-85) I-63.-65)
-55 - -20'
» »
t ' »
•6D -30
* 1
* »
* ' II
-COM -06M
I2M -89M
-09M -»0t<
-S3M <30M
t-84. 9S) (>900,-22)<
(-51.-87S) (0,4 155)
•.7a».-e2
(-80,00) • +138
(-7S.-90) (» Change) (% Change)
Nrrosan Nitrmin Sfflxigly Weakly WeaMy
Adsorbed Surtaca Nitiaem Aed Adsotbed Arfeortoadl
Phases rtunolt PercoUe 5W* leactiats SW
-15 -5 • t » I
•H5.-541 <-25,-72>,- +10 H7 1 # «
-56 «3 4IO t * *
(-T2.-25)
1 « t # # «
1 * -tlfl * » «
•60 -35 47« It * «
t i-25,-ii) >e t » *
i -n +? • » §
» » • • « • •
-81M -*3M +15BM a « 0.40
'-JIM -?$M +220U* « # »
-98M -39M +12M * « »
•53M- -11 H»M.+a) « * -S»U
t-60,-94) [-42,4600) (6M.+18) -78 (+SM,-50).
4D,«-100 l.+B1
(-69a,-906) i-67,-60) 0. 1 • »
-72.-70 -42i,.45
(-SO.-90).- (0.445) * » » »
«0
t * » {-75.-5C1 * +500
•91 .-82 t^WO.-»»i » « • »
tf
« « 1 ft *
4
* » 4 » » »
» • « » » »
-» -88 « » » »
r a • {-w.-ii) * (+1&.+27)
» • * . <-33M.-2J 1 (+60M.-2')
Chapter 40-100:10/98
-------
Chapter 4C: Erosion and Sediment Control 101
Table 4c-2. (Continued)
M (b. (0 W .«
Water Budsct
Practice
and CGmeW Surtsca
Num&ar and Sol Runoff
SA'
SUty (-16.-25),-
Sandy 20
Clayey -31
-B8M
TsrrncBS H-S'
with
Under- Sandy -14
ground Silly (-24.-60)
Outlets Ctayay (-3Q.-3S)
600
SA-S'
Sandy -14M '
Silty (-73.+43M)
Clayey (-15.-3flM)
WASCOB' H*
63S
Sandy -40
Silty (-8S.-42)
Clayey ff
SA'
Sandy t
Silly -73
Clayey -30
Sedrmanl
D«ep Yinld
Percolation (% Change)
« (-36,-92},-63
* -45
« -90M
* (-9S.-98)
(+V2.+500)' (-87.-9S)
(+5.KMO)' (-90.-95)
+67M (-9S.-96)
+162M (-95,-S2M)
(+5.+29QM)4 (-95.-91M)
+15 (-9S.-99)
* (-95.-50).-86
# (-&0.-55)
* (-95.-9B) -
' * -95
+5 (-90.-S5)
(% Oungo)
Seahrent flunotf
» *
« »
t »
-9$ -60
» -30
-99M -42M
-97M -72M
-9&A -S5M
» -71
1 «
* »
•73 +86*
* . f
' Climatic conditk>m: H-S • Huniri • Snow; H » Humd; SAS - S«ni-Arid - STOW; >nd S& >
' Measured value* were jmsll numbers; perevMage change rr*y have hige raluei.
• Data hro acallMd «J«rt.
n (ui
Nlttog«n Pesticides
(% Chang«> (% Changa)
Nitrogeo
Adsoioed
Phaias
A
«
•95
•95
-99M
•97M
-96M
-65
•S5
1
t
Surr»And.
NUraia in StmngV Waakly
Surfica Nilrolc in Adsorbed Adsartod
Runotl Percolate SW* Loachate
t » (-39,-aij «
t » t «
Nolsig. # « #
a * t t .
(-70.+55)" +15 » *
-30 +10 « «
•42M +20M * »
•78M +37M » »
-91 M (10 to nigh
values)
-60 +15 » »
(•B6.-44) +a » «
II * « tf
» • • « »
-60 * « «
» II * »
Adsotbed
a.
»
8
ft
(-73.-91M)
(-84.-91W)
<-69M.-
78M)
-4
*
* Mo«s.rtd vnluM were l«rgo nun-lj«.-».
' WalotardSedirnerit Contact B*»in
" • Unknonri. iit«-dopondorn. or centlic*--) v>lu»-
Conservation tillage is now promoted widely by a large number of groups
and organizations because it is both profitable and effective in controlling erosion.
For example, researchers at Louisiana State University have shown that the use of
no-till with or without a cover crop (2-6 tons of soil loss per acre per year) is
much more effective at controlling erosion on cotton fields than is use of conven-
tional tillage with or without a cover crop (13-16 tons per acre per year) (Zeneca,
1994). It is reported that the top three reasons soybean farmers adopt no-till are
reduced soil erosion, increased profit potential, and time and labor savings (Alesi,
1998). The percentage of soybeans planted in no-till has increased from 1992 to
1997 at an average annual rate of 11.6 percent, ranging from 4 percent (Minne-
sota) to 25 percent (North Dakota) in the Upper Midwest (CTIC, 1997). Accord-
ing to some of the leading authorities on conservation tillage, the economic and
environmental benefits of farming with conversation tillage are simply too numer-
ous to ignore (CTIC, ca. 1997). CTIC reported that, on average, no-till resulted in
93 percent less erosion and 69 percent less water runoff than moldboard plowing.
Chapter 4C-101: 10/98
-------
102 Chapter 4: Management Measures
Site conditions,
cost, and
maintenance
requirements are
considered for
practice selection.
Local
demonstrations are
also needed to
refine practices
and encourage
adoption.
Factors in the Selection of Management Practices
Two fundamental options exist to minimize water and wind erosion from
agricultural land and the delivery of sediment to receiving waters: (1) Controlling
soil loss from fields or streambanks by reducing detachment and transport of sedi-
ment, and (2) Encouraging deposition of eroded sediment to prevent delivery to—
surface waters. Different management strategies are employed with the different
options. Preventing initial soil loss (option "(1)") is generally the most desirable
option because it not only minimizes the delivery of sediment to receiving waters
but also provides an agronomic benefit by preserving soil resources. Option "(2)"
minimizes the delivery of sediment to receiving waters, but does not necessarily
provide the agronomic benefits of upland erosion control. In some cases, for ex-
ample, management or economic constraints may prevent full installation of all
practices needed to adequately reduce field soil loss, and additional practices to
prevent delivery of eroded sediment may be needed. In other cases, even if field
soil loss can be reduced to "T" level, additional practices may be needed to pre-
vent delivery of sediment to critical or sensitive water bodies. Using one or both of
these options, planners have the flexibility to address erosion and sediment prob-
lems in a manner that best reflects State and local needs and preferences.
Management practices for a given site should not result in undue economic
impact on the operator. Many of the practices that could be used to implement this
measure may already be encouraged or required by Federal, State, or local pro- ,
grams (e.g., filter strips or field borders along streams) or may otherwise be in use
on agricultural fields. By building upon existing erosion and sediment control
efforts, the time, effort, and cost of implementing this measure will be reduced.
It should be noted that basic erosion control measures will not always provide
adequate control of nutrients, pesticides, or other sediment-attached pollutants.
Erosion control practices tend to be most effective on larger particles, which tend
to carry a lower proportion of adsorbed pollutants than do finer particles like
clays. Many erosion control practices or structures may not effectively control the
majority of pollutants that are attached to fine soil particles. If pollutants attached
to soil particles are the primary concern, practices specifically designed to control
fine sediments should be applied.
Conversely, some nutrient or irrigation management practices may contribute
to erosion control, even though their primary purpose is not erosion control. Waste
utilization, for example, may help reduce soil erodibility by both water and wind
through improvements in soil organic matter content. Improved irrigation water
management may help reduce wind erosion potential by maintaining adequate soil
moisture during critical periods.
Continued performance of this measure will be ensured through supporting
maintenance operations where appropriate. Although some practices are designed
to be effective and withstand a design storm, they may suffer damage when larger
storms occur. It is expected that damage will be repaired after such storms and
that practices will be inspected periodically. To ensure that practices selected to
implement this measure will continue to function as designed and installed, some
operational functions and maintenance will be necessary over the life of the prac-
tices.
Chapter 40-102:10/98
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Chapter 4C: Erosion and Sediment Control 103
Reliable and current
information on cost
of initial investment,
along with
annualized cost
throughout practice
life, helps planners
and farmers make
sound decisions.
Most structural practices for erosion and sediment control are designed to operate
without human intervention. Management practices such as conservation tillage, how-
ever, do require some attention each time they are used. Field operations should be
conducted with practices like contouring or terraces in mind to ensure that the prac-
tices or structures are not damaged or destroyed by the operations. For example, herbi-
cides should not be applied to areas of permanent vegetative cover that are used as
part of erosion control practices, such as waterways and filter strips.
Structural practices such as diversions, grassed waterways, and filter strips may
require grading, shaping, and reseeding. Trees and brush should not be allowed to
grow on berms, dams, or other structural embankments. Cleaning of sediment reten-
tion basins will be needed to maintain their original design capacity and trapping effi-
ciency.
Filter strips and field borders must be maintained to prevent channelization of
flow and the resulting short-circuiting of filtering mechanisms. Reseeding of filter
strips may be required on a frequent basis. Grazing and other livestock activities
should be managed to avoid damage to vegetation cover, especially near streams.
Finally, conditions sometimes occur when serious wind erosion is imminent or has
just begun, and immediate action is needed to protect soil and crops. Several emer-
gency techniques can lessen or slow wind erosion. Emergency measures are not as
effective as long-term planned erosion control; they'are last resort options and should
not be relied on for primary erosion control or continued use. The following emer-
gency control methods can reduce damage from anticipated wind erosion (Cooperative
Extension, Institute of Agriculture and Natural Resources, University of Nebraska):
D Emergency tillage to produce ridges and clods
O Addition of crop residue
O Application of manure
O Irrigation to increase soil moisture
O Temporary, artificial wind barriers
D Soil additives or spray-on adhesives
Choice of specific methods depends on severity of erosion, soil type, crop type
and growth stage, and equipment available.
Cost of Practices
Both national and selected State costs for a number of common erosion control
practices are presented in Table 4c-3. The variability in costs for practices can be
accounted for primarily through differences in site-specific applications and costs,
differences in the reporting units used, and differences in the interpretation of reporting
units.
The cost estimates for control of erosion and sediment transport from agricultural
lands in Table 4c-4 are based on experiences in the Chesapeake Bay Program. It is
important to note that for some practices, such as conservation tillage, the net costs
often approach zero and in some cases can be negative because of the savings in labor
and energy. In fact, it is reported that cotton growers can lower their cost per acre by
$24.32 due to lower fixed costs associated with conservation tillage (Zeneca, 1994).
Chapter 4C-103:10/98
-------
104 Chapter 4: Management Measures
Table 4c-3. Representative costs of selected erosion control practices.
Practice
Diversions
Terraces
Waterways
Permanent
Vegetative Cover
Conservation
Tillage
Unit
ft
a.s.
ft
ac
a.e.3
ac
ac
Range of Capital Costs
1.97-5.51
3.32 -14.79
24.15-66.77
5.88 - 8.87
113-4257
1250-2174
69 - 270
9.50-6 3.35
References
Sanders etal., 1991
Smolen and Humenik, 1989
Smolen and Humenik, 1989
Russell and Christiansen, 1984
Sanders etal., 1991
Barbarika, 1987; NCAES,
1982; Smolen and Humenik, 1989
Russell and Christiansen, 1984
Barbarika, 1987; Russell and
Christiansen, 1984; Sanders et al., 1991;
Smolen and Humenik, 1989
NCAES, 1982; Russell and
Christiansen, 1984; Smolen and
Humenik, 1989
Reported costs inflated to 1998 dollars by the ratio of indices of prices paid by farmers for
all production items, 1991=100.
acre served
3
acre established
[Note: 1991 dollars from CZARA were adjusted by +15%, based on ratio of 1998 Prices Paid by Farmers/1991 Prices Paid
by Farmers, according to USDA National Agricultural Statistics Service, httpS/www.usda.gov/nass/sources.htm 28
September, 19981 .
Chapter 4C-104: 10/98
-------
Chapter 4C: Erosion and Sediment Control 105
Table 4c-4. Annualized cost estimates for selected management practices from Chesapeake Bay
installations3 (Camacho, 1991).
Practice
Practice Life Span Median Annual Costs"
(Years) (EACcVS/acre/vrl
Nutrient Management
Strip-cropping
Terraces
Diversions
Sediment Retention Water Control Structures
Grassed Filter Strips
Cover Crops
Permanent Vegetative Cover on Critical Areas
Conservation Tillage*1
Reforestation of Crop and Pasture"
Grassed Waterways9
Animal Waste System'
3
5
10'
10
10
5
1
5
1
10
10
10
2.40
11.60
84.53
52.09
89.22
7.31
10.00
70.70
17.34
46.66
1 .00/LF/vr
3.76/ton/vr
Median costs (1990 dollars) obtained from the Chesapeake Bay Program Office (CBPO) BMP tracking data
base and Chesapeake Bay Agreement Jurisdictions' unit data cost. Costs per acre are for acres benefited
by the practice.
Annualized BMP total cost including O&M, planning, and technical assistance costs.'
c EAC = Equivalent annual cost: annualized total costs for the life span. Interest rate = 10%.
d Government incentive costs.
e Annualized unit cost per linear foot of constructed waterway.
Units for animal waste are given as $/ton of manure treated.
Chapter 4C-105:10/98
-------
106 Chapter 4: Management Measures
Chapter 40-106:10/98
-------
Chapter 4D: Facility Wastewater and Runoff from Confined Animal Facilities 107
4D: Facility Wastewater and Runoff
from Animal Feeding Operations (AFOs)
Management Measure for Facility Wastewater and
Runoff from Animal Feeding Operations
Animal Feeding
Operations should
be designed.and
operated to avoid
waste discharge by
having engineered
runoff controls,
waste storage,
waste utilization,
and nutrient
management.
The national goal for management of animal feeding operations (AFOs) is:
no adverse environmental impacts from AFOs to waters of the U.S. except in
extraordinary circumstances.
To meet this national goal, management of AFOs should address the following
eight components:
1. Divert clean water. Siting or management practices should divert clean water
(run-on from uplands, water from roofs) from contact with feedlots and hold-
ing pens, animal manure, or manure storage systems.
2. Prevent leakage. No leakage to ground or surface water from buildings, col-
lection systems, conveyance systems, and storage facilities.
3. Provide adequate storage. Liquid manure storage systems should be (a) de-
signed to safely store the quantity and contents of animal manure and waste-
water produced, contaminated runoff from the facility, and rainfall from the
25-year, 24-hour storm and (b) consistent with planned utilization or utiliza-
tion practices and schedule. Dry manure, such as that produced in certain
poultry and beef operations, should be stored in production buildings, storage-
facilities, or otherwise covered to prevent precipitation from qoming into di-
rect contact with the manure.
4. Apply manure in accordance with a nutrient management plan that meets the
performance expectations of the nutrient management measure.
5. Address lands receiving wastes. Areas receiving manure should be managed
in accordance with the erosion and sediment control, irrigation, and grazing
management measures as applicable, including practices such as crop and
grazing management practices to minimize movement of nutrient and organic
materials applied, and buffers or other practices to trap, store, and "process"
materials that might move during precipitation events.
6. Recordkeeping. AFO operators should keep records that indicate the quantity
of manure produced and its utilization or disposal method, including land
application. v
7. Manage dead animals. Dead animals should be disposed of in a way that does
not adversely affect ground or surface waters.
8. Consider the full range of environmental constraints and requirements. Ma-
nure should be used or disposed of in ways that reduce the risk of environmen-
tal degradation, including air quality and wildlife impacts, and comply with
Federal, State, and local law. •
Chapter 4D-107:10/98
-------
108 Chapter 4: Management Measures
AFOs, CAFOs, and CZARA
Existing regulatory definitions of AFOs and concentrated animal feeding
operations (CAFOs) are given at 40 CFR 122.23 and Part 122, Appendix B.
/These regulations define an AFO as a facility that meets the following criteria: _
1. Animals (other than aquatic animals) have been, are, or will be stabled or
confined and fed or maintained for a total of 45 days or more in any 12-month
period, and
2. Crops, vegetation forage growth, or post-harvest residues are not sustained in
the normal growing season over any portion of the lot or facility.
As described in Chapter 1, EPA published guidance specifying management
measures for sources of nonpoint pollution in coastal waters as required under
section 6217(g) of CZARA. With regard to the management measures for live-
stock operations (EPA, 1993), EPA defined a confined animal facility as a lot or
facility that meet the same two criteria (1 and 2) specified above for AFOs. AFOs
include the areas used to grow or house the animals, areas used for processing and
storage of product, manure and runoff storage areas, and silage storage areas.
The subset of AFOs within the section 6217 coastal management areas that
are subject to the CZARA management measures for confined animal facilities is
determined by the number of head at the operation and whether or not the opera-
tion is designated as a CAFO. Those facilities that are required by Federal regula-
tion 40 CFR 122.23(c) to apply for and receive discharge permits, are NOT
covered by section 6217 since they are CAFOs. CAFOs are defined generally as
an AFO that:
D Confines more than 1,000 animal units (AU): or '
O Confines between 301 to 1,000 AU and discharges pollutants:
— Into waters of the U.S. through ajnan-made ditch, flushing system, or
similar man-made device; or
— Directly into waters of the U.S. that originate outside of and pass over;
across, or through the facility or otherwise come into direct contact with
the animals confined in the operation.
In addition, 40 CFR 122.23(c) provides that the Director of a National Pol-
lutant Discharge Elimination System (NPDES) permit program may designate any
AFO as a CAFO upon determining that it is a significant contributor of water
pollution. AFOs containing fewer than the number of head listed in Table 4d-1 for
small confined animal facilities are not subject to the CZARA management mea-
sures for confined animal facilities. Figure4d-l shows the relationship between ,
AFOs, CAFOs, and large and small confined animal facilities under CZARA.
40-108- 10/98
-------
Chapter 4D: Facility Wastewater and Runoff from Confined Animal Facilities 109
Table 4d-1. Large and Small Confined Animal Facilities under CZAR A.
Animal Type
Beef Feedlots
Stables (horses)
Dairies
Layers
Broilers
Turkeys
Swine
Large Confined Animal
Facilities under CZARA
Number of Head
>300
>200
>70
>15000 .
>15000
> 13750
>200
Small Confined Animal
Facilities under CZARA
Number of Head
51 - 299
100- 199
20-69
5,000 - 14,999
5,000 - 14,999
5,000 - 13,749
100- 199
Figure 4d-1.
ANIMAL FEEDING OPERATION }-
301-1,000 animal units ]
(at described in 40 CFR
122. Appendix B) I
Owr 1.000 animal unK*
(*• dwcrttMd In 40 CFR
1H. Appendix 8)
Fewer than 300 animal
units (as described In 40
CFR 122, Appendix 0
Potential to
discharge through
man-made devise
or directly to
waters ol the U.S.
Potential to
discharge through
man-made devise
or directly to
waters of th» U.S.
Potential lo
dlecnarg* Oirougn
any mean* of convty*nc«
Potential to
discharge through
any other means ol
conveyance
Case-by-case
designation
Case-by-case
designatlo
CZARA wicllof
SUK HtquinmiMitt
• NPOES permit
re^utrementt: BAT
of BCT bftS4d on BPJ
NPOES permit
mqulmnent*: BAT
Of BCT bu»d on BPJ
Chapter 4D-109:10/98
-------
110 Chapter 4: Management Measures
Management of Soil Phosphorus Levels to
Protect Water Quality
Phosphorus in Agriculture
Phosphorus (P) is important to and used extensively in both the crop production and confined livestock
segments of agriculture, making it one of the most common elements used in agriculture today.
One of the most important functions of P in plants is the storage and transfer of energy. Phosphorus is
essential for seed production, promotes increased root growth, stalk strength and early plant maturity,
and aids in resistance to root rot diseases and winterkill.
In the confined livestock segment, producers use P as a diet supplement, in addition to the P already
contained in feeds, to improve animal performance. To avoid excessive buildup of soil-P on the lands
surrounding confined animal operations, consideration must be given to the amount of land available to
absorb P from livestock.
Environmental Impacts
In areas of intense crop and livestock production, continued inputs of fertilizer and manure P in excess
of crop requirements have led to a build-up of soil P levels. This increases the potential for nonpoint
source (NPS) runoff to carry excess phosphorus to surrounding streams and lakes.
Phosphorus is usually the limiting nutrient in aquatic systems. When excess phosphorus enters streams
and lakes, creating P concentrations between the critical values of 0.01 and 0.02 ppm (Sawyer, 1947;
Vollenweider, 1968), accelerated eutrophication occurs. Eutrophication, a natural process that usually
occurs over a long period of time, is characterized by increased aquatic plant growth, oxygen depletion,
and pH variability. It eventually leads to a decline in plant species quality and adverse food chain
effects (Sharpley, et al., 1994), all of which may reduce water quality.
Transport Mechanism
Phosphorus enters the soil through mineral dissolution, desorption from clay and mineral surfaces, and
biological conversion from organic materials to inorganic forms. As rainfall or irrigation water inter-
acts with a thin layer of surface soil, P is either moved into agriculture runoff through dissolution from
the soil and plant material, or is transported by erosion, remaining either attached to soil or in vegeta-
tion. The dissolved P is immediately available for uptake by aquatic biota (bioavailable), while the
paniculate P is available only after all of the dissolved P is consumed. Once bioavailable P moves from
the field into receiving waters, it can contribute to eutrophication (Wood, etal.)
Another mechanism for P transport occurs when large accumulations of P occupy all available sites on
the soil surface, causing additional P to leach downward through the soil column. When this leaching
is followed by lateral movement of water under the soil surface, especially under high water table
conditions, dissolved P may be added to the surface waters.
m/QP
-------
Chapter 4D: Facility Wastewater and Runoff from Confined Animal Facilities 111
Soil Testing
The prime goal of soil testing methods have also been developed and tested to determine if they might more
accurately predict the runoff and drainage P levels. Some of the most promising new methods are:
(1) Breeuswmaetal., 1995-developed to determine the degree of P saturation in soils
(2) Chardon et al., 1996 - using an iron oxide coated filter paper strip as an "infinite sink" to measure
the amount of P in soils that is subject to runoff or leaching
(3) Pote et al., 1996 - using distilled water to extract readily desorbable soil P, simulating the rapid
release of P to runoff water.
Soil test extractants now used for phosphorus in the U.S. (Kamprath and Watson. 1980)
Soil Test Category
Dilute concentrations of strong acids: Solvent nature of acids
primarily extracts Al and Fe bound P, plus some Ca-P. Best for
soils with pH < 7.0
Dilute concentrations of strong acids plus a complexing ion:
Extractants remove P by solvent action of acids and complexing
ability of fluoride ion for Al-P. Best on acidic soils.
Dilute concentrations of weak acids: Anion replacement
Buffered Alkaline Solutions: Extract P by hydrolysis of cations
binding P. Precipitate CaCO3 from calcareous, alkaline, and
neutral soils, reducing Ca and increasing P concentrations in
solution, making P more accurately and easily measured.
Common
Soil Test
Mehlich 1
Bray PI
Mehlich 3
Morgan and
Modified
Morgan
Olsen
AB-DTPA
Regions in the U.S. Where
Commonly Used
Southeast and Mid-Atlantic
Bray: North Central and Midwest
Mehlich 3: Widespread use in U.S.
Northeast
West and Northwest
Other Control Options
One reason for high phosphorus levels in runoff from fields fertilized with poultry or swine litter is that these
animals lack phytase enzymes, making most of the phytate P (65% of total P) in corn and soybeans unavailable
to these animals. In order for normal growth and development, other forms of P must be added to the diet.
This addition of inorganic P results in much higher levels of P in manure.
Phytase products - One way to reduce the level of inorganic P fed to these animals, thus lowering the level of P
in manure, is to add phytase enzyme to the feed aiding the breakdown of phytate P.
Low phytic acid or high available P (HAP)'Corn - Another way to reduce the amount of additional P needed in
the animal diets, thus reducing amounts of P in manure, is to feed the animals a corn hybrid containing lower
amounts of phytate P or higher amounts of available P.
While some studies have shown that P levels in runoff decrease with the use of these products in livestock diets,
more comprehensive research must be done before any conclusions can be drawn.
Chanter. 40-111:10/98
-------
112 Chapter 4: Management Measures
Management Measure for Facility Wastewater and
Runoff from Animal Feeding Operations: Description
The water quality problems associated with confined animal facilities result
from accumulated animal wastes, facility wastewater, and storm runoff, all of-—
which may be controlled under this management measure (Figure 4d-2). The goal
of this management measure is to minimize the discharge of contaminants in facil-
ity wastewater, runoff, and leakage to ground water, while at the same time pre-
venting any other negative environmental impacts such as increased air pollution.
Accumulated animal wastes include manure, litter, or other waste products that
are deposited within the confinement area and are periodically removed by scrap-
ing, flushing, or other means and can be conveyed to a storage area or facility.
Facility wastewater is water discharged in the operation of an animal facility as a
result of animal or poultry watering; washing, cleaning, or flushing pens, barns,
manure pits, or other animal facilities; washing or spray cooling of animals; and
dust control. Animal lot runoff includes any precipitation (rain or snow) that
comes into contact with manure, feed, litter, or bedding and may potentially leave
the facility either by overland flow or by infiltration.
Figure 4d-2. Management measure for facility wastewater and runoff from confined animal facilities
(large units) (EPA, 1993).
(A) Runoff from enctoied confined rKMIe*
(S) Runoff from stage storage areas
(c) Runoff from open confined wen '
(o) Runoff trom minute storage areas
(E) FacHles wastewaler
0
Storage for up to & including
i 25-yt. 24 hr frequency norm
Mh*tilze et>nt«mln»ttefi ol grourdwaler
Mtnaga itortd runoff
and •ecumulittd
lolldt from facility
through *n
Ippropriataj weite
utllliMlon lyittra
Chanter 40-112: 10/98
-------
Chapter 4D: Facility Wastewater and Runoff from Confined Animal Facilities 113
Implementation of this management measure will greatly reduce the volume
of runoff, manure, and facility wastewater reaching a water body due to structural
practices such as solids separation basins in combination with vegetative practices
and other techniques that reduce runoff while also protecting ground water. The
measure can be implemented by using practices that divert clean runoff water
from upslope sites and roofs away from the facility, thereby minimizing the
amount of contaminated water to be stored and managed. Accumulated animal
wastes should be protected as much as possible from runoff and stored in such a
way that any runoff water, seepage, or leachate can be captured and managed with
runoff and wastewater. Runoff water and facility wastewater should be routed
through a settling structure or debris basin to remove solids, and then stored in a
pit, pond, or lagoon for application on agricultural land in accordance with the
Nutrient Management Measure. If manure is managed as a liquid, all manure,
runoff, and facility wastewater can be stored in the same structure and there is no
need for an additional debris basin. In some areas, certain systems may be pre-
ferred over others due to competing environmental concerns (e.g., liquid systems
may raise concerns regarding air quality), and innovative alternatives that achieve
the management measure goals should be considered.
Diverting clean water
from upslope areas
and roof runoff away
from the animal lot
and waste storage
structure can reduce
waste volume and
storage requirements.
Animal feeding
operations have the
potential to
contribute large
pollutant loads to
waterways. Because
they may be located
near streams and
water supplies,
AFOs require well-
planned and
maintained systems
of practices to
minimize human
health and aquatic
ecosystem impacts.
Movement to
Surface Waters
This management measure is consistent with, yet more specific than the
CZARA management measure for large confined animal facilities, and it goes
beyond the expectation for small confined animal facilities under CZARA by call-
ing for storage. This does NOT change, however, the performance expectations
foj either large or small facilities that are subject to the CZARA management
measures.
Contaminant Movement from Animal Feeding
Operations into Surface and Ground Water
The concentration of livestock production and housing in large systems has
resulted in large accumulations of animal wastes with the potential to contribute
nutrients, suspended solids, pathogens, oxygen-demanding materials, and heavy
metals to surface and ground waters. Animal operations can also be a source of
atmospherically transported pollutants, particularly ammonia, via volatilization
(Harper and Sharpe, 1997). The pollution potential of such accumulations is influ-
enced by the number and type of animals in the operation, the facilities and prac-
tices used to collect and store the wastes, and the methods chosen to manage the
wastes (e.g., application to the land). In a study of 18 states with large numbers of
beef feedlots, total confinement systems had minimal runoff problems, while 35%
of paved drylot, 25% of unpaved drylot, and 27% of openlot systems had signifi-
cant runoff problems (Johnson and Davis, 1975).
The volume of runoff from animal facilities is influenced by several major
factors including: (1) water inputs, dependent on rain storm intensity and duration,
time since last runoff, snowpack accumulation and melting, and runoff entering
from outside the facility; and (2) runoff generation from impervious surfaces such
as roofs and paved areas. While precipitation inputs cannot usually be managed,
the diversion of clean water from upgradient areas, and the reduction and diver-
sion of runoff from impervious areas (e.g. installation of roof gutters on facility
Chapter 40-113:10/98
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114 Chapter 4: Management Measures
buildings) to avoid contact with pollutants can affect the volume of runoff that
needs to be controlled. In regions of the country with very high rainfall, some
animal facilities are entirely roofed to prevent precipitation from coming into con-
tact with animal wastes and to minimize the total volume of stored wastes that
must be managed.
The pollutant load carried in runoff from animal facilities is affected by sev-
eral additional factors, including: (1) pollutants available for transport in the facil-
ity; (2) the rate and path of runoff-movement through the facility; and (3) passage
of runoff through settling or filtering practices before exiting the facility. Manage-
ment activities like scraping manure from pavement areas or proper storage of
feeds and bedding can significantly reduce the availability of pollutants for trans-
port. Structures such as detention basins can affect pollutant transport by regulat-
ing runoff movement and increasing settling within the facility. Vegetated filter
strips, riparian buffers, or other vegetated areas located around animal facilities
can reduce delivery of pollutants to surface waters by settling, trapping, or trans-
forming nutrients, sediment, and pathogens in runoff leaving the facility.
The ranges in concentrations of pollutants from some typical sources on a
dairy farm are shown in Table 4d-2. The total pounds of pollutants that could
come from a typical 100-cow dairy is shown in Table 4d-3. These values were
obtained by multiplying the concentrations by the typical volume in Table 4d-2.
The pounds per year from these concentrated sources may be small but represent
significant pollutant sources if not controlled. Each farm is different, as shown by
the range in concentration and amount of pollutants from the various sources.
Some of the variation is under the control and management of the farmer and their
day-to-day operations, while some of it is due to the type and layout of the facility.
Table 4d-2. Waste characteristics from dairy farms (Wright, 1 996).
Potential
Pollutant
Source
Milking Center
Waste
Silage Leachate
Barnyard
Runoff
Dairy Manure
Domestic Waste
• 5 day BOD
" yearly volumes
c Typical values
Biochemical Nitrogen Phosphorus Volume
Oxygen pprn ppm gallons per
Demand* ppm 100 cows"
400-10,000 80-900 25-170 73,000
12,000-90,000 4,400C 500C 105,000
1,000-10,000 , 50-2,100 - 5-500 80,000
20,000C 5,600° 900C 660,000
150-250 20-30 5-10 365,000
assuming: 2 gallon s/cow/day milking center waste
bunk silo, 25% DM, no drainage water, 36" precipitation
70 ft2/cow, 36" precip., scraped daily, good solid retention
22,000 LB/cow/yr. milk production, 18 gal./cow/day
10 people producing 1 00 gal/day/person
Chanter 4D-114: 10/98
-------
Chapter 4D: Facility Wastewater and Runoff from Confined Animal Facilities 115
Table 4d-3. Annual waste production on a typical" 100 cow dairy (Wright, 1996).
Potential
Pollutant
Source
Biochemical
Oxygen
Demand* ppm
Nitrogen
Ib.
Phosphorus
Ib.
Milking Center
Waste
Silage Leachate
Barnyard
Runoff
Dairy Manure
Domestic Waste
250-6,100
10,500-79,000
670-6,700
110,000C
450-760
50-550
3900'
30-1,400
31,000°
60-90
15-100
440C
3-330
5,000C
15-30
• 5 day BOD
"yearly volumes assuming:
c Typical values
2 gallons/cow/day milking center waste
bunk silo, 25% DM, no drainage water, 36" precipitation
70 ftVcow, 36" precip., scraped daily, good solid retention
22,000 LB/cow/yr. milk production, 18 gal./cow/day
10 people producing 100 gal ./day/person
Movement to
Ground Water
Facility wastewater volumes and pollutant loads are controlled primarily
through the design and operation of the facilities involved in watering, washing,
and cleaning. Frequency of wash^downs and the volume of water used, for ex-
ample, will influence both total volume of wastewater to be managed and the con-
centrations of pollutants in the wastewater. In dairy milking center wastewater,
both volume and concentrations of pollutants in the wastewater are controlled by
the type of milking and plumbing systems and the formulation of cleaning com-
pounds used.
An important part of the treatment of milking center waste is to reduce the
volume of water and the amount of material that must be handled. The amount of
waste can be affected by management as shown by the variability of both the
flows and the concentrations in Tables 4d-2 and 4d-3. Reducing the volume of
wastewater to be treated will reduce the cost of wastewater treatment. Energy
savings for reduced pumping costs and water heating can also be realized. Using
only the amount of cleaners that are necessary and using low phosphorus deter-
gents can significantly decrease the amount of phosphorus in the wastewater. Us-
ing automated systems appropriately and water treatment where needed can result
in a cost savings. Manure reduction methods for milking centers are shown in
Table 4d-4 and methods for phosphorus reduction are described in Table 4d-5.
It is recognized that implementation of some surface runoff controls may
increase the potential for movement of water and soluble pollutants through the
soil profile to the ground water. It is not the intent of this measure to address a
surface water problem at the expense of ground water. Facility wastewater and
runoff control systems can and should be designed to protect against the contami-
nation of ground water. Ground water protection will also be provided by mini-
mizing seepage of stored, contaminated water to ground water, and by
implementing the nutrient and pesticide management measures.
Chapter 40-115:10/98
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116 Chapter 4: Management Measures
Table 4d-4. Manure reduction methods and costs for milking centers (Wright, 1996).
Manure Reduction Methods
Reduction
Potential
Estimated Cost
Schedule the cleaning of alleys and holding
areas to minimize the amount of manure
tracked into parlors
Scrape the cow platforms before hosing down
parlors
Don't install drains in the cow platform
Slope the floors of the parlor to facilitate
scraping to the holding area
Install deep traps in drains
Keep traffic from manure areas out of the milk
High
High
High
High
Low
Low
<300tO >$1,200
<$300
>$1,200
>$300
$300-$1,200
<$300
Table 4d-5. Phosphorus reduction methods and costs (Springman, 1992).
Phosphorus Reduction Methods
Install water softener and/or increase softening
time
Install an iron filter if needed
Install automatic, programmable CIP
dispensing system
Use low or no phosphorus containing
detergents and acid rinses
Reuse CIP detergent and/or acid rinse water
Install water conservation methods in CIP
Reduction
Potential
High
Low
Medium
High
Medium
Medium
Estimated Cost
<$1 ,200
<$300
>$1 ,200
<$300
f >$300
>$300
Containment is an
issue for older
earthen waste
storage facilities.
Liners of clay or
synthetic materials
are recommended
for new storage
facility construction.
Most parts of AFOs are either paved or highly compacted, and therefore
relatively impervious. Thus, in most cases, threats to ground water by infiltration
are low and most actions for ground water protection should be approached
through the Nutrient Management Measure. There are, however, a few important
concerns within the facility. Unpaved feedlots and earthen storage pits or lagoons
are generally believed to be "self-sealing" through compaction or with fine organic
matter and bacterial cells after a few months of operation. The rate and effective-
ness of sealing varies with waste and soil type. Cattle manure generally seals bet-
ter than swine waste; fine-textured soils generally seal more quickly and
effectively than do more porous soils. This sealing, however, is neither immediate
nor 100% effective. Significant leaching of pathogens or soluble pollutants such as
nitrate may occur early in the life of a facility, and the very slow seepage after
"sealing" may still pose a long-term threat to ground water. Additional sealing by
compaction, soil additives, or impermeable membranes is often required over po-
Chaoter4D-116: 10/98
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Chapter 4D: Facility Wastewater and Runoff from Confined Animal Facilities 117
rous soils or fractured bedrock. Whenever possible, liners made of clay or syn-
thetic materials should be used in the original design and construction of the facil-
ity. Construction with concrete or use of closed storage tanks are effective means
of preventing seepage.
Vegetated filter strips located within or adjacent to the facility may sometimes
represent an additional ground water concern. When such areas receive a high
pollutant load and infiltration occurs, ground water levels of nitrate may be in-
creased. While it may not be necessary to implement a nutrient management plan
on the vegetative control practices themselves, ground water should be protected
by taking care to not exceed the capacity of the practices to assimilate nutrients.
Finally, wells within the facility represent a direct path to ground water and
may be vulnerable to direct contamination by runoff water or by accidental spills
of wastes. This is a particular concern where drinking water may be threatened by
bacteria, viruses, or other pathogens. Care should be taken to protect wells from
routine or accidental contamination. Wells should be properly sealed and unused
wells should be plugged. Participation in Farm*A*Syst, a voluntary farmstead
pollution risk assessment program, is an excellent way to identify ways to prevent
contamination of wells (Farm* A*Syst staff, undated).
Animal Feeding Operation Management Practices
and Their Effectiveness
AFO • '
Management Practices
Although not addressed by this management measure, one of the most impor-
tant considerations in preventing water pollution from AFOs is the location of the
facility. For new facilities and expansions to existing facilities, consideration
should be given to siting the facility:
D Away from surface waters;
D Away from areas with high leaching potential;
O. Away from sinkholes and other critical or sensitive areas;
O To avoid odor drift to homes, churches, and communities; and
O In areas where adequate land is available; to apply animal wastes in accor-
dance with the nutrient management measure.
Combinations of the following practices can be used to satisfy the require-
. ments of this management measure. The Natural Resource Conservation Service
(NRCS) practice number and definition are provided for each management prac-
tice, where available. Additional information about the purpose and function of
individual practices is provided in Appendix A. In some emergency situations,
such as extreme animal mortality or structure failure, certain disposal methods
such as commercial rendering, incineration, or approved burial sites may be called
for.
d Roof runoff management (558): A facility forcontrol|ing.and disposing of
runoff water from roofs.
D Dikes (356): An embankment constructed of earth or other suitable materials
to protect land against overflow or to regulate water.
Chapter 4D-117: 10/98
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1118 Chapter 4: Management Measures
A large set of
management
practices are
available to custom
fit most facilities for
an effective pollution
prevention system.
D Diversions (362): A channel constructed across the slope with a supporting
ridge on the lower side.
O Field Border (386): A strip of perennial vegetation established at the edge of
a field by planting or by converting it from trees to herbaceous vegetation or
shrubs.
O Terrace (600): An earthen embankment, a channel, or combination ridge and
channel constructed across the slope.
O Grassed waterway (412): A natural or constructed channel that is shaped or
graded to required dimensions and established in suitable vegetation for the
stable conveyance of runoff.
O Lined waterway or outlet (468): A waterway or outlet having an erosion-
resistant lining of concrete, stone, or other permanent material. The lined sec-
tion extends up the side slopes to a designed depth. The earth above the
permanent lining may be vegetated or otherwise protected.
O Heavy use area protection (561): Protecting heavily used areas by establish-
ing vegetative cover, by surfacing with suitable materials, or by installing
needed structures.
O Filter strip (393): A strip or area of vegetation for removing sediment, or-
ganic matter, and other contaminants from runoff and wastewater.
O Sediment basin (350): A basin constructed to collect and store debris or sedi-
ment.
a Water and sediment control basin (638): An earth embankment or a combi-
nation ridge and channel generally constructed across the slope and minor
water courses to form a sediment trap and a water detention basin.
D Waste storage pond (425): An impoundment made by excavation or earth fill
for temporary storage of animal or other agricultural wastes.
O Waste storage structure (313): A fabricated structure for temporary storage
of animal wastes or other organic agricultural wastes.
H Waste treatment lagoon (359): An impoundment made by excavation or
earth fill for biological treatment of animal or other agricultural wastes.
O Waste utilization (633): Using agricultural wastes or other wastes on land in
an environmentally acceptable manner while maintaining or improving soil
and plant resources.
O Composting facility (317): A facility for the biological stabilization of waste
organic material.
O Application of manure and/or runoff water to agricultural land: Manure
and runoff water are applied to agricultural lands and incorporated into the
soil in accordance with the Nutrient Management Measure.
O Constructed wetlands: A constructed aquatic ecosystem with rooted emer-
gent hydrophytes designed and managed to treat agricultural wastewater.
Chapter 4D-118: 10/98
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Chapter 4D: Facility Wastewater and Runoff from Confined Animal Facilities 119
Practice
Effectiveness
The effectiveness of practices to control contaminant losses from confined
livestock facilities depends on several factors including:
O The contaminants to be controlled and their likely pathways in surface, sub-
surface, and ground water flows;
O The types of practices and how these practices control surface, subsurface,
and ground water contaminant pathways; and
O Site-specific variables such as soil type, topography, precipitation characteris-
tics, type of animal housing and waste storage facilities, method of waste
collection, handling and disposal, and seasonal variations. The site-specific
conditions must be considered in system design, thus having a large effect on
practice effectiveness levels.
The gross effectiveness estimates reported in Table 4d-5 simply indicate sum-
mary literature values. For specific cases, a wide range of effectiveness can be
expected depending on the value and interaction of the site-specific variables cited
above. When runoff from storms up to and including the 24-hour, 25-year fre-
quency storm is stored, there should be no release of pollutants from an AFO via
surface runoff. Rare storms of a greater magnitude or sequential storms of com-
bined greater magnitude may produce runoff, however.
Table 4d-5. Relative gross effectiveness3 (load reduction) of animal feeding operation control
measures (Pennsylvania State University, 1992b).
Total** Totald ' Fecal
Practice11 Runoff Phosphorus Nitrogen Sediment Coliform
Category Volume (%) {%) (%) (%)
Animal Waste reduced 90 80 60
Systems6
Diversion Systems' reduced 70 45 NA
Filter StriDsS reduced 85 NA 60
Terrace System reduced 85 55 80
Containment reduced 60 65 70
Structures0
85
NA
55
NA
90
NA = not available.
" Actual effectiveness depends on site-specific conditions. Values are not cumulative between practice categories.
b Each category includes several specific types of practices.
d Total phosphorus includes total and dissolved phosphorus; total nitrogen includes oroanic-N. ammonia-N. and nitrate-N.
* Includes methods for collecting, storing, and disposing of runoff and process-generated wastewater.
Specific practices include' diversion of uncontaminated water from confinement facilities.
8 Includes all practices that reduce contaminant losses using vegetative control measures.
Includes such practices as waste storage ponds, waste storage structures, waste treatment lagoons.
Table 4d-6 shows reductions in pollutant concentrations that are achievable
with solids separation basins that receive runoff from small barnyards and feed-
lots. Concentration reductions may differ from the load reductions presented in
Table 4d-1 since loads are determined by both concentration and discharge vol-
ume. Solids separation basins combined with drained infiltration beds and veg-
Chapter 40-119:10/98
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120 Chapter 4: Management Measures
etated filter strips (VFS) provide additional reductions in contaminant concentra-
tions. The effectiveness of solids separation basins is highly dependent on site
variables. Solids separation; basin sizing and management (clean-out); character-
istics of VFS areas such as soil type, land slope, length, vegetation type, vegeta-
tion quality; and storm amounts and intensities all play important roles in the
performance of the system.
Table 4d-6. Concentration reductions in barnyard and feedlot runoff treated with solids separation.
Site Location
Ohio - basin only8'"
Ohio - basin combined w/infiltration
bed3
VFSb
Canada - basin only0
Canada - basin w/VFSc
Illinois - basin w/VFSd
Constituent Reduction (%)
TS COD Nitrogen
49-54 51-56 35
82 85 —
87 _ 89 83
56 38 14(TKN)
(High 90's in fall and spring)
73 80(TKN)
TP
21-41 '
80
84
—
78
° Edwards etal.. 1986.
" Edwards etal., 1983.
0 Adam etal., 1986. - •
d Dickey, 1981.
Constructed wetlands have been developed and evaluated for animal waste
treatment. These constructed wetlands use the same plants, soils and microorgan-
isms as natural wetlands to remove contaminants, nutrients and solids from the
wastewater. Constructed wetlands have been used for years to treat municipal
wastewater, industrial wastewater, and stormwater. More recently, they have been
used for animal wastewater treatment. A literature review cited in Constructed
Wetlands and Wastewater Management for Confined Feeding Operations pub-
lished by the Gulf of Mexico program identified 68 different sites using con-
structed wetlands to treat wastewater from confined animal feeding operations.
Overall, the wetlands reduced the concentration of wastewater constituents such as
5-day biochemical oxygen demand, total suspended solids, ammonia nitrogen,
total nitrogen, and total phosphorus. Table 4d-7 shows the average treatment per-
formance.
Of the 68 sites identified, 46 were at dairy and cattle feeding operations. The
herd sizes ranged .from 25 to 330, with an average of 85 head. Dairy wastewater
often included water from milking barns and from feedingAoafmg yards with vary-
ing characteristics. Cattle feeding wastewater typically came from areas where
animals were confined. Usually, dairy and cattle wastewaters were pretreated or
diluted before being discharged to constructed wetlands.
Chanter 4D-120: 10/98
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Chapter 4D: Facility Wastewater and Runoff from Confined Animal Facilities 121
Table 4d-7. Summary of average performance of wetlands treating wastewater
from confined animal feeding operations8.
Wastewater Constituent
Average Concentration
Inflow Outflow
5-Day biochemical oxygen demand (BOD5)
Total suspended solids (TSS)
Ammonium nitrogen (NH4-N)
Total nitrogen (TN)
Total phosphorus (TP)
Average Reduction (%)
263
585
122
254
24
93
273
64
148
14
65
53
48
42
42
' Data from the Livestock Wastewater Treatment Wetland Database (LWDB). which includes wetland
systems at dairy, cattle, swine, poultry, and aquaculture sites (Knight et al., 1996).
b Average concentration is based on a hydraulic loading rate of 1.9 inches per day (50,000 gallons per
day per acre [gpd/ac)). Averages were calculated from data for 30 to 86 systems.
mg/L = milligrams per liter
Swine operations accounted for 19 of the wetland systems in the study. Swine
wastes were collected using flush water from solid floor barns and paved lots, or
they were collected directly from slatted floors in farrowing or nursery barns. In
many cases, the wastewater was pretreated in lagoons and then discharged to a
wetland system to further reduce concentrations to a level that could be applied to
the land.
Constructed wetland systems which provided high levels of nitrogen removal
for swine wastewater was recently reported by Rice et al. 1998. Three sets of two
3.6 x 33.5 m wetlands received lagoon liquid from a 2600-pig nursery operation.
In these wetlands, mass reduction of total nitrogen was 94% when the low nitro-
gen loading rate of 3 kg/ha specified for advanced treatment for stream discharge
was used. However, discharge requirements for nitrogen and phosphorus could not
consistently be achieved at this low loading rate, so the goal was changed to deter-
mine the maximum loading and nitrogen removal that could be achieved. At the
current loading rate of approximately 25 kg/ha/day, the mean nitrogen removal
efficiency was 87%. The nitrogen loading rates and mass removal efficiencies for
these investigated loading rates are shown in Table 4d-8.
Table 4d-8. Nitrogen loading rates and mass removal efficiencies for the
constructed wetlands, Duplin Co., NC (June 1993-November 1997) (Rice et al., 1998).
Nitrogen
3 kg/ha/day
8 kg/ha/day
. 15 kg/ha/day
25 kg/ha/day
% Mass Removal = %
nutrient mass inflow.
System
Rush/bulrush
Cattails/bur-reed
Rush/bulrush
Cattails/bur-reed
Rush/bulrush
Cattail/bur-reed
Rush/bulrush
Cattail/bur-reed
mass reduction of N (NH3-M + NO3-N) in
% Mass Removal
94
94
88
86
85
81
90
84
the effluent with respect to the
Chapter 4D-121: 10/98
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122 Chapter 4: Management Measures
It was determined that there was not enough nitrate in the wetlands for deni-
trification; hence, treatment experiments were also conducted with nitrified waste-
water, for which the nitrogen removal rate was 4 to 5 times higher than when
non-nitrified wastewater was added. Also, wetlands with plants were more effec-
tive than those with bare soil. These results suggest that vegetative wetlands with
nitrification pretreatment is a viable treatment alternative for the removalof large
quantities of nitrogen from swine wastewater.
Major conclusions of these studies were that wetlands by themselves cannot
remove sufficient amounts of nitrogen and phosphorus to meet stream discharge
requirements but do show promise for high rates of nitrogen mass removal. Since
wetlands are nitrate limited, the mass removal rate can be increased by nitrifying
the wastewater prior to wetland application. With nitrification pretreatment, wet-
lands have the potential to annually remove more than 14,000 kg N/ha. By se-
quencing nitrification and denitrificationunit processes, advanced wastewater
treatment levels can be achieved. Such systems could provide a safer alternative to
anaerobic lagoons, with reduced ammonia volatilization and odor.
Operation and :
Maintenance
Appropriate operation and maintenance are critical to achieving the full envi-
ronmental benefits of this management measure. Holding ponds and treatment N
lagoons should be operated such that the design storm volume is available for
storage of runoff. Facilities filled to or near capacity should be pumped. Solid
separation basins should be pumped or cleaned out according to design specifica-
tions. Pollutant loads can be reduced by managing manure to prevent or minimize
accumulation on open lots.
It is appropriate to
evaluate the waste
management
capabilities and
interests of the
grower, herdsman,
or stock manager.
Factor this
information into the
daily and periodic
site operation
requirements for
facility design.
Diversions will need periodic reshaping and should be free of trees and brush
growth. Gutters and downspouts should be inspected annually and repaired when
needed. Established grades for lot surfaces and conveyance channels should be
maintained at all times.
Channels should be free of trees and brush growth. Cleaning of debris basins,
holding ponds, and lagoons will be needed to ensure that design volumes are main-
tained. Clean water should be excluded from the storage structure unless it is
needed for further dilution in a liquid system.
Infiltration areas or vegetative filter areas need to be maintained in permanent
vegetative cover, with vegetation harvested when conditions permit. Where pos-
sible, runoff should be alternated between two infiltration areas to provide alter-
nating use and rest periods.
To protect ground .water, it is important to avoid disturbing the manure-soil
seal when cleaning or emptying a feedlot, barnyard, or waste storage structure.
Factors in the Selection of Management Practices
The first priority in the selection of management practices should be clean
water diversion. Diverting as much precipitation, snowmelt, and overland flow as
possible away from the facility before the water can come into contact with wastes
will greatly reduce the volumes of contaminated runoff and wastewater requiring
Chapter 4D-122: 10/98
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Chapter 4D: Facility Wastewater and Runoff from Confined Animal Facilities 123
later management. Once all clean water sources are diverted, facility runoff and -
wastewater should be collected and conveyed to the management systems. S imple
facilities may have a single outlet that makes collection relatively easy; large fa-
cilities with complex topography and layout may require regrading, curbs, diver-
sions, dikes, channels, or pipes to effectively collect and convey runoff and
wastewater.
Proper design and construction are essential to the performance of settling
basins, storage structures, and filter strips. Management practices and components
must be physically compatible with the functional layout of the facility itself. La-
goons or rainfall runoff storage ponds should always be located so that gravity
flow can be employed, but precautions have to be taken so that all runoff is ex-
cluded from these lower areas on the site. It is also desirable to position buildings
and waste treatment systems so that prevailing winds do not immediately transport
dust and odors to sensitive areas. Distance and topography play a major role in
determining what portions of the site will receive direct land application of waste
or irrigation of lagoon liquid. State and local NRCS offices, Cooperative Exten-
sion Service offices, State agriculture departments, State Land Grant Universities,
and the American Society of Agricultural Engineers are good sources of informa-
tion for size and layout requirements for management practices.
Wastewater management systems must protect water, soil and air quality.
Therefore; consideration also needs to be directed to storage, treatment and land
application techniques that minimize odor and ammonia volatilization. Nitrogen
loss during land application of manure by ammonia volatilization for various
waste management techniques is shown in Table 4d-9. Concerns also exist regard-
ing uncontrolled methane released from animal waste because it is considered to
be an important factor in gases that cause global warming. Odor has become one
of the major concerns of the general public and livestock producers. Therefore,
techniques to reduce in-house odors, such as alternative manure collection and
emptying techniques and dietary .studies which reduce waste volume and odor have
received increased attention. Major soil quality concerns include the buildup of
phosphorus. Concern also exists about other constituents that accumulate in the
soil, such as copper and zinc. Therefore, management practices should be selected
that are both compatible with a given facility and protective of water, air and soil
quality.
Soil and manure testing data must be considered along with fertilizer recom-
mendations to be sure that the proper amount of manure is applied to land. Land
application techniques which minimize ammonia volatilization and thus loss of
fertilizer value need to be employed. These techniques will also protect air quality
so that ammonia volatilization and odor are minimized. Calibration methods to
assist in the proper land application of manure are given in Table 4d-10.
The management of stored runoff and accumulated solids through an appro-
priate waste utilization system can be achieved under a range of options, including
land application, composting, biogas generation, recycling as feedstuffs, aquacul-
ture, and biomass production (Hauck, 1995). Early efforts to conserve animal
waste nutrients and other valuable components for fertilizer are directing renewed
interest to conserve and process waste into value-added products. These strategies
involve using manure and dead animals in conjunction with other materials such
as sawdust, soybean and corn products, culled sweet potatoes, soybean hulls, and
other organic waste products processed by rendering, extrusion, fluid bed cook-
Chapter 4D-123: 10/98
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124 Chapter 4: Management Measures
Table 4d-9. Nitrogen losses during land application of manure (percent of nitrogen
applied that is lost within 4 days of application)
Application method v
Type of waste
Broadcast
Broadcast with
immediate cultivation
Injection
Drag-hose injection
Sprinkler irrigation
Solid
Liquid
Solid
Liquid
Liquid
Liquid
Liquid
Percent of
nitrogen lost
15 to 30
10 to 25
1 to 5
1 to 5
Oto2
Oto2
15 to 35
This table shows typical nitrogen losses due to volatilization—evaporation into the air.
Remember, practices that reduce volatilization losses will also reduce surface runoff losses.
Source: Hlrschi et al., 1997, adapted from Livestock Waste Facilities handbook. MWPS-18,
3rd edition, 1993. ©MidWest PlanService, Ames,IA50011-3080.
dehydration procedures and other techniques to produce value-added products.
Crab bait is one successful value-added byproduct produced from animal waste at
the North Carolina State University Animal and Poultry Waste Processing Center
which has successfully utilized these waste nutrients and reduced the use of bait
fish. Any stored water, accumulated solids, processed dead animals, or manure
should be applied in accordance with the Nutrient Management Measure.
Cost of Practices
Construction costs for control of runoff and manure from confined animal
facilities are provided in Table 4d-l 1. The annual operation and maintenance costs
average 4% of construction costs for diversions, 3% of construction costs for
settlement basins, and 5% of construction costs for retention ponds (DPRA,
1992). Annual costs for repairs, maintenance, taxes, and insurance are estimated
to be 5% of investment costs for irrigation systems (DPRA, 1992).
.Chapter 40-124:10/98
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Chapter 4D: Facility Wastewater and Runoff from Confined Animal Facilities 125
Table 4d-10. Calibration methods (some common ways to calculate the
application rate of manure spreaders) (Hirschi et al., 19??).
Manure
source
What you need
to know
Calculations
Liquid manure
in a tank
Liquid manure
in spreader
volume method
Liquid manure
in spreader
weight method*
Solid manure
in spreader.
spreader volume
method"*
Solid manure
in spreader
plastic sheet
weight method
Shortcut method #1
with plastic sheet:
for lighter application
rates (use a 9' x 12' sheet)
Shortcut method #2
with plastic sheet:
for heavier application
rates (use a 4'8" x 4'8"
sheet or 87" x 3' sheet),
1. Tank load size
(gallons of manure)
2. Acreage over which
manure is spread at
even rate
1. Spreader load size
(gallons of manure)
2: Distance driven and
width spread (feet)
1. Spreader load size
(pounds of manure)
2. Distance driven and
width spread (feet)
1. Spreader struck-level
load size
(bushels of manure)
2. Distance driven and
width'spread (feet)
1. Pounds of manure on
the sheet after drive-over
2. Square footage of
plastic sheet
1. Pounds of manure on
the sheet after drive-over
1. Pounds of manure on
the sheet after drive-over
gallons _ application rate
acreage" (gallons per acre)
gallons x 43.560 _ application rate
distance x width ~ (gallons per acre)
pounds x 5.248 _ application rate
distance x width ~ (gallons per acre)
bushels x 1.688 _ application rate
distance x width ~ (tons per acre)
pounds x 21.78 _ application rate
square footage (tons per acre)
of plastic sheet
pounds+ 5 _ application rate
(tons per acre)
pounds of manure _ application rate
collected on the sheet ~ (tons per acre)
"The calculation for this method assumes that a gallon of manure will weigh a certain number of pounds.
An average figure is used.
"The calculation for this method assumes that a bushel of manure will weigh a certain number of pounds.
An average figure is used.
Chapter 4D-125: 10/98
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126 Chapter 4: Management Measures
Table 4d-11. Costs for runoff control systems (DPRA, 1992; USDA, 1998).
Practice'
Unit
Cost/Unit
Construction in 1997
. Dollars b'c'd
Diversion
Irrigation
- Piping (4-inch)
- Piping (6-inch)
- Pumps (10 hp)
- Pumps (15hp)
- Pumps (30 hp)
- Pumps (45 hp)
- Sprinkler/gun (150 gpm)
- Sprinkler/gun (250 gpm)
- Sprinkler/gun (400 gpm)
- Contracted service to empty retention pond
Infiltration e
Manure Hauling
Dead Animal Composting Facility
Retention Pond
- 241 cubic feet in size
- 2,678 cubic feet in size
- 28,638 cubic feet in size
- 267,123 cubic feet in size
Settling Basin
- 53 cubic feet in size
- 488 cubic feet in size
- 5,088 cubic feet in size
- 49,950 cubic feet in size
foot
foot
foot
unit
unit
unit
unit
unit
unit
unit
1,000 gallon
acre
mile per 4.5-ton load
cubic foot
cubic foot
cubic foot
cubic foot
cubic foot
cubic foot
cubic foot
cubic foot
cubic foot
2.38
. 2.35
3.02
2,350
2,690
4,030
4,700
1,180
2,350
4,300
3.68
2980
2.64
5.96
3.08
1.48
0.72
0.37
5.08
3.27
2.04
1.29
o Expected lifetimes of practices are 20 years for diversions, settling basins, retention ponds, and filtration areas and
15 years for irrigation equipment.
b Table is derived from DPRA estimates presented in an earlier edition adjusted by USDA price indices.
c Table does not present annualized costs.
o Costs for pumps, sprinklers, and infiltration are rounded to the nearest 10 dollars.
e Does not include land costs.
Sources:
* OPRA. Draft Economic Impact Analysis of Coastal Zone Management Measures Affecting Confined Animal Facilities,
DPRA, Inc., Manhattan, KS, 1992.
* United States Department of Agriculture (USDA), Agricultural Prices -1997 Summary, National Agricultural Statistics
Service, July 1998.
Chapter 4D-126: 10/98
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Chapter 4E: Grazing Management 127
The restoration or
protection of
designated water
uses (e.g. fisheries)
is the goal of BMP
systems designed to
minimize the water
quality impact of
cattle grazing
activities on pasture
and range lands.
4E: Grazing Management
Management Measure for Grazing Management
Protect water quality, range, pasture, and other grazing lands:
1. By excluding livestock to the extent practicable to protect sensitive areas such
as streambanks, wetlands, estuaries, ponds, lake shores, and riparian zone.
2. By otherwise minimizing livestock access to and deleterious impact upon
sensitive areas through implementing one or more of the following practices
where exclusion is not practicable:
a. Provide stream crossings or hardened watering access for drinking,
b. Provide alternative drinking water locations,
c. Locate salt and additional shade, if needed, away from sensitive areas,
d. Use improved grazing management systems (e.g., herding) to reduce the
physical disturbance and reduce direct loading of animal waste and sedi-
ment to sensitive areas.
and
3. By achieving either of the following on all range, pasture, and other grazing
lands not addressed under 1. or 2. above:
a. Apply the progressive planning approach of the U.S. Department of Agri-
culture, Natural Resources Conservation Service (NRCS) to implement
the range and pasture components in accordance with one or more of the
following from NRCS: a Conservation Management System (CMS)1;
National Range and Pasture Handbook (USDA, 1997b); NRCS Field
Office Technical Guide; and the NRCS Prescribed Grazing Practice
528A.
b. Maintain or improve range, pasture and other grazing lands in accordance
with activity plans or grazing permit requirements established by the Bu-
reau of Land Management, the Park Service, or the Bureau of Indian
" Affairs of the U.S. Department of Interior, or the Forest Service of
USDA.
Management Measure for Grazing Management:
Description
The management measure is intended to be applied to activities on range,
irrigated and non-irrigated pasture, and other grazing lands used by domestic live-
stock. Implementation of the management measure on grazing systems that contain
both public and private range and pasture lands should be planned and achieved in
a manner that addresses the complete grazing system.
1 For a discussion of the range and pasture components of a Conservation Management System (CMS), see Appendix
2A of USEPA. 1993a. Guidance specifying management measures for sources of nonpoint pollution in coastal waters.
EPA 840-B-92-002. U.S. Environmental Protection Agency, Office of Water, Washington, DC.
Chapter 4E-127:10/98
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128 Chapter 4: Management Measures
The management measure is designed to protect water quality and sensitive
areas through livestock exclusion, improved herd management, and conservation
of range, pasture, and other grazing lands. It is recognized that livestock exclusion
is more practicable on pasture than range in many cases, but livestock exclusion
can be essential to the protection of water quality in key sensitive areas on range
lands. In large grazing systems, such as western range lands, major environmental
improvements can be achieved by minimizing livestock access to streambanks and
riparian areas during periods of streambank instability and regrowth of key ripar-
ian vegetation.
It is important for the reader to be aware of the difference between range and
pasture. Range refers to those lands on which the native or introduced vegetation
(climax or natural potential plant community) is predominantly grasses, grasslike
plants, forbs, or shrubs suitable for grazing or browsing. Range includes natural
grassland, savannas, many wetlands, some deserts, tundra, and certain forb and
shrub communities. Pastures are those improved lands that have been seeded,
irrigated, and fertilized and are primarily used for the production of adapted, do-
mesticated forage plants for livestock. Other grazing lands include woodlands,
native pastures, and crop lands producing forages.
The major differences between range and pasture are the kind of vegetation
and level of management that each land area receives. In most cases, range sup-
ports native vegetation that is extensively managed through the control of livestock
rather than by agronomy practices, suchuas fertilization, mowing, or irrigation.
Range also includes areas that have been seeded to introduced species (e.g., clover
or crested wheatgrass) but are managed the same as native range.
Pastures are represented by those lands that have been seeded, usually to
introduced species (e.g., legumes or tall fescue) or in some cases to native plants
(e.g., switchgrass or needle grass), and which are intensively managed using
agronomy practices and control of livestock. Permanent pastures are based around
perennial warm-season (e.g., bermudagrass) or cool-season (e.g., tall fescue)
grasses and legumes (e.g., warm-season alfalfa, cool-season red clover), while
temporary pastures are generally plowed and seeded each year with annual le-
gumes (e.g., warm-season lespedezas, cool-season crimson clover) and grasses
such as warm-season pearl millet and cool-season rye (Johnson et al., 1997). Plant
selection for pastures should be based upon consideration of climate, soil type, soil
condition, drainage, livestock type and expected forage intake rates, and the type
of pasture management to be used. Management of pH and soil fertility is essential
to both the establishment and maintenance of pastures (Johnson et al., 1997). In
some climates (e.g., Georgia), overseeding of summer perennials with winter an-
nuals is done to provide adequate forage for the period from mid-winter to the
following summer.
Special attention must be given to grazing management in riparian and wet-
land areas if management measure objectives are to be met. Riparian areas are
defined by Mitsch and Gosselink( 1986) and Lowranceet al. (1988) as:
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Chapter 4E: Grazing Management 129
vegetated ecosystems along a water body through which energy,
materials, and water pass. Riparian areas characteristically have
a high water table and are subject to periodic flooding and
influence from the adjacent water body.
The health of the riparian system, and thus the water quality, is dependent on
the use, management, and condition of the related uplands. Therefore, the proper
management of riparian and wetland ecosystems will involve the correct manage-
ment of livestock grazing and other land uses in the entire watershed.
Conservation management systems (CMS) include any combination of con-
servation practices and management that achieves a level of treatment of the five
natural resources (i.e., soil, water, air, plants, and animals) that satisfies criteria
contained in the Natural Resources Conservation Service (NRCS) Field Office
Technical Guide (FOTG), such as a resource management system (RMS) or an
acceptable management system (AMS). The range and pasture components of a
CMS address erosion control, proper grazing, adequate pasture stand density, and
range condition. National (minimum) criteria pertaining to range and pasture un-
der an RMS are applied to achieve environmental objectives, conserve natural
resources, and prevent soil degradation.
Grazing and Pasturing: An Overview
Livestock can obtain their needed nutrients through feed supplied to them in a
confined livestock facility, through forage, or through a combination of forage and
feed supplements. Forage systems can be pasture-based or range-based. The man-
ager of a forage system must be concerned with care and management of the live- '
stock, control of noxious plants, and the quality of forage (McGinty, 1996)
Factors Affecting
Animal Performance on Grazed Lands
Both forage quality and forage intake must be managed to ensure the perfor-
mance, or quality, of livestock on pasture and grazing lands.
Forage quality
Forage quality is generally measured in terms of its nutritional value and
digestibility. Nutritional value can be assessed based on the amount of protein,
phosphorus, and energy the plants contain (Ruyle, 1993). The nutritional value of
range forage varies with season (e.g., higher in spring and summer), and differs
among forage types. For example, protein availability from grasses decreases
rapidly as the grasses mature, while shrubs are good sources of protein even at full
maturity. The protein content of forbs (e.g., weeds, wildflowers) falls between that
of grasses and shrubs. Grasses are generally considered to be good sources of
energy, shrubs are good energy sources before fruit development, and the value of
forbs is intermediate between that of grasses and shrubs.
Chapter 4E-129: 10/98
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130 Chapter 4: Management Measures
Range condition also affects the nutritive value of forage plants, with better
range condition yielding more digestible plants (Ruyle, 1993). Stocking rate and
the type of grazing system can affect grazing animal nutrition as well, with heavy
stocking rates resulting in lower animal performance and degraded forage quality.
Long-term heavy stocking will cause a shift toward less productive and less palat-
able forage plants, resulting in decreased forage intake due to less total forage and
less desirable forage (Lyons et al., 1996a). The preservation of some of the forage
on grazed lands is necessary to protect the resource, but forage quality may suffer
if too much old growth is maintained. Closely-grazed forage is generally good'for
animal performance since it results in younger forage that is higher in nutrient
value and more digestible (Johnson etal., 1997). The quality of regrowth in pas-
tures is improved with intensive grazing, but the rate of regrowth, and therefore
the yield, is reduced (Cannon et al., 1993). The extent of grazing (measured in
terms of stubble height) that can be allowed without resulting in overgrazing var-
ies with the plant species.
In Oregon, it is recommended that pastures be grazed from about 2,400 to
2,800 pounds of dry matter growth per acre down to about 1,500-1,600 pounds of
dry matter growth per acre, maintaining a height of 2-6 inches for clover and
grasses (Cannon et al., 1993). Guidelines for Texas ranchers recommend mini-
mum stubble height and plant residue as follows: 1.5 inches and 300-550 pounds
per acre for short grass; 4-6 inches and 750-1,000 pounds per acre for mid-grass;
and 8-10 inches and 1,200-1,500 pounds per acre for tall grass (McGinty, 1996).
Other factors affecting the quality of forage include the plant parts eaten
(e.g., leaves versus stem), the presence of secondary compounds (e.g., lignin,
tannins, terpenes) in the plants (Lyons et al., 1996a), and pests (Johnson et al.,
1997).
Forage intake
Forage intake generally increases as forage quality increases (Lyons et al.,
1995). As illustrated in Figure 4e-l, forage intake increases with digestibility since
digestion creates room for additional forage. Livestock do not generally stop eat-
ing once their nutrient requirements are met. Because of this, ranchers cannot
assume that higher quality forage alone will result in adequate resource protection.
Grazing management systems will still be needed to protect the resource from
overgrazing. With low-quality forage, more forage is needed to meet nutrient
needs, but the lower digestibility makes it much more difficult for the livestock to
meet their nutrient needs since the forage does not pass through the rumen as
quickly.
Forage intake is also affected by herbivore species and size, foraging behav-
ior, physiological status, animal production potential, supplemental feed, forage
availability, and environmental factors (Lyons et al., 1995). Smaller herbivore
species (e.g., sheep) have greater intake rates when measured as a percentage of
live weight than do larger species (e.g., beef cattle). Sheep and goats tend to be
more selective of the plants they graze than are cattle, and tend to have higher
forage intake rates due to their consumption of a readily digestible mixture of
grass, forbs, and browse (leaves"from woody plants). Horses may consume up to
70 percent more forage than a cow of similar size due mostly to the rapid passage
rate of horses.
rhantor 4E-130: 10/98
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Chapter 4E: Grazing Management 131
Figure 4e-1. Relationship between forage digestibility, the amount
of forage ruminants can eat, and the amount of forage needed to
meet nutrient requirements as a percentage of body weight (BW)
(Lyons et al., 1995).
m
a
o
o
2
o
u.
Potential
Intake
Required
Intake
40
80
Forage Digestibility, %
The forage selected by herbivore species varies, and is determined largely by
their mouth parts and the anatomy of their digestive systems (Lyons etal., 1996).
For example, horses eat more grass than cattle, sheep, and goats as a percentage
of their annual diet, while goats eat the most browse, and sheep eat the greatest
share of forbs. Diet also varies across season within a given species. Browse con-
stitutes 34 percent of the diet of Texas-raised goats in spring and 53 percent in fall
and winter, while forbs account for 6 percent of the diet of cattle in fall and 25
percent in spring.
The importance of physiological status is evidenced by the fact that lactating
animals generally have a higher nutrient demand and greater forage intake rate
than animals that are dry, open, or pregnant (Lyons et al., 1995). In fact, an ani-
mal can eat 35 to 50 percent more when lactating than when dry, open, or preg-
nant. Highly productive cows early in lactation require the highest quality feed to
maintain production (Cannon et al., 1993). Thus, the good farm manager gives
high priority .to the provision of adequate forage to lactating dairy herds in order
to avoid a drop in milk production.
Ranchers may need to provide nutrient supplements to ensure suitable live-
stock production on range lands (Ruyle, 1993). As with nutrient management on
croplands, however, ranchers should determine the cost-benefit of supplying addi-
tional nutrients since maximum profits are very often not achieved at maximum
yield levels. Protein supplements are often given to livestock grazing on low-pro-
tein forages, and the quantity and timing of the supplemental feeding can affect
forage intake (Lyons et al., 1995). For example, supplemental protein can increase
forage intake to a point, beyond which forage intake is reduced with increasing
supplemental protein. •
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132 Chapter 4: Management Measures
Forage availability is often measured in terms of stocking rates, or the num-
ber of animals that use a unit of land for a specified period of time (White, 1995;
Sedivec, 1992). Forage growth and production can vary greatly over any given
land area, as seasons change, and as a function of weather conditions, so matching
stocking rates with forage availability is dependent upon assumptions regarding
forage production. Further, since forage intake is dependent upon forage quality, it
becomes necessary to carefully monitor forage quality and quantity to determine if
stocking rates need to be adjusted. A general rule-of-thumb for grazing is to allow
livestock to use 50 percent of the forage (Sedivec, 1992). USDA encourages de-
velopment of a feed, forage, livestock balance sheet to assist in management of
grazing lands, and provides procedures and worksheets to assist managers
(USDA, 1997b).
An alternative approach to addressing forage availability in management
decisions is based on the concept of a forage allowance, which is the weight of
forage allocated per unit of animal demand at any instance (Cropper, 1998). For-
age allowance is expressed as a percentage of live body weight or as pounds of
forage per animal per day, and generally averages 2.5-3% for beef and sheep, 2%
for horses, and 3-4% for lactating cows (Cropper, 1998). Research has shown that
forage intake increases with forage allowance, reaching a maximum level at a
forage allowance of about 6.5% of herd live weight (Figure 4e-2). Forage utiliza-
tion rate, however, decreases as forage allowance is increased, meaning that more
forage is potentially wasted since it is not consumed by livestock. With knowledge
of the number of animals on the pasture, the percentage of forage intake derived
from the pasture, forage intake per animal, and the desired forage utilization rate,
one can manage forage and livestock to achieve desired animal performance with-
out wasting or degrading pasture (Cropper, 1998).
Figure 4e-2. Relationship of forage allowance to forage intake and utilization
(after Cropper, 1998).
100
80
Forage htate
(% of maximun)
50
-1100
80 '
Utilization
[y. available forage)
50
40
2.S
Forage AJlowance
live vueicfrt)
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Chapter 4E: Grazing Management 133
Environmental factors, including air temperature, soil moisture, and
snowcover, also affect forage intake. Each species of herbivore has a temperature-
based comfort zone, the thermoneutral zone, within which forage intake is not
affected (Lyons et al., 1995). Above and below the thermoneutral zone, however,
intake may increase or decrease depending upon outside conditions.
Because of the many sources of variability in forage quality, forage availabil-
ity, and forage intake, the rancher faces a significant challenge in providing an
appropriate mix of forage to ensure that livestock receive adequate nutrition
throughout the year.
Water
Water is essential to the survival, growth, and productivity of livestock. In-
sufficient water supply will result in reductions in feed intake, production, and
profits (Paries et al., 1998). High salinity, high nitrate and nitrite levels, bacterial
contamination, excessive growth of blue-green algae, and spills of petroleum,
pesticides, and fertilizers are the water quality problems that most affect livestock
production.
Research in Missouri has shown that water consumption of pastured beef
cow-calf pairs increased almost linearly as the temperature increased from 50
degrees to 95 degrees Fahrenheit (Gerrish, 1998). At 50 degrees F, water con-
sumption was approximately 6 gallons per day, increasing to about 24 gallons per
day at 95 degrees F. Cattle in Texas drink from 7 to 16 gallons per day, while
horses (8-12 gallons per day) and sheep and goats (1-4 gallons per day) drink less
(McGinty, 1996). Dry cows drink 8-10 gallons of water per day, while cows in
their last three months of pregnancy need up to 15 gallons of water per day (Fanes
et al., 1998). A recent study showed that distance from water supply had a large
effect on water consumption, as cows within 800 feet of water drank 15 percent
more water than cows further than 800 feet from water (Gerrish, 1998). The
maximum distance that livestock will travel to water in Texas ranges from 0.5
miles in rough terrain to 2.0 miles in smooth, flat terrain (McGinty, 1996).
The frequency with which livestock seek water varies, ranging from 3-5 times
per day for beef cows in the Midwest, to less frequent visits in drier climates
(Gerrish, 1998). Cows can drink at a rate of about 2 gallons per minute over a
period of 1-3 minutes, but the rate and duration of drinking varies with climate
and distance to water.
Salt
Sodium and chlorine are essential to several bodily functions of animals, and
livestock on the range should consume about 20 pounds of salt per year
(Schwennesen, 1994). Livestock are attracted to salt, and will remain with it as
long as it remains, making salt a very useful range management tool. By placing
measured quantities of salt at various locations throughout the year, ranchers can
manage the location of livestock to control grazing, help manage range condition
through directed trampling, and keep livestock away from water sources.
Chapter 4E-133:10/98
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134 Chapter 4: Management Measures
Weed and Brush Management
Weeds can reduce forage production and lower forage quality (Johnson et al.,
1997). Well-managed pastures present fewer weed problems as grasses can
outcompete most weeds. Weed management on range lands may involve prescribed
burning or the use of herbicides (McGinty, 1996).
Grazing Systems
There is a wide range of grazing systems for rangeland and pastures that
managers may select from (Table 4e-l). Specific terms and definitions used may
vary considerably across the nation. In all cases, however, the key management
parameters are grazing frequency, livestock stocking rates, livestock distribution,
timing and duration of each rest and grazing period, livestock kind and class, and
forage use allocation for livestock and wildlife. Factors to consider in determining
the appropriate grazing system for any individual farm or ranch include the avail-
ability of water in each pasture, the type of livestock operation, the kind and type
of forage available, the relative location of pastures, the terrain, and the number
and size of different pasture units available (Sedivec, 1992).
While many systems may be derived from combinations of the key manage-
ment parameters, the basic choice is between continuous and rotational grazing.
Under continuous grazing, the livestock remain on the same grazing unit for ex-
tended periods, while rotational grazing involves moving the livestock from unit to
unit during the growing season (Johnson et al., 1997). A prescribed grazing sched-
ule for range is a system in which two or more grazing units are alternately de-
ferred or rested and grazed in a planned sequence over a period of years (USDA,
1997b). Rest periods are generally non-grazing periods of a full year or longer,
while deferment typically involves a non-grazing period of less than twelve
months.
Continuous, season-long grazing is typically done on larger pastures, with
less fencing and less livestock management than required for rotational grazing
(Johnson et al., 1997). A central problem with this approach is the difficulty of
matching the stocking rate with the changing forage growth rate during the graz-
ing season. For example, forages may grow at a rate of 90 pounds per acre per
day in spring, followed by summer growth rates of as little as 5 pounds per acre
per day, resulting in a mismatch of supply and demand if the stocking rate is kept
constant (Cropper, 1998).
Rotational grazing generally involves smaller pastures or paddocks, more
fencing, and more livestock management than required for continuous grazing
(Johnson et al., 1997). If forage growth exceeds forage intake, forage from some
paddocks may be harvested and stored for winter grazing. Rotational grazing
provides opportunities to better manage the available forage to meet livestock
needs (Johnson et al., 1997). In some cases, the additional costs for fencing and
supplying water in each paddock may be prohibitive. Options exist, however, for
designing paddocks such that drinking water sources can be shared by more than
one paddock, thus eliminating the need for additional water development (Drake
and Oltjen, 1994). In addition, affordable, portable fencing is often used in man-
agement-intensive grazing systems (SAKE, 1997).
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Chapter 4E: Grazing Management 135
Table 4e-1. Some commonly used grazing systems (Sedivec, 1992; McGinty, 1996; Frost and
Ruyle, 1993; USDA, 1997).
Grazing
System
Continuous
Rotation
Switchback
Description
Unrestricted livestock access to any part
of the range during the entire grazing
season. No rotation or resting.
Intensive grazing followed by resting.
Livestock are rotated among 2 or more
pastures during grazing season.
Livestock are rotated back and forth
between 2 pastures.
Rest-rotation One pasture rested for an entire grazing
year or longer. Others grazed on
rotation. Multiple pastures with multiple
or single herd.
Deferred rotation Grazing discontinued on different parts
of range in succeeding years to allow
resting and re-growth. Generally
involves multiple herds and pastures.
Twice-over Variation of deferred rotation, with faster
rotation rotation. Uses 3-5 pastures.
Short-duration Grazing for 14 days or less. Large herd,
grazing many small pastures (4-8 cells), high
stocking density.
High intensity- Heavy, short duration grazing of all
low frequency animals on one pasture at a time. Rotate
to another pasture after forage use goal is
met. Multiple pastures with single herds.
Merrill Each of 4 pastures grazed 12 months and
rested 4 months.
Decision rotation No specific number of herds or pastures. No set movement pattern.
Comments
Difficult to match stocking rate to forage growth
rate. Severe overgrazing occurs where cattle
congregate. Other areas underutilized. Long-
term productivity depends upon moderate levels
of stocking. Can be year-long or seasonal
continuous grazing. Less fence and labor than
for rotation.
Each pasture may be alternately grazed and
rested several times during a grazing season.
Cattle are moved to different grazing area after
desired stubble height or forage allowance is
reached.
Every 2-3 weeks in ND. In TX, graze 3 months
on pasture 1, 3 months on pasture 2, then 6
months on pasture 1, etc.
In ND, 4 pastures used with 1 rested, one each
grazed in spring, summer, and fall. Rest periods
are generally 'longer than grazing periods.
Length of grazing period is generally .longer than
the deferment period.
Long period of rest between rotations. Sequence
alternates from year to year.
Rest period is 30-90 days. Allows 4-5 grazing
cycles. Requires a high level of. grass and herd
management skills. Similar to high intensity-low
frequency, but length of grazing and rest periods
are both shorter for short-duration grazing.
Grazing period is shorter than rest period, and
grazing periods for each pasture change each
year. In TX, grazing period is more than 14 days,
and resting period is more than 90 days. TX
typically has single herd on 4 or more pastures.
Three herds.
A number of different stocking methods are used to manage pastures, includ-
ing allocation stocking methods (continuous set stocking, continuous variable
stocking, set rotational stocking, variable rotational stocking), nutrition optimiza-
tion stocking methods (creep grazing, strip grazing, frontal grazing), and seasonal
stocking methods (deferred stocking, sequence stocking) (USDA, 1997b). Rota-
tional stocking, or top grazing, is an adaptation of rotational grazing that improves
the efficiency with which forage is used. This approach is based upon the fact that
cattle select the highest quality forage available before grazing lower quality for-
age (Johnson etal., 1997). In rotational stocking, for example, a lactating dairy
herd might be rotated to a paddock where it can obtain 100 percent of its forage
intake needs at a low forage utilization rate (see. Figure 4e-2). Forage allowances
for high-producing, lactating diary cattle need to be generous to maintain milk
Chapter 4E-135: 10/98
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136 Chapter 4: Management Measures
Experts indicate that
the ecological
integrity of grazing
lands is threatened.
The loss of
streambank stability,
riparian vegetation,.
stream habitat, and
modification of
hydrologic regime
due to poor grazing
practices has a
devastating effect
on stream life.
Compaction and
vegetation loss due
to improper grazing
can increase
runoff, erosion, and
sediment delivery
to streams.
production, resulting in utilization rates of 50 percent or less (Cannon etal.,
1993). Dry cows and heifers might be rotated to the same paddock after the lactat-
ing dairy herd is removed to increase the forage utilization rate (Cropper, 1998).
Grazing Impacts on Surface and Ground Water
The focus of the grazing management measure is on the riparian zone, yet the
control of erosion from range, pasture, and other grazing lands above the riparian
zone is also beneficial. Application of this management measure will reduce the
physical disturbance to sensitive areas and reduce the discharge of sediment, ani-
mal waste, nutrients, pathogens, and chemicals to surface waters.
More than half the commercial operators with beef cattle herds in the West
graze federal lands. According to a recent report by the Council for Agricultural
Science and Technology (CAST) (Laycock, 1996), a leading consortium of 33
professional scientific societies, individuals are becoming increasingly concerned
about the ecological effects of grazing on federal lands. Major concerns include
diminished biodiversity, deteriorating range, watershed, and streambank condi-
tions; soil erosion'and desertification; decreased wildlife population and habitat;
and lost recreational opportunities.
Riparian areas constitute important sources of livestock grazing. One acre of
riparian meadow has the potential grazing capacity equal to 10 to 15 acres of
surrounding forested range. In the Pacific Northwest, riparian meadows often
cover only 1 to 2% of the summer range area, but provide about 20% of the sum-
mer forage.
Streambank stability is directly related to the quality of riparian vegetation
(Figure 4e-3). During high water, riparian vegetation protects the banks from
erosion, reducing water velocity along the stream edge, and causing sediments to
settle out. Platts (1991) has summarized the importance of riparian vegetation in
providing cover and maintaining streambank stability. Trees provide shade and
streambank stability because of their large and massive root systems. Trees that
fall into or across streams create high quality pools and contribute to channel
stability. Brush protects the streambank from water erosion, and its low overhang-
ing height adds cover that is used by fish. Grasses form the vegetative mats and
sod banks that reduce surface erosion and erosion of streambanks. As well-sodden
banks gradually erode, they create the undercuts important to salmonids as hiding
cover. Root systems of grasses and other plants trap sediment to help rebuild dam-
aged banks.
When animals, graze directly on streambanks, slumping from trampling, hoof
slide, and streambank collapse cause soil to move directly into the stream. Exces-
sive grazing on riparian vegetation reduces the ability of vegetation to protect
streambanks and trap sediments.
Soil erosion and sedimentation are the primary causes for poor water quality
in California (George, 1996). For example, overgrazing contributes to the removal
of most vegetative cover and soil compaction, exposing soil, degrading soil struc-
ture, and inhibiting infiltration, which leaves soil susceptible to wind and water
erosion. Due to the steep slopes, highly erodible soils, and storm events, the sedi-
ment delivery ratio from rangeland can be very high (Carpenteret al., 1994).
Chapter 4E-136: 10/98
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Chapter 4E: Grazing Management 137
Figure 4e-3. Benefits that a riparian buffer can provide (Doskkey, 1997).
flood protection
filter agricultural runoff
wildlife habitat
bank stability
aquatic habitat
economic products
visual diversity
Pathogen impacts
on waterways are a
grazing land issue.
Nutrient inputs from grazing lands to surface water come mainly in the form
of nitrogen and phosphorus from manure and decaying vegetation (Carpenter et
al., 1994). Livestock also generate pathogens as they graze on pasture and range-
lands. Fecal coliform levels in the soil, used as an indicator of pathogen contami-
nation, increase with livestock intensity; and delivery of pathogens to surface and
ground water can threaten water uses such as contact recreation and drinking.
Contamination levels are usually determined by livestock density, sizing, time and
frequency of grazing, and access to the surface water (Carpenter et al., 1994).
Schepers and Francis (1982) found increases in nutrients in a cow-calf pasture in
Nebraska. Nutrient levels were correlated primarily with grazing density.
Nutrient impacts on water quality vary considerably in study results, and are
dependent on specific site conditions such as precipitation, runoff, vegetation
cover, grazing density, proximity to the stream, and period of use. The risk of
nutrient enrichment is low in arid rangelands where animal wastes are distributed
and runoff is comparatively light. Studies by the ARS and BLM found little evi-
dence of nutrient enrichment from unconfined livestock grazing in Reynolds
Creek, an arid watershed in southern Idaho (USDA-ARS, 1983). This risk can
also be low in humid climates if grazing lands are managed correctly. In a humid
site in east-central Ohio (Owens et al., 1989), nutrient concentrations did not in-
crease significantly with summer grazing of the unimproved pasture, and were
also low when continuously grazed.
Grazing Management Practices and their Effectiveness
The Grazing Management Measure was selected based on an evaluation of
available information that documents the beneficial effects of improved grazing
management. Specifically, the available information shows that
O Riparian habitat conditions are improved with proper livestock management;
n The amount of time livestock spend drinking and loafing in the riparian zone
is dramatically reduced through the provision of supplemental water and fenc-
ing; and
Chapter 4E-137: 10/98
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138 Chapter 4: Management Measures
O Nutrient and sediment delivery is reduced through the proper use of vegetation,
streambank protection, planned grazing systems, and livestock management.
For any grazing management measure to work, it must be tailored to fit the
needs of the vegetation, terrain, class or kind of livestock, and particular operation
involved.
For both pasture and range, areas should be provided for livestock watering,
salting, and shade that are located away from streambanks and riparian zones where
necessary and practical. This will be accomplished by managing livestock grazing
and providing facilities for water, salt, and shade as needed.
The rancher may seek technical assistance from Cooperative Extension, NRCS,
Resource Conservation Districts, or other agencies.to help identify water quality
problems, develop management measures (statements of water quality goals or ob-
jectives), and select management practices. The amount or extent to which a practice
is applied must be consistent with national, State, and basin water quality goals and
should reflect the relative contribution of that type of land use activity toward water
quality problems within the basin. This technical assistance will result in a plan,
typically known as a ranch plan or conservation plan.
Contact your county
Cooperative
Extension agent,
USDA-NRCS district
conservationist, or
the local Soil and
Water Conservation
District.
Additional information on grazing management can be found in the NRCS Na-
tional Range and Pasture Handbook (USDA-NRCS, 1997), as well as the Bureau of
Land Management's (BLM) Technical Reference Series on Grazing.1
The Management Practices set forth below have been found by the U.S. Envi-~
ronmental Protection Agency (EPA) to be representative of the types of practices that
can be applied successfully to achieve the management measure for grazing. The
NRCS management practice number and definition are provided for each manage-
ment practice, where available.
Grazing = :
Management Practices
Appropriate grazing management systems ensure proper grazing use by adjust-
ing grazing intensity and duration to reflect the availability of forage and feed desig-
nated for livestock uses, and by controlling animal movement through the operating
unit of range or pasture. Proper grazing use will maintain enough live vegetation and
litter cover to protect the soil from erosion; willachieve riparian and other resource
objectives; and will maintain or improve the quality, quantity, and age distribution of
desirable vegetation. Practices that accomplish this are:
O Deferred Grazing (352): Postponing grazing or resting grazing land for pre-
scribed period.
O Pasture and Hayland Management (510): Proper treatment and use of pasture
and hayland.
D Planned Grazing System (556): A practice in which two or more grazing units
are alternately rested and grazed in a planned sequence for a period of years, and
rest periods may be throughout the year or during the growing season of key
plants.
O Prescribed Grazing Use (528A): Grazing at an intensity that will maintain
enough cover to protect the soil and maintain or improve the quantity and quality
of desirable vegetation.
Two key references within the.BLM's Technical Reference Series on Grazing include Grating Manayementfiir Riparian- Weiland Areas (Leonard el. al.
1997) and Process fur Assessing Proper Functioning Condition (Prichard et. al 19.93). Otherjeferences of similar interest include Successful Strategies
for Grazing Cattle in Riparian Zones. Riparian Tech Bulletin #4. USDOI. Montana BLM. January 1998: and Effective Cattle Management in Riparian
Zones: A Field Survey and Literature Review, Riparian Tech Bulletin #3, USDOI. Montana BLM, November 1997.
Chaoter4E-138: 10/98
-------
Chapter 4E: Grazing Management 139
O Proper Woodland Grazing (530): Grazing wooded areas at an intensity that
will maintain adequate cover for soil protection and maintain or improve the
quantity and quality of trees and forage vegetation.
O Use Exclusion (472): Exclusion of animals, people, or vehicles from an area
to protect, maintain, or improve the quantity and quality of the plant, animal,
soil, air, water, and aesthetic resources and human health safety.
Alternate '
Water Supply Practices
Practices have
been developed
for grazing
management,
alternative water
supply, riparian
grazing, and land
stabilization.
Providing water and salt supplement facilities away from streams will help
keep livestock away from streambanks and riparian zones. The establishment of
alternate water supplies for livestock is an essential component of this measure
when problems related to the distribution of livestock occur in a grazing unit. In
. most western states, securing water rights may be necessary. Access to a devel-
oped or natural water supply that is protective of streambank and riparian zones
can be provided by using the stream crossing (interim) technology to build a wa-
tering site. In some locations, artificial shade may be constructed to encourage use
of upland sites for shading and loafing. Providing water can be accomplished
through the following NRCS practices and the stream crossing (interim) practice
of the following section. Practices include:
O Improved Water Application (197): Increase efficiency and decrease water
runoff from irrigation of pastures.
n Pipeline (516): Pipeline installed for conveying water for livestock or for
recreation.
D Pond (378): A water impoundment made by constructing a dam or an em-
bankment or by excavation of a pit or dugout.
n Trough or Tank (614): A trough or tank, with needed devices for water con-
trol and waste water disposal, installed to provide drinking water for livestock.
O Well (642): A well constructed or improved to provide water for irrigation,
livestock, wildlife, or recreation.
O Spring Development (574): Improving springs'and seeps by excavating,
cleaning, capping, or providing collection and storage facilities.
Riparian
Grazing Practices
It may be necessary to minimize livestock access to riparian zones, ponds or
lake shores, wetlands, and streambanks to protect these areas from physical dis-
turbance. This can also be accomplished by establishing special use pastures to
manage livestock in areas of concentration. These management practices should be
linked in the ranch plan to proper grazing use and other ranch water quality goals.
Practices include:
O Fencing (382): Enclosing or dividing an area of land with a suitable perma-
nent structure that acts as a barrier to livestock, big game, or people (does not
include temporary fences). The following are added practices: Fence (382A);
Fence, Suspension (382B); Fence, Electrical (382C).
Chapter 4E-139: 10/98
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140 Chapter 4: Management Measures
D Stock Trails or Walkways (575): A livestock trail or walkway constructed to
improve grazing distribution and access to forage and water. This practice
may be used to reduce livestock concentrations, facilitate proper grazing use
and planned grazing systems.
O Stream Crossing (Interim): A stabilized area to provide controlled access
across a stream for livestock and farm machinery.
Land and
Streambank Stabilization Practices
It may be necessary to improve or reestablish the vegetative cover on range
and pastures or on streambanks to reduce erosion rates. The following practices
can be used to reestablish vegetation:
O Channel Vegetation (322): Planting vegetation, such as trees, shrubs, vines,
grasses, or legumes suited for riparian habitats.
O Rangeland Fertilization (203): To ap.ply the appropriate nutrients to improve
the quantity and quality of forage for livestock and wildlife.
D Pasture and Hay Planting (512): Establishing and reestablishing long-term
stands of adapted species of perennial, biannual, or reseeding forage plants.
(Includes pasture andhayland renovation. Does not include grassed water-
ways or outlets or cropland.)
O Range Planting (550): Establishing adapted plants by seeding on native graz-
ing land. (Range does not include pasture and hayland planting.)
O Critical Area Planting (342): Planting vegetation, such as trees, shrubs,
vines, grasses, or legumes, on highly credible or critically eroding areas.
(Does not include tree planting mainly for wood products.)
O Brush (and Weed) Management (314): Managing and manipulating stands
of brush (and weeds) on range, pasture, and recreation and wildlife areas by
mechanical, chemical, or biological means or by prescribed burning. (Includes
reducing excess brush (and weeds) to restore natural plant community balance
and manipulating stands of undesirable plants through selective and patterned
treatments to meet specific needs of the land and objectives of the land user.)
O Grazing Land Mechanical Treatment (548)i Renovating, contour furrowing,
pitting, or chiseling native grazing land by mechanical means.
P Grade Stabilization (410): A structure used to stabilize the grade and control
erosion in natural or artificial channels, to prevent the formation and advance
of gullies, and to enhance environmental quality and reduce pollution hazards.
O Prescribed Burning (338): Applying fire to predetermined areas under condi-
tions under which the intensity and spread of the fire are controlled.
O Stream Corridor Improvement (204): Restoration of a modified or damaged
stream to a more natural state using bioengineering techniques to protect the
banks and reestablish the riparian vegetation.
O Landslide Treatments (453): Treatments to prevent or stabilize landslides to
protect life and property and to prevent excessive erosion'and sedimentation.
O Sediment Basin (350): A basin constructed to collect and store debris or
sediment. Stock water ponds often actas sediment basms.- -
Chapter 4E-140: 10/98
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Chapter 4E: Grazing Management 141
O Wildlife Wetland Habitat Management (644): Retaining, creating or man-
aging habitat for wildlife. The construction or restoration of wetlands.
O Stream Channel Stabilization (584): Using vegetation and structures to sta-
bilize and prevent scouring and erosion of stream channels.
O Wetland Restoration (657A): Establishing adapted wetland plants by seeding
native species.
O Streambank and Shoreline Protection (580): Using vegetation or structures
to stabilize and protect banks and streams, lakes, or estuaries, against scour
and erosion.
Monitoring
Grazing Land Condition
Monitoring is essential to determining whether grazing management objec-
tives are being achieved (Chancy et al., 1993). A wide array of monitoring options
exist, including the use of photo points, vegetation sampling, and water quality
monitoring (see Chapter 6). A number of methods are available for measuring
utilization and residuals to determine the effects of grazing and browsing on
rangeland (Interagency Technical Team, 1996a). Clipping procedures have been
developed to aid in balancing available forage with the needs of livestock (Brence
and Sheley, 1997), and other vegetation monitoring approaches are available as
well (Ruyle and Frost, 1993; Interagency Technical Team, 1996).
Decisions regarding changes to stocking rates and preservation of an ad-
equate amount of forage to ensure good range health and minimize water quality
impacts are dependent upon good information. Pastures should be checked, as a
minimum, near the end of the normal forage growth periods and at the end of win-
der (White, 1995). For most of Texas, it is recommended that pastures be checked
in June, November, and March.
Spreadsheet applications are available to make tracking and management of
grazing cells much easier (Gum and Ruyle, 1993). These spreadsheets address
both growing and dormant seasons, and incorporate such factors as the number
and size of paddocks, the number of days each paddock is to be rested, and the
relative quality of forage in each paddock.
Recognizing that the pattern of grazing use varies across an enclosed grazing
area, or management unit, USDA recommends the identification of key grazing
areas and key plant species to aid in grazing land management (USDA, 1997b).
By protecting and monitoring the key grazing areas and key plant species, it is
believed that the management unit as a whole will be protected.
Practice
Effectiveness
Eckert and Spencer (1987) studied the effects of a three-pasture, rest-rotation
management plan on the growth and reproduction of heavily grazed native bunch
grasses in Wyoming. The results indicated that range improvement under this
otherwise appropriate rotation grazing system is hindered by heavy grazing.
Stocking rates on the study plots exceeded the carrying capacity of the land and
would decrease native grasses and increase potential erosion and sedimentation.
Chapter 4E-141: 10/98
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142 Chapter 4: Management Measures
Van Poollen and Lacey (1979) showed that herbage production was greater
for managed grazing versus continuous grazing, greater for moderate versus heavy
intensity grazing, and greater for light- versus moderate-intensity grazing.
Tiedemann et al. (1988) studied the effects of four grazing strategies on bac-
teria levels in 13 Oregon watersheds in the summer of 1984. Results indicate that
lower fecal coliform levels can be achieved at stocking rates of about 20 ac/AUM
if management for livestock distribution, fencing, and water developments are
used (Table 4e-2). The study also indicates that, even with various management
practices, the highest fecal coliform levels were associated with the higher stock-
ing rates (6.9 ac/AUM) employed in strategy D.
Table 4e-2. Bacterial water quality responses to four grazing strategies (Tiedemann et al., 1988).
Practice
Geometric Mean Fecal
Coliform Count
Strategy A: Ungrazed
Strategy B: Grazing without management for. livestock distribution; 20.3
ac/AUM.
Strategy C: Grazing with management for livestock distribution: fencing
and water developments; 19.0 ac/AUM.
Strategy D: Intensive grazing management, including practices to attain
uniform livestock distribution and improve forage production
with cultural practices such as seeding, fertilizing, and forest
thinning; 6.9 ac/AUM.
40/L
150/L
90/L
920/L
Owens et al. (1982) measured nitrogen losses from an Ohio pasture under a
medium-fertility, 12-month pasture program from 1974 to 1979. The results in-
cluded no measurable soil loss from three watersheds under summer grazing only,
and increased average TN concentrations and total soluble N loads from water-
sheds under summer grazing and winter feeding versus watersheds under summer
grazing only (Table 4e-3).
Table 4e-3. Nitrogen losses from medium-fertility, 12-month pasture program (Owens et al., 1982).
Practice
Soil Loss Total Sediment N Total N Concentration Total Soluble N
(kg/ha) Transport (kg/ha) (mg/l*) Transport (kg/ha)*
Summer Grazing Only
Growing season - —
Dormant season —
Year —
Summer Grazing - Winter Feeding
Growing season 251
Dormant season 1,104
Year 1,355
1.4
6.6
8.0
3.7
1.8
3.0
4.9
14.6
10.7
0.4
0.1
0.5
2.5
11.3
13.8
•Five-year average (1974-1979)
Chapter 4E-142:10/98
-------
Chapter 4E: Grazing Management 143
Data from a comparison of the expected effectiveness of various grazing and
streambank practices in controlling sedimentation in the Molar Flats Pilot Study
Area in Fresno County, California indicate that planned grazing systems are the
most effective single practice for reducing sheet and rill erosion (Fresno Field
Office, 1979).
By switching grazing allotments from continuous, season-long grazing to a
three-pasture, rest-rotation system, the U.S. Forest Service was able to achieve
major improvements in the vegetation in the Tonto National Forest in Arizona
(Chancy et al., 1990). For example, cottonwood populations increased from 20
per 100 acres to more than 2,000 per 100 acres in six years, while at the same
time the amount of livestock forage grazed increased by 27 percent. Similar im-
provements from improved grazing management were documented through case
studies in Idaho, Nevada, Oregon, South Dakota, Texas, Utah, and Wyoming.
Hubert et al. (1985) showed in plot studies in Wyoming that livestock exclu-
sion and reductions in stocking rates can result in improved habitat conditions for
brook trout. In this study, the primary vegetation was willows, Pete Creek stock-
ing density was 7.88 ac/AUM (acres per animal unit month), and Cherry Creek
stocking density was 10 cows per acre (Table 4e-4).
Table 4e-4. Grazing management influences on two brook trout streams in Wyoming
(Hubert etal.. 1985).
Parameter
Width
Depth
Width/depth ratio
Coefficient of variation in depth
Percent greater than 22 cm deep
Percent overhanging bank cover
Percent overhanging vegetation
Percent shaded area
Percent silt substrate
Percent bare soil along banks
Percent litter along banks ,
Pete
Heavily
Grazed
(mean)
2.9
0.07
43
47.3
9.0
2.7
0
0.7
35
19.7
7.0
Creek (n=3)
Lightly
Grazed
(mean)
2.2"
0.11-
21
66.6"
22.3"
30.0a
11.7-
18.3a
52
13.3
6.0
• Cherry
Outside
Exclosure
(mean)
2.9
0.08
37
57
' 6.7
24.0
8.5
23.5
22
22.8
10.0
Creek (n=4)
Inside
Exclosure
(mean)
2.5"
0.09"
28"
71
21.0'
15.3
18.0
28.0
13"
12.3'
6.8"
a Indicates statistical significance at p<=0.05.
b Indicates statistical significance at p<=0.1 .
The benefits of
livestock exclusion
were shown by a
plot study in Utah.
Platts and Nelson (1989) used plot studies in Utah to evaluate the effects of
livestock exclusion on riparian plant communities and streambanks. Several
streambank characteristics that are related to the quality offish habitat were mea-
sured, including bank stability, stream shore depth, streambank angle, undercut,
overhang, and streambank alteration. The results clearly show better fish habitat
in the areas where livestock were excluded (Table 4e-5).
Chapter 4E-143:10/98
-------
144 Chapter 4: Management Measures
Table 4e-5. Streambank characteristics for grazed versus rested riparian areas (Platts and Nelson, 1989).
Streambank Characteristic (unit)
Extent (m)
Bank stability (%)
Stream-short depth (cm)
Bank angle (°)
Undercut (cm)
Overhang (cm)
Streambank alteration (%)
Grazed
4.1
32.0
6.4
127.0 ,
6.4
1.8
72.0
Rested
2.5
88.5
14.9
... 81.0
16.5
18.3
19.0
Grazing
management
research indicates
that local demon-
strations and
practices designed
for area soils,
vegetation, and
stocking practices
are more likely to
succeed than
applying one
system of BMPs
across the entire
range.
Kauffman et al. (1983a) showed that fall cattle grazing decreases the stand-
ing crop of some riparian plant communities by as much as 21 % versus areas
where cattle are excluded, while causing increases for other plant communities.
This study, conducted in Oregon from 1978 to 1980, incorporated stocking rates .
of3.2to4.2ac/AUM.
Buckhouse (1993) did an extensive review of livestock impacts on riparian
systems. Researchers documented many factors interrelated with grazing effects,
primarily dealing with instream ecology, terrestrial wildlife, and riparian vegeta-
tion. Permanent removal of grazing will not guarantee maximum herbaceous plant
production. Researches found that a protected Kentucky bluegrass meadow
reached peak production in six years and then declined until production was simi-
lar to the adjacent area grazed season-long. The accumulation of litter over a pe-
riod of years seems to retard forage production in wetlands. Thus, some grazing of
riparian areas could have beneficial effects. Stoltzfus and Lanyon (1992) also
identified that fencing a riparian zone protects herd health from infectious bacte-
ria, hoof diseases, and poor quality drinking water, provides a wildlife habitat and
is a good neighbor policy.
The effect of grazing on streambanks depends on site conditions, management
practices, timing, and other factors. Kauffman et al. (1983b) found that
late-season grazing increased bank erosion relative to ungrazed areas in Oregon.
Hallock (1996) found that delaying grazing in.riparian pastures until the soil dries
in the late spring did not degrade the streambanks or change stream morphology
significantly in a Coastal California Watershed.
Lugbill (1990) estimates that stream protection in the Potomac River Basin
will reduce total nitrogen (TN) and total phosphorus (TP) loads by 15%, while
grazing land protection and permanent vegetation improvement will reduce TN
and TP loads by 60%.
Nutrient loss is minimal where the riparian pasture remains in good condi-
tions. Vegetation buffers the stream from direct waste input and assimilates the
nutrients into plant tissue. Gary et al. (1983) evaluated the effects on a small
stream in central Colorado of spring cattle grazing on pastures. Nitrate nitrogen
did not increase significantly and ammonia increased significantly only once.
Chapter 4E-144:10/98
-------
Chapter 4E: Grazing Management 145
Photos have been used to document improvements in riparian condition due
to such practices as rest rotations and exclusion (Chancy et ah, 1993). The au-
thors emphasize the importance, however, of looking beyond the vegetation and
examining whether water quality benefits also accrue.
Miner et al. (1991) showed that the provision of supplemental water Facilities
reduced the time each cow spent in the stream within 4 hours of feeding from 14.5
minutes to 0.17 minutes (8-day average). This pasture study in Oregon showed
that the 90 cows without supplemental water spent a daily average of 25.6 minutes
per cow in the stream. For the 60 cows that were provided a supplemental water
tank, the average daily time in the stream was 1.6 minutes per cow, while 11.6
minutes were spent at the water tank. Based on this study, the authors expect that
a 90% decreased in time'spent in the stream will decrease bacterial loading from
the cows.
McDougald et al. (1989) tested the effects of moving supplemental feeding
locations on riparian areas of hardwood range in California. With stocking rates
of approximately 1 ac/AUM, they found that moving supplemental feeding loca-
tions away from water sources into areas with high amounts of forage greatly
reduces the impacts of cattle on riparian areas (Table 4e-6).
Table 4e-6. The effects of supplemental feeding location on riparian area vegetation
(McDougald et al., 1989).
Percentage of riparian area with the following levels of
residual dry matter in early October
Practice
Low
Moderate
Supplemental feeding located close to riparian areas:
1982-85 Range Unit 1
1982-85 Range Unit 8
1986-87 Range Unit 8
Supplemental feeding moved away from riparian area:
1986-87 Range Unit 1
48
59
54
38
29
33
27
High
13
12
13
72
Factors in the Selection of Management Practices
The selection of grazing management practices for this measure should be
based on an evaluation of current conditions, problems identified, quality criteria,
and management goals. Successful resource management on range and pasture
includes appropriate application of a combination of practices that will meet the
needs of the range and pasture ecosystem (i.e., the soil, water, air, plant, and ani-
mal (including fish and shellfish) resources) and the objectives of the land user.
For a sound grazing land management system to function properly and to
provide for a sustained level of productivity, the following should be considered:
O Know the key factors of plant species management, their growth habits, and
their response to different seasons and degrees of use by various kinds and
classes of livestock.
Chapter 4E-145: 10/98
-------
146 Chapter 4: Management Measures
Plant species
.production
management is
central to effective
grazing BMPs.
Consider
ecosystem
productivity,
harvest rates by
stock and wildlife,
and regenerative
capacity.
O Know the demand for, and seasons of use of, forage and browse by wildlife
species.
D Know the amount of plant residue or grazing height that should be left to
protect grazing land soils from wind and water erosion, provide for plant re-
growth, and provide the riparian vegetation height desired to trap sediment or
other pollutants.
O Know the range site production capabilities and the pasture suitability group
capabilities so an initial stocking rate can be established.
O Know how to use livestock as a tool in the management of the range ecosys-
tems and pastures to ensure the health and vigor of the plants, soil tilth, proper
nutrient cycling, erosion control,-and riparian area management, while at the
same time meeting livestock nutritional requirements.
O Establish grazing unit sizes, watering, shade (where possible) and salt loca-
tions, etc. to secure optimum livestock distribution and proper vegetation use.
O Provide for livestock herding, as needed, to protect sensitive areas from exces-
sive use at critical times.
O Encourage proper wildlife harvesting to ensure proper population densities
and forage balances.
D Know the livestock diet requirements in terms of quantity and quality to en-
sure that there are enough grazing units to provide adequate livestock nutrition
for the season and the kind and classes of animals on the farm/ranch.
O Maintain a flexible grazing system to adjust for unexpected environmentally
and economically generated problems.
O Follow special requirements to protect threatened or endangered species.
To speed up the rehabilitation process of riparian zones, seeding can be used
as a proper management practice. This strategy, however, can be very expensive
and risky. Riparian zones can be rehabilitated positively and at a lower cost by
improving livestock distribution, better systems, fencing, or reducing stock rates.
In areas where the desirable native perennial forage plants are nearly extinct, seed-
ing is essential. Such areas will have a poor to very poor rating of forage condition
and are difficult to restore.
Cost of Practices
Much of the cost associated with implementing grazing management prac-
tices is due to fencing installation, water development, and seeding. Costs vary
according to region and type of practice. Generally, the more components or struc-
tures a practice requires, the more expensive it is. However, cost-share is usually
available from the USDA and other Federal agencies for most of these practices.
*
The principal direct costs of providing grazing practices vary from relatively
low variable costs of dispersed salt blocks to higher capital and maintenance costs
of supplementary water supply improvements. Improving the distribution of graz-
ing pressure by developing a planned grazing system or strategically locating wa-
ter troughs, salt, or feeding areas to draw cattle away from riparian zones can
result in improved utilization of existing forage, better water quality, and improved
riparian habitat.
Chapter 4E-146:10/98
-------
Chapter 4E: Grazing Management 147
Principal direct costs of excluding livestock from the riparian zone for a pe-
riod of time are the capital and maintenance costs for fencing to restrict access to
streamside areas and/or the cost of herders to achieve the same results. In addition,
there may be an indirect cost of the forage that is removed from grazing by the
exclusion. _
Principal direct costs of improving or reestablishing grazing land include the
costs of seed, fertilizer, and herbicides needed to establish the new forage-stand
and the labor and machinery costs required for preparation, planting, cultivation,
and weed control (Table 4e-7). An indirect cost may be the forage that is removed
from grazing during the reestablishment work and rest for seeding establishment.
Table 4e-7. Cost of forage improvement/reestablishment for grazing management (EPA, 1993).
Constant Dollar*
Location
Year
Type
Unit
Reported
Capital Costs
S/Unit
Capital Costs
1991 S/Unit
Annualized
Costs
1991 S/Unit
Alabama"
1990
planting
(seed, lime &
fertilizer)
acre
84- 197
83 - 195
12.37 - 29.00
Nebraska0
Oregon"
1991
1991
establishment
seeding
establishment
acre
acre
acre
47
45 .
27
" • 47
45
27
7.00
6.71
4.02
• Reported costs inflated to 1991 constant dollars by the ratio of indices of prices paid by farmers for seed, 1997=100.
Capital costs are annualized at 8% interest for 10 years.
b Alabama Soil Conservation Service, 1990.
cHermsmeyer, 1991.
"USDA-ASCS, 1991b.
Water
Development
Use
Exclusion
The availability and feasibility of supplementary water development varies
considerably between arid western areas and humid eastern areas, but costs for
water development, including spring development and pipeline watering, are simi-
lar (Table 4e-8). Additional cost data for watering troughs, piping, and holding
tanks are given in Table 4e-10. These costs should be applied on a per-foot or per-
gallon basis.
There is considerable difference between multistrand barbed wire, chiefly
used for perimeter fencing and permanent stream exclusion and diversions, and
single- or double-strand smooth wire electrified fencing used for stream exclusion
and temporary divisions within permanent pastures. The latter may be all that is
needed to accomplish most livestock exclusion in a smaller, managed, riparian
pasture (Table 4e-9). Additional cost data for fencing are provided in Table 4e-10.
Chapter 4E-147:10/98
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148 Chapter 4: Management Measures
Table 4e-8. Cost of water development for grazing management (EPA, 1993).
Constant Dollar*
Location
Year
Type
Unit
Reported Annualized
Capital Costs Capital Costs Costs
$/Unit 1991 S/Unit 1991 S/Unit
California"
Kansas0
Mained
Alabama"
Nebraska'
Utah»
Oregonh
1979
1989
1988
1990
1991
1968
1991
pipeline
spring
spring
pipeline
spring
pipeline
trough
pipeline
tank
spring
pipeline
tank
foot
each
each
each
each
foot
each
foot
each
each
foot
each
0.28
1,239.00
1,389.00
831.00
1,500.00
1.60
1,000.00
1.31
370.00
200.00
0.20
183.00
0.35
1,282.94
1,438.26
879.17
1,520.83
1.62
1,013.89
1.31
370.00
389.33
0.20
183.00
0.05
191.20
214.34
131.02
226.65
0.24
151.10
0.20
55.14
58.02
0.03
27.27
• Reported costs inflated to 1991 constant dollars by the ratio of indices of prices paid by farmers for building and'
fencing, 1977=100. Capital costs are annualized at 8% interest for 10 years.
" Fresno Field.Off ice, 1979.
cNorthupetal., 1989. ^
"Cumberland County Soil and Water Conservation District, undated.
•Alabama Soil Conservation Service, 1990.
'Hermsmeyer, 1991.
5 Workman and Hooper, 1968.
"USDA-ASCS, 19916.
Table 4e-9. Cost of livestock exclusion for grazing management (EPA, 1993).
Constant Dollar*
Location
Year
Type
Unit
Reported Annualized
Capital Costs Capital Costs Costs
S/Unit 1991 S/Unit 1991 S/Unit
California"
Alabama1
Nebraska13
Great Lakes'
Oregon1
1979
1990
1991
1989
1991
permanent
permanent
net wire
electric
permanent
permanent
permanent
mile
mile
mile
mile
mile
mile
mile
2,000
3,960
5,808
2,640
2,478
2,100 -
2,400
2,640
2,474.58
4,015.00
5,888.67
2,676.67
2,478.00
2,174.47-
"2,485.11
2,640.00
368.78
,598.35
877.58
398.90
369.30
324.06 •
370.35
393.44
• Reported costs inflated to 1991 constant dollars by
fencing, 1977=100. Capital costs are annualized at
"Fresno Field Office, 1979.
c Alabama Soil Conservation Service, 1990.
d Hermsmeyer, 1991.
•DPRA, 1989.
'USDA-ASCS, 1991 b.
the ratio of indices of prices paid by farmers for building and
8% interest for 10 years.
Chapter 4E-148:10/98
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Chapter 4E: Grazing Management 149
Table 4e-10. Unit price of fencing, piping, watering trough and storage tank materials — 1997.
Fencing
Piping
Material
Standard 6' Heavy T-posts
Round Treated Wood Post:
7' tall, 4" round
8' tall, 5" round
Electric Wire - 1/4 Mile Role
Gallagher Plug In Controller/Charger
15 Miles Power
Parmak Solar Battery and Charger
Ground Rod
Insulators
Domestic Barbed Wire
15 1/2 Gauge/1/4 Mile
PVC:
1/2".sen 40 heavy/100 ft.
1/2" class 315/100 ft. '
3/4" sch 40/100 ft.
3/4" class 200/100 ft.
Polyethylene:
1/2" poly/100 ft.
3/4" poly/100 ft.
Holding Tanks
Norwesco Plastic - 2,500 gallon
Norwesco Plastic - 5,000 gallon
Galvanized Steel - 2,500 gallon
Galvanized Steel - 5,000 gallon
Water Troughs
Plastic Rubber Maid - 300 gallon
Galvanized Round - 500 gallon
Unit Price
$2.40 each _.__
$6.10 each
$9.45 each
$38.95 each
$100.00 each
$215.00 each
$10.95 each
$ .40-.60 each
$32.95 each
$13.29 each
$8.06 each
$17.75 each
$9.90 each
$18.00 each
$25.00 each
$1,100 each
$2,200 each
$1,300 each
$2,000 each
$175.00 each
$200.00 each
Source: Farm Supply, San Luis Obispo, California, 1996.
Overall Costs : : ,
of the Grazing Management Measure
Since the combination of practices needed to implement the management
measure depends on site-specific conditions that are highly variable, the overall
cost of the measure is best estimated from similar combinations of practices ap-
plied under the Agricultural Conservation Program (ACP), Rural Clean Water
Program (RCWP), and similar activities. The following 7 ranch examples have
been developed to demonstrate how various grazing management practices can be
implemented to produce the overall management measure for the ranch.
Chapter 4E-149:10/98
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150 Chapter 4: Management Measures
The size of this ranch is 575 acres and has a carrying capacity of approximately 13 acres/cow.
The establishment of a pipeline for water troughs supplied from a spring box was installed by the
rancher. This water system provides water for 2 paddocks.
Piping
G 2,652 feet of 3/4° poly pipe black pipeline and preparation for right of way.
D Backhoe to dig ditch for placing the pipe, back filling, and restoring right of way.
D The cost of the pipeline and labor was approximately $1.13/ft. '
Water Troughs
G 4x4 dump truck hauling rip rap (concrete slabs) for two trough sites.
G Backhoe to place concrete rip rap and a hookup inlet/outlet for the troughs.
O Two troughs made of recycled steel tank that was cut in half holding 250 gallons.
G The cost of troughs and labor was approximately $1,93/gal.
Total Cost Per Ranch
Total Cost Per Acre
Total Cost Per Cow
$3,962.00
$6.90
$90.00
The size of this ranch is 334 acres and has a carrying capacity of approximately 2 acres/cow.
The establishment of a five wire, barbed wire fence and pipeline for five watering troughs with storage
tank was installed by college student labor. The water source was provided by a well but was not
included in the cost. This water system provides water for 9 paddocks.
Fencing
G 3,000 feet of barbed wire'fence.
G 62 round posts.
G 185 steel posts.
O The cost of the fencing and labor was approximately $.54/ft.
Piping
O 5,700 feet of 1 1/2" of Sch 40 PVC pipe.
G The cost of pipe and labor was approximately $.28/ft.
Water Troughs and Storage Tanks
G Five F.R. Baumgartner & Son 500 gallon concrete water troughs.
G One 5,000 gallon plastic storage tank. - •
G The cost of storage tank and troughs were approximately $1.46/gal, including labor.
Total Cost Per Ranch
Total Cost Per Acre
Total Cost Per Cow
$10,516.00
$31.50
$63.00
Chapter 4E-150: 10/98
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Chapter 4E: Grazing Management 151
The size of this ranch is 184 acres and has a carrying capacity of approximately 2 acres/cow.
The establishment of an electric fence and water system was installed by college student labor. The
water source was provided by a well but was not included in the cost. This water system provides water
for approximately 8 paddocks.
Fencing
O Two wire electric fence with posts extends 6,200 feet.
O One wire electric off-set fence extends 10,100 feet.
G One Gallagher energizer with post and case.
O One small Gallagher portable energizer with solar panel.
D The cost of fencing and labor was approximately $.47/ft.
Water Troughs
O Three water concrete troughs holding 500 gallons with pads.
O The cost of the troughs and labor were $1.60/gal.
Piping
G 8,000 feet of polyethylene pipe.
D The cost of the pipe and labor was approximately $.40/ft. .
Total Cost Per Ranch
Total Cost Per Acre
Total Cost Per Cow
$8,541.00
$46.30
$92.50
The size of this ranch is 1,754 acres and has a carrying capacity of approximately 10 acres/cow.
The establishment of an electric fence and water system was Installed by college student labor.
The water source was provided by a well but was not included in the cost. This water system
provides water for approximately 23 paddocks. . ,
Fencing
G Two wire electric fence with posts extends 21 ;933 feet.
O One wire off-set electric fence extends 4,525 feet.
G A Gallagher energizer with post and case.
G The cost of fencing and labor was approximately $.72/ft.
Piping
O 1" polyethylene pipe, SDR 11 extended 10,575 feet.
G Fifteen pipe transitions.
O The cost of pipe and labor was approximately $.41/ft.
Water Troughs and Storage Tanks
G Seven F.R. Baumgartner & Son concrete water troughs holding 435 gallons.
G One 5,000 gallon poly linear back-up tank.
O One 10,000 gallon poly linear tank.
O The cost of troughs and tanks and labor were approximately $3.10/gal.
Total Cost Per Ranch
Total Cost Per Acre
Total Cost Per Cow
$51,128.00
$29.20
$291.00
Chapter 4E-151: 10/98
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152 Chapter 4: Management Measures
The size of this ranch is 400 acres and has a carrying capacity approximately 16 acres/cow.
The establishment of a barbed wire fence was installed by the California Conservation Corps and
San Luis Obispo County.
Fencing
D Five wire, barbed wire fence extending 10,000 feet.
D The cost of the fencing and labor was approximately $2.12/ft.
Total Cost Per Ranch
Total Cost Per Acre
Total Cost Per Cow
$21,200.00
553.00
$848.00
The size of this ranch is 640 acres and has a carrying capacity approximately 10 acres/cow. The
establishment of the electric fence and pipline for three watering troughs with storage tank was installed by
a fencing and irrigation contractor. The water source for both was provided by a well but was not included
in the cost. This water system provides water for 30 paddocks.
Fencing
D 11,055 feet of three wire electric fence.
D 324 feet of a one wire offset fence.
O 105 feet of insulated cable in conduit.
CD Eleven pasture gates.
D One M-1500 energizer.
O One ground system.
D Lightening choke.
D The cost of the fencing and labor is approximately $1.11/ft.
Piping
O PVC 1 1/4" of Cl 200 of pipe 13,847 feet.
a 1 1/4" of Sch 40 for 5,891 feet.
D Five air release valves and PVC unions at gate valves.
O The cost of piping and labor was approximately $.84/ft.
Water Troughs and Storage Tank
O One 18,000 gallon concrete tank.
O Three 1,550 gallon concrete troughs.
O Base material at troughs.
O Vibra plate compactor.
O Isolation valve at highway.
D GSP unions at ARV and tank, and an in line trough.
D The cost of the storage tank and watering troughs and labor were approximately $4.91/gal.
Total Cost Per Ranch
Total Cost Per Acre
Total Cost Per Cow
$112,283.00
$175.50
$1754.00
Chapter 4E-152: 10/98
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Chapter 4E: Grazing Management 153
The size of this ranch is 400 acres and has a carrying capacity approximately 6 acres/cow. The
establishment of an electric fence and purchase of three troughs were installed by the rancher. This
water system provides water for 2 paddocks. . __
Fencing
O Two wire electric fence 4,400 feet.
O Steel T-posts with plastic insulators.
D One Rechargeable solar battery with energizer.
O One gate.
O The cost of fencing was approximately $.60/ft.
Water Troughs
O Three 500 gallon F.R. Baumgartner & Son concrete troughs. .
O The cost of the troughs was approximately $.64/gal., excluding tax and labor.
Total Cost Per Ranch
Total Cost Per Acre ,
Total Cost Per Cow
$3,600.00
$9.00
$54.00
Chapter 4E-153:10/98
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154 Chapter 4: Management Measures
Chapter 4E-154:10/98
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Chapter 4F: Irrigation Water Management 155
4F: Irrigation Water Management
A primary concern
for irrigation water
management is
discharge of salts,
pesticides, and
nutrients to ground
water and discharge
of these pollutants
plus sediment to
surface water.
Management Measure for Irrigation Water Management
To reduce nonpoint source pollution of surface waters caused by irrigation:
(1) Operate the irrigation system so that the timing and amount of irrigation water
applied match crop water needs. This will require, as a minimum: (a) the ac-
curate measurement of soil-water depletion volume and the volume of irriga-
tion water applied, and (b) uniform application of water.
(2) When chemigation is used, include backflow preventers for wells, minimize
the harmful amounts of chemigated waters that discharge from the edge of the
field, and control deep percolation. In cases where chemigation is performed
with furrow irrigation systems, a tailwater management system may be
needed.
The following limitations and special conditions apply:
(1) In some locations, irrigation return flows are subject to other water rights or
are required to maintain stream flow. In these special cases, on-site reuse
could be precluded and would not be considered part of the management mea-
sure for such locations.
(2) By increasing the water use efficiency, the discharge volume from the system
will usually be reduced. While the total pollutant load may be reduced some-
what, there is the potential for an increase in the concentration of pollutants in
the discharge. In these special cases, where living resources or human health
may be adversely affected and where other management measures (nutrients
and pesticides) do not reduce concentrations in the discharge, increasing water
use efficiency would not be considered part of the management measure.
1
(3) In some irrigation districts, the time interval between the order for and the
delivery of irrigation water to the farm may limit the irrigator's ability to
achieve the maximum on-farm application efficiencies that are otherwise pos-
sible.
(4) In some locations, leaching is necessary to control salt in the soil profile.
Leaching for salt control should be limited to the leaching requirement for the
root zone.
(5) Where leakage from delivery systems or return flows supports wetlands or
wildlife refuges, it may be preferable to modify the system to achieve a high
level of efficiency and then divert the "saved water" to the wetland or wildlife
refuge. This will improve the quality of water delivered to wetlands or wildlife
refuges by preventing the introduction of pollutants from irrigated lands to
such diverted water.
(6) In some locations, sprinkler irrigation is used for frost or freeze protection, or
for crop cooling. In these special cases, applications should be limited to the
amount necessary for crop protection, and applied water should remain on-
site. •
Chapter 4F-155: 10/98
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156 Chapter 4: Management Measures
Effective irrigation
management
reduces runoff and
leachate losses,
controls deep
percolation and,
along with cropland
sediment control,
reduces erosion and
sediment delivery to
waterways.
Management Measure for Irrigation Water
Management: Description
The goal of this management measure is to reduce movement of pollutants
from land into ground or surface water from the practice of irrigation. This goal is
accomplished through consideration of the following aspects of an irrigation sys:~
tem, which will be discussed in this chapter:
1. Irrigation scheduling
2. Efficient application of irrigation water
3. Efficient transport of irrigation water
4. Use of runoff or tailwater
5. Management of drainage water
A well designed and managed irrigation system reduces water loss to evapo-
ration, deep percolation, and runoff; removes leachate efficiently; and minimizes
erosion from applied water. Application of this management measure will reduce
the waste of irrigation water, improve water use efficiency, and reduce the total
pollutant discharge from an irrigation system. It focuses on components to manage
the timing, amount and location of water applied to match crop water needs, and
special precautions (i.e., backflow preventers, prevent tailwater, and control deep
percolation) when chemigation is used.
Irrigation and Irrigation Systems — An Overview
Irrigation, the addition of water to lands via artificial means, is essential to
profitable crop production in arid climates. Irrigation is also practiced in humid
and sub-humid climates to protect crops during periods of drought. Figure 4f-l
shows the distribution of irrigated farmland in the U.S. (USDA, 1997a).
Figure 4f-1. Irrigated land in farms, 1992. Source: USDA ERS based on
USDC 1992 Census of Agriculture data.
One dot = 10,000 acres ''^ \'£'" •'
Chapter 4F-156:10/98
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Chapter 4F: Irrigation Water Management 157
Soil-Water- :
Plant Relationships
Effective and efficient irrigation begins with a basic understanding of the
relationships among soil, water, and plants. Figure 4f-2 illustrates the on-farm
hydrologic cycle for irrigated lands, and Table 4f-l provides definitions of several
terms associated with irrigation. Water can be supplied to the soil through "precipi-
tation, irrigation, or from groundwater (e.g., rising water table due to drainage
management). Plants take up water that is stored in the soil (soil water), and use
this for growth (e.g., nutrient uptake, photosynthesis) and cooling. Transpiration is
the most important component of the on-farm hydrologic cycle (Duke, 1991), with
the greatest share of transpiration devoted to cooling. Water is also lost via evapo-
ration from leaf surfaces and the soil. The combination of transpiration and evapo-
ration is evapotranspiration, or ET. ET is influenced by several factors, including
plant temperature, air temperature, solar radiation, wind speed, relative humidity,
and soil water availability (USDA, 1997). The amount of water the plant needs,
its consumptive use, is equal to the quantity of water lost through ET. Due to inef-
ficiencies in the delivery of irrigated water (e.g., evaporation, runoff, wind drift,
and deep percolation losses), the amount of water needed for irrigation is greater
than the consumptive use. In arid and semi-arid regions, salinity control may be a
consideration, and additional water or "leaching requirement" may be needed.
Figure 4f-2. On-farm hydrologic cycle for irrigated lands.
Precipitation
Evaporation
/ I
Transpiration
Evaporation
Soil Water Storage
Water Held
in Pore
Spaces
Soil Particles
. Air in Pore
Spaces
Chapter 4F-157: 10/98
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158 Chapter 4: Management Measures
Table 4f-1. Soil-water-plant relationship terms. |
Term
Evaporation
Transpiration
Evapotranspi ration (ET)
Soil water
Soil-water potential
Soil-water tension
Soil moisture tension
Gravitational water
Free water
Capillary water
Field capacity
Available water capacity
Water holding capacity
Permanent wilting point
Management allowable depletion (MAD)
Consumptive use
Soil texture
Soil structure
Bulk density
Definition
The transformation of water to vapor without passing through
the plant. . . —
The movement of water into plant roots, through the plant, and
out the stomata as water vapor.
Evaporation + Transpiration
Water stored in the soil.
A measure of the strength with which the soil holds the water.
Soil water potential is the amount of work required per unit
quantity of water to transport water in soil, and is measured in
units of bars and atmospheres or cm. A tension is a negative
potential. Water moves from high to low potential.
Water that moves downward freely in soils under the force of
gravity.
Water that moves more slowly through smaller pores in soils,
from wetter to drier areas.
The amount of soil water stored in the soil after free water
(gravitational water) passes through the soil profile. Sometimes
referred to as 2-3 day drainage or a soil water potential of
about -1/3 bar.
The amount of stored soil water that is available to the plant.
The amount of water that can be stored in the soil at field
capacity.
The soil-water content at which most plants cannot obtain
sufficient water to prevent permanent tissue damage, about
-15 bars.
The greatest amount of water that can be removed by plants
before irrigation is needed to avoid undesirable crop water
stress.
The amount of water that is used by the plant. Is equal to ET.
The proportion of the various sizes of soil particles (sand, silt,
and clay). Defines coarseness or fineness of soil.
The arrangement and organization of soil particles into natural
units of aggregation.
The weight of a unit volume of dry soil.
Plant growth depends upon a renewable supply of soil water, which is gov-
erned by the movement of water in the soil, the soil-water holding capacity, the
amount of soil water that is readily available to plants, and the rate at which soil
water can be replenished (Duke, 1991). Cost-effective irrigation provides plants
with this renewable supply of soil water with a minimum of wasted time, energy,
and water. Knowledge and understanding of the factors that affect water move-
ment in the soil, storage of water in the soil, and the availability of water to plants
are essential to achieving maximum irrigation efficiencies.
Chapter 4F-158: 10/98
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Chapter 4F: Irrigation Water Management 159
Movement of soil water
When water is applied to soils it moves via such pathways as infiltration,
runoff, and evaporation (Figure 4f-2). The ultimate fate and transport of applied
water is determined by various forces, including gravity and capillary force. Grav-
ity pulls water downward freely in soils with large pores, causing it to move-
through the root zone quickly if not taken up by the crop (Duke, 1991). As the
water passes through the soil, the pores are filled again with air, preventing crop
damage that could arise due to excess water. In soils with smaller pores, water
moves via capillary forces. This "capillary water" moves more slowly than gravi-
tational water, and tends to move from wetter areas to drier areas. The lateral
distribution of capillary water makes it more important to the irrigated crop since
it provides greater wetting of the soil (Duke, 1991). In saturated conditions, grav-
ity is the primary force causing downward water movement (Watson, et al. 1995),
while capillary action is the primary force in unsaturated soil.
The above discussion uses subjective terms such as "capillary water" and
"gravitational water" (see Table 4f-l) to simplify the description of how water
moves in soils. USDA describes this movement in the more technically correct
terms of soil-water potential, measured in units of bars and atmospheres (USDA,
1997). Soil-water potential is the sum of matric, solute, gravitational, and pressure
potential, detailed discussions of which are beyond the scope of this document. In
simple terms, however, water in the soil moves toward decreasing potential energy,
or generally from higher water content to lower water content (USDA, 1997).
Storage and availability of soil water
The amount of water that soil can hold, its water holding capacity, is a key
factor in irrigation planning and management since the soil provides the reservoir
of water that the plant draws upon for growth. Water is stored in the soil as a film
around each soil particle, and in the pore spaces between soil particles (Risinger
and Carver, 1987). The magnified area in Figure 4f-2 illustrates how soil water
and air are held in the pore spaces of soils.
All soil water is not equally available for extraction and use by plants. The
ability of plants to take water from the soil depends upon a number of factors,
including soil texture, soil structure, and the layering of soils (Duke, 1991). Tex-
ture is classified based upon the proportion of sand, silt, and clay particles in the
soil (Figure 4f-3). Structure refers to how the soil particles are arranged in groups
or aggregates, while layering refers to the vertical distribution of soils in the soil
profile (e.g., clay soils underlying a sandy loam layer). The type and extent of
layering can influence the percolation and lateral distribution of applied water.
Soil texture and structure affect the size and quantity of pores in the soil, and
therefore the space available to hold air or water. For example, the available water
capacity of coarse sand ranges from .1 to .4 inches of water per foot of soil depth
(in/ft), while silt holds 1.9-2.2 in/ft, and clay^iolds 1.7-1.9 in/ft (USDA, 1997).
The structure-of some volcanic ash soils allows them to carry very high water
content at field capacity levels, but pumice and cinder fragments may contain
some trapped water that is not available to plants (USDA, 1997). In fine-textured
soils and soils affected by salinity, sodicity, or other chemicals, a considerable
volume of soil water may not be available for plant use (USDA, 1997).
Chapter 4F-159: TO/98
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160 Chapter 4: Management Measures
Figure 4f-3. Soil textural triangle for determining textural class (Duke, 1991).
20
JSIL.TT
XCLAY LOAM A CLAY
SANDY CLAY\ ./_ALOAM_
LOAM
100Z
SILT
100% go
SAND
Percent SAND
Field capacity is the amount of water a well-drained soil holds after "free"
water has drained because of gravity (USDA, 1997). "Free" water, which is con-
ceptually similar to "gravitational" water, can drain from coarse-textured (e.g.,-
sandy) soils in a few hours from the time of rainfall or irrigation, from medium-
textured (e.g., loamy) soils in about 24 hours, and from fme-textured (e.g., clay)
soils in several days. Soil properties that affect field capacity are texture, struc-
ture, bulk density, and strata within the soil profile that restrict water movement.
Available water capacity is the difference between the amount of water held at
field capacity and the amount held at the permanent wilting point (Burt, 1995).
Uptake of soil water by plants
Water stored in soil pore spaces is the easiest for the plant to extract, while
water stored in the film around soil particles is much more difficult for the plant to
withdraw (Risinger and Carver, 1987). As evapotranspiration draws water from
the soil, the remaining water is held more closely and tightly by the soil. Soil mois-
ture tension increases as soils become drier, making it more difficult for the plant
to extract the soil water. Figure 4f-4 is a soil moisture release curve that shows
how greater energy (tension measured in bars, or potential measured in negative
(-) bars) is needed to extract water from the soil as soil-water content decreases
(USDA, 1997). This figure also illustrates the greater soil-water tension (or lesser
soil-water potential) in clays versus loam and sand for any given soil-water con-
tent. Because clay holds water at greater tension than medium-textured soils (e.g.,
loam) at similar water contents, it has less available water capacity despite its
greater water holding capacity (USDA, 1997).
Chapter 4F-160:10/9.8
-------
Chapter 4F: Irrigation Water Management 161
Figure 4f-4. Typical water release curves for sand, loam, and clay (USDA, 1997).
100
T I I £ I | r I • | ' I • I '
Reid capacity 1
456 8 10 12
Soil water tension (bars)
Texture Tension level (atmospheres or bars)
@ field capacity @ Perm, wilting point
16
Course 0.1
Medium & fine 0.33
15.0
15.0
Wilting occurs when the plant cannot overcome the forces holding the water
to the soil particles (i.e., the soil-water tension). Irrigation is needed at this point to
save the plant. The permanent wilting point (represented as -15 bars in Figure 4f-
4) is the soil-water content at which most plants cannot obtain sufficient water to
prevent permanent tissue damage (USDA, 1997). Based upon yield and product
quality objectives, growers decide how much water to allow plants to remove from
the soil before irrigation. This amount, the Management Allowable Depletion
(MAD), is expressed as a percentage of the available water-holding capacity and
varies for different crops and irrigation methods. As a general rule of thumb,
MAD is 50%. Smaller MAD values, which result in more frequent irrigations,
may be desirable where micro-irrigation is practiced, when saline water is used,
for shallow root zones, and in cases where the water supply is uncertain (Burt,
1995). Large MAD values might be desirable when hand-move and hose-pull
sprinklers are used, where furrows are long and soils are sandy, or for crops such
as some varieties of cotton that need to be stressed on heavy soil to develop a suf-
ficient number of cotton bolls (Burt, 1995).
Chapter 4F-161:10/98
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162 Chapter 4: Management Measures
Irrigation
Methods and System Designs
Irrigation systems consist of two basic elements: (1) the transport of water
from its source to the field, and (2) the distribution of transported water to the
crops in the field. A number of soil properties and qualities are important to the
design, operation, and management of irrigation systems, including water holding
capacity, soil intake characteristics, permeability, soil condition, organic matter,
slope, water table depth, soil erodibility, chemical properties, salinity, sodicity, and
pH (USDA, 1997). Some soils cannot be irrigated due to various physical prob-
lems, such as low infiltration rates and poor internal drainage which may cause
salt buildup. The chemical characteristics of the soil and the quantity and quality
of the irrigation water will determine whether irrigation is a suitable management
practice that can be sustained without degrading the soil or water resources
(Franzen et al., 1996; Scherer et al., 1996; and Seelig and Richardson, 1991).
Water supply and demand
Producers need to factor the availability of good quality water (in terms of
amount, timing, and rate) into their irrigation management decisions. Both surface
water and ground water can be used to supply irrigation water. An assessment of
the total amount of water available during an irrigation season is essential to de-
termining the types and amounts of irrigated crops that can be grown on the farm.
- The quality of some water is not suitable for irrigating crops. Irrigation water
must be compatible with both the crops and soils to which it will be applied
(Scherer and Weigel, 1993; Seelig and Richardson, 1991). The quality of water
for irrigation purposes is determined by its salt content. Irrigation water can also
contain appreciable amounts of nutrients that should be factored into the overall
nutrient management plan.
Efficient irrigation scheduling depends upon knowledge of when water will be
available to the producer. In some areas, particularly west of the Mississippi
River, irrigation districts or some other outside entities may manage the distribu-
tion of water to farms, while farmers in other areas have direct access to and con-
trol over their water supplies. An irrigation project is defined as blocks of irrigated
land within a defined boundary, developed or administered by a group or agency
(USDA, 1997). Water is delivered from a source to individual turnouts via a sys-
tem of canals, laterals, or pipelines. Figure 4f-5 depicts the Ainsworth Unit in
northern Nebraska within which water from the Merrill Reservoir is distributed to
the Ainsworth Irrigation District via the 53-mile long, concrete-lined Ainsworth
Canal (Hermsmeyer, 1991). A system of laterals and drains serves approximately
35,000 acres of cropland in the irrigation district. Irrigation projects or districts
that deliver water to farms on a rotational basis control when the fanner can irri-
gate, leaving the farmer to choose only the rate and methods of irrigation. In cases
where farmers are able to control the availability of irrigation water it is possible,
however, to develop a predetermined irrigation schedule.
The amount of water that is needed on a daily basis for adequate irrigation
depends upon climate and crop growth stage. Different crops require different
amounts of water, and the water demand for any particular crop varies throughout
the growing season. Producers need to factor the peak-use rates, the amount of
water used by a crop during its period of greatest water demand (usually during
period of peak growth), into both the initial design of an irrigation system and
annual irrigation planning.
Chapter 4F-162:10/98
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Chapter 4F: Irrigation Water Management 163
Figure 4f-5. Ainsworth Unit in northern Nebraska.
AINSWORTH
Pine
Irrigation methods
There are four basic methods of applying irrigation water: (1) surface, (2)
sprinkler, (3) trickle, and (4) subsurface. Factors that are typically considered in
selecting the appropriate irrigation method include land slope, water intake rate of
the soil (i.e., how fast the soil can absorb applied water), water tolerance of the
crops, and wind. For example, sprinkler, surface, or trickle methods may be used
on soils (e.g., fine soils) with low water intake rates, but surface irrigation may
not be appropriate for soils (e.g., coarse soils) with high water intake rates. Two
of the key factors that determine water intake rates are soil texture and surface
sealing due to compaction and salts, particularly sodium.
Water available to the farm from either on-site or off-site sources can be
transported to fields via gravity (e.g. canals and ditches) or under pressure (pipe-
line). Pressure for sprinkler systems is usually provided by pumping, but gravity
can be used to create pressure where sufficient elevation drops are available.
Gravity-based, or surface irrigation systems, rely on the ponding of water on the
surface for delivery through the soil profile (Figure 4f-6), whereas pressure-based
sprinkler systems are generally operated to avoid ponding for all but very short
time periods (USDA, 1997).
Irrigation systems
There are several irrigation system options for each irrigation method se-
lected for the farm. The options for irrigation by gravity include level basins or
borders, contour levees, level furrows, graded borders, graded furrows, and con-
tour ditches (Figure 4f-7) (USDA, 1997). Pressure-based irrigation systems in-
clude periodic move, fixed or solid-set, continuous (self) move, traveling gun, and
traveling boom sprinkler systems, as well as micro-irrigation and subirrigation
systems. Operational modifications to center pivot and linear move systems, in-
cluding Low Energy Precision Application (LEPA) and Low Pressure In Canopy
(LPIC), increase the range of pressure-based options to select from (USDA,
1997). Figure 4f-8 illustrates a range of sprinkler systems. Micro-irrigation sys-
tems (Figure 4f-9) include point-source emitters (drip, trickle, or bubbler emit-
Chapter4F-163:10/98
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164 Chapter 4: Management Measures
ters), surface or subsurface line-source emitters (e.g., porous tubing), basin bub-
blers (Figure 4f-10), and spray or mini-sprinklers. Table 4f-2 summarizes the
basic features of each type of irrigation system (USDA, 1997), and Figure 4f-l 1
shows typical layouts of graded-furrow with tailwater recovery and reuse,
solid-set, center pivot, traveling gun, and micro-irrigation systems (USDA, 1997;
Turner, 1980). -
The advantages and disadvantages of the various types of irrigation systems
are described in a number of existing documents and manuals (USDA, 1997;
EduSelf Multimedia Publishers Ltd., 1994).
Figure 4f-6. Water infiltration characteristics for sprinkler, border, and furrow irrigation
systems (USDA, 1997).
Sprinkler
Water ittoveiueitl vertically
Completely flooded
i 1 I
Wau*r HMHvniiMH viitic.iHy downward
Furrow
\Vuu-r [
i btttli ilowTiwarti and uutwnnl (rum V
Chapter 4F-164:10/98
-------
Chapter 4F: Irrigation Water Management 165
Figure 4f-7. Irrigation system options for irrigation by gravity (Turner, 1980).
STRIP
LEVEE
FLOOD
GATE
STRIP
HEAD DITCH"
FLOOD
GATE
•amAwSi*^*^*?^-*' «"?• i.ffW^^K
^i^ElfiBbRDERMrf^^
Level border type, of surface system.
HEAD
PIPELINE
Contour levee type of surface system.
>•%*
GRADED BORDER
Level furrow type of surface system.
Graded border type of graded surface system.
;-, -:. *Ji-
GRADED FURROVT 7:;,
CONTOUR DITCH
Graded furrow type of graded surface system. Contour ditch type of graded surface system.
Chapter 4F-165:10/98
-------
166 Chapter 4: Management Measures
Figure 4f-8. Typical types of sprinkler irrigation systems (Turner, 1980).
SINGLE-SPRINKLER
TRACTOR-MOVED ! SELF-PROPELLED
OR WINCH
MULTI-SPRINKLER
BOOM-SPRINKLER
Figure 4f-9. Micro system components (USDA, 1997).
Controls
Pump
tr
v 'here
, , / needed)
Solenoid / / /
valve / / / Submainline
1 -^ --^ -
* ^x "-
_ ' Primary
Fertilzer. gjter
injector
/ / /'•Drain
/ / / (where
Secondary
fllter
Flow
control
Lateral lines
with emitters
Submaui line
Chapter 4F-166: 10/98
-------
Chapter 4F: Irrigation Water Management 167
Figure 4f-10. Basin bubbler system (USDA, 1997).
Buried lateral
Figure 4M1. Typical irrigation system layouts (USDA, 1997; Turner, 1980).
r*
j ST'
l
J '
i
I I
T?
_r,_riti< J.
i
n
J~w*wti. J
Typical layout (or a taitwater recovery and reuse facility.
UKOSBCHOUHO '
MAINLINE OR WtU. CENTtn
MCWTBI PIVOT
Field layout for sctl-propclled. conter-pivot system.
Solid set sprinkler system layout.
Traveling gun typo spnnkler system layout.
Typical orchard micro-system layout.
Chapter 4F-167:10/98
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168 Chapter 4: Management Measures
Table 4f-2. Types of Irrigation Systems.
&*«^$&MWfSfe
tJrrfgatlon;System:Type A- ^:^u<^- «>/>.? :%><<• vMaJor Features of System -j«y*®p^gT^Si-l
Gravity-Level Basins
Gravity-Contour Levees
Gravity-Level Furrows
Gravity-Graded Borders
Gravity-Graded Furrows
Gravity-Contour Ditches
Pressure-Periodic Move
Sprinkler
Pressure- Fixed or
Solid-Set Sprinkler
Pressure-Continous Move
Sprinkler
Pressure-Traveling Gun
Sprinkler
Pressure-Traveling Boom
Sprinkler
Micro/Pressure-Point
Source Emitters
Micro/Pressure-Line
Source Emitters
Micro/Pressure-Basin
Bubblers
Micro/Pressure-Spray or
Mini-Sprinklers
Subirrigation •
Large flow rates over short periods to flood entire field or basin. Level fields surrounded
by low dike or levee. Best for soils with low to medium water intake rate.
Similar to level basins except for rice. Small dikes or levees constructed on contour. For
rice, ponding is maintained. Best for soils with very low intake rate.
Large flow rates over shdrt periods. Level fields. End of furrow or field is blocked to
" contain water. Best for soils with moderate to low water intake rate and moderate to
high available water capacity.
Controlled surface flooding. Field divided into strips bordered by parallel dikes or border
ridges. Water introduced at upper end.
Like graded borders, but only furrows are covered with water. Water distribution via
vertical and lateral infiltration. Water application amount is a function of intake rate of
soil, spacing of furrows, and length of field. Heavy soils (small pores sizes) provide
slower infiltration and greater lateral movement.
Controlled surface flooding. Water discharged with siphon tubes, over ditch banks, or
from gated pipes located upgradient and positioned across the slope on contour. Sheet
flow is goal.
Sprinkler is operated in a fixed location for a specified period of time, then moved to the
next location. Many design options including hand-moved laterals, side-roll laterals,
end-tow laterals, hose-fed (pull) laterals, guns, booms, and perforated pipe.
Laterals are not moved, but one or more sections of sprinklers are cycled on and off to
provide coverage of entire field over time.
Center pivot (irrigates in circular patterns, or rectangular with end guns or swing lines)
or linear (straight lateral irrigates in rectangular patterns) move continuously to irrigated
field. Multiple sprinklers located along the laterals.
High-capacity, single-nozzle sprinkler fed by flexible hose. Hose is dragged or on a
reel. Gun is guided by cable, and moved from field to field. Best for soils with high water
intake rates.
Similar to traveling gun, except a boom with several nozzles is used.
Frequent, low-volume, low-pressure applications through small tubes and drop, trickle,
or bubbler emitters. Water must be filtered. Used for orchards, vineyards, ornamental
landscaping. Emitters discharge from 0.5 to 30 gallons per hour.
Frequent, low-volume, low-pressure applications through surface or buried tubing that
is porous or has uniformly spaced emitter points. For permanent crops, but also
vegetables, cotton, melons.
Water applied via risers into small basins adjacent to plant. Bubblers discharge less
than 60 gallons per hour. Water filtration not required. Orchards and vineyards. Best for
medium to fine textured soils.
Water applied as spray droplets from small, low-pressure heads. Wets a greater area
(2 to 7 feet in diameter) than drop emitters. Discharges less than 30 gallons per hour.
Manage water table by providing subsurface drainage, providing controlled drainage,
and irrigating via buried laterals.
A comprehensive set of publications, videos, interactive software, and slides
on irrigation has been assembled by the U.S. Department of Agriculture to train
its employees (USDA, 1996). This irrigation "toolbox" covers soil-water-plant
relationships, irrigation systems planning and design, water measurement, irriga-
tion scheduling, soil moisture measurement, irrigation water management plan-
ning, and irrigation system evaluation. Updated material is provided periodically
as it becomes available. Other sources of material may be found in USDA, 1997,
Sec. 652-1502.
Chapter 4F-168:10/98
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Chapter 4F: Irrigation Water Management 169
Pollutant
Transport from Irrigated Lands
Return flows, runoff, and leachate from irrigated lands may transport the
following types of pollutants to surface and ground waters:
O Sediment and paniculate organic solids; • . -—-
O Particulate-bound nutrients, chemicals, and metals, such as phosphorus, or-
ganic nitrogen, a portion of applied pesticides, and a portion of the metals
applied with some organic wastes;
D Soluble nutrients, such as nitrogen, soluble phosphorus, a portion of the ap-
plied pesticides, soluble metals, salts, and many other major and minor nutri-
ents; and
D Bacteria, viruses, and other microorganisms.
The movement of pollutants from irrigated lands is affected by the pathways
taken by applied water and precipitation; the physical, chemical, and biological
characteristics of the irrigated land; the type and efficiency of the irrigation system
' used; crop type; the degree to which erosion and sediment control, nutrient man-
agement, and pesticide management are employed; and the management of the
irrigation system. .
Transport of irrigation water from the source of supply to the irrigated field
via open canals and .laterals can be a source of water loss if the canals and laterals
are not lined. Water is also transported through the lower ends of canals and later-
als as part of flow-through requirements to maintain water levels. In many soils,
unlined canals and laterals lose water via evaporation and seepage in bottom and
side walls. Seepage water either moves into the ground water through percolation
or forms wet areas near the canal or lateral. This water will carry with it any
soluble pollutants in the soil, thereby creating the potential for pollution of ground
or surface water (Figure 4f-12).
Figure 4f-12. Fate of water and pollutants in an irrigated hydrologic system.
o
•^
(0
_D>
Chapter 4F-169:-10/98
-------
170 Chapter 4: Management Measures
. Since irrigation is a consumptive use of water, any pollutants in the source
waters that are not consumed by the crop (e.g., salts, pesticides, nutrients) can be
concentrated in the soil, concentrated in the leachate or seepage, or concentrated in
the runoff or return flow from the system. Salts that concentrate in the soil profile
must be managed in order to sustain crop production.
Irrigation :
Scheduling
Both long-term and short-term irrigation decisions must be made by the pro-
ducer. Long-term decisions, which are associated with system design and the allo-
cation of limited seasonal water supplies among crops, rely on average water use
determined from historical data (Duke, 1991). Particularly in arid areas, long-term
irrigation decisions are needed to determine seasonal water requirements of differ-
ent possible crops, determine which crops to grow based upon crop adaptability
and water availability, and in some cases to determine when and how much to
stress the various crops to maximize economic return. Short-term decisions deter-
mine when and how much to irrigate, and are based upon daily water use. In areas
where rainfall is either insignificant or falls predictably during the growing season,
long-term decisions can be used to construct an irrigation schedule at the begin-
ning of the growing season (Duke, 1991), although better water management is
obtained by constant updating of information. In semi-arid and humid areas where
weather varies significantly on a daily basis, short-term irrigation decisions are
used in lieu of pre-determined irrigation schedules. The emphasis of this guidance
is placed on short-term irrigation decisions.
Irrigation scheduling is the use of water management strategies to prevent
over-application of water while minimizing yield loss from water shortage or
drought stress (Evans et al., 199Id). Irrigation scheduling will ensure that water is
applied to the crop when needed and in the amount needed (USDA, 1997). Effec-
tive scheduling requires knowledge of the following factors (Evans et al., 1991 c;
Evans etal., 199Id):
O Soil properties
O Soil variability within the field
D Soil-water relationships and status
O Type of crop and its sensitivity to drought stress
D The stage of crop development and associated water use
O The status of crop stress
D The potential yield reduction if the crop remains in a stressed.condition
O Availability of a water supply
O Climatic factors such as rainfall and temperature
Research in
irrigation scheduling
indicates the need
for specific site-
dependent data for
plan development.
Much of the above information can be found in Natural Resource Conserva-
tion Service soil surveys and Extension Service literature. However, all informa-
tion should be site-specific and verified in the field.
Chapter 4F-170:10/98
-------
Chapter 4F: Irrigation Water Management 171
In environments where salts tend to concentrate in the soil profile, additional
information is needed to sustain crop production, including:
O Salt tolerance of the crop
D Salinity of the soil
* . •-•--.
O Salinity of the irrigation water
O Leaching requirement of the soil
Deciding when to irrigate
There are three ways to determine when irrigation is needed (Evans et al.,
1991d):
D Measuring soil water
D Estimating soil water using an accounting approach
O Measuring crop stress
Soil water can be measured directly by sampling the soil and determining the
water content through gravimetric analysis. The distribution of plant roots and
their pattern of development during the growing season are very important consid-
erations in deciding where and at what depth to take soil samples to determine soil
water content (USDA, 1997). For example, all plants have very shallow roots
early in their development, and the concentration of moisture-absorbing roots of
most plants is usually greatest in the upper quarter of the root zone. Further, since
roots will not grow into a dry soil, it may be important to measure soil moisture
beyond the current root zone to determine irrigation needs associated with full root
development. Figure 4f-13 illustrates the typical water extraction pattern in a
uniform soil, again pointing out the need to relate soil sampling decisions to crop
development.
Soil moisture can also be determined indirectly using a range of devices
(Evans et al., 1991 b; Werner, 1992), including tensiometers (Figure 4f-14), elec-
trical resistance blocks (Figure 4f-14), neutron probes, heat dissipation sensors,
time domain reflectometers, and carbide soil moisture testers (USDA, 1997).
Table 4f-3 provides an overview of these devices. The appropriate device for any
given situation is a function of the acreage of irrigated land, soils, cost, available
trained labor, and other site-specific factors.
Direct measurement of soil water status or crop status is always more accu-
rate than estimating its magnitude, but because of the cost associated with obtain-
ing representative samples in some situations, it may be more appropriate to use
estimation techniques (Duke, 1991). Accounting approaches estimate the quantity
of plant-available water remaining in the effective root zone. A variety of methods
' can be used to estimate and predict the root zone water balance, including a simple
checkbook method (USDA, 1997), computer-assisted methods (Hill, 1997 and
Allen, 1991), graphical methods (Figure 4M5), and tabular methods. In essence,
these methods begin with an estimate of initial soil-water depletion and use mea-
surements or estimates of daily water inputs (rain, irrigation) and outputs (evapo-
transpiration) to determine the current soil-water depletion volume (Equation
Chapter 4F-171: 10/98
-------
172 Chapter 4: Management Measures
Figure 4f-13. Typical water extraction pattern in uniform soil profile
(USDA, 1997).
40% extraction here
Figure 4f-14. Soil moisture measurement devices: (a) tensiometer and
(b) electrical resistance block.
Cap
Reservoir
Rubber
Stopper
Digital
display
Meter
Chapter 4F-172: 10/98
-------
Chapter 4F: Irrigation Water Management 173
Table 4f-3. Devices and methods to measure soil moisture.
Device (Other Names)
How It Works
Comments
Tensiometer
Measures soil suction which is
related to soil water content.
Available in lengths from 6 to 72 inches.
Requires careful installation and'field
maintenance. Most applicable when soil
moisture is between 50-75 percent of field
capacity, and on medium to fine-textured soils
with frequent irrigation.
Electrical Resistance Block
(Gypsum or Moisture or
Porous Block)
Measures electrical resistance which
is related to soil water content via a
calibration curve.
Inexpensive. Simple to use. Gives accurate
readings over wider moisture range than
tensiometers, but limited to medium to coarse-
textured soils. Most accurate when soil
moisture is below field capacity. Sodic soils
problematic. Gypsum blocks need replacement
each growing season; nylon, plastic, fiberglass
more durable.
Neutron Probe (Neutron
Scattering)
Measures thermalized neutrons (fast
neutrons that are slowed by collisions
with hydrogen molecules in water)
which are related to volumetric soil
water content by a calibration curve.
Can be most accurate and precise method.
Requires calibration using gravimetric
procedures, especially if used for top 6 inches
of soil profile, in clay soils, soils with high
organic matter content, and soils with boron
ions. Requires licensed operator since
radioactive. Expensive.
Thermal Dissipation Block
(Heat Dissipation Sensor)
Estimates soil water based upon the
relationship between heat
conductance and soil water content.
Requires calibration. Work across wide range
of soil-water content.
Time Domain Reflectometer
(TDR) & Frequency Domain
Reflectometer (FDR)
(Dialectric Constant Method)
Senses the dielectric property of soil
which is related to water content.
Requires careful installation. TDR works across
wide range of soil texture, bulk density, and
salinity. FDR results may be skewed as salinity
increases.
Carbide Soil Moisture Tester
(Speedy Moisture Tester)
Measures gas pressure from reaction
of calcium carbide with water in soil
sample.
Provides percent water content of soil. Works in
field. Practice necessary for reliable results.
Feel and Appearance
Method
Soil samples are compared to tables
or pictures that give moisture
characteristics of different soil
textures.
Experienced individuals can estimate soil
moisture within 10 percent of true value, but
tables and pictures use ranges of 25 percent.
Gravimetric Method (Oven
Dry)
Soil samples from field are weighed,
dried, and weighed again in the lab..
Accurate measure of water content. Requires
sensitive scales, drying method, and known or
estimated bulk density value to calculate %
volume of water.
Net irrigation depth is the depth of water applied multiplied by the irrigation
efficiency, which ranges from 75-100% for drip systems to 20-60% for furrow
irrigation on sandy soils (Duke, 1991). Effective precipitation is the amount of
precipitation minus losses due to runoff or unnecessary deep percolation. At some
pre-determined moisture deficit (e.g., the MAD value), irrigation must be started
(Figure 4f-15). The water balance must be updated at least weekly, including field
checks on estimated parameters, to be useful for scheduling irrigations (Duke,
1991).
Chapter 4F-173: 10/98
-------
174 Chapter 4: Management Measures
Figure 4f-15. Graphical format for irrigation scheduling (Duke, 1991).
rasa ctruoet
§
u
z
i
n-urr
DAT!
Equation 4f-1. Soil-water depletion volume (Duke, 1991).
D = D0 + ET-IR-R-WT
where D = soil-water depletion at end of day (D=0 at field capacity)
D0 = soil-water depletion for previous day
ET = ET for the day
IR = net irrigation depth (depth of applied water which is stored
in soil root zone) for the day
R = effective precipitation during the day
WT = upward movement of water during the day from water table
close to bottom of root zone
If the water table is not near the root zone, the last term (WT) may be
dropped.
Potential sources of data for Equation 4f-l include field measurements to
determine the initial soil-water content, field measurements to determine effective
rooting depth as the plant matures, ET measurements or estimates based upon
data from weather stations, irrigation depth measurements, measured precipita-
tion, and estimates of water table contributions. Clearly, good estimates or mea-
surements of ET are essential to successful accounting approaches since crop
water use can vary considerably with crop type, stage of growth, temperature,
sunshine, wind speed, relative humidity, and soil moisture content (Figure 4f-16).
Direct measurement of ET with lysimeters may not be practical for most farms,
but evaporation pans and atmometers can be used effectively. There is also, how-
ever, a wide range of computational techniques for estimating ET from weather
data (Doorenbos and Pruitt, 1975; Jensen et al., 1990; USDA, 1993). Crop ET
data are often available in'newspapers, through telephone dial-up service, or on
television, and some farms have on-site weather stations that provide the necessary
Chapter 4F-174: 10/98
-------
Chapter 4F: Irrigation Water Management 175
ET data (USDA, 1997). There is also a growing number of computer programs
that aid the irrigation decisionmaker, including the NRCS Scheduler (Figure 4f-
17) and others (Smith, 1992; Allen, 1991; and Hill, 1991).
Figure 4f-16. Crop water use for corn, wheat, soybean, and potato based on average
climatic conditions for North Dakota (Lundstrom and Stegman, 1991).
u
I
•o
.
o.
o
4 6.8 10 12
Weeks After Emergence
14
16
Figure 4M7. NRCS (SCS) Scheduler - seasonal crop ET (USDA, 1997).
Personal Computer Irrigation Scheduler
Farm home: XFARM
Crop type: CORN
Emergence Date: May 21,1998
Growing Season: 119 days
.•• • Reference ET0.
/\A Calculated Crop ETC
£
o
. -30
.25
.20
.10
.05
0
Cumulative ET0 : 12^8 inches
Cum. Calc. ETC : 12.14 inches
06/15
07HO 08/04
Data
08/29
09/23
Chapter 4F-175: 10/98
-------
176 Chapter 4: Management Measures
Measuring crop stress is another way to determine when irrigation is needed.
Unavailability of water during crop stress periods could result in crop failure or
reduced yields that leave unused nutrients vulnerable to runoff and deep percola-
tion. Devices and methods used to measure crop stress include the crop water
stress gun, leaf moisture stress as measured in a pressure chamber, and infrared
photography (USDA, 1997). However, infrared photography is typically not ah
option for "real time" water management due to slow turnaround times. The crop
water stress gun calculates plant water stress and expresses it as an index value
based on measurements of plant canopy temperature, ambient air temperature,
relative humidity, and a range of solar radiation. Using a crop water stress index,
irrigation can be scheduled depending on the severity of moisture stress. Threshold
values must be developed for each crop.
Deciding how much water to apply
Once the decision to irrigate has been made, the amount of water to apply
must be determined. As is true for the decision regarding when to irrigate, a deci-
sion rule should also be established to determine how much water to apply, with
the basic choices being full irrigation to replenish the root zone to field capacity or
partial irrigation. Partial irrigation, which is more easily achieved via sprinkler
systems, may be preferred if there is opportunity for rainfall to provide some of
the water needed to reach field capacity.
Factors in determining the amount of irrigation water to apply include the
soil-water depletion volume in the effective root zone and local weather forecasts
for rain. The application rate should not exceed the water intake rate of the soil
when using sprinkler systems, and the application depth should not exceed the
soil-water depletion volume, except as necessary for leaching of salts (Duke,
1991). Local weather forecasts for rain should be considered before irrigating to
avoid over-application. -
The relationship between irrigation system capacity, irrigated area, and time
of irrigation may be expressed as
Q = 453 Ad
fT .
where Q is system discharge capacity (gpm),/4 is irrigated .area (acres), d is gross
application depth (in),/is time allowed for completion of one irrigation (days), •
and 7 is actual operating time (hr/day) (USDA, 1983). Normally A, T, and d are
fixed in a design process. The time allowed for completion of one irrigation should
be set to insure that the area initially irrigated does not become stressed before the
next irrigation is applied. Note that a system design that just meets the peak crop
water demand may be determined as illustrated in Table 4f-4. Partial irrigations
may facilitate covering a larger area to prevent immediate crop damage, but they
increase the frequency of irrigation necessary, and could impede root growth or
harm a crop that will be stressed if the soil is not adequately saturated.
Deep percolation of irrigation water can be greatly reduced by limiting the
amount of applied water to the amount that can be stored in the plant root zone.
The deep percolation that is necessary for salt management can be accomplished
with a sprinkler system by using longer sets or very slow pivot speeds or by apply-
ing water during the non-growing season. Salt management by surface irrigation
methods is much less efficient than other irrigation methods, and water used to
Chapter 4F-176:10/98
-------
Chapter 4F: Irrigation Water Management 177
leach salts should be applied when nutrients or pesticides are least vulnerable to
leaching, such as when maximum uptake or dissipation of the chemical has oc-
curred. Sprinkler irrigation followed by furrow irrigation after germination is
recommended to address germination problems associated with soil salinity (Burt,
1995).
Table 4f-4. System capacity needed in gal/min-acre for different soil textures and
crops to supply sufficient water in 9 out of 10 years (Scherer, 1994).
Crop
Potatoes"
Dry beans
Soybeans
Corn
Sugarbeets
Small grains
Alfalfa
Root
Zone
Depth
(ft)
2.0"
2.0
2.0
3.0
3.0
3.0
4.0
Coarse
Sand
and
Gravel
8.2
7.9
7.9
7.3
7.3
7.3
6.8
Sand
7.5
7.1
7-1
6.6
6.6
6.6
5.9
Loamy
Sand
7.0
6.4
6.4
5.9
5.9
5.9
5.6
Sandy
Loam
6.4
6.1
6.1
5.5
5.5
5.5
5.1
Fine
Sandy
Loam
6.1
5.7
5.7
5.3
5.3
5.3
5.0
Loam
and
Silt
Loam
5.7
5.4
5.4
4.9
4.9
4.9
4.5
• Adjusted for 40% depletion of available water.
"An application efficiency of 80% and a 50% depletion of available soil water were used for calculations.
Accurate measurements of the amount of water applied are essential to maxi-
mizing irrigation efficiency. A wide range of water measurement devices is avail-
able (USDA, 1997). For example, the quantity of water applied can be measured
by such devices as a totalizing flow meter that is installed in the delivery pipe or
calibrated canal gates. If water is supplied by ditch or canal, weirs or flumes in the
ditch can be used to measure the rate of flow. Rain gauges should also be used in
the field to determine the quantity of water added through rainfall. Such gauges
are also a valuable tool for checking uniformity of application of sprinkler sys-
tems.
Efficient ;
Transport and Application of Irrigation Water
There are several measures of irrigation efficiency, including conveyance
efficiency (Table 4f-5), irrigation efficiency, application efficiency, project appli-
cation efficiency, potential or design application efficiency, uniformity of applica-
tion, distribution uniformity, and Christiansen's uniformity (USDA, 1997). Project
water conveyance and control facility losses can be as high as 50% or more in
long, unlined, open channels in alluvial soils (USDA, 1997). Seepage losses asso-
ciated with canals and laterals can be reduced by lining them, or can be eliminated
by conversion from open canals and laterals to pipelines. Flow-through losses or
spill, however, will not be changed by lining canals and laterals, but can be elimi-
nated or greatly reduced by conversion to pipelines or through changes in opera-
tion and management. Flow-through water constitutes over 30% of canal capacity
in some water districts, but simple automatic gate/valve control devices can limit
flow-through water to less than 5% (USDA, 1997). Conversion to pipelines may
Chapter 4F-177:10/98
-------
178 Chapter 4: Management Measures
in some cases cause impacts to wildlife due to loss of beneficial wet areas, and an
environmental assessment or environmental impact statement may be needed be-
fore the conversion is made (USD A, 1997).
Table 4f-5. Measures of irrigation efficiency.
•s
Measure of Irrigation Efficiency
Conveyance Efficiency
(to farm)
Irrigation Efficiency
(on farm)
Application Efficiency
(on farm)
Project Application Efficiency
(to and on farm)
Definition
w
'"Oel^red ^.QQ
W
''Ontntd
W
B«"fc« .100
w
'"Applied
W
""Stored 1QO
W
Applied
W
Stored t10Q
W '~~
'"divtrtfd
Where
wddivered = Water delivered
^diverted ~ Total water diverted or pumped into an open channel or pipeline at upstream end
wbenefkaai = Av9- depth of water beneficially used
^applied = Avg. depth of applied water
wstored = Avg. depth of water infiltrated and stored in the plant root zone
Water application efficiency can vary considerably by method of application.
Increased application efficiency reduces erosion, deep percolation, and return
flows. In general, trickle and sprinkler application methods are more efficient than
surface and subsurface methods. Two major hydraulic distinctions between sur-
face irrigation methods and sprinkler and micro irrigation are key to this difference
in efficiencies (Burt, 1995):
1. The soil surface conveys the water along border strips or furrows in surface
irrigation, whereas the water infiltrates into the soil very near to the point of
delivery from sprinkler and micro irrigation systems.
2. Water application rate exceeds soil water infiltration rate in surface irrigation,
and the soil controls the amount of water that will infiltrate. In properly de-
signed and managed sprinkler and micro irrigation systems, the application
rate is equal to the soil water infiltration rate.
The type of irrigation system used will dictate which practices can be em-
ployed to improve water use efficiency and to obtain the most benefit from sched-
uling. Flood systems will generally infiltrate more water at the upper end of the
Chapter 4F-178:10/98
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Chapter 4F: Irrigation Water Management 179
field than at the lower end because water is applied to the upper end of the
field first and remains on that portion of the field longer. This will cause the upper
end of the field to have greater deep percolation losses than the lower end. This
situation can sometimes be improved by changing slope throughout the length of
the field or shortening the length of run. For example, furrow length can be re-
duced by cutting the field in half and applying water in the middle of the field.
This will require more pipe or ditches to distribute the water across the middle of
the field. Other methods used to improve application efficiency in surface systems
are surge and cut-back irrigation. In surge irrigation, flow is pulsed into the fur-
row allowing for wet and dry cycles, while in cut-back irrigation, the furrow in-
flow rate is reduced after a period of time. Both of these methods improve
irrigation efficiency by allowing for a more uniform time of infiltration. A wide
range of options exist for manipulating field lengths, slopes, flow rate, irrigation
time, and other management variables to increase surface irrigation efficiency
(Burt, 1995; USDA, 1997).
A properly designed and operated sprinkler irrigation system should have a
7uniform distribution pattern. The volume of water applied can be changed by
altering the total time the sprinkler runs; by altering the pressure at which the
sprinkler operates; or, in the case of a center pivot, by adjusting the speed of travel
of the system. There should be no irrigation runoff or tail water from most well-
designed and well-operated sprinkler systems (USDA, 1997).
Use of Runoff
or Tailwater
Surface irrigation systems are usually designed to have a percentage (up to
30%) of the applied water lost as tailwater. The volume and peak runoff rate of
tailwater will depend upon both the irrigation method and its management.
Tailwater recovery and reuse facilities collect irrigation runoff and return it to the
same, adjacent, or lower fields for irrigation use (USDA, 1997). If the water is
pumped to a field at higher elevation, the facility is a return-flow or pumpback
facility. Sequence-use facilities deliver the water to adjacent or lower-elevation
fields. Those facilities that store runoff and precipitation for later use are reservoir
systems, while cycling-sump facilities have limited storage and pump the water
automatically to irrigate fields.
The components of a tailwater reuse or pumpback facility include tailwater
collection ditches to collect the runoff; drainageways, waterways, or pipelines to
convey the water to a central collection area; a sump (cycling-sump facilities) or
reservoir (reservoir systems); a pump and power unit for pumpback facilities; and
pipelines or ditches to deliver the recovered water (USDA, 1997). A typical
pumpback facility plan is illustrated in Figure 4f-18. For new facilities, runoff
flows must be measured or estimated to properly size tailwater reuse sumps, reser-
voirs, and pumping facilities. Capacity should be provided to handle concurrent
peak runoff events from both precipitation and tailwater, unexpected interruption
of power, and other uncertainties.
Chapter 4F-179:10/98
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180 Chapter 4: Management Measures
Figure 4f-18. Typical tailwater collection and reuse facility for quick-cycling
pump and reservoir (USDA, 1997).
Water —i
supply
t
Head
ditch
Inlet
=re
Regulating
reservoir
— '
r—
Collector ditch
M
¥
M 1— 1 M
I
H
Sump&
pump
Return
pipeline
Tailwater management is needed to reduce the discharge of pollutants such as
suspended sediment and farm chemicals which can be found in the runoff. In res-
ervoir systems, tailwater is typically stored until it can be either pumped back to
the head of the field and reused or delivered to additional irrigated land. In some
locations, there may be downstream water rights that are dependent upon
tailwater, or tailwater may be used to maintain flow in streams. These require-
ments may take legal precedence over the reuse of tailwater.
If a tailwater recovery system is used, it should be designed to allow storm
runoff to flow through the system without damage. Where reservoir systems are
used, storm runoff containing a large sediment volume should bypass or be
j trapped before entering the storage reservoir to prevent rapid loss of storage ca-
pacity (USDA, 1997). Additional surface drainage structures su'ch as filter strips,
field drainage ditches, subsurface drains, and water table control may also be used
to control runoff and leachate if site conditions warrant their use.
Management
of Drainage Water
Drainage of agricultural lands is intended to control and manage soil mois-
ture in the crop root zone, provide for improved soil conditions, and improve plant
root development (USDA, 1997). Incases where the water table impinges upon
the root zone, water table control is an essential element of irrigation water man-
agement. However, installation of subsurface drainage should only be considered
when good irrigation water management, good nutrient management, and good
pesticide management are being conducted. Further, impacts to wetlands, wildlife
habitat, and water quality must be thoroughly investigated, and relevant federal,
state, and local laws fully considered prior to installation of drainage practices.
Chapter 4F-180:10/98
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Chapter 4F: Irrigation Water Management 181
Daily accounting for
the cropland field
water budget helps
determine irrigation
scheduling.
Drainage increases water infiltration, which reduces soil erosion and also
allows application of excess water to keep salts leached below the root zone.
Drainage also provides more available soil moisture and plant food by increasing
the depth of the root zone. Subsurface drainage may concentrate soluble nutrients
in irrigation return flows. Properly installed subsurface drainage systems can be
used successfully as a supplemental source of irrigation water if the water isx>f
good quality (USDA, 1997).
Irrigation Water Management Practices
and Their Effectiveness
The practices that can be used to implement this management measure on a
given site are commonly used and are recommended by NRCS for general use on
irrigated lands. Many of the practices that can be used to implement this measure
(e.g., water-measuring devices, tailwater recovery systems, and backflow
preventers) may already be required by State or local rules or may otherwise be in
use on irrigated fields.
The NRCS practice number and definition are provided for each management
practice, where available. Additional information about the purpose and function
of individual practices is presented in Appendix A.
Irrigation
Scheduling Practices
Proper irrigation scheduling is a key element in irrigation water management.
Irrigation scheduling should be based on knowing the daily water use of the crop,
the water-holding capacity of the soil, and the lower limit of soil moisture for each
crop and soil, and measuring the amount of water applied to the field. Also, natu-
ral precipitation should be considered and adjustments made in the scheduled irri-
gations.
Whether the irrigation source is surface or ground water, water availability
during the growing season should be adequate to support the most water sensitive
crop in the rotation. The design capacity of the irrigation system depends on re-
gional climate, irrigation efficiency, crop, and soil (USDA, 1993; USDA, 1972).
See Table 4f-4 for typical required system capacities for various crops and soils.
A practice that may be used to accomplish proper irrigation scheduling is:
D Irrigation Water Management (449): Determining and controlling the rate,
amount, and timing of irrigation water in a planned and efficient manner.
Tools to assist in achieving proper irrigation scheduling include:
D Water-Measuring Device: An irrigation water meter, flume, weir, or other
water-measuring device installed in a pipeline or ditch.
D Soil and Crop Water Use Data: From soils information the available water-
holding capacity of the soil can be determined along with the amount of water
that the plant can extract from the soil before additional irrigation is needed
(MAD). Water use information for various crops can be obtained from vari-
ous United States Department of Agriculture (USDA) publications. Crop
water use for some selected irrigated crops is shown in Figure 4f-l 6.
Chapter 4F-181:10/98
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182 Chapter 4: Management Measures
The purpose of collecting these data is to allow the manager to estimate the
amount of available water remaining in the root zone at any time, thereby
indicating when the next irrigation should be scheduled and the amount of
water needed. Methods to measure or estimate the soil moisture should be
employed, especially for high-value crops or where the water-holding capacity
of the soil is low. •
Practices for
Efficient Irrigation Water Application
Irrigation water should be applied in a manner that ensures efficient use and
distribution, minimizes runoff or deep percolation, and minimizes soil erosion.
The method of irrigation employed will vary with the type of crop grown, the
topography, and soils. There are several systems that, when properly designed and
operated, can be used as follows:
D Irrigation System, Drip or Trickle (441): A planned irrigation system in
which all necessary facilities are installed for efficiently applying water di-
rectly to the root zone of plants by means of applicators (orifices, emitters,
porous tubing, or perforated pipe) operated under low pressure (Figure 4f-19).
Figure 4f-19. Basic components of a trickle irrigation system (USDA-SCS, 1984).
Form
Water
Supply
Primary Filter
'low Control
.Chemical Tank
•Secondary Filter
Flow Meter.
1
^Control Heod
E miner
Lateral
-Flow Control on/W
Row/Pressure Regulator
Manifold
Irrigation System, Sprinkler (442): A planned irrigation system in which all
necessary facilities are installed for efficiently applying water by means of
perforated pipes or nozzles operated underpressure.
Irrigation System, Surface and Subsurface (443): A planned irrigation sys-
tem in which all necessary water control structures have been installed for
efficient distribution of irrigation water by surface means, such as furrows,
borders, contour levees, or contour ditches, or by subsurface means.
Chapter 4F-182:10/98
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Chapter 4F: Irrigation Water Management 183
D Irrigation Field Ditch (388): A permanent irrigation ditch constructed to
convey water from the source of supply to a field or fields in a farm distribu-
tion system.
D Irrigation Land Leveling (464): Reshaping the surface of land to be irrigated
to planned grades.
Practices for
Efficient Irrigation Water Transport
Irrigation water transportation systems that move water from the source of
supply to the irrigation system should be designed and managed .in a manner that
minimizes evaporation, seepage, and flow-through water losses from canals and
ditches. Delivery and timing need to be flexible enough to meet varying plant wa-
ter needs throughout the growing season.
Transporting irrigation water from the source of supply to the field irrigation
rigation system can be a significant source of water loss and cause of degradation of both
" ... surface water and ground water. Losses during transmission include seepage and
' evaporation from canals and ditches. The primary water quality concern is the
development of saline seeps below the canals and ditches and the discharge of
. . . saline waters. Another water quality concern is the potential for erosion caused by
" ™ '9 ' the discharge of canal flows. Practices that are used to ensure proper transporta-
® tionof irrigation water from the source of supply to the field irrigation system can
to cropland field.— fae found in the USDA-NRCS Handbook of Practices (NRCS, 1977) and include:
D irrigation water conveyance, ditch and canal lining (428);
G irrigation water conveyance, pipeline (430); and
D structure for water control (587).
Practices for
Irrigation Erosion Control
The design of farm irrigation systems must provide for conveying and distrib-
uting irrigation water without causing damaging soil erosion. All unlined ditches
should be located on nonerosi ve gradients. If water must be conveyed down slopes
that are steep enough to cause excessive flow velocities, the irrigation system de-
sign should provide for the installation of such erosion-control structures as drops,
chutes, buried pipelines, or erosion-resistant ditch linings. Conservation treatments
such as land leveling, irrigation water management, reduced tillage, and crop rota-
tions should be used to control irrigation-induced erosion.
On surface irrigated lands susceptible to irrigation-induced erosion, the addi-
tion of polyaerylamide (PAM) to surface irrigation water may be appropriate to
minimize or control soil erosion. However, the environmental impacts of land-
scape-scale application of PAM are not adequately understood; therefore, it is not
recommended for use other than small-scale, targeted erosion control efforts.
On sprinkler irrigated land, the design rate of application should be within a
range established by the minimum practical application rate under local climatic
conditions and the maximum rate consistent with the intake rate of the soil and the
conservation practices used on the land. Sprinkler systems should be designed for
zero runoff so no water leaves the point of application. The effects on erosion and
Chapter 4F-183:10/98
-------
184 Chapter 4: Management Measures
the movement of sediment, and soluble and sediment-attached substances carried
by runoff should be considered whether surface or sprinkler irrigation systems are
employed.
Practices for
Use of Runoff Water or Tailwater
The use of runoff water to provide additional irrigation or to reduce the
amount of water diverted increases the efficiency of use of irrigation water. For
surface irrigation systems that require runoff or tailwater as part of the design and
operation, a tailwater management practice is needed. The practice is described as
follows:
O Irrigation System, Tailwater Recovery (447): A facility to collect, store,
and transport irrigation tailwater for reuse in the farm irrigation distribution
system.
Practices for ,
Drainage Water Management
Drainage water from an irrigation system should be managed to reduce deep
percolation, move tailwater to the reuse system, reduce erosion, and help control
adverse impacts on surface water and ground water. A total drainage system
should be an integral part of the planning and design of an efficient irrigation sys-
tem. This may not be necessary for those soils that have sufficient natural drain-
age abilities.
There are several practices to accomplish this:
O Filter Strip (393): A strip or area of vegetation for removing sediment, or-
ganic matter, and other pollutants from runoff and waste water.
O Surface Drainage Field Ditch (607): A graded ditch for collecting excess
water in a field.
O Subsurface Drain (606): A conduit, such as corrugated plastic tile, or pipe,
installed beneath the ground surface to collect and/or convey drainage water.
O Water Table Control (641): Water table control through proper use of sub-
surface drains, water control structures, and water conveyance facilities for
the efficient removal of drainage water and distribution of irrigation water.
D Controlled Drainage (335): Control of surface and subsurface water through
use of drainage facilities and water control structures.
Practices for
Backflow Prevention
The American Society of Agricultural Engineers recommends, in standard
EP409, safety devices to prevent backflow when injecting liquid chemicals into
pressurized irrigation systems (ASAE, 1989).
The process of supplying fertilizers, herbicides, insecticides, fungicides,
nematicides, and other chemicals through irrigation systems is known as
chemigation. A backflow prevention system will "prevent chemical backflow to
the water source" in cases when the irrigation pump shuts down (ASAE, 1989).
Chapter 4F-184:10/98
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Chapter 4F: Irrigation Water Management 185
Three factors an operator must take into account when selecting a backflow
prevention system are the characteristics of the chemical that can backflow, the
water source, and the geometry of the irrigation system. Areas of concern include
whether injected material is toxic and whether there can be backpressure or
backsiphonage (ASAE, 1989; EPA, 1989b). Several different systems used as
backflow preventers are: .
O Air gap. A physical separation in the pipeline resulting in a loss of water
pressure. Effective at end of line service where reservoirs or storage tanks are
desired.
n Check valve with vacuum relief and low pressure drain. Primarily used as
an antisiphon device (Figure 4f-20).
Figure 4f-20. Backflow prevention device using check valve with vacuum
relief and low pressure drain (USDA, 1997).
From chemical tank
To Solenoid valve
irrigation
system
Injection port
with check valve
Pressure \
gauge^
rfc
•Flow
Injection
pump
JEL
Vacuum breaker
and inspection
port
From water
supply
Coupler
Gate
valve
Low
pressure
drain
O
Double check valve. Consists of two single check valves coupled within one
body and can handle both backsiphonage and backpressure.
Reduced pressure principle backflow preventer. This device can be used for
both backsiphonage and backpressure. It consists of a pressure differential
relief valve located between two independently acting check valves.
Atmospheric vacuum breaker. Used mainly in lawn and turf irrigation sys-
tems that are connected to potable water supplies. This system cannot be in-
stalled where backpressure persists and can be used only to prevent
backsiphonage.
Pump interlocking. Application of chemicals in sprinkler systems require an
injection pump. By interlocking the injection pump with the water pump, the
injection pump is only powered when the water pump is operating.
Chapter 4F-185:10/98
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186 Chapter 4: Management Measures
Practice
Effectiveness
Irrigation manage-
ment practice
systems can reduce
suspended sediment
loading to streams.
The following is information on pollution reductions that can be expected
from installation of the management practices outlined within this management
measure.
In a review of a wide range of agricultural control practices, EPA (1982)
determined that increased use of call periods, on-demand water ordering, irrigation
scheduling, and flow measurement and control would all result in decreased losses
of salts, sediment, and nutrients. Various alterations to existing furrow irrigation
systems were also determined to be beneficial to water quality, as were tailwater
management and seepage control.
Logan (1990) reported that chemical backsiphon devices are highly effective
at preventing the introduction of pesticides and nitrogen to ground water. The
American Society of Agricultural Engineers (ASAE) specifies safety devices for
chemigation that will prevent the pollution of a water supply used solely for irriga-
tion (ASAE, 1989).
Properly designed sprinkler irrigation systems will have little runoff (Boyle
Engineering Corp., 1986). Furrow irrigation and border check or border strip
irrigation systems typically produce tailwater, and tailwater recovery systems may
be needed to manage tailwater losses (Boyle Engineering Corp., 1986). Tailwater
can be managed by applying the water to additional fields, by treating and releas-
ing the tailwater, or by reapplying the tailwater to upslope cropland.
Steele et al. (1996) found that improved methods of irrigation scheduling can
produce significant savings in seasonal irrigation water totals without yield reduc-
tions. In a six-year continuous corn field study, a 31% savings in seasonal irriga-
tion totals was realized compared to the average commercial grower in the same
irrigation district. Corn grain yields were maintained at 3% above average corn
grain yields in the irrigation district.
The Rock Creek Rural Clean Water Program (RCWP) project in Idaho is the
source of much information regarding the benefits of irrigation water management
(USDA, 1991). Crops in the Rock Creek watershed are irrigated with water di-
verted from the Snake River and delivered through a network of canals and later-
als. The combined implementation of irrigation management practices, sediment
control practices, and conservation tillage resulted in measured reductions in sus-
pended sediment loadings ranging from 61% to 95% at six stations in Rock Creek
(1981-1988). Similarly, 8 of 10 sub-basins showed reductions in suspended sedi-
ment loadings over the same time period. The sediment removal efficiencies of
selected practices used in the project are given in Table 4f-6.
Normally, drip irrigation will have the greatest irrigation efficiency and con-
tour ditch irrigation will have the lowest irrigation efficiency. See Table 4f-7 for
application efficiencies of various systems and Table 4f-8 for a range of deep
percolation and runoff losses from surface and sprinkler methods. Tailwater re-
covery irrigation systems are expected to have the greatest percolation rate. USDA
projects significant increases in overall irrigation efficiencies when tailwater re-
covery facilities are used (Table 4f-9).
Chapter 4F-186:10/98
-------
Chapter 4F: Irrigation Water Management 187
Table 4f-6. Sediment removal efficiencies and comments on BMPs evaluated (USDA, 1991).
Practice •
Sediment basins: field, farm, subbasin
Mini-basins
Buried pipe systems (incorporating
mini-basins with individual outlets
into a buried drain)
Vegetative filters
Placing straw in furrows
Sediment Removal
Efficiency (%)
Average Range
87 " 75-95
86" 0-95
83 75-95
50° ' 35-70
50 40-80
Comment
Cleaning costly.
Controlled outlets essential. Many
failed. Careful management required.
High installation cost. Potential for
increased production to offset costs.
Eliminates tailwater ditch. Good
control of tailwater.
Simple. Proper installation and
management needed.
Labor-intensive without special
equipment. Careful management
required.
• Mean of those that did not fail.
Table 4f-7. Ranges of irrigation application efficiencies from various sources.
Irrigation System
Application Efficiency, %
USDA, 1987' USDA, 1997 Hill, 19942
Center Pivot
Linear Move
LEPA
Solid Set Sprinklers
Periodic Move Lateral
Drip
Level Basin
Border
Furrow
Furrow - sandy soil
Furrow - clay soil
Contour Ditch
70-90
75-100
70-90
20-60
50-90
75-85
80-87
90-95
60-75
60-75
35-60
80
80
' 70-80
70-80
80-90
80
60-75
60-70
40-50
65
45-55
1 Typical single event efficiencies
2 Possible values for various systems with good design and above average management practices
Table 4f-8. Ranges of Application Efficiency Ea and runoff, deep percolation,
and evaporation losses (Hill, 1994)1
Method
Surface Irrigation
E.
Runoff Losses
Deep Percolation Losses
Sprinkler Irrigation
E.
Evaporation Losses
Deep Percolation Losses
Hi
72
55
65
84
45
37
Low
24
5
20
52
8
8
'
Typical
50
20
30
70
12
18
'determined from field evaluations in Utah
Chapter 4F-187:10/98
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188 Chapter 4: Management Measures
Table 4f-9. Overall efficiencies obtainable by using tail water recovery and
facility (USDA, 1997).
Original %of
applic water
effic reused
%
60
50
40
30
20
40
60
80
40
60
80
40
60
80
40
60
80
40
60
80
%of
orig
water
used
16
24
32
20
30
40
24
36
48
28
42
56
32
48
64
First reuse
Effect Accum
use - effect
%of
orig %
9.6
14.4
19.2
10.0
15.0
20.0
9.6
14.4
19.2
8.4
12.6
16.8
6.4
9.6
12.8
69.6
74.4
79.2
60.0
65.0
70.0
49.6
54.4
59.2
38.4
42.6
46.8
26.4
29.6
32.8
— Second reuse
% of Effect Accum
orig use - effect
water %of
used orig %
2.6
5.8
10.2
4.0
9.0
16.0
5.8
13.0
23.0
7.8
17.8
31.4
10.2
23.0
41.0
1.5
3.5
6.1
2.0
4.5
8.0
2.3
5.2
9.2
2.4
5.3
9.4
2.1
4.6
8.2
•71.1
77.9
85.3
62.0
69.5
78.0
52.9
59.6
68.4
40.8
49.9
56.2
28.5
34.2
41.0
— Third reuse —
% of Effect Accum
orig use • effect
water %of
used orig %
1.1
1.4
3.3
0.8
2.7
6.4
1.4
4.7
11.0
2.2
7.5
17.6
3.2
11.0
26.2
0.7
0.8
2.0
0.4
1.4
3.2
0.6
1.9
4.4
0.7
2.3
5.3
0.7
2.2
5.3
71.8
78.7
87.3
62.4
70.9
81.2
53.5
61.5
72.8
41.5
52.2
61.5 :
29.2
36.4
46.3
reuse
Fourth reuse
% of Effect Accum
orig use - effect
water %of
used orig %
0.2
0.4
1.0
0.2
0.8
2.6
0.3
1.7
5.3
0.6
3-1
9.8
1.0
5.3
17.5
0.1
0.2
0.6
0.1
0.4
1.3
0.1
0.7
2.1
0.2
0.9
3.0
0.2
1.1
3.5
71.9
78.9
87.9
62.5
71.3
82.5
53.6
62.2
74.9
41.7
53.1
64.5
29.4
37.5
49.8
Plot studies in California have shown that in-season irrigation efficiencies for
drip irrigation and Low Energy Precision Application (LEPA) are greater than
those for improved furrow and conventional furrow systems (Table 4f-10). LEPA
is a linear move sprinkler system in which the sprinkler heads have been removed
and replaced with tubes that supply water to individual furrows (Univ. Calif.,
1988). Dikes are placed in the furrows to prevent water flow and reduce soil ef-
fects on infiltrated water uniformity.
Table 4f-10. Irrigation efficiencies of selected irrigation systems for cotton (California SWRCB, 1992).
System
Subsurface Drip Irrigation
LEPA (Low Energy
Precision Application)
Improved Furrow
Conventional Furrow
Year
19891
19901
1989
1990
1988
1990
1989
1990
Seasonal
Irrigation (in.)
23.54
24.04
19.89
26.55
29.77
20.19
30.75
28.76
Distribution Irrigation
Uniformity (%) ' Efficiency (%)
79
76
80
92
60
82
61
72
86
81
82
74
35
66
35
62
Deep
Percolation (in.)
2.43
3.98
2.88
6.13
18.9
6.06
19.39
9.85
1 includes one preirrigation with hand move sprinklers
Mielke et al. (1981) studied the effects of tillage practice and type of center
pivot irrigation on herbicide (atrazine and alachlor) losses in runoff and sediment.
Study results clearly show that, for each of three tillage practices studied, low-
pressure spray nozzles result in much greater herbicide loss in runoff than either
high-pressure or low-pressure impact heads.
Chapter 4F-188:10/98
-------
Chapter 4F: Irrigation Water Management 189
Polyacrylamide Application for Erosion and
Infiltration Management
Polyacrylamide (PAM) is a water soluble polymer produced for agricultural use to control erosion and
promote infiltration on irrigated lands. When applied to soils, it binds to soil particles and forms a gel that decreases
soil bulk density, absorbs water, and binds fine-grained soil particles within the top 1/16 in. (1-2 mm) of soil. It is
not only used for erosion control, but it is also employed in municipal water treatment, paper manufacturing, food
and animal feed processing, cosmetics, friction reduction, mineral and coal processing, and textile production.
PAM has proven to be very effective at controlling erosion. Studies have shown up to a 94% reduction of
sediment in irrigation runoff, although there is a great deal of variability in results due to differing application
techniques and management practices. Additional water quality benefits may result from PAM use, and in some
cases PAM results in higher crop yields. However, the effects of widespread application of PAM on water quality and
wildlife have yet to be determined. Although limited use of PAM may be the best solution for erosion in some cases,
other erosion control practices with known environmental consequences may be better choices in general to prevent
potential environmental harm.
Availability and Application
PAM is available in powder, aqueous concentrate, blocks and cubes, or emulsified concentrate. There are
also two crystal forms available. Standard crystals (500-3000 microns) form large, individual lumps of gel with
resulting high pore space. Fine crystals (0-500 microns) create an amorphous, sticky mass. Each form has benefits
and drawbacks that would alter efficacy in different settings and with different application methods. Additional
factors that affect PAM's effectiveness include irrigation inflow rate, duration of furrow exposure and soil salinity.
PAM costs range from S4-S35 per pound, depending on the application form purchased, and is typically effective at
applications of 1 Ib. per crop-acre.
Application rates of PAM recommended by the Natural Resources Conservation Service's Agricultural
Research Service (NRCS-ARS) are 10 ppm in the irrigation inflow during the furrow-advance period (only). It is
also effective at 5 ppm concentration during furrow advance followed by episodic applications at 5 ppm concentra-
tion for 5-15 minutes. Other application techniques include:
O adding dry granules to the irrigation water in a gated irrigation pipe
n adding a stock solution to furrow heads
D compressed air injection (especially for grape vines)
n for tree crops, adding one cup to one pint of crystals to the backfill and bare root dipping with a
slurry using a fine, pulverized version of the crystals.
The NRCS encourages adjustment of furrow irrigation practices to take advantage of the erosion-abating and
infiltration-enhancing properties of the PAM practice. This entails increasing the irrigation inflow rate, resulting in
shortened advance times and preventing leaching from over-irrigation of the near end of the field.
Table 1. PAM's beneficial effects on the environment and crop production.
What PAM Does Environmental Benefit
Decrease sediment loading
Decrease turbidity
Improve clarity
Decrease P, N, pesticides, salts, pathogens
Decrease BOD, eutrophication
Lower soil bulk density
Increase infiltration
Decrease runoff
Improve soil tilth
Decrease compaction
Binds fine soil particles
Decrease wind erosion
Decrease evaporation from soil surface
increase soil water storage
Decrease need for irrigation
Decrease plant stress
Improve plant vigor
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190 Chapter 4: Management Measures
Environmental Pros and Cons
PAM can provide several benefits to the environment (Table 1). PAM practices undoubtedly improve surface
water quality by decreasing suspended sediments and the phosphorus, nitrogen, pesticides, pathogens, salts, BOD, and
eutrophication that are usually associated with sediment loading. PAM also improves crop vigor by enriching soils and
ensuring against drought stress.
However, PAM may detrimentally affect groundwater quality by increased leaching of fertilizer, pesticides, animal
waste and pathogens as a result of improved infiltration (Table 2). Additionally, crops may suffer nutrient stress if
nutrient supplies are not adjusted for increased leaching. >
Table 2. PAM's potential detrimental effects on the environment and crop production.
What PAM Does Potential Detrimental Effect Preventative Measures
Improve infiltration Leaching of nutrients, pesticides, animal Increase irrigation flow rate to prevent
waste and pathogens to groundwater over-irrigation of near end of field
Nutrient shortage for plant uptake Monitor levels of fertilizer in soil
Bind fine soil Soil crusting, impaired seedling emergence, Careful application and monitoring
particles decreased infiltration, increased erosion
Unknown effects on Toxicity, habitat alteration? ?
wildlife
Although management practices can partially mitigate these effects, the impact of PAM practices on water
quality and wildlife are still unknown. Questions have arisen as to PAM's environmental toxicity. Anionic PAM, the
form found most often in erosion control products, has not been proven to be toxic to aquatic, soil or crop species. The
molecule is too large to cross membranes, so it is not absorbed by the gastrointestinal tract, is not metabolized, and does
not bioaccumulate in living tissue. Cationic PAM, although not of major concern for agricultural applications, has
been shown to be toxic to fish due to its affinity to anionic hemoglobin in the gills. PAM's effect on biota is buffered if
the water contains sediments, humic acids, or other impurities.
Most of the concern for PAM toxicity has arisen because of acrylamide (AMD), the monomer associated with
PAM and a contaminant of the PAM manufacturing process. AMD has been shown to be both a neurotoxin and a
carcinogen in laboratory experiments. Current regulations require that AMD not exceed 0.05% in PAM products. At
the application rates prescribed by the NRCS, the concentration of AMD in outflow waters is several orders of magni-
tude less than what is considered toxic. Although there seems to be little risk from AMD as a result of prescribed
application of PAM, it is uncertain what effects may result from spills, over-application, or other unforeseen accidents.
Conclusion
Limited applications of PAM may be a solution for erosion in some cases, but there are .other techniques for
which the environmental impacts are known and not of concern (e.g., conservation tillage, sediment basins, drip and
sprinkler irrigation), and may therefore offer a better solution. Responsible application and monitoring practices will
help to ensure that adverse environmental effects from PAM are minimized.
Chapter 4F-190:10/98
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Chapter 4F: Irrigation Water Management 191
Factors in Selection of Management Practices
Irrigation :
Scheduling
Selecting a water scheduling method will depend on the availability of cli-
matic data. Crop water use depends on the type of crop, stage of growth, tempera-
ture, sunshine, wind speed, relative humidity and soil moisture content. Water use
can be estimated based on maximum daily temperatures and the growth stage of
the crop. If climatic data cannot be measured on site or is not available nearby, it
may be more appropriate to schedule irrigation from representative field soil water
measurements.
Determining water holding capacity for the field is critical in water schedul-
ing. Where large differences in soil texture are found in an irrigated field, particu-
lar attention should be paid to the coarsest textures/Coarse textures will hold less
available water than finer textured soils and will reach depletion sooner. Knowl-
edge of soil texture and soil moisture status will help determine the appropriate
application rate and depth, so runoff and deep percolation are minimized. Variable
rate application of water should be considered if water holding capacities range
significantly.
Efficient —
Irrigation Water Application
The selection of an appropriate irrigation system should be based on having
sufficient capacity to adequately meet peak crop water demands for the least effi-
cient crop in the rotation. The system capacity is dependent on the peak period
evapotranspiration rate, crop rooting depth, available water holding capacity of
the soil, and irrigation efficiency. Other potentially limiting factors are water deliv-
ery capacity and permitted water allocation (Table 4f-11).
Table 4f-11. System capacity needed in gal/min-acre for different soil textures and
crops to supply sufficient water in 9 out of 10 years (Scherer, 1994).
Crop
Potatoes8
Dry beans
Soybeans
Corn
Sugarbeets
Small grains
Alfalfa
Root
Zone
Depth
(ft)
2.0"
2.0
2.0
3.0
3.0
3.0
4.0
Coarse
Sand
and
Gravel
8.2
7.9
7.9
7.3
7.3
7.3 .
6.8
Sand
7.5
7.1
7.1
6.6
6.6
6.6
5.9
Loamy
Sand
7.0
6.4
6.4
5.9
5.9
5.9
5.6
Sandy
Loam
6.4
6.1
6.1
5.5
5.5
5.5
5.1
Fine
Sandy
Loam
6.1
5.7
5.7
5.3
5.3
5.3
5.0
Loam
and
Silt
Loam
5.7
5.4
5.4
4.9
4.9
4.9
4.5
•Adjusted for 40% depletion of available water.
"An application efficiency of 80% and a 50% depletion of available soil water were used for calculations.
Chapter 4F-191:10/98
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192 Chapter 4: Management Measures
Other factors that should be considered when selecting an irrigation system
are the shape and size (acres) of the field and the topography. Field slope and
steepness will determine whether surface or sprinkler irrigation can be used. If
surface application of water is chosen, land leveling may be required to more effi-
ciently spread water over the field.
A sprinkler system can and should be designed to apply water uniformly
without runoff or erosion. The application rate of the sprinkler system should be
matched to the intake rate of the most restrictive soil in the field. If the application
rate exceeds the soil intake rate, the water will run off the field or relocate within
the field resulting in areas of over application that could percolate soluble chemi-
cals to ground water. Care should be taken in a pivot system to match endguns
with soil water intake rates. -
If secondary salinization from irrigation is a problem, an application method
must be chosen to keep salts leached below the root zone.
The selected water application method will also depend on whether
chemigation is to be used. Coverage, timing, and type of chemical application will
determine which application method will be most efficient. Chemigation with sur-
face irrigation should be avoided when alternative methods are available for the
application of fertilizers and pesticides. Additional costs for pollution prevention
may be incurred when chemigating.
Tailwater recovery may be required if surface chemigation is practiced, and
backflow prevention is needed if sprinkler chemigation is used.
Cost of Practices
Costs to install, operate and maintain an irrigation system will depend on the
type of irrigation system used. In order to efficiently irrigate and prevent pollution
of surface and ground waters, the irrigation system must be properly maintained
and water measuring devices used to estimate water use.
A cost of $10 per irrigated acre is estimated to cover investments in flow
meters, tensiometers, and soil moisture probes (EPA, 1992; Evans, 1992). The
cost of devices to measure soil water ranges from $3 to $4,900 (Table 4f-12).
Gypsum blocks and tensiometers are the two most commonly used devices.
Table 4M2. Cost of soil water measuring devices.
Device
Approximate Cost
Tensiometers8
Gypsum blocks'1
Neutron Probec
Phene Cell2
Tensiometers and soif moisture probes"
$50 and up, depending on size
$3-4, $200-400 for meter
$4.900
$4,000-4,500
$10 per irrigated acre
•Hydratec,1998.
"Sneed, 1992.
'Cambell Pacific Nuclear, 1998.
"Evans, 1992.
Chapter 4F-192:10/98
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Chapter 4F: Irrigation Water Management 193
For quarter-section center pivot systems, backflow prevention devices cost
about $416 per well (Stolzenburg, 1992). This cost (1992 dollars) is for: (1) an
8-inch, 2-foot-long unit with a check valve inside ($386); and (2) a one-way injec-
tion point valve ($30). Assuming that each wel 1 will provide about 800-1,000
gallons per minute, approximately 130 acres will be served by each well. The cost
for backflow prevention for center pivot systems then becomes approximately
$3.20 per acre. In South Dakota, the cost for an 8-inch standard check valve is
about $300, while an 8-inch check valve with inspection points and vacuum re-
lease costs about $800 (Goodman, 1992). The latter are required by State law. For
quarter-section center pivot systems, the cost for standard check valves ranges
from about $1.88 per acre (comers irrigated, covering 160 acres) to $2.31 per
acre (circular pattern, covering about 130 acres). To maintain existing equipment
so that water delivery is efficient, annual maintenance costs can be figured at
1.5% of the new equipment cost (Scherer, 1994).
Tailwater can be prevented in sprinkler irrigation systems through effective
irrigation scheduling, but may need to be managed in furrow systems. The reuse of
tailwater downslope on adjacent fields is a low-cost alternative to tailwater recov-
ery and upslope reuse (Boyle Engineering Corp., 1986). Tailwater recovery sys-
tems require a suitable drainage water receiving facility such as a sump or a
holding pond, and a pump and pipelines to return the tailwater for reapplication
(Boyle Engineering Corp., 1986). The cost to install a tailwater recovery system
was about $125/acre in California (California SWRCB, 1987) and $97.00/acre in
the Long Pine Creek, Nebraska, RCWP (Hermsmeyer, 1991). Additional costs
may be incurred to maintain the tailwater recovery system.
The cost associated with surface and subsurface drains is largely dependent
upon the design of the drainage system. In finer textured soils, subsurface drains
may need to be placed at close intervals to adequately lower the water table. To
convey water to a distant outlet, land area must be taken out of production for
surface drains to remove seeping ground water and for collection of subsurface
drainage.
The Agricultural Conservation Program (ACP) is currently being phased out
and replaced by the Environmental Quality Incentive Program (EQIP) in the 1996
Farm Bill. However, the Statistical Summaries (USDA-ASCS, 1996) from the
ACP contain reliable cost-share estimates. The following cost information is taken
from these summaries and assumes a 50% cost-share to obtain capital cost esti-
mates. The ACP program has a unique set of practice codes that are linked to a
conservation practice. The cost to install irrigation water conservation systems
(FSA practice WC4) for the primary purpose of water conservation in the 33
States that used the practice was about $73.00 per acre served in 1995. Practice
WC4 increased the average irrigation system efficiency from 47% to 64% at an
amortized cost of $ 10.41 per acre foot of water conserved. The components of
practice WC4 are critical area planting, canal or lateral, structure for water con-
trol, field ditch, sediment basin, grassed waterway or outlet, land leveling, water
conveyance ditch and canal lining, water conveyance pipeline, trickle (drip) sys-
tem, sprinkler system, surface and subsurface system, tailwater recovery, land
smoothing, pit or regulation reservoir, subsurface drainage for salinity, and toxic
salt reduction. When installed for the primary purpose of water quality, the aver-
age installation cost for WC4 was about $67 per acre served. For erosion control,
practice WC4 averaged approximately $82 per acre served. Specific cost data for
each component of WC4 are not available.
Chapter 4F-193:10/98
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194 Chapter 4: Management Measures
Water management systems for pollution control, practice SP35, cost about
$94 per acre served when installed for the primary purpose of water quality. When
installed for erosion control, SP35 costs about $72 per acre served. The compo-
nents ofSP35 are grass and legumes in rotation, underground outlets, land
smoothing, structures for water control, subsurface drains, field ditches, mains or
laterals, and toxic salt reduction. —
The design lifetimes for a range of salt load reduction measures are presented
in Table 4f-13 (USDA-ASCS, 1988).
Table 4f-13. Design lifetime for selected salt load reduction measures (USDA-ASCS, 1988).
Practice/Structure
Design Life (Years)
Irrigation Land Leveling
Irrigation Pipelines - Aluminum Pipe
Irrigation Pipelines - Rigid Gated Pipe
Irrigation Canal and Ditch Lining
Irrigation Head Ditches
Water Control Structure
Trickle Irrigation System
Sprinkler Irrigation System
Surface Irrigation System
Irrigation Pit or Regulation Reservoir
Subsurface Drain
Toxic Salt Reduction
Irrigation Tailwater Recovery System
Irrigation Water Management
Underground Outlet
Pump Plant for Water Control
10
20
15
20
1
20
10
15
15
20
20
1
20
1
20
15
Chapter 4F-194:10/98
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Using Management Measures
to Prevent and Solve Nonpoint
Source Problems in Watersheds
Watershed Approach
Watersheds are areas of land that drain to a single stream or other water
resource. Watersheds are defined solely by drainage areas and not by land owner-
ship or political boundaries. The watershed approach is a coordinating frame-
work for environmental management that focuses public and private sector
efforts to address the highest priority problerhs within hydrologically-defined
geographic areas (e.g., watersheds), taking into consideration both ground and
surface water flow (EPA, 1995a).
EPA supports watershed approaches that aim to prevent pollution, achieve
and sustain environmental improvements and meet other goals important to the
community. Although watershed approaches may vary in terms of specific objec-
tives, priorities, elements, timing, and resources, all should be based on the fol-
lowing guiding principles.
O Partnerships: Those people most affected by management decisions are in-
volved throughout and shape key decisions.
This ensures that environmental objectives are well integrated with those for
economic stability and other social and cultural goals. It also provides that
the people who depend upon the natural resources within the watersheds are
well informed of and participate in planning and implementation activities.
O Geographic Focus: Activities are directed within specific geographic areas,
typically the areas that drain to surface water bodies or that recharge or over-
lay ground waters or a combination of both.
O Sound Management Techniques based on Strong Science and Data: Collec-
tively, watershed stakeholders employ sound scientific data, tools, and tech-
niques in an iterative decision making process. This includes:
i. assessment and characterization of the natural resources and the commu-
nities that depend upon them;
ii. goal setting and identification of environmental objectives based on the
condition or vulnerability of resources and the needs of the aquatic eco-
system and the people within the community;
iii. identification of priority problems;
iv. development of specific management options and action plans;
v. implementation; and
\
vi. . evaluation of effectiveness and revision of plans, as needed.
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196 Chapter 5: Using Management Measures to Prevent and Solve NFS Problems in Watersheds
Because stakeholders work together, actions are based upon shared informa-
tion and a common understanding of the roles, priorities, and responsibilities of
all involved parties. Concerns about environmental justice are addressed and,
when possible, pollution prevention techniques are adopted. The iterative nature
of the watershed approach encourages partners to set goals and targets and to
make maximum progress based on available information while continuing analy-
sis and verification in areas where information is incomplete.
Watershed projects should have a strong monitoring and evaluation compo-
nent. Using monitoring data, stakeholders identify stressors that may pose health
and ecological risk in the watershed and any related aquifers, and prioritize these
stressors. Monitoring is also essential to determining the effectiveness of man-
agement options chosen by stakeholders to address high-priority stressors. Be-
cause many watershed protection activities require long-term commitments from
stakeholders, stakeholders need to know whether their efforts are achieving real
improvements in water quality. Monitoring is described in greater detail in Chap-
ter 6.
Watershed projects must also be consistent with state regulatory programs
such as development of total maximum daily loads (TMDLs) and basinwide
water quality assessments. In fact, a watershed may be selected for a special
project because of the need for a complex TMDL involving point and nonpoint
sources (see Chapter 7 for a discussion of TMDLs).
Operating and coordinating programs on a watershed basis makes good
sense for environmental, financial, social, and administrative reasons. For ex-
ample, by jointly reviewing the results of assessment efforts for drinking water
protection, point and nonpoint source pollution control, fish and wildlife habitat
protection and other resource protection programs, managers from all levels of
government can better understand the cumulative impacts of various human ac-
tivities and determine the most critical problems within each watershed. Using
this information to set priorities for action allows public and private managers
from all levels to allocate limited financial and human resources to address the
most critical needs. Establishing environmental indicators helps guide activities
toward solving those high priority problems and measuring success.
(
The final result of the watershed planning process is a plan that is a clear
description of resource problems, goals to be attained, and identification of
sources for technical, educational, and funding assistance needed. The successful
plan will provide a basis for seeking support and for maximizing the benefits of
that support.
Implementing Management
Measures in Watersheds
Management measures can be implemented in either a preventive or restor-
ative mode depending upon the State and local needs identified through the wa-
tershed planning process. Similarly, although management measures are
generally considered to be technology-based, they can also be used as key ele-
ments of a water quality-based approach to solving identified water quality prob-
lems. Technology-based pollution control measures are identified based upon
Chapter 5-196:10/98
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Chapter 5: Using Management Measures to Prevent and Solve NPS Problems in Watersheds 197
technical and economic achievability rather than on the cause-and-effect linkages
between particular land use activities and particular water quality problems that
drive water quality-based approaches.
Technology-based Implementation
As noted earlier, a clear assessment of the problem is essential to identifying
appropriate solutions. For example, the Section 6217 management measures were
specified to address the growing water quality problems in the Nation's coastal
areas. These management measures were developed as affordable technology-
based controls that could be implemented broadly within coastal drainage areas
to improve and protect the quality of coastal waters. The Section 6217 program
also includes provisions for implementing additional control measures where
water quality problems are not solved through implementation of the manage-
ment measures alone (USDOC and EPA, 1993). This iterative approach to solv-
ing coastal problems is consistent with the guiding principles of the watershed
approach.
Primary justification for applying management measures through a technol-
ogy-based approach is that the measures are known to reduce pollution signifi- .
cantly, and they are generally affordable. Vermont's Accepted Agricultural
Practices, which are very similar to the management measures in this guidance,
are "basic practices that all farmers must follow as part of their normal opera-
tions" (Vermont Department of Agriculture, 1995). They "are intended to reduce,
not eliminate, pollutants associated with nonpoint sources." The next level of
control in Vermont's program is Best Management Practices which "are more
restrictive than Accepted Agricultural Practices and will be site specific practices
prescribed to correct a problem on a specific farm." By implementing manage-
ment measures or practices in a technology-based approach, a level of water
quality protection is achieved which makes it easier to then focus on remaining
sources that need additional control.
The means by which management measures are implemented in a technol-
ogy-based approach can range from voluntary to regulatory. All States have some
form of voluntary program for addressing agricultural nonpoint source pollution.
These programs include USDA's Farm Bill programs (Chapter 1) and State and
local cost-share and assistance programs. Gost-share programs are very often
technology-based since implementation is frequently based primarily upon
farmer interest rather than on any direct linkage between an identified water
quality problem and the practices to be implemented by the farmer. Cost-share
programs can be directed to high-priority watersheds in much the same way that
Section 6217 is focused within coastal drainage areas. Private sector efforts are
also technology-based in many cases, including, for example, prescription farm-
ing techniques.
Water Quality-based Implementation
In areas where specific water quality problems have been identified and
characterized in detail, it is possible to tailor implementation to achieve well-
defined goals. For example, TMDLs result in allocations of the quantity of pollu-
tion that can be discharged from point sources (wasteload allocation) and
nonpoint sources (load allocation) to ensure that water quality standards are
Chapter 5-197:10/98
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198 Chapter 5: Using Management Measures to Prevent and Solve NPS Problems in Watersheds
achieved within a specified margin of safety (see Chapter 7). Management mea-
sures can be applied to achieve all or part of the pollution control needed by
agricultural sources to achieve the load allocation. Management measures can
also be used in permits to address the portion of a wasteload allocation assigned
to animal operations designated as point sources.
Understanding :
Hydrology
Understanding site and watershed hydrology is essential to understanding
nonpoint source problems and the impacts that management measure implemen-
tation may have on water quality. Each action taken on a farm has the potential to
impact hydrology. For example, diversions and buffers clearly affect water move-
ment, and even grazing management affects hydrology through its changes to
grazing land quality and/or riparian condition. Nutrient management can also
affect hydrology directly if the application of nutrients includes liquids, but nutri-
ent management can affect hydrology indirectly through its effects on crop
growth. The extent to which management decisions affect hydrology needs to be
understood and estimated since hydrology is so important to the transport and
delivery of pollutants.
In agricultural watersheds, hydrology can be affected by a number of factors
including the use of tile drains and irrigation practices, installation of grassed
waterways and diversions, field buffers and buffer strips, crop type; and tillage
type. The combined effects on hydrology of all management measures and man-
agement practices implemented should be considered both at the farm level and
at the watershed scale in order to estimate the impacts on receiving water quality.
Field-scale and watershed-scale models can aid analysis of the impacts on hy-
drology, and thus decisions on appropriate selection and placement of measures
and practices in the watershed. In some cases, a thoughtful discussion or simple
analysis will provide the answers regarding impacts to hydrology, but some form
of modeling will usually be needed to integrate the"various small and large im-
pacts that management measures and practices are likely to have on watershed
hydrology.
If the watershed within which agricultural management measures will be
implemented includes land uses other than agriculture, then planners will need to
consider agriculture's role within the watershed. In other words, the degree to
which agricultural lands control watershed hydrology should be investigated and
understood to enable analysis of the potential impacts that management, measures
and practices will have on watershed hydrology. Once again, some sort of water-
shed modeling capability will usually be needed to aid this analysis.
Assessing _,
On-Site Treatment Needs
Once watershed hydrology is understood, analysis of on-site treatment needs
and the impacts of management measures on pollutant sources and delivery pat-
terns can be conducted. At a particular farm it may be simple to determine which
management measures are needed. For example, if nutrients and pesticides are
applied, then nutrient and pesticide management should be implemented. If run-
off from a confined animal facility leaves the farm without any attenuation or
treatment, then storage and treatment of runoff is probably needed. More difficult
Chapter 5-198:10/98
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Chapter 5: Using Management Measures to Prevent and Solve NFS Problems in Watersheds 199
cases willbe those in which some management is practiced, but not enough to
fully achieve the management measures. Even more difficult may be the cases
where management measures are fully achieved but water quality goals or stan-
dards are still no being met.
On-site assessments should be performed to determine the needs on any
individual farm. USDA and Soil and Water Conservation Districts have expertise
in performing on-site assessments. EPA has developed guidance for tracking and
evaluating the implementation of nonpoint source control measures (EPA,
1997b). Tools such as Farm*A*Syst (Jackston et al., undated) can be helpful as
well.
It is usually beneficial to perform a stream walk to view the watershed from
the perspective of the receiving water body. This may lead to discovery of
sources that would not be found from a typical on-site assessment. In some wa-
tershed projects upland erosion control and riparian protection have been imple-
mented with the expectation that sedimentation problems would be solved.
Results, however, indicated that sedimentation problems persisted. For example,
in the Rock Creek, Idaho, Rural Clean Water Program project, improved irriga-
tion, sediment retention structures, filter strips, and conservation tillage were
implemented to address sediment problems impacting a cold-water fishery (EPA,
1990b). The project did achieve and measure reduced levels of suspended sedi-
ment, but it was concluded that the project should have included the contribution
of sediment from streambanks and the effects of hydromoficatiqn to fully achieve
water quality objectives. A thorough stream walk could have helped in the initial
planning stages for this project.
Targeting
Even properly designed management practice systems constitute only part of
an effective land treatment strategy. In order for a land treatment strategy to be
most effective, properly designed management practice systems must be placed
in the correct locations in the watershed (i.e., "critical areas") and the extent of
land treatment must be sufficient to achieve water quality improvements (Line
and Spooner, 1995). RCWP results indicate that 75% of the critical areas (as
designated in that program) need to be treated to achieve water quality goals. For
livestock-related water quality problems, generally 100% of the critical area
; should be treated with BMP systems (Meals, 1993). "Critical areas" are generally
considered to be sub-areas within, a watershed or recharge area that encompass
the major pollutant sources that have a direct impact on the impaired water re-
source (Gale et al., 1993). The discussion below and in Chapter 7 provides infor-
mation related to the delineation of critical areas. Although the term "critical
area" is not generally used in TMDLs, the allocation of loads to sources in the
watershed is entirely consistent with the concept.
In cases where implementation of management measures is water-quality
based or voluntary, the implementation should be prioritized based upon the
water quality benefits to be derived. Phased implementation on a priority basis
may be best if financial resources are limited.
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200 Chapter 5: Using Management Measures to Prevent and Solve NPS Problems in Watersheds
Estimating
On-Site and Off-Site impacts
On-site benefits are highly desirable, yet unless the needed off-site benefits
are derived from the collective implementation of management measures and
practices across the watershed, then implementation has not been fully success--
ful. It is important to estimate the collective impacts of all management activities
in the watershed to gage whether water quality goals will be achieved. In water-
sheds with easily characterized problems (e.g., bacterial contamination is due to a
few obviously polluting animal operations in a watershed that has no other iden-
tifiable sources of pathogens) it may be very easy to project that water quality
benefits will be achieved through implementation of the management measures
for nutrient management, erosion and sediment control, and facility wastewater
and runoff, for example. However, in a watershed with multiple land uses where
agriculture is considered to contribute about one-third or so of the pollutants, it is
more complicated to estimate the combined impacts of a variety of management
measures and practices on a fairly large number of diverse farming operations. In
this type of situation, computer modeling may be needed.
A variety of models exist to help assess the benefits of implementing prac-
tices at the farm level, some of which could also be used on small watersheds.
These include the following:
O GLEAMS (Knisel et al., 1991) simulates the effects of management practices
and irrigation options on edge of field surface runoff, sediment, and dissolved
and sediment attached nitrogen, phosphorus, and pesticides. The model con-
siders the effects of crop planting date, irrigation, drainage, crop rotation,
tillage, residue, commercial nitrogen and phosphorus applications, animal
waste applications, and pesticides on pollutant movement. The model has been
used to predict the movement of pesticides (Zacharias et al., 1992) and nutri-
ents and sediment from various combinations of land uses and management
(Knisel and Leonard, 1989; Smith et al., 1991).
O EPIC (Sharpley and Williams, 1990) simulates the effect of management
strategies on edge of field water quality and nitrate nitrogen and pesticide
leaching to the bottom of the soil profile. The model considers the effect of
crop type, planting date, irrigation, drainage, rotations, tillage, residue, com-
mercial fertilizer,'animal waste, and pesticides on surface and shallow ground
water quality. The EPIC model has been used to evaluate various cropland
management practices (Sugiharto et al., 1994; Edwards et al., 1994).
H NLEAP (Follet et al., 1991) evaluates the potential of nitrate nitrogen leach-
ing due to land use and management practices. The NLEAP model has been
used to predict the potential for nitrogen leaching under various management
scenarios (Wylie et al., 1994; Wylie et al., 1995).
D PRZM (Mullens etal. 1993) simulates the movement of pesticides inunsatur-
ated soils within and immediately below the root zone. Several different field
crops can be simulated and up to three pesticides are modeled simultaneously
as separate parent compounds or metabolites. The PRZM model has been
used under various conditions to assess pesticide leaching under fields
(Zacharias et al., 1992; Smith et al., 1991).
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Chapter 5: Using Management Measures to Prevent and Solve NPS Problems in Watersheds 201
O WEPP (Flanagan and Nearing, 1995) simulates water runoff, erosion, and
sediment delivery from fields or small watersheds. Management practices
including crop rotation, planting and harvest date, tillage, compaction,
stripcropping, row arrangement, terraces, field borders, and windbreaks can
be simulated. The WEPP model has been applied to various land use and
management conditions (Tiscareno-Lopez et al., 1993; Liu et al., 1997) -
O DRAINMOD (Skaggs, 1980) simulates the hydrology of poorly drained, high
water table soils. Breve (1994) developed DRAINMOD-N, a nitrogen version
of the model to evaluate nitrogen dynamics in artificially drained soils. The
DRAINMOD model has been used to predict pollutant losses associated with
various drainage management scenarios (Deal etal., 1986).
O BARNY (Vermont NRCS, 1985) is a spreadsheet model that estimates total
phosphorus losses from dairy barnyards and estimates phosphorus loads en-
tering waterways. Other similar models include STACK, PHRED, and
MILKHOUSE. These models have had limited use.
a SWRRBWQ (Arnold et al., 1990) simulates the effect of agricultural manage-
ment practices such as crop rotation, conservation tillage, residue, nutrient,
and pesticide management; and improved animal waste application methods
on water quality. The SWRRB model has been used on several watersheds to
assess management practices and to test its validity (Arnold and Williams,
1987; Bingner et al., 1987).
O AGNPS (Young et al. 1994) is a spatially-distributed model for estimating
pollutant runoff from agricultural watersheds. Within cells, the model can
evaluate practices such as feedlot management, terraces, vegetative buffers,
grassed waterways, and farm ponds. Simulated nutrient, sediment, and pesti-
cide concentrations and yields are available for any cell within the watershed.
The AGNPS model has been applied to many field and watershed size areas to
estimate pollutant runoff from various land uses and management practices
(Line et al., 1997; Sugiharto et al., 1994; Bingner et al., 1987)
O ANSWERS (Beasley, 1980) is a spatially-distributed watershed model. The
model is primarily a runoff and sediment model as soil nutrient processes are
not simulated. The ANSWERS model has been applied to several small field-
sized areas with various management practices (Griffin etal., 1988; Bingner
etal., 1987).
O NTRM (Shaffer and Larson, 1985) simulates the impact of soil erosion on the
short and long-term productivity of soil, and is intended to assist with evalua-
tion of existing and proposed soil management practices in the subject areas of
erosion, soil fertility, tillage, crop residues, and irrigation. The NTRM model
has been applied to evaluate effects of conservation tillage, supplemental ni-
trogen and irrigation practices (Shaffer, 1985) and moldboard plow and chisel
plow tillage (Shaffer et al., 1986) on soil erosion and productivity. This model
has had limited use.
A series of protocols has been developed by EPA to assist in the development
of TMDLs and implementation plans to achieve the TMDLs (EPA, 1997 -
DRAFT at this point). These protocols focus primarily on the application of
computer models that simulate watershed conditions and the changes that could
result from implementation of various land management scenarios. Most models
contain default values for the quantity of pollutants that are delivered in runoff
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202 Chapter 5: Using Management Measures to Prevent and Solve NPS Problems in Watersheds.
from various sources (e.g., cropland deliver X pounds of nitrogen per acre per
inch of runoff). These default values can generally be replaced with better infor-
mation that is available for a particular watershed. Further, some models have
functions that are intended to simulate the implementation of management prac-
tices, enabling modelers to estimate changes due to a range of land management
options. Such models can be helpful tools for planning the implementation of man-
agement measures to achieve water quality goals, but the limitations of models and
appropriate interpretation of modeling results should be fully understood before
implementation decisions are made. The application of models to estimate pollut-
ant loads is discussed further in Chapter 7.
Adaptive
Management
Because many of the decisions made regarding the appropriate type, extent,
and location of management measures and practices are based upon estimates
and partial information, it is highly likely that changes will be needed. If progress
is monitored (see Chapter 6) adequately, managers and landowners will be able
to adjust implementation plans and schedules as needed to ensure more cost-
efficient achievement of water quality objectives. One of the major findings from
the Rural Clean Water Program is that water quality monitoring can provide valu-
able feedback for defining areas needing priority treatment (Gale et al., 1993).
Preventing Unintended
Adverse Environmental Effects
As noted in Chapter 2, this guidance does not address all environmental con-
. siderations at a particular site or within a watershed. Resource management sys-
tems are more broad, yet planners and managers should even go beyond the scope
of an RMS to consider whether management measure or practice implementation
at the site or watershed scale will have any unintended environmental impacts. For
example, methane generation from structures implemented to store runoff and
facility wastewater from confined animal facilities may be problematic in certain
areas. Alternatives to conventional storage structures might be needed.
Alternatively, wildlife might be impacted in a watershed where livestock ex-
clusion is achieved with extensive fencing of riparian areas. Softer approaches to
riparian area protection (e.g., controlled access or intensive rotational grazing
approaches) might be needed to allow for wildlife corridors. Similarly, extensive
changes to water management could impact baseflows in streams. Different con-
figurations and design specifications for diversions and storage devices might be
able to provide needed water quality improvement without causing negative im-
pacts to baseflow patterns. Whole-farm planning approaches such as those speci-
fied in Chapter 2 (e.g., Idaho One Plan) can go a long way toward preventing
these types of unintended environmental impacts at the farm level, but potential
watershed-wide or landscape-scale impacts need to considered from a more glo-
bal perspective,
Chapter 5-202:10/98
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Chapter 5: Using Management Measures to Prevent and Solve NFS Problems in Watersheds 203
Estimating the Effectiveness of Management Measures
and Management Practice Systems
It is very difficult to estimate the effectiveness of management practice systems. Some
researchers have proposed that the effectiveness of management practice systems should be
calculated by adding the average relative effectiveness of individual practices. As an example of this
approach, assume a system to control sediment is composed of surface drainage, terraces, and
conservation tillage. Based upon data in the literature (Foster et al., 1996), the average sediment
load reductions achieved by these practices are 36% for surface drainage, 91% for terraces, and
69% for conservation tillage. Under this approach, the average pollutant load reduction for surface
drainage is subtracted from the total load of 100% (100% - 36% = 64%). Thus, 64% of the sediment
remains after surface drainage is accounted for. If terraces reduce sediment loads by 91%, then the
remaining pollutant load after surface drainage and terraces is about 6% (.64 x [1.00 - .91] = .058 =
5.8%). The remaining practice in the system, conservation tillage, reduces sediment loads by 69%,
resulting in a final sediment delivery of approximately 2% (.058 x [1.00 - .69] = .018 = 1.8%).
The Idaho RCWP project, however, demonstrated that the effectiveness of individual practices
in a system of practices are not additive. The effectiveness of some of the BMPs used in the project
was measured by the USDA-Agricultural Research Service, and the results are given in Table 5-1
(Maretetal., 1991).
Table 5-1. Sediment removal effectiveness of selected
individual BMPs used in the Snake River RCWP Project (Idaho).
Individual BMP
Sediment Basins
Mini-basin
Buried Pipe Systems
Vegetative Filters
Straw Mulch
Mean %
Effectiveness
87
86
83
50
50
% Effectiveness
Range
75-95
0-95
75-95
35-70
40-80 •
Sediment loads in the Idaho RCWP project were reduced by 75%. Even though the
effectiveness of only five of the nineteen BMPs used in the project was measured (Table 5-1), it can
be seen that the overall reduction of 75% would not have been estimated accurately by using the
above approach in which average effectiveness of practices was considered to be additive. Using
the additive approach, the sediment delivery would have been reduced to essentially zero if the
mean effectiveness values for the five practices in Table 5-1 were used in the analysis.
In summary, the aggregate effectiveness of any system of management practices is a function
of not only the mean effectiveness of individual practices, but also the interactions between the
individual practices within the range of site-specific conditions experienced.
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204 Chapter 5: Using Management Measures to Prevent and Solve NFS Problems in Watersheds
Chapter 5-204:10/98
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Monitoring and Tracking Techniques
Knowledge of land management activities and water quality conditions is
important in many ways to efforts involving implementation of management
measures and practices. As discussed in Chapter 5, the watershed planning pro-
cess includes an assessment of environmental problems, goal setting, and priority
setting. The development of action plans and implementation follow, with evalu-
ation of effectiveness and revisions of plans as needed. Good water quality data
are essential to problem identification and characterization, goal setting," priority
setting, development of implementation plans, and evaluation. Without good data
regarding land management activities, including the control of point sources,
accurate interpretation of the causes of water quality problems and improvements
is not possible.
Water Quality Monitoring
Since the relationship between public health and water quality began to
influence legislation in the early 1900s, water quality management and its related
information needs have evolved considerably. Today, the Intergovernmental Task
Force on Monitoring Water Quality (ITFM, 1995b) defines water quality moni-
toring as an integrated activity for evaluating the physical, chemical, and biologi-
cal character of water in relation to human health, ecological conditions, and
designated water uses. Water quality monitoring for nonpoint sources (NFS) of
pollution includes the important element of relating the physical, chemical, and
biological characteristics of receiving waters to land use characteristics. Without
current information, water quality and the effects of land-based activities on
water quality cannot be assessed, effective management and remediation pro-
grams cannot be implemented, and program success cannot be evaluated.
The most fundamental step in the development of a monitoring plan is to
define the goals and objectives, or purpose, of the monitoring program. In gen-
eral, monitoring goals are broad statements such as "to measure improvements in
Hojnacki Creek" or "to verify nutrient load reductions into Stumpe Lake." In the
past, numerous monitoring programs did not document this aspect of the design
process and the resulting data collection efforts led to little useful information for
decision making (GAO, 1986; MacDonald etal., 1991; National Research Coun-
cil, 1986; Ward et al., 1990). As a result, the identification of monitoring goals is
the first component of the design framework outlined by the ITFM (1995b). Fig-
ure 6-1 presents one approach for developing a monitoring plan.
Monitoring programs can be grouped according to the following general
purposes or expectations (irFM, 1995b; MacDonald et al., 1991):
D Describing status and trends
O Describing and ranking existing and emerging problems
O Designing management and regulatory programs
• Chapter 6-205:10/98
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206 Chapter 6: Monitoring and Tracking Techniques
Figure 6-1. Development of a monitoring project (after MacDonald et al., 1991).
QA Planning
QA Implementation
&
QA Assessment
Define personnel and budgetary constraints
Define monitoring parameters,
sampling frequency, sampling location
and analytic procedures
Evaluate hypothetical
or, if available, real data
Will the data meal the
proposed monitoring objectives?
Yes
Is the proposed monitoring
program compatible with
available resources?
Yes
No
Initiate monitoring activities on a pilot basis
Analyze and evaluate data
Does the pilot project meet
the monitoring objectives?
Yes
No
Continue monitoring and data analysis
I Reports and recommendations [
Revise the
objectives
or the
monitoring
procedures
Revise
monitoring
plan as
needed
Chapter 6-206:10/98
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Chapter 6: Monitoring and Tracking Techniques 207
O Evaluating program effectiveness
D Responding to emergencies
O Describing the implementation of best management practices
D Validating a proposed water quality model
D Performing research
Unlike monitoring goals, monitoring objectives are more specific statements
that can be used to complete the monitoring design process including scale, vari-
able selection, methods, and sample size (Plafkin et al., 1989; USDA-NRCS,
1996b). Monitoring program objectives must be detailed enough to allow the
designer to define precisely what data will be gathered and how the resulting
information will be used. Vague or inaccurate statements of objectives lead to
program designs that provide too little or too much data, thereby failing to meet
management needs or costing too much.
The remainder of the design framework outlined by the ITFM (1995b) in- .
eludes coordination and collaboration, design, implementation, interpretation,
evaluation of the monitoring program, and communication. Numerous guidance
documents have been developed, or are in development, to assist resource man-
agers in developing and implementing monitoring programs that address all as-
pects of the ITFM's design framework. Appendix A in Monitoring Guidance for
Determining the Effectiveness ofNonpoint Source Controls (EPA, 1997a) pre-
sents a review of more than 40 monitoring guidances for both point and NFS
pollution. These guidances discuss virtually every aspect of NPS pollution moni-
toring, including monitoring program design and objectives, sample types and
sampling methods, chemical and physical water quality variables, biological
monitoring, data analysis and management, and quality assurance and quality
control.
Once the monitoring goals and objectives have been established, existing
data and constraints should be considered. A thorough review of literature per-
taining to water quality studies previously conducted in the geographic region of
interest should be completed before starting a new study. The review should help
determine whether existing data provide sufficient information to address the
monitoring goals and what data gaps exist.
Identification of project constraints should address financial, staffing, and
temporal elements. Clear and detailed information should be obtained on the time
frame within which management decisions need to be made, the amounts and
types of data that must be collected, the level of effort required to collect the
necessary data, and equipment and personnel needed to conduct the monitoring.
From this information it can be determined whether available personnel and bud-
get are sufficient to implement or expand the monitoring program.
As with monitoring program design, the level of monitoring that will be
conducted is largely determined when goals and objectives are set for a monitor-
ing program, although there is some flexibility for achieving most monitoring
objectives. Table 6-1 provides a summary of general characteristics of various
types of monitoring.
Chapter 6-207:10/98
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208 Chapter 6: Monitoring and Tracking Techniques
Table 6-1. General characteristics of monitoring types (MacDonald et al., 1991).
Type of
Monitoring
Trend
Baseline
Implementation
Effectiveness
Project
Validation
Compliance
Number and Type
of Water Quality
Parameters
Usually water
column
Variable
None
Near activity
Variable
Few
Few
Frequency of
Measurements
Low
Low
Variable '
Medium to high
Medium to high
High
Variable
Duration of
Monitoring
Long
Short to
medium
Duration of
project
Usually short
to medium
Greater than
project duration
Usually medium
to long
Dependent on
project
Intensity of
Data Analysis
Low to
moderate
Low to
moderate
Low
Medium
Medium
High
Moderate to
high
The overall scale of a monitoring program has two components—a temporal
scale and a geographic scale. The temporal scale is the amount of time required
to accomplish the program objectives. It can vary from an afternoon to many
years. The geographic scale can also vary from quite small, such as plots along a
single stream reach, to very large, such as an entire river basin. The temporal and
geographic scales, like a program's design and monitoring level, are primarily
determined by the program's objectives.
If the main objective is to determine the current biological condition of a
stream, sampling at a few stations in a stream reach over 1 or 2 days might suf-
fice. Similarly, if the monitoring objective is to determine the presence or ab-
sence of a NFS impact, a synoptic survey might be conducted in a few select
locations. If the objective is to determine the effectiveness of a nutrient manage- •
ment program for reducing nutrient inputs to a downstream lake, however, moni-
toring a subwatershed for 5 years or longer might be necessary. If the objective is
to calibrate or verify a model, more intensive sampling might be necessary.
Depending on the objectives of the monitoring program, it might be neces-
sary to monitor only the waterbody with the water quality problem or it might be
necessary to include areas that have contributed to the problem in the past, areas
containing suspected sources of the problem, or a combination of these areas. A
monitoring program conducted on a watershed scale must include a decision
about a watershed's size. The effective size of a watershed is influenced by drain-
age patters, stream order, stream permanence, climate, number of landowners in
the area, homogeneity of land uses, watershed geology, and geomorphology.
Each factor is important because each has an influence on stream characteristics,
although no direct relationship exists.
Chapter 6-208:10/98
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Chapter 6: Monitoring and Tracking Techniques 209
There is no formula for determining appropriate geographic and temporal
scales for any particular monitoring program. Rather, once the objectives of the
monitoring program have been determined, a combined analysis of them and any
background information on the water quality problem being addressed should
make it clear what overall monitoring scale is necessary to reach the objectives.
• Other factors that should be considered to determine appropriate temporal
and geographic scales include the type of water resource being monitored and the
complexity of the NFS problem. Some of the constraints mentioned earlier, such
as the availability of resources (staff and money) and the time frame within
which managers require monitoring information, will also contribute to determi-
nation of the scales of the monitoring program.
For additional details regarding NFS monitoring techniques, including
chemical and biological monitoring, the reader is referred to Monitoring Guid-
ance for Determining the Effectiveness ofNonpoint Source Controls (EPA,
1997a). This technical document focuses on monitoring to evaluate the effective-
ness of management practices, but also includes approximately 300 references
and summaries of more than 40 other monitoring guides. In addition, Chapter 8
of EPA's management measures guidance for Section 6217 contains a detailed
discussion of monitoring with emphasis on coastal areas (EPA, 1993).
Tracking Implementation of Management Measures
The implementation of management measures may be tracked to determine
the extent to which management measures are implemented in a watershed, re-
charge area, or other geographic area.
Implementation and trend monitoring can be used to address the following
goals:
O Determine the extent to which management measures and practices are
implemented in accordance with relevant standards and specifications.
D Determine whether there has been a change in the extent to which manage-
ment measures and practices are being implemented.
D . Establish a baseline from which decisions can be made regarding the need
for additional incentives for implementation of management measures,
D Measure the success of voluntary implementation efforts,
D Support work-load and costing analyses for assistance or regulatory pro-
grams,
D Determine the relative adoption rates of various management measures
across different geographic areas,
O Determine the extent to which management measures are properly main-
tained and operated.
Methods to assess the implementation of management measures are a key
focus of the technical assistance to be provided by EPA and NOAA.
Chapter 6-209:10/98
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210 Chapter 6: Monitoring and Tracking Techniques
Implementation assessments can be performed on several scales. Site-spe-
cific assessments can be used to assess individual management measures or prac-
tices, and watershed assessments can be used to look at the cumulative effects of
implementing multiple management measures. With regard to "site-specific"
assessments, individual practices must be assessed at the appropriate scale for the
practice of interest. For example, to assess the implementation of management""
measures and practices for animal waste handling and disposal on a farm, only
the structures, areas, and practices implemented specifically for animal waste
management (e.g., dikes, diversions, storage ponds, composting facility, and
manure application records) would need to be inspected. In this instance, the
animal waste storage facility would be the appropriate scale and "site." To assess
erosion control, the proper scale might be fields over 10 acres and the site could
be 100-meter transect measurements of crop residue. For nutrient management,
the scale and site might be an entire farm. Site-specific measurements can then
be used to extrapolate to a watershed or statewide assessment. It is recognized
that some studies might require a complete inventory of management measures
and practice implementation across an entire watershed or other geographic area.
Sampling design, approaches to conducting the evaluation, data analysis
techniques, and ways to present evaluation results are described in EPA's Tech-
niques for Tracking, Evaluating, and Reporting the Implementation ofNonpoint
Source Control Measures - Agriculture (EPA, 1997b). Chapter 8 of EPA's man-
agement measures guidance for Section 6217 contains a detailed discussion of
techniques and procedures to assess implementation, operation, and maintenance
of management measures (EPA, 1993).
Determining Effectiveness of
Implemented Management Measures
By tracking management measures and water quality simultaneously, ana-
lysts will be in a position to evaluate the performance of those management mea-
sures implemented. Management measure tracking will provide the necessary
information to determine whether pollution controls have been implemented,
operated, and maintained adequately. Without this information, analysts will not
be able to fully interpret their water quality monitoring data. For example, ana-
lysts cannot determine whether the management measures have been effective
unless they know the extent to which these controls were implemented, main-
tained, and operated.
A major challenge in attempting to relate implementation of management
measures to water quality changes is determining the appropriate land manage-
ment attributes to track. For example, a "bean count" of the number of manage-
ment measures implemented in a watershed has little chance of being useful in
statistical analyses that relate water quality to land treatment since the count will
be only remotely related (i.e., a mechanism is lacking) to the measured water
quality parameter (e.g., phosphorus concentration). Land treatment and land use
monitoring should relate directly to the pollutants or impacts monitored at the
water quality station (Coffey and Smolen, 1990). For example, the tons of animal
waste managed may be a much more useful parameter to track than the number
of confined animal facilities constructed. Since the impact of management mea-
Chapter 6-210:10/98
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Chapter 6: Monitoring and Tracking Techniques 211
sures on water quality may not be immediate or implementation may not be sus-
tained, information on other relevant watershed activities (e.g., urbanization,
growth in animal numbers) will be essential for the final analysis.
Water quality and land treatment monitoring must be coordinated to maxi-
mize the chance of meaningful results. In order to provide the manager with a
sense of the nature of the coordination needed, an overview of monitoring pro-
gram design is provided in Figure 6-2.
Monitoring program design, as shown in Figure 6-2, begins by defining the
monitoring objective. Once the objective is defined, the experimental design
(e.g., upstream/downstream, pre- and post-BMP, and paired watershed) is deter-
mined. Based on the experimental design, separate but coordinated parallel water
quality and land treatment activities are specified.
Figure 6-2. Land treatment and water quality monitoring program design (Coffey et al., 1995).
Define monitoring objective
Determine experimental design
WATER QUALITY
I
LAND TREATMENT
Locate treatment and
control (or reference)
monitoring sites
1
Develop a land treatment
tracking system for each
subwatershed draining
to a water quality
monitoring site
Gather baseline water
quality (2 years)
I
Gather baseline,
land treatment, and land
use data
Link water quality and land
treatment data bases
Continued water quality
monitoring during treatment
Start land treatment
Monitor post-implementation
water quality (2-5 years)
Continued tracking of land
treatment and land use
Link water quality and land
treatment data bases
Chapter 6-211:10/98
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212 Chapter 6: Monitoring and Tracking Techniques
Appropriately collected water quality information can be evaluated with
trend analysis to determine whether pollutant loads have been reduced or
whether water quality has improved. Valid statistical associations drawn between
implementation and water quality data can be used to indicate:
(1) Whether management measures have been successful in improving water.
quality in a watershed or recharge area, and
(2) The need for additional management measures to meet water quality objec-
tives in the watershed or recharge area.
Greater detail regarding methods to evaluate the effectiveness of land treat-
ment efforts can be found in EPA's NFS monitoring guidance (EPA, 1997a) and
management measures guidance for section 6217 (EPA, 1993).
Quality Assurance and Quality Control
Introduction
Quality assurance (QA) and quality control (QC) are commonly thought of
as procedures used in the laboratory to ensure that all analytical measurements
made are accurate. Yet QA and QC extend beyond the laboratory and are essen-
tial components of all phases and all activities within each phase of a NFS moni-
toring project. This section defines QA and QC, discusses their value in NFS
monitoring programs, and explains EPA's policy on these topics. The following
sections provide detailed information and recent references for planning and
ensuring quality data and deliverables that can be used to support specific deci-
sions involving NPS pollution.
Definitions of Quality Assurance and Quality Control
Quality assurance is
an integrated system of management procedures and
activities used to verify that the quality control system is
operating within acceptable limits and to evaluate the
quality of data (Taylor, 1993; EPA, 1994a).
Quality control is
a system of technical procedures and activities
developed and implemented to produce measurements
of requisite quality (Taylor, 1993; EPA, 1994a).
Chapter 6-212:10/98
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Chapter 6: Monitoring and Tracking Techniques 213
Quality control procedures include the collection and analysis of blank,
duplicate, and spiked samples and standard reference materials to ensure the
integrity of analyses and regular inspection of equipment to ensure it is operating
properly. Quality assurance activities are more managerial in nature and include
assignment of roles and responsibilities to project staff, staff training, develop-
ment of data quality objectives, data validation, and laboratory audits. Table 6-2
lists some common activities that fall under the headings of QA and QC. Such
procedures and activities are planned and executed by diverse organizations
through carefully designed quality management programs that reflect the impor-
tance of the work and the degree of confidence needed in the quality of the re-
sults.
Table 6-2. Common QA and QC activities (adapted from Drouse et al., 1986,
and Erickson et al., 1991).
Q A Activities
Organization of project into component parts
Assignment of roles and responsibilities to project staff
Use of statistics to determine the number of samples and sampling sites
needed to obtain data of a required confidence level
Tracking of sample custody from field collection through final analysis
Development and use of data quality objectives to guide data collection
efforts
Audits of field and laboratory operations
Maintenance of accurate and complete records of all project activities
Personnel training to ensure consistency of sample collection techniques
and equipment use
QC Activities
Collection of duplicate samples for analysis
Analysis of blank and spike samples
Replicate sample analysis
Regular inspection and calibration of analytical equipment
Regular inspection of reagents and water for contamination
Regular inspection of refrigerators, ovens, etc. for proper operation
Importance of QA/QC Programs
Although the value of a QA/QC program might seem questionable while a
project is under way, its value should be quite clear after a project is completed.
If the objectives of the project were used to design an appropriate data collection
and analysis plan, all QA/QC procedures were followed for all project activities,
and accurate and complete records were kept throughout the project, the data and
information collected from the project will be adequate to support a choice from .
Chapter 6-213:10/98
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214 Chapter 6: Monitoring and Tracking Techniques
among alternative courses of action. In addition, the course of action chosen will
be defensible based on the data and information collected. Development and
implementation of a QA/QC program can require up to 10 to 20% of project
resources (Cross-Smiecinski and Stetzenback, 1994), but this cost can be recap-
tured in lower overall costs due to the project's being well planned and executed.
Likely problems are anticipated and accounted for before they arise, eliminating*
the need to spend countless hours and dollars resampling, reanalyzing data, or
mentally reconstructing portions of the project to determine where an error was
introduced. QA/QC procedures and activities are cost-effective measures used to
determine how to allocate project energies and resources toward improving the
quality of research and the usefulness of project results (Erickson et al., 1991).
EPA Quality Policy
EPA has established a QA/QC program to ensure that data used in research
and monitoring projects are of known and documented quality to satisfy project
objectives. The use of different methodologies, lack of data comparability, un-
known data quality, and poor coordination of sampling and analysis efforts can
delay the progress of a project or render the data and information collected from
it insufficient for decision making. QA/QC practices should be used as an inte-
gral part of the development, design, and implementation of an NFS monitoring
project to minimize or eliminate these problems (Erickson et al., 1991; Pritt and
Raese, 1992; EPA, 1994b).
Additional information on QA/QC can be found in Chapter 5 of EPA's
nonpoint source monitoring guide (EPA, 1997a).
Chapter 6-214:10/98
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Load Estimation Techniques
A pollutant load is the mass or weight of pollutant transported in a specified
unit of time from pollutant sources to a waterbody. The loading rate, or flux, is
the instantaneous rate at which the load is passing a point of reference on a river,
such as a sampling station, and has units of mass/time such as grams/second or
tons/day (Richards, 1997). Mathematically, the load is the integral over time of
the flux.
Pollutant load estimation is a fundamental element in the development of
many watershed management plans. Reliable estimates of the quantity of pollut-
ants delivered from various sources within a watershed are needed to develop a
watershed plan that will address the identified water quality problems-or issues.
Establishing the link between an identified water quality problem and the sources
causing the problem often entails a mass balance analysis, a quantitative account-
ing of the sources and sinks of the pollutants of interest.
There are many reasons for developing management plans, including the
development of a total maximum daily load (TMDL) pursuant to the require-
ments of section 303(d) of the Clean Water Act (see Highlight). For those waters
either not supporting or not projected to support designated uses even after the
implementation of point source or other required pollution controls, a TMDL is
needed. The steps typically taken to develop a TMDL are:
1. Problem definition
2. Endpoint identification
3. Source analysis
4. Linkage of endpoint and source analysis
5. Allocation of loads
6. Monitoring and adaptive management
7. Assembling the TMDL
In source analysis for a TMDL, the relative contributions of different
sources are assessed. An estimate of pollutant loads from both point sources and
nonpoint sources is essential to this analysis, as is the ability to determine if the
load reduction needed to meet water quality standards can be achieved under
different management scenarios (e.g., implementation of the management mea-
sures). The load allocation for nonpoint sources (and the wasteload allocation
for point sources) is determined from an analysis that links the desired endpoints
. (e.g., achievement of a water quality standard) to various management alterna-
tives that could be applied to the identified sources.
The following sections present some basic information regarding monitoring
and modeling to estimate pollutant loads. References to more detailed treatments
of the topics are included as well.
Chapter 7-215:10/98
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216 Chapter 7: Load Estimation Techniques
Clean Water Act
Total Maximum Daily Load (TMDL) Program
Section 303(d) of the Clean Water Act and EPA's implementing regulations
at 40 CFR Section 130.7 require States to develop TMDLs for their
waterbodies that do not or are not expected to meet applicable water
quality standards after the application of technology-based point source or
other required pollution controls. EPA's regulations at 40 CFR Section
130.2 define some of the elements of the TMDL programs. These include:
O Loading capacity - The greatest amount of loading that a
water can receive without violating water quality standards.
O Load allocation - The portion of a receiving water's loading
capacity that is attributed either to one of its existing or future
nonpoint sources of pollution or to natural background
sources.
O Wasteload allocation - The portion of a receiving water's
loading capacity that is allocated to one of its existing or fu-
ture point sources of pollution.
D Total maximum daily load (TMDL) - The sum of the indi-
vidual wasteload allocations for point sources and load allo-
cations for nonpoint sources and natural background.
TMDLs can be expressed in terms of either mass per time,
toxicity, or other appropriate measure that relate to a State's
water quality standard. A margin of safety is required as part
of each TMDL to account for the uncertainty about the rela-
tionship between the pollutant loads and the quality of the
receiving waterbody.
CD Water quality-limited segments - Those water segments
that do not or are not expected to meet applicable water
quality standards even after the application of technology-
based effluent limitations for point sources as required by
sections 301 (b) and 306 of the Clean Water Act. Technolr
ogy-based controls include, but are not limited to, best practi-
cable control technology currently available and secondary
treatment.
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Chapter 7: Load Estimation Techniques 217
Estimating Pollutant Loads Through Monitoring
Every monitoring effort should have clearly stated objectives. The estima-
tion of pollutant loads is a general objective that should be refined to clarify the
monitoring needs. The specific reasons why the pollutant loads are to be-esti-
mated could affect decisions regarding the required precision and the conditions
under which monitoring should be conducted. For example, if the pollutant is
bacteria and the watershed management concerns are associated with the instan-
taneous value and the 30-day geometric mean (of 5 or more samples), then the
sampling protocol should consider multiple samples at a sufficient frequency to
calculate the geometric mean as well as evaluate the various conditions under
which loading occurs (wet and dry weather). On the other hand, if nutrients are
causing accelerated eutrophication in a reservoir then it may only be important to
estimate seasonal loads. The time scales and frequency of monitoring needed **
will be a function of the critical conditions and the receiving water response to
the loading of the pollutant of concern.
The averaging period for loading estimates may be hourly, daily, monthly, or
longer depending upon site-specific conditions and needs. The variability of
loads within the average period of interest and the certainty with which water
quality standards violations need to be documented will drive decisions regarding
sampling design and frequency, thus affecting cost as well. The importance of
clearly stated objectives is described more fully in existing monitoring guides
(EPA, 1997a; EPA, 1991c; USDA, 1996). Due to the importance of statistical
considerations, those designing monitoring plans are strongly encouraged to seek
assistance from a trained statistician with experience in water monitoring.
Components of a Load
The three basic steps for determining pollutant loads are:
D measuring water discharge (e.g., cubic meters per second),
D measuring pollutant concentration (e.g., milligrams per liter), and
O calculating pollutant loads (multiplying discharge times concentration over
the time frame of interest).
f
Since pollutant flux, the instantaneous loading rate, is measured as the prod-
uct of concentration and flow, which both vary continuously, the key challenge in
measuring loads is to determine when to sample to obtain the best estimate at
least cost. Richards (1997) points out that it is not uncommon for 80 to 90% or
more of the annual load to be delivered during the 10% of the time which corre-
sponds with high fluxes. Depending on the constituent being evaluated, fluxes'
during snowmelt and storm events are often many times greater than those during
periods of low flow (i.e., dry weather conditions). Thus, monitoring programs
must be designed with full consideration given to periods of greatest pollutant
flux.
Measuring Water Discharge
The major options for monitoring stream discharge are flumes, weirs, natu-
ral channels, and existing structures (USDA, 1996; Brakensiek, et al., 1979).
The use of culverts is generally discouraged since at high flows culverts can be
Chapter 7-217:10/98
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218 Chapter 7: Load Estimation Techniques
submerged, a hydraulic jump may form at the culvert entrance, or the water level
may drop because an entrance is constricted, all of which yield false stage values
(USDA, 1996). Device selection for stream discharge is a function of site-spe-
cific conditions such as slope, sediment load, and stream size. Selection of a
device for runoff measurement depends on peak runoff rate, runoff variability,
the extent to which trash and debris are carried in the runoff, icing conditions,—
and other factors (Brakensiek, etal., 1979). Discharge monitoring approaches,
and the selection, implementation, and use of various devices are described by
Brakensiek, et al. (1979) and USDA (1996).
Load and Flux
The pollutant load is the integral over time of the flux
Load = kfflux(t) dt
t
where k is a constant for converting units, and t is time.
Since we cannot measure flux directly, we measure it as the product of
concentration and discharge.
Load = k/c(t)q(t)dt
t
where c(t) is the concentration at time=t, and q(t) is the water
discharge at time=t.
Water runoff,
sediment delivery,
and nutrient loading
can be estimated
using watershed
models. Match
modeling objectives,
staff expertise, data
requirements, and •
available budget for
proper model
selection.
For established gaging stations, flow measurements are relatively inexpen-
sive to make, and are available almost on a continuous basis (Richards, 1997). It
is, however, likely that gaps in the flow record will still occur as a result of
equipment failure, operational errors, or extreme flow events. Methods to fill
gaps in flow records are described by Brakensiek, et al. (1979) and USGS
(Rantz, et al., 1982).
Measuring Pollutant Concentration
Continuous monitoring of pollutant concentration is only feasible for a
small number of pollutants within limited ranges of concentration, and is gener-
ally not performed due to cost constraints and/or site or equipment limitations.
Instead, periodic measurements in the field (in situ or sample analysis with a
field kit) or laboratory measurements performed on collected water samples are
typically used to provide the pollutant concentration values that will be used in
load estimation.
Chapter 7-218:10/98
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Chapter 7: Load Estimation Techniques 219
Water sampling approaches have been categorized in several ways, some
based more upon the equipment used, and others based more upon the statistical
design employed (USDA, 1996; EPA, 1979; EPA, 1991c). Grab, point, compos-
ite, integrated, continuous, random, systematic, and stratified sampling are fre-
quently described in the literature. In practice, sampling involves a decision
regarding the population and population units to be sampled (e.g., instantaneous
concentration at single point or integrated over depth, average concentration at
single point or integrated over depth for a specified time interval or flow inter-
val), a determination of the statistical approach to be used (e.g., simple random
sampling, stratified random sampling, systematic sampling), and a choice of
sampling equipment and configuration (e.g., grab sample taken manually or auto-
matically with a mechanical sampler, time-weighted or flow-weighted sampling
with a programmed mechanical sampler).
Types of Water Samples
Grab Sample — A single sample taken at one place a single time.
Composite Sample — A series of grab samples, usually collected in the same
location but at different times, combined to form one sample for analysis.
Composite samples are usually:
Flow-Weighted - Sample is taken after a specified quantity of water has
passed the monitoring station (e.g., draw 10 ml sample every 750,000 liters
of flow); or .
Time-Weighted - A pre-determined sample volume is taken at a predeter-
mined time interval (e.g., draw 10 ml sample every 15 minutes).
Integrated Sample - Subsamples are taken at various depths or distances from
the stream bank, and integrated into a single sample.
Continuous Sample - Probes are used to continuously record contaminant con-
centration in stream. Not widely applicable to nonpoint source programs.
For any given watershed, the best approach for estimating loads will be
determined based upon the needs and characteristics of the watershed. Still, some
general rules-of-thumb should be considered (USDA, 1996; Richards, 1997).
.O Accuracy and precision increase with increased frequency of sampling
O Grab, Point, or Instantaneous Samples - may be insufficient to determine
loads unless concentrations are correlated to discharge which is measured
continuously.
Chapter 7-219:10/98
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220 Chapter 7: Load Estimation Techniques
O Depth-Integrated and Width-Integrated Grab Samples - can account for
stratification in concentration with depth or horizontally across a stream, but
still depends upon correlation to discharge for suitability in load estimation.
CJ Time-Weighted Composite Samples - not sufficient for load estimation
since they do not adequately reflect changes in discharge and concentration -
during the period over which samples are composited.
D Flow-Weighted Composite Samples - well-suited to load estimation, but
difficult to collect since stage-discharge relationship is needed and a "smart
sampler" is needed to trigger sampling as a function of flow rate. Projecting
sample size and number of bottles needed is difficult.
n Systematic Sampling - as efficient as, or more efficient than, simple random
sampling if the sampling interval is not equal to a multiple of any strong
period of fluctuation in the sampled population (e.g., sampling weekly on the
day when a particular pollutant is always at its peak level due to scheduling
by a discharger).
C3 Stratified Random Sampling - with most samples taken during periods of
high flow, can be of great importance in providing increased precision for a
given number of samples.
For many TMDLs, the daily pollutant load may be the .population unit of
greatest importance. In these cases, sampling should emphasize obtaining accu-
rate estimates of daily loads for the pollutant of interest. Since TMDLs establish
maximum wasteload and load allocations that can be discharged without violat-
ing water quality standards, the monitoring effort should provide data that will be
helpful in,making those allocations. For example, if water quality standards are
more likely violated under low-flow (dry weather) conditions, then the monitor-
ing should provide reliable data regarding low-flow loads. Conversely, in cases
where water quality standards are violated during high-flows (wet weather or
snowmelt) or as a result of loads from high flows, the monitoring should empha-
size high-flow monitoring. In other cases, such as those in which annual or sea-
sonal loads are critical, high quality estimates of low-flow and high-flow loads
may be equally important.
Sampling location should be determined based upon the monitoring objec-
tives, water resource characteristics, and source characteristics. For example, it
may be appropriate to sample at the outlets of tributaries to a lake, or above and
below a farm or set of farms, depending upon whether the objective is to estimate
lake loading from tributary watersheds or stream loading from an individual farm
or farms. Additional information regarding sampling location can be found in
existing guides (EPA, 1997a; USDA, 1996; Ponce, 1980).
Detailed discussions of statistical sampling approaches (e.g., random sam-
pling) can be found in several sources (EPA, 1997a; Richards, 1997; USDA,
1996; Gilbert, 1987). Older sampling equipment is described by Brakensiek, et
al. (1979), while USDA (1996) provides an overview of more current devices,
including a helpful list of references regarding sampling equipment.
Chapter 7-220:10/98
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Chapter 7: Load Estimation Techniques 221
Calculating Pollutant Loads
The pollutant load is the integral of flux overtime, but flux cannot be mea-
sured directly (Richards, 1997). In Figure 7-1 the flux is calculated as the prod-
uct of concentration and discharge, with appropriate conversion units. Each
calculated flux is a discrete value that is assumed to apply across the sampling
interval, which is 24 hours in this hypothetical example (daily composites). The
cumulative load in Figure 7-1 is determined by adding the calculated fluxes over
all sampling intervals.
Figure 7-1. Flux and cumulative load over time.
TTI—ii !rif'"i''i—i—i r !T. i i , , TI—\\—i—i—i—r v i i '
Time —>
• Load (tons) Q Discharge (cfs)
jffi TSS(mg/L) j§ Flux(lb/min)
Because there will be more discharge data than concentration data in almost
all chemical monitoring efforts, there will be a need to make estimates of concen-
tration, and therefore pollutant flux, for periods between water quality observa-
tions (Richards, 1997). Figure 7-2 illustrates how missing values can greatly
affect the calculated load estimates. • Load A is the same load as shown in Figure
7-1, whereas Load B was calculated after deleting every other concentration
value used to calculate Load A.
Figure 7-2. Effect of missing concentration data.
Time — >
Load A (tons) H Load 8 (tons)
Discharge (cfs)
Chapter 7-221:10/98
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222 Chapter 7: Load Estimation Techniques
Data gaps can be filled by estimating missing concentration values for pair-
ing with the flow data, or by adjusting the load estimate made from the observa-
tions where both flow and concentration were measured (Richards, 1997). Flow
data typically form the basis for making flux estimates for periods during which
water quality (concentration) data are lacking.
Some of the methods for estimating pollutant loads include numeric integra-
tion, the worked record procedure, averaging approaches, the flow interval tech-
nique, ratio estimators, regression approaches, and flow-proportional sampling
(Richards, 1997). A review of evaluative studies of .loading approaches has re-
sulted in the following points of consensus (Richards, 1997):
O Averaging methods (e.g., for monthly or quarterly loads) are generally bi-
ased, and the bias increases as the size of the averaging window increases
and/or the number of samples decreases. For example, an annual load deter-
mined by adding four quarterly loads will generally be more biased than an
annual load determined by adding 12 monthly loads.
CD In most studies, ratio approaches performed better than regression ap-
proaches, and both performed better than averaging approaches.
n Regression approaches can perform well if the relationship between flow
and concentration is well-defined, linear throughout the range of flows, and
constant throughout the year.
Methods for Estimating Pollutant Loads (Richards, 1997)
Numeric Integration - Total load is calculated as the sum of the individual loads calculated for each
sample.
Worked Record Procedure - Chemical observations are plotted onto a detailed hydrograph, and
smooth curves are drawn through chemical data points based upon analyst's experience with the
relationship of concentration and flow.
Averaging Approaches - Calculation that uses averaging of concentration and/or flow to estimate
loads. For example, analyst might multiply average weekly suspended solids concentration by daily
flow to estimate daily loads for the week.
Flow Interval Technique - Semi-graphical technique that calculates "interval loads" as the product
of average flux for a range of daily flow values times the number of days in which flows were within
the particular flow range.
Ratio Estimators - Total loads are estimated using a known relationship between the less-fre-
quently sampled parameter of interest and a more-frequently sampled parameter (e.g., discharge)
to fill gaps in the data record for the parameter of interest.
Regression Approaches - Relationship is established between concentration and flow based on
samples taken, and then applied to estimate concentration for days not sampled.
Flow-Proportional Sampling - Mechanical approach in which representative samples are taken to
determine concentration for a known discharge. Pollutant load is calculated as the sum of the
sample concentrations multiplied by the measured discharge
Chapter 7-222:10/98
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Chapter 7: Load Estimation Techniques 223
Greater detail and illustrative examples regarding averaging approaches,
regression approaches, ratio estimators, and sampling approaches can be found in
Richards (1997).
Estimating Pollutant Loads Through Modeling
Types of Models Available
Loading models include techniques primarily designed to predict pollutant
movement from the land surface to waterbodies (EPA, 1997f). Watershed load-
ing models range from simple loading rate assessments in which loads are a func-
tion of land use type only, to complex simulation techniques that more explicitly
describe the processes of rainfall, runoff, sediment detachment, and transport to
receiving waters. Some loading models operate on a watershed scale, integrating
all loads within a watershed, and some allow for the subdivision of the watershed
into contributing subbasins.
Field-scale models, which have traditionally specialized in agricultural sys-
tems, are loading models that are designed to operate on a smaller, more local-
ized scale. Field-scale models have often been employed to aid in the selection
of management measures and practices. For example, a dynamic simulation
model was used to predict the long-term patterns of phosphorus export from
fields under a variety of management scenarios (Cassell and Clausen, 1993). The
process model simulated the annual inputs and outputs of phosphorus, and was
determined by the authors to be useful for simulating long-term patterns. Process
models such as this one, however, are dependent upon local export coefficients
and a thorough understanding of pollutant transport processes.
Other types of models include receiving-water models, which emphasize the
response of a waterbody to pollutant loadings, flows, and ambient conditions,
and ecological models that simulate biological communities and their response to
stressors such as toxics and habitat modification (EPA, 19970- Integrated mod-
eling systems link models, data, and a user interface within a single system. The
advent of geographic information systems (GIS) has facilitated the development
of and expanded the capabilities of integrated modeling systems.
The emphasis of this section will be on watershed loading models. The
reader is encouraged to seek additional information regarding field-scale, eco-
logical, and integrated models in existing documents (EPA, 1997f; EPA, 1992a).
Watershed Loading Models
Watershed loading models are configured and characterized in several ways
(see Modeling Jargon), but they can be grouped into three general categories:
simple methods, mid-range models, and detailed models (EPA, 1997'f). The de-
fining characteristics of models are the degree .to which processes (and complexi-
ties of systems) are simplified and the time scale that is used for analysis and
display of output information.
Simple methods are generally used to provide quick and easy identification
of critical pollutant sources in the watershed. Detailed watershed models repre-
sent the other extreme, featuring costly and. time-consuming efforts to provide
Chapter 7-223:10/98
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224 Chapter 7: Load Estimation Techniques
quantitative estimates of pollutant loads from a range of management alterna-
tives. Richards (1997) cautions that modeling of agricultural settings is often
inadequate to evaluate the success of management practices in reducing loads
because there are mixed land uses that change annually and these land uses have
different loading rates. An additional concern is that most models fail to ad-
equately address stream channel and bank dynamics, including the impact of ---
management practices on these factors. Some detailed models such as
GLEAMS, however, attempt to capture the variability associated with cropping
practices and rotations in the agricultural setting.
Simple Watershed Methods
Uses
n Support assessment of relative significance of sources
O Guide decisions for management plans
O Focus continuing monitoring efforts
Features
O Typically derived from empirical relationships between physiographic
characteristics of the watershed and pollutant export
O Often applied using a spreadsheet or hand-held calculator
Pros
o Rapid
O Minimal data requirements (large-scale aggregation; low resolution)
O Minimal effort
Cons
O Output is typically mean annual values or storm loads
D Rough estimates of loadings
a Very limited predictive capability
a Low transferability to other regions due to empirical basis
a Do not consider degradation and transformation processes
D Few incorporate detailed representation of pollutant transport within and
from watershed
D Can not account for most management practices
Chapter 7-224:10/98
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Chapter 7: Load Estimation Techniques 225
Mid-range watershed models are generally midway between the cost, com-
plexity, and accuracy of simple methods and detailed watershed models. Mid-
range models provide qualitative estimates of management alternatives (EPA,
1997T).
Mid-Range Watershed Models
Uses
D Assist in defining target areas for pollution mitigation programs on watershed basis
O Support relative comparisons of management alternatives
Features
O Compromise between empiricism of simple methods and complexity of detailed
mechanistic models
• Use simplified relationships for the generation and transport of pollutants
• Greater reliance on site-specific data than for simple methods
• Can address land use patterns and landscape configurations in watersheds
O Typically require some calibration
O Often tailored to site-specific applications (e.g., agriculture only)
Pros
O Can assess seasonal or inter-annual variability of loadings, and long-term water
quality trends
O Those with continuous simulation can compare storms over a range of storm events
or conditions
D Those with GIS interface facilitate parameter estimation
D Relatively broad range of regional applicability
O Usually include detailed input-output features to simplify processing
O Often have built-in graphical and statistical capabilities
Cons
a Use of simplifying assumptions can limit accuracy of predictions
D Do not consider degradation and transformation processes
O Few incorporate detailed representation of pollutant transport within and from
watershed
a Can not account for most management practices
Figure 7-3 shows examples of models and integrated modeling systems for
load estimation. EPA's Compendium of Tools for Watershed Assessment and
TMDL Development has additional details regarding the capabilities, limitations,
and data requirements for these and other models (EPA, 1997f).
Chapter 7-225:10/98
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226 Chapter 7: Load Estimation Techniques
Detailed Watershed Models
Uses
G If properly applied, can provide accurate estimates of pollutant loads and impacts
on water
a Identify causes of problems rather than simply describing overall conditions
Features
O Use storm event or continuous simulation to predict flow and pollutant
concentraions for a range of flow conditions (small time steps)
O Algorithms more closely simulate the physical processes of infiltration, runoff,
pollutant accumulation, instream effects, and ground/surface water interaction
Pros
G Input/output have greater spatial and temporal resolution than simple and mid-
range models
O Detailed hydrologic simulations can be used to design potential control actions
O Linkage to biological modeling is possible
O Those with new interfaces and GIS linkages facilitate use of models
a Provide relatively accurate predictions of variable flows and water quality at any
point in a watershed if properly applied and calibrated
Cons
O Considerable time and expenditure required for data collection and model
application
G Complex — not designed for untrained staff
O Require rate parameters for flow velocities, settling, and decay
O Input data file preparation and calibration require professional training and
adequate resources
Figure 7-3. Load estimation models.
Watershed-Scale Loading Models
Simple Methods
EPA Screening
Simple Method
Regression Method
SLOSS-PHOSPH
Federal Highway
Administration Model
Watershed Mangement
Model
Field-Scale Loading Models
• CREAM/GLEAMS
• Opus
• WEPP
Mid-Range Models
SITEMAP
GWLF
Urban Catchment Model
Automated Q-ILLUDAS
AGNPS
SLAMM
Detailed Models
STORM
DR3M-QUAL
SWRRBWQ
SWMM
HSPF
Integrated Modeling Systems
PC-VIRGIS
WSTT
LWMM
G1SPLM
BASINS
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Chapter 7: Load Estimation Techniques 227
Modeling Jargon
Terms You Should Know When Communicating With Modelers
Deterministic models — Mathematical relationships based on physical or
mechanistic processes are represented in the model. For example, runoff output is
produced in response to precipitation input.
Empirical models — Mathematical relationships in the model (i.e., coefficients for
parameters) are based upon measured data rather than theoretical relationships.
Must be calibrated.
Steady-state models — Mathematical model of fate and transport that uses
constant values of input variables to predict constant values (e.g., receiving water
quality concentrations).
Dynamic models — Mathematical model describing the physical behavior of a
system or process and its temporal variability.
Hydrodynamic models — Mathematical model that describes circulation,
transport, and deposition processes in receiving waters.
Physical models — The building of a scale model of the system and testing it.
Distributed parameter models — Incorporate the influences of the spatially
variable, controlling parameters (e.g., topography, soils, land use) in a manner
internal to its computational algorithms (EPA, 1982a). Allows simultaneous
simulation of conditions at all points within the watershed. Also facilitates
incorporation of equations that represent unique processes that occur at only
specific points in the watershed.
Lumped parameter models — Use average values for characterizing the
influence of specific, non-uniform distributions of each parameter (e.g., soil type,
cover, slope steepness).
Calibrated models — Require calibration with measured data for each site-
specific application.
"Uncalibrated" or measured-parameter models — Can be used without
calibration. Use measured or estimated parameters.
Event-based simulatiqn — Modeling of individual storms. Does not simulate, or
account for, periods between storms.
Annualized — Modeling of a longer time series than individual storms. Event-
based model outputs can be annualized.
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228 Chapter 7: Load Estimation Techniques
Planning and Selection of Models
Setting modeling objectives should be the first step in developing a model-
ing approach. In some cases, the objectives may be achievable using a simple
model, but in other cases it may be necessary to perform complex modeling in-
volving more than one model. Criteria that apply in selecting a model may in-...
elude the value of the resource under consideration, data needs, hardware needs,
cost, accuracy required, type of pollutants/stressors, management considerations
such as long-term commitment to the modeling effort, availability of trained
personnel, user experience with the model, and acceptance of the model (EPA,
19970- It is also important in many cases to involve stakeholders from the outset
of modeling exercises to increase the potential for broad acceptance of modeling
results.
Once the modeling objectives are agreed upon, the following steps should
be taken to further define the modeling approach (EPA, 1997g):
1. Use available information to develop a good understanding of watershed char-
acteristics, watershed problems, and watershed hydrology.
2. Consult with program and project managers to develop a clear understanding of
project needs and modeling objectives.
3. Select a model or models that best meet the project needs and modeling objec-
tives.
4. Choose the processes to be simulated and the level of complexity, and focus on
the processes that govern the problems of concern.
5. Configure the watershed representation to the desired degree of complexity
including the number of subwatersheds, reaches, and land use categories.
6. Choose a simulation process such as single-event or continuous simulation
based upon the specified modeling objectives and the system being modeled.
7. Select the time step and imulation time frame necessary to meet the modeling
objectives.
8. Design a model calibration and validation process.
9. Evaluate the assumptions and limitations of the modeling approach.
10. Develop a post-processing data analysis and data interpretation plan.
For applications to nonpoint source problems, the key features of nonpoint
sources of pollution need to be fully considered, including but not limited to the
following:
1. Hydrology (i.e., rainfall, snowmelt, and sometimes irrigation) drives the pro-
cess.
2. Pollutant sources are land-based and distributed, with pollutant loads often
highly variable in both space and time.
Chapter 7-228:10/98
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Chapter 7: Load Estimation Techniques 229
3. Land use types range from highly urbanized to undisturbed forest.
4. Management measures and practices vary from non-structural (e.g., nutrient
management) to structural (e.g., waste storage ponds).
5. Land management and land cover change over time, including seasonal fertili-
zation, tillage, crop growth, road maintenance, and off-season inactivity.
Additional considerations and details regarding modeling approach, model
selection, and data requirements can be found in existing guidance documents
(EPA, 1997f; EPA, 1985).
Model Calibration and Validation
The analyst must evaluate how the model will be used to address manage-
ment or future conditions. The adequacy of the calibration and validation can be
evaluated based on consideration of the type of changes expected to occur, the
types of management expected, and the loading and assimilation processes that
dominate the system. In some cases, changes in land use distribution can be
modeled well by a calibrated system. In other cases, a new land use, such as a
new crop, may require that supplemental calibration be performed to account for
its unique features. Detailed discussions of model calibration and validation
steps and procedures can be found in existing documents (EPA, 1997f; EPA,
1993b; EPA, 1989b; EPA, 1985; ASCE, 1993; Haan etal., 1995; Donigian,
1983).
A very important consideration in estimating nonpoint
source loads is the quality and representativeness of the
water quality data used in model calibration. A water qual-
Calibration — process of adjusting J jty data set tnat does not include a representative sample of
output values to more closely agree ^ , , ... ,,._.._
with corresponding observed values. | relevant to the concern addressed in the modeling effort. For
example, if the goal is to determine the extent to which phos-
Validation — comparison of model • phorus loads are reduced through the implementation of
results with an independent data set • management measures in a watershed dominated by agricul-
(without further adjustment). • tura, nonpoint source impactS) it is important that runoff
Verification - examination of the I conditions are represented adequately in the calibration.
numerical technique in the computer
code to ascertain that it truly represents • II is ^so important that the water quality data used in
the conceptual model and that there are • model calibration coyer the same range of wet and dry con-
not inherent numerical problems. pi ditions that are to be used in model validation and predic-
tion. For example, measured loads to New York's Owasco
Lake were greater than estimates generated by a simple unit-
area loading method due largely to the fact that the measured loads were based
on sampling during wet years (Heidtke and Auer, 1993). The simple model used
in this example does not explicitly represent rainfall runoff processes, and is
therefore very sensitive to the conditions under which it is developed. An adjust-
ment of loading coefficients based upon data from the wet years would likely
result in over-prediction of long-term average annual loads.
Successful model validation should not be blindly interpreted to prove that a
model has predictive capabilities. In some cases, the calibration and validation
data sets may come from the same period prior to implementation of control
Chapter 7-229:10/98
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230 Chapter 7: Load Estimation Techniques
measures and practices. For example, if a data set from a period prior to imple-
mentation of measures or practices is arbitrarily split in half, with half of the data
used for calibration and the other half used for validation, then validation merely
confirms that the model can represent conditions prior to implementation of con-
trols. If the measures and practices are intended to change pollutant loads
through source reduction, delivery reduction, and/or runoff attenuation, then "
post-implementation water quality and flow may (and are expected to) respond
very differently to precipitation events as compared to pre-implementation condi-
tions. Thus, the model has not really been proven as a predictive tool because
the ability to forecast a change in water quality and flow has not been tested with
a data set that reflects the changed response to precipitation. Even if the calibra-
tion and validation data sets are determined to be independent through statistical
analyses, the predictive capabilities are not proven through successful validation
unless the validation data set is derived from or reflects conditions of the mod-
eled "future" condition. This is not to say, however, that validation is not impor-
tant. Successful validation will increase the credibility of modeling results, but
the results must be interpreted with care.
Model Calibration and Validation
A good calibration using bad data is a bad calibration.
Ensure that the water quality data used in the calibration and validation process
are representative of the true distribution of water quality conditions in the
watershed.
• DonYuse data sets with only low-flow concentrations to simulate high-flow
conditions.
• Do use data sets with concentration values covering the range of flow and land
management conditions in the watershed.
Land use and land management data should be logically linked both to the water
quality parameters simulated and to the sources and management measures
and practices that will be implemented.
• Don't calibrate nutrient concentrations against general land use variables that
cannot be logically linked to nutrient management.
• Do incorporate to the extent possible data that reflect long-term crop rotations,
erosion control, nutrient control, management at other significant sources, and
the control of other pollutants that will be managed and simulated in the
modeling.
Unit Loads
Several simple methods (see "Simple Watershed Methods" on p. 176) for
watershed loading determination use unit loads, or unit-area loads, to represent
pollutant contributions from various land uses. Unit loads are expressed as mass
per unit area per unit time. One concern associated with unit-load approaches is
the availability of good local data regarding the unit loads for watershed-specific
physical, chemical, and climatological conditions (Heidtke and Auer. 1993). In
Chapter 7-230:10/98
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Chapter 7: Load Estimation Techniques 231
the absence of local data, unit loads are approximated using values that may
come from nearby studies or studies conducted in distant regions, thus introduc-
ing error to the analysis.
Scale should be considered when selecting unit loads, or export coefficients.
A study of 210 paired observations of total phosphorus (TP) export taken from
38 studies showed that TP export in agricultural catchments is not a linear func-
tion of catchment area, but instead varies as the 0.77 power of drainage basin
area (T.-Prairie and Kalff, 1986). This decline in unit-area export was attribut-
able to the TP export from row crops and pasture catchments. In addition, the
study found that the unit-area export of TP from forested catchments did not
change a's catchment size increased.
Addressing Uncertainty in Modeling Predictions
Because models simplify the real world, the predictions from a model are
uncertain, and quantification of the prediction uncertainty should be included in
the modeling approach (EPA, 1980). Prediction uncertainty is caused by natural
process variability, and bias and error in sampling, measurement, and modeling.
Reliably estimated prediction uncertainty can be useful to the planner as a means
for judging the value of the prediction and assessing the risk of not achieving
management objectives (e.g., meeting the load allocation of a TMDL). Modeling
may also result in "unquantified supplemental uncertainty," which is uncertainty
introduced through such things as the use of inappropriate export coefficients.
This uncertainty, which is unknown to the analyst, is unquantified, and therefore
introduces hidden planning risks.
To address the high variability of pesticide loads, a Monte Carlo simulation
approach was developed and applied to estimate atrazine and carbofuran loads
from hypothetical com fields in Georgia and Iowa (Haith, 1985). The approach
incorporated mathematical models of weather, hydrology, and soil chemistry.
One advantage of this approach is the ability to generate a frequency distribution
of pollutant loads rather than just a single value, thus allowing an assessment of
the probability that any given single value for the pollutant load will occur.
Because of the complexity of quantifying modeling uncertainty, modelers
are encouraged to consult with trained statisticians to devise the best approach
for their modeling applications. Detailed examples of uncertainty analyses can
be found in existing documents (EPA, 1980; EPA, 1.989b; Haan, 1989; Beck,
1987).
Model Applications Using GIS Technology
A unit-load approach for estimating phosphorus loads to Owasco Lake in
New York used geographic information system (GIS) technology to distribute
land-based attributes within the watershed (Heidtke and Auer, 1993). The GIS
enabled the modelers to match unit loads with the appropriate areas within the
watershed in a distributed manner. GIS technology was also used to facilitate
watershed modeling with models such as AGNPS (AGricultural Non-Point
Source Pollution) (Line et al., 1997) and SWAT (Soil and Water Assessment
Tool) (Engel.etal. 1993).
Chapter 7-231:10/98
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232 Chapter 7: Load Estimation Techniques
Using BASINS to Develop a TMDL for Fecal Coliform Bacteria
Problem: The Lost River in the state of West Virginia exhibits water quality impairment due to
elevated levels of fecal coliform bacteria. Suspected sources of contamination include cattle .....
grazing and feedlots, poultry houses, failing septic systems, geese, wild turkey, and deer, as well
as point source dischargers. Section 303(d) of the Clean Water Act and EPA's Water Quality
Planning and Management Regulations (40 CFR Part 130) require states to develop Total
Maximum Daily Loads (TMDLs) for waterbodies that are not meeting designated uses under
technology-based controls. The TMDL process establishes the allowable loadings of pollutants or
other quantifiable parameters for a waterbody based on the relationship between pollution sources
and instream water quality conditions.
Approach: The U.S. EPA Better Assessment Science Integrating Point and Nonpoint Sources
(BASINS) system Version 2.0 (USEPA 1998) and the Nonpoint Source Model (NPSM) were
selected to predict the significance of fecal coliform sources and fecal coliform levels in the Lost
River watershed. BASINS is a multipurpose environmental analysis system designed for use in
performing watershed- and water quality-based studies. A geographic information system provides
the integrating framework for BASINS and allows for the display and analysis of a wide variety of
landscape information (e.g., land uses, monitoring stations, point source dischargers). NPSM
simulates nonpoint source runoff from selected watersheds, as well as the transport and flow of the
pollutants through stream reaches. A key reason for using BASINS as the modeling framework is
its ability to integrate both point and nonpoint source simulation, as well as its ability to assess
instream water quality response.
To obtain a spatial variation of the concentration of bacteria along the Lost River, the
watershed was subdivided into 11 subwatersheds. This allowed analysts to address the relative
contribution of sources within each subwatershed to the different segments of the river. The
watershed subdivision was based on a number of factors, including the locations of flow monitoring
stations, the locations of stream sampling stations, the locations of feedlots and poultry houses,
and land use coverage. To develop a representative linkage between the sources and the
instream water quality response in the 11 reaches of the Lost River, model parameters were
adjusted to the extent possible for both hydrology and bacteria loading.
Results: Output from NPSM indicates violations of the 200 cfu/100 mL geometric mean
standard throughout the Lost River watershed for the existing conditions using the representative
time period (October 1990 through September 1991). After applying the load allocations, the
NPSM model indicated that all 11 subwatersheds were in compliance with the fecal coliform
bacteria standard. The model analysis indicates that water quality standards will be achieved if
fecal coliform loads from pastureland are reduced by 38.34 percent, loads from forestland are
reduced 12.8 percent, and loads from cropland are reduced by 37.75 percent. No change in the
point source load was required. The load reductions at the source are expected to be sufficient to
meet the 30-day geometric mean, on a daily basis, throughout the year. The margin of safety, an
evaluation of the uncertainty in the TMDL, was included implicitly in the model setup and
formulation. Conservative assumptions included loads associated with wildlife, septic systems, and
existing BMP implementation. Further refinement and corresponding higher accuracy in the
analysis could be achieved by more detailed source characterization (actual daily or monthly
manure application rates), further evaluation of the viability and dieoff of fecal coliform in the
various types of manure, and continued data collection and calibration.
Attainment of the load reductions is expected through implementation of manure storage
and application guidelines, crop and pasture management, and wildlife management. No explicit
modeling of the BMP effectiveness was performed. Follow-up monitoring is expected to track
water quality improvements.
Chapter 7-232:10/98
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Glossary
10-year, 24-hour storm — A rainfall event of 24-hour duration and 10-year
frequency that is used to calculate the runoff volume and peak discharge rate to a
BMP.
25-year, 24-hour storm — A rainfall event of 24-hour duration and 25-year
frequency that is used to calculate the runoff volume and peak discharge rate to a
BMP.
ACP — Agricultural Conservation Program.
Adsorption — The adhesion of one substance to the surface of another.
Allelopathy — The inhibition of growth in, one species of plants by chemicals
produced in another species.
Aquifer — A saturated, permeable geologic unit of sediment or rock that can
transmit significant quantities of water under hydraulic gradients.
ASCS — Agricultural Stabilization and Conservation Service of USDA (now
called Farm Service Agency).
Animal unit — A unit of measurement for any animal feeding operation calcu-
lated by adding the following numbers: the number of slaughter and feeder cattle
multiplied by 1.0, plus the number of mature dairy cattle multiplied by 1.4, plus
the number of swine weighing over 25 kilograms (approximately 55 pounds)
multiplied by 0.4, plus the number of sheep multiplied by 0.1, plus the number of
horses multiplied by 2.0.
AUM — Animal unit month. A measure of average monthly stocking rate that is
the tenure of one animal unit for a period of 1 month. With respect to the litera-
ture reviewed for the grazing management measure, an animal unit is a mature,
1,000-pound cow or the equivalent based on average daily forage consumption of
26 pounds of dry matter per day (Platts, 1990). Alternatively, an AUM is the
amount of forage that is required to maintain a mature, 1,000-pound cow or the
equivalent for a one-month period. See animal unit for the NPDES definition.
Best management practice (BMP) -— A practice or combination of practices
that are determined to be the most effective and practicable (including techno-
logical, economic, and institutional considerations) means of controlling point
and nonpoint pollutants at levels compatible with environmental quality goals.
BMP system — A combination of two or more individual BMPs into a "system"
that functions to reduce the same pollutant.
Biochemical oxygen demand (BOD) — A quantitative measure of the strength
of contamination by organic carbon materials.
Chapter 8-233:10/98
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234 Chapter 8: Glossary
Chemigation — The addition of one or more chemicals to the irrigation water.
Conservation management system (CMS) — a generic term used by the NRCS
that includes any combination of conservation practices and management that
achieves a level of treatment of the five natural resources that satisfies criteria
contained in the USDA-Natural Resource Conservation Service National Hand-
book of Conservation Practices, such as a resource management system or an
acceptable management system.
Critical area — An area or source of nonpoint source pollutants identified in a
watershed or project area as having the most significant impact on the impaired
use of the receiving waters.
CZARA — Coastal Zone Act Reauthorization Amendments of 1990.
Designated use — A beneficial use type established by a State for each water
resource and specified in water quality standards, whether or not it is being at-
tained.
Denitriflcation — The chemical or biochemical reduction of nitrate or nitrite to
gaseous nitrogen, either as molecular nitrogen or as an oxide of nitrogen.
Deposition — The accumulation of material left in a new position by a natural
transporting agent such as water, wind, ice, or gravity, or by the activity of man.
Drainage area — Watershed; an area of land that drains to one point.
EPA — United States Environmental Protection Agency
Erosion — Wearing away of the land surface by running water, glaciers, winds,
and waves. The term erosion is usually preceded by a definitive term denoting
the type or source of erosion such as gully erosion, sheet erosion, or bank ero-
sion.
Eutrophication — The natural process whereby a lake or other body of water
evolves from low productivity and low nutrient concentrations to high productiv-
ity and high nutrient levels that is greatly accelerated by nutrient enrichment
from human activities. Results of eutrophication can include algal blooms, low
dissolved oxygen, and changes in community composition.
Fertigation — Application of plant nutrients in irrigation water.
FOTG — USDA-NRCS's Field Office Technical Guide.
Integrated Pest Management (IPM) — A pest population management system
that anticipates and prevents pests from reaching damaging levels by using all
suitable tactics including natural enemies, pest-resistant plants, cultural manage-
ment, and the judicious use of pesticides, leading to an economically sound and
environmentally safe agriculture.
Lateral — Secondary or side channel, ditch, or conduit."
Leachate — Liquids that have percolated through a soil and that contain sub-
stances in solution or suspension.
Chapter 8-234:10/98
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Chapter 8: Glossary 235
Management measures — As defined in section 6217(g)(5) of CZARA; "eco-
nomically achievable measures for the control of the addition of pollutants from
existing and new categories and classes of nonpoint sources of pollution, which
reflect the greatest degree of pollutant reduction achievable through the applica-
tion of the best available nonpoint source control practices, technologies, pro-
cesses, siting criteria, operating methods, and other alternatives." —
MCL — Maximum contaminant level. The enforceable standard or number
against which your system's water samples are judged for compliance with U.S.
Environmental Protection Agency regulations.
Micronutrient — A plant nutrient found in relatively small amounts (<100 mg
kg'1) in plants. These are usually B, Cl, Cu, Fe, Mn, Mo, Ni, Co, and Zn.
Nitrogen — An element occurring in manure and chemical fertilizer that is es-
sential to the growth and development of plants, but which, in excess, can cause
water to beqome polluted and threaten aquatic animals.
NFS pollution — Nonpoint source pollution; pollution originating from diffuse
areas (land surface or atmosphere) having no well-defined source.
Natural Resource Conservation Service (NRCS) — An agency of the U.S.
Department of Agriculture.
Nutrients — Elements or compounds essential as raw materials for organism
growth and development, such as carbon, nitrogen, phosphorus, etc.
Pasture — Those improved lands that are primarily used for the production of
adapted domesticated forage plants for livestock.
Phosphorus — An element occurring in manure and chemical fertilizer that is
essential to the growth and development of plants, but which, in excess, can
cause water to become polluted and threaten aquatic animals.
Range — Those lands on which the native or introduced vegetation (climax or
natural potential plant community ) is predominantly grasses, grasslike plants,
forbs, or shrubs suitable for grazing or browsing use. Range includes natural
grassland, savannas, many wetlands, some deserts, tundra, and certain forb and
shrub communities.
Return flow — That portion or the water diverted from a stream that finds its
way back to the stream channel either as surface or underground flow.
Resource management system (RMS) — A term used by NRCS defined as a
combination of NRCS conservation practices and management identified by land.
or water uses that, when installed, will prevent resource degradation and permit
sustained use by meeting criteria established in the FOTG for treatment of soil,
water, air, plant, and animal resources.
Riparian areas — Vegetated ecosystems along a water body through which
energy, materials, and water pass. Riparian areas characteristically have a high
water table and are subject to periodic flooding and influence from the adjacent
water body.
Chapter 8-235:10/98
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236 Chapter 8: Glossary
Runoff — The portion of rainfall or snow melt that drains off the land into
ditches and streams by overland flow.
Rural Clean Water Program (RCWP) — A 15-year federally sponsored
nonpoint source pollution control program initiated in 1980 as an experimental
effort to address agricultural nonpoint source pollution problems in watersheds -
throughout the United States.
Sediment — The solid material, both mineral and organic, that is in suspension,
is being transported, or has been moved from its site or origin by air, water, grav-
ity, or ice.
Sedimentation — The process of sediment deposition. .
Tailwater — Irrigation water that reaches the lower end of a field.
Tillage — The mechanical manipulation of the soil profile for any purpose; but
in agriculture, it is usually restricted to modifying soil conditions, managing crop
residues and/or weeds, or incorporating chemicals for crop production.
Total Maximum Daily Load (TMDL) — The loading capacity is the maximum
amount of pollution that a water body can receive without violating water quality
standards. Total Maximum Daily Loads are the sum of point and nonpoint
source loads.
Watershed — A geographic area in which water, sediments, and dissolved mate-
rials drain to a common outlet- a point on a larger stream, a lake, an underlying
aquifer, an estuary, or an ocean. This area is also called the drainage basin of the
receiving water body.
Watershed approach — A coordinating framework for environmental manage-
ment that focuses public and private sector efforts to address the highest priority
problems within hydrologically defined geographic areas, taking into consider-
ation both ground and surface water.
Chapter 8-236:10/98
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262 Chapter 9: References
Chapter 9-262:10/98
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Appendix
Appendix A: Best Management Practices — Definitions
and Descriptions
Best management practices mentioned in this guidance are listed in alphabetical
order below. The NRCS or other code number, if any, is given for each BMP,
followed by a short definition. Additional explanatory text about selected BMPs is
presented in italicized text below the practice, code, and definition.
Access Road (560): A travelway constructed as part of a conservation plan.
. Animal Trails and Walkways (575): A livestock trail or walkway constructed to
improve grazing distribution and access to forage and water.
Bedding (310): Plowing, blading, or otherwise elevating the surface of flat land
into a series of broad, low ridges separated by shallow, parallel channels.
Brush (and Weed) Management (314): Managing and manipulating stands of
brush (and weeds) on range, pasture, and recreation and wildlife areas by me-
chanical, chemical, or biological means or by prescribed burning. (Includes reduc-
ing excess brush (and weeds) to restore natural plant community balance and
manipulating stands of undesirable plants through selective and patterned treat-
ments to meet specific needs of the land and objectives of the land user.)
Improved vegetation quality and the decrease in runoff from the practice will
reduce the amount of erosion and sediment yield. Improved vegetative cover acts
as a filter strip to trap the movement of dissolved and sediment attached sub-
stances, such as nutrients and chemicals from entering downstream water
courses. Mechanical brush management may initially increase sediment yields
because of soil disturbances and reduced vegetative cover. This is temporary
until revegetation occurs.
Channel Vegetation (322): Establishing and maintaining adequate plants on chan-
nel banks, berms, spoil, and associated areas.
Chiseling and Subsoiling (324): Loosening the soil, without inverting and with a
minimum of mixing of the surface soil, to shatter restrictive layers below normal
plow depth that inhibit water movement or root development.
Composting Facility (317): A facility for the biological stabilization of waste
organic material.
The purpose is to treat waste organic material biologically by producing a hu-
mus-like material that can be recycled as a soil amendment and fertilizer substi-
tute or otherwise utilized in compliance with all laws, rules, and regulations.
Conservation Cover (327): Establishing and maintaining perennial vegetative
cover to protect soil and water resources on land retired from agricultural produc-
tion.
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264 Chapter 10: Appendix
Agricultural chemicals are usually not applied to this cover in large quantities
and surface and ground water quality may improve where these material are not
used. Ground cover and crop residue will be increased with this practice. Ero-
sion and yields of sediment and sediment related stream pollutants should de-
crease. Temperatures of the soi, I surface runoff and receiving water may be
reduced. Effects will vary during the establishment period and include increases
in runoff, erosion and sediment yield. Due to the reduction of deep percolation,
the leaching of soluble material will be reduced, as will be the potential for caus-
ing saline seeps. Long-term effects of the practice would reduce agricultural
nonpoint sources of pollution to all water resources.
Conservation Cropping Sequence (328): An adapted sequence of crops designed
to provide adequate organic residue for maintenance or improvement of soil tilth.
This practice reduces erosion by increasing organic matter, resulting in a reduc-
tion of sediment and associated pollutants to surface waters. Crop rotations that
improve soil tilth may also disrupt disease, insect and weed reproduction cycles,
reducing the need for pesticides. This removes or reduces the availability of some
pollutants in the watershed. Deep percolation may carry soluble nutrients and
pesticides to the ground water. Underlying soil layers, rock and unconsolidated
parent material may block, delay, or enhance the delivery of these pollutants to
ground water. The fate of these pollutants will be site specific, depending on the
crop management, the soil and geologic conditions.
Conservation Tillage (329) (NoTill): Any tillage and planting system in which at
least 30 percent of the soil surface is covered by plant residue after planting to
reduce soil erosion by water; or, where soil erosion by wind is the primary con-
cern, at least 1,000 pounds per acre of flat small grain residue-equivalent are on
the surface during the critical erosion period.
This practice reduces soil erosion, detachment and sediment transport by provid-
ing soil cover during critical times in the cropping cycle. Surface residues reduce
soil compaction from raindrops, preventing soil sealing and increasing infiltra-
tion. This action may increase the leaching of agricultural chemicals into the
ground water.
In order to maintain the crop residue on the surface it is difficult to incorporate
fertilizers and pesticides. This may increase the amount of these chemicals in the
runoff and cause more surface water pollution.
The additional organic material on the surface may increase the bacterial action
on and near the soil surface. This may tie-up and then breakdown many pesti-
cides which are surface applied, resulting in less pesticide leaving the field. This
practice is more effective in humid regions.
With a no-till operation the only soil disturbance is the planter shoe and the
compaction from the wheels. The surface applied fertilizers and chemicals are
not incorporated and often are not in direct contact with the soil surface. This
condition may result in a high surface runoff of pollutants (nutrient and pesti-
cides). Macropores develop under a no-till system. They permit deep percolation
and the transmittal of pollutants, both soluble and insoluble to be carried into
the deeper soil horizons and into the ground water.
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Chapter 10: Appendix 265
Reduced tillage systems disrupt or break down the macropores, incidentally in-
corporate some of the materials applied to the soil surface, and reduce the ef-
fects ofwheeltrack compaction. The results are less runoff and less pollutants in
the runoff.
Constructed Wetland (ASCS-999): A constructed aquatic ecosystem with rooted
emergent hydrophytes designed and managed to treat agricultural wastewater.
This is a conservation practice for which NRCS has developed technical require-
ments under a trial program leading to the development of a conservation prac-
tice standard.
Contour Farming (330): Farming sloping land in such a way that preparing land,
planting, and cultivating are done on the contour. This includes following estab-
lished grades of terraces or diversions.
This practice reduces erosion and sediment production. Less sediment and re-
lated pollutants may be transported to the receiving waters.
Increased infiltration may increase the transportation potential for soluble sub-
stances to the ground water.
Contour Orchard and Other Fruit Area (331): Planting orchards, vineyards, or
small fruits so that all cultural operations are done on the contour.
Contour orchards and fruit areas may reduce erosion, sediment yield, and pesti-
cide concentration in the water lost. Where inward sloping benches are used, the
sediment and chemicals will be trapped against the slope. With annual events,
the bench may provide 100 percent trap efficiency. Outward sloping benches may
allow greater sediment and chemical loss.
The amount of retention depends on the slope of the bench and the amount of
cover. In addition, outward sloping benches are subject to erosion from runoff
from benches immediately above them. Contouring allows better access to rills,
permitting maintenance that reduces additional erosion. Immediately after estab-
lishment, contour orchards may be subject to erosion and sedimentation in ex-
cess of the now contoured orchard. Contour orchards require more fertilization
and pesticide application than did the native grasses that frequently covered the
slopes before orchards were started. Sediment leaving the site may carry more
adsorbed nutrients and pesticides than did the sediment before the benches were
established from uncultivated slopes. If contoured orchards replace other crop or
intensive land use, the increase or decrease in chemical transport from the site
may be determined by examining the types and amounts of chemicals used on the
prior land use as compared to the contour orchard condition.
Soluble pesticides and nutrients may be delivered to and possibly through the
root zone in an amount proportional to the amount of soluble pesticides applied,
the increase in infiltration, the chemistry of the pesticides, organic and clay con-
tent of the soil, and amounts of surface residues. Percolating water below the
root zone may carry excess solutes or may dissolve potential pollutants as they
move. In either case, these solutes could reach ground water supplies and/or
surface downslope from the contour orchard area. The amount depends on soil
type, surface water quality, and the availability of soluble material (natural or
applied).
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266 Chapter 10: Appendix
Contour Stripcropping (585): Growing crops in a systematic arrangement of
strips or bands on the contour to reduce water erosion. The crops are arranged so
that a strip of grass or close-growing crop is alternated with a strip of clean-tilled
crop or fallow or a strip of grass is alternated with a close-growing crop.
This practice may reduce erosion and the amount of sediment and related sub-
stances delivered to the surface waters. The practice may increase the amount of
water that infiltrates into the root zone, and, at the time there is an overabun-
dance of soil water, this water may percolate and leach soluble substances into
the ground water.
Controlled Drainage (335): Control of surface and subsurface water through use
of drainage facilities and water control structures.
The purpose is to conserve water and maintain optimum soil moisture to (J)
store and manage infiltrated rainfall for more efficient crop production; (2) im-
prove surface water quality by increasing infiltration, thereby reducing runoff,
which may carry sediment and undesirable chemicals; (3) reduce nitrates in the
drainage water by enhancing conditions for denitrification; (4) reduce subsid-
ence and wind erosion of organic soils; (5) hold water in channels in forest areas
to act as ground fire breaks; and (6) provide water for wildlife and a resting and
feeding place for waterfowl.
Cover and Green Manure Crop (340): A crop of close-growing grasses, le-
gumes, or small grain grown primarily for seasonal protection and soil improve-
ment. It usually is grown for 1 year or less, except where there is permanent cover
as in orchards.
Erosion, sediment and adsorbed chemical yields could be decreased in conven-
tional .tillage systems because of the increased period of vegetal cover. Plants
will take up available nitrogen and prevent its undesired movement. Organic
nutrients may be added to the nutrient budget reducing the need to supply more
soluble forms. Overall volume of chemical application may decrease because the
vegetation will supply nutrients and there may be allelopathic effects of some of
the types of cover vegetation on weeds. Temperatures of ground and surface
waters could slightly decrease.
Critical Area Planting (342): Planting vegetation, such as trees, shrubs, vines,
grasses, or legumes, on highly erodible or critically eroding areas. (Does not in-
clude tree planting mainly for wood products.)
This practice may reduce soil erosion and sediment delivery to surface waters.
Plants may take up more of the nutrients in the soil, reducing the amount that
can be washed into surface waters or leached into ground water.
During grading, seedbed preparation, seeding, and mulching, large quantities of
sediment and associated chemicals may be washed into surface waters prior to
plant establishment-
Crop Residue Use (344): Using plant residues to protect cultivated fields during
critical erosion periods.
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Chapter 10: Appendix 267
When this practice is employed, raindrops are intercepted by the residue, reduc-
ing detachment, soil dispersion, and soil compaction. Erosion may be reduced
and the delivery of sediment and associated pollutants to surface water may be
reduced. Reduced soil sealing, crusting and compaction allows more water to
infiltrate, resulting in an increased potential for leaching of dissolved pollutants
into the ground water.
Crop residues on the surface increase the microbial and bacterial action on or
near the surface. Nitrates and surface-applied pesticides may be tied-up and less
available to be delivered to surface and ground water. Residues trap sediment
and reduce the amount carried to surface water. Crop residues promote soil ag-
gregation and improve soil tilth.
Cross Wind Ridges/StripCropping/Trap Strips (589): Ridges formed by tillage
or planting, crops grown in strips, or herbaceous cover aligned perpendicular to
the prevailing wind direction.
Deferred Grazing (352): Postponing grazing or resting grazing land for pre-
scribed period.
In areas with bare ground or low percent ground cover, deferred grazing will
reduce sediment yield because of increased ground cover, less ground surface
disturbance, improved soil bulk density characteristics, and greater infiltration
rates. Areas mechanically treated will have less sediment yield when deferred to
encourage revegetation. Animal waste would not be available to the area during
the time of deferred grazing and there would be less opportunity for adverse
runoff effects on surface or aquifer water quality. As vegetative cover increases,
the filtering processes are enhanced, thus trapping more silt and nutrients as
well as snow if climatic conditions for snow exist. Increased plant cover results
in a greater uptake and utilization of plant nutrients.
Delayed Seed Bed Preparation (354): Any cropping system in which all of the
crop residue and volunteer vegetation are maintained on the soil surface until ap-
proximately 3 weeks before the succeeding crop is planted, thus shortening the
bare seedbed period on fields during critical erosion periods.
The purpose is to reduce soil erosion by maintaining soil cover as long as practi-
cal to minimize raindrop splash and runoff during the spring erosion period.
Other purposes include moisture conservation, improved water quality, increased
soil infiltration, improved soil tilth, and food and cover for wildlife.
Dikes (356): An embankment constructed of earth or other suitable materials to
protect land against overflow or to regulate water.
Where dikes are used to prevent water from flowing onto the floodplain, the pol-
lution dispersion effect of the temporary wetlands and backwater are decreased.
The sediment, sediment-attached, and soluble materials being transported by the
water are carried farther downstream. The final fate of these materials must be
investigated on site. Where dikes are used to retain runoff on the floodplain or in
wetlands, the pollution dispersion effects of these areas may be enhanced. Sedi-
ment and related materials may be deposited, and the quality of the water flow-
ing into the stream from this area will be improved.
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268 Chapter 10: Appendix
Dikes are used to prevent wetlands and to form wetlands. The formed areas may
be fresh, brackish^ or saltwater wetlands. In tidal areas, dikes are used to stop
saltwater intrusion, and to increase the hydraulic head of fresh water which will
force intruded salt water out of the aquifer. During construction there is a poten-
tial of heavy sediment loadings to the surface waters. When pesticides are used
to control the brush on the dikes and fertilizers are used for the establishment
and maintenance of vegetation, there is the possibility for these materials to be
washed into the surface waters.
Diversion (362): A channel constructed across the slope with a supporting ridge
on the lower side.
This practice will assist in the stabilization of a watershed, resulting in the re-
duction of sheet and rill erosion by reducing the length of slope. Sediment may
be reduced by the elimination of ephemeral and large gullies. This may reduce
the amount of sediment and related pollutants delivered to the surface waters.
Fencing (382): Enclosing or dividing an area of land with a suitable permanent
structure that acts as a barrier to livestock, big game, or people (does not include
temporary fences).
Fencing is a practice that can be on the contour or up and down slope. Often a
fence line has grass and some shrubs in it. When a fence is built across the slope
it will slow down runoff, and cause deposition of coarser grained materials re-
ducing the amount of sediment delivered downslope. Fencing may protect ripar-
ian areas which act as sediment traps and filters along voter channels and
impoundments.
Livestock have a tendency to walk along fences. The paths become bare channels
which concentrate and accelerate runoff causing a greater amount of erosion
within the path and where the path/channel outlets into another channel. This
can deliver more sediment and associated pollutants to surface waters. Fencing
can have the effect of concentrating livestock in small areas, causing a concen-
tration of manure which may wash off into the stream, thus causing surface wa-
ter pollution.
Field Stripcropping (586): Growing crops in a systematic arrangement of strips
or bands across the general slope (not on the contour) to reduce water erosion. The
crops are arranged so that a strip of grass or a close-growing crop is alternated
with a clean-tilled crop or fallow.
This practice may reduce erosion and the delivery of sediment and related sub-
stances to the surface waters. The practice may increase infiltration and, when
there is sufficient water available, may increase the amount of teachable pollut-
ants moved toward the ground water.
Since this practice is not on the contour there will be areas of concentrated flow,
from which detached sediment, adsorbed chemicals and dissolved substances will
be delivered more rapidly to the receiving waters. The sod strips will not be effi-
cient filter areas in these areas of concentrated flow.
Field Border (386): A strip of perennial vegetation established at the edge of a
field by planting or by converting it from trees to herbaceous vegetation or shrubs.
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Chapter 10: Appendix 269
This practice reduces erosion by having perennial vegetation on an area of the
field. Field borders serve as "anchoring points "for contour rows, terraces,
diversions, and contour strip cropping. By elimination of the practice of tilling
and planting the ends up and down slopes, erosion from concentrated flow in
furrows and long rows may be reduced. This use -may reduce the quantity of sedi-
ment and related pollutants transported to the surface waters.
Field windbreak (392): A strip or belt of trees or shrubs established in or adja-
cent to a field as a barrier to wind.
Filter Strip (393): A strip or area of vegetation for removing sediment, organic
matter, and other pollutants from runoff and wastewater.
Filter strips for sediment and related pollutants meeting minimum requirements
may trap the coarser grained sediment. They may not filter out soluble or sus-
pended fine-grained materials. When a storm causes runoff in excess of the de-
sign runoff, the filter may be flooded and may cause large loads of pollutants to
be released to the surface water. This type of filter requires high maintenance
and has a relative short service life and is effective only as long as the flow
through the filter is shallow sheet flow.
Filter strips for runoff jrom concentrated livestock areas may trap organic mate-
rial, solids, materials which become adsorbed to the vegetation or the soil within
the filter. Often they will not filter out soluble materials. This type of filter is
often wet and is difficult to maintain.
Filter strips for controlled overlandflow treatment of liquid wastes may effec-
tively filter out pollutants. The filter must be properly managed and maintained,
including the proper resting time. Filter strips on forest land may trap coarse
sediment, timbering debris, and other deleterious material being transported by
runoff This may improve the quality of surface water and has little effect on
soluble material in runoff or on the quality of ground water.
All types of filters may reduce erosion in the area on which they are constructed.
Filter strips trap solids from the runoff flowing in sheet flow through the filler.
Coarse-grained and fibrous materials are filtered more efficiently than fine-
grained and soluble substances. Filter strips work for design conditions, but
when flooded or overloaded they may release a slug load of pollutants into the
surface water.
Floodwater Diversion (400): A graded channel with a supporting embankment or
dike on the lower side constructed on lowland subject to flood damage.
Forest Land Erosion Control System (408): Application of one or more erosion
control measures on forest land. Erosion control system includes the use of conser-
vation plants, cultural practices, and erosion control structures on disturbed forest
land for the control of sheet and rill erosion, gully formation, and mass soil move-
ment.
Grade Stabilization Structure (410): A structure used to control the grade and
head cutting in natural or artificial channels.
Where reduced stream velocities occur upstream and downstream from the struc-
ture, streambank and streambed erosion will be reduced. This will decrease the
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270 Chapter 10: Appendix
yield of sediment and sediment-attached substances. Structures that trap sedi-
ment will improve downstream water quality. The sediment yield change will be a
function of the sediment yield to the structure, reservoir trap efficiency and of
velocities of released water. Ground water recharge may affect aquifer quality
depending on the quality of the recharging water. If the stored water contains
only sediment and chemical with low water solubility, the ground water quality
should not be affected.
Grassed Waterway (412).: A natural or constructed channel that is shaped or
graded to required dimensions and established in suitable vegetation for the stable
conveyance of runoff.
This practice may reduce the erosion in a concentrated flow area, such as in a
gully or in ephemeral gullies. This may result in the reduction of sediment and
substances delivered to receiving waters. Vegetation may act as a filter in remov-
ing some of the sediment delivered to the waterway, although this is not the pri-
mary function of a grassed waterway.
Any chemicals applied to the waterway in the course of treatment of the adjacent
cropland may wash directly into the surface waters in the case where there is a
runoff event shortly after spraying.
When used as a stable outlet for another practice, waterways may increase the
likelihood of dissolved and suspended pollutants being transported to surface
waters when these pollutants are delivered to the waterway.
Grasses and Legumes in Rotation (411): Establishing grasses and legumes or a
mixture of them and maintaining the stand for a definite number of years as part
of a conservation cropping system.
Reduced runoff and increased vegetation may lower erosion rates and subse-
quent yields of sediment and sediment-attached substances. Less applied nitro-
gen may be required to grow crops because grasses and legumes will supply
organic nitrogen. During the period of the rotation when the grasses and le-
gumes are growing, they will take up more phosphorus. Less pesticides may simi-
larly be required with this practice. Downstream water temperatures may be
lower depending on the season when this practice is applied. There will be a
greater opportunity for animal waste management on grasslands because ma-
nures and other wastes may be applied for a longer part of the crop year.
Grazing Land Mechanical Treatment (548): Renovating, contour furrowing,
pitting, or chiseling native grazing land by mechanical means.
Heavy Use Area Protection (561): Protecting heavily used areas by establishing
vegetative cover, by surfacing with suitable materials, or by installing needed
structures.
Protection may result in a general improvement of surface water quality through
the reduction of erosion and the resulting sedimentation. Some increase in ero-
sion may occur during and immediately after construction until the disturbed
areas are fully stabilized.
Some increase in chemicals in surface water may occur due to the introduction of
fertilizers for vegetated areas and oils and chemicals associated- with paved ar-
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Chapter 10: Appendix 271
eas. Fertilizers and pesticides used during operation and maintenance may be a
source of water pollution.
Paved areas installed for livestock use will increase organic, bacteria, and nutri-
ent loading to surface waters. Changes in ground water quality will be minor.
Nitrate nitrogen applied as fertilizer in excess of vegetation needs may move with
infiltrating waters. The extent of the problem, if any, may depend on the actual
amount of water percolating below the root zone.
Hedgerow Planting (422): Establishing a living fence of shrubs or trees in,
across, or around a field.
Hillside Ditch (423): A channel that has a supporting ridge on the lower side
constructed across the slope at definite vertical intervals and gradient, with" or
without a vegetative barrier.
Improved Water Application (197): Increase efficiency and decrease water run-
off from irrigation of pastures.
Irrigation Canal or Lateral (320): A permanent irrigation canal or lateral con-
structed to convey water from the source of supply to one or more farms.
Irrigation Field Ditch (388): A permanent irrigation ditch constructed to convey
water from the source of supply to a field or fields in a farm distribution system.
The standard for this practice applies to open channels and elevated ditches of
25 ft3/'second or less capacity formed in and with earth materials.
Irrigation field ditches typically carry irrigation water from the source of supply-
ing to afield or fields. Salinity changes may occur in both the soil and water.
This will depend on the irrigation water quality, the level of water management,
and the geologic materials of the area. The quality of ground and surface water
may be altered depending on environmental conditions. Water lost from the irri-
gation system to downstream runoff may contain dissolved substances, sediment,
and sediment-attached substances that may degrade water quality and increase
water temperature. This practice may make water available for wildlife, but may
not significantly increase habitat.
Irrigation Land Leveling (464): Reshaping the surface of land to be irrigated to
planned grades.
The effects of this practice depend on the level of irrigation water management.
If plant root zone soil water is properly managed, then quality decreases of sur-
face and ground water may be avoided. Under poor management., ground and
surface water quality may deteriorate. Deep percolation and recharge with poor
quality water may lower aquifer quality. Land leveling may minimize erosion and
when runoff occurs concurrent sediment yield reduction. Poor management may
cause an increase in salinity of soil, ground and surface waters. High efficiency
surface irrigation is more probable when earth moving elevations are laser con-
trolled. .
Irrigation Pit or Regulating Reservoir, Irrigation Pit (552A): A small storage
reservoir constructed to regulate or store a supply of water for irrigation.
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272 Chapter 10: Appendix
Irrigation Pit or Regulating Reservoir, Regulating Reservoir (552B): A small
storage reservoir constructed to regulate or store a supply of water for irrigation.
Irrigation Storage Reservoir (436): An irrigation water storage structure made
by constructing a dam.
Irrigation System, Drip or Trickle (441): A planned irrigation system in which
all necessary facilities are installed for efficiently applying water directly to the
root zone of plants by means of applicators (orifices, emitters, porous tubing, or
perforated pipe) operated under low pressure (Figure 2-20). The applicators can
be placed on or below the surface of the ground (Figure 2-21).
Surface water quality may not be significantly affected by transported substances
because runoff is largely controlled by the system components (practices).
Chemical applications may be applied through the system. Reduction of runoff
will result in less sediment and chemical losses from the fie Id during irrigation.
If excessive, local, deep percolation should occur, a chemical hazard may exist to
shallow ground water or to areas where geologic materials provide easy access
to the aquifer.
Irrigation System, Sprinkler (422): A planned irrigation system in which all
necessary facilities are installed for efficiently applying water by means of perfo-
rated pipes or nozzles operated under pressure.
Proper irrigation management controls runoff and prevents downstream surface
water deterioration from sediment and sediment attached substances. Over irri-
gation through poor management can produce impaired water quality in runoff
as well as ground water through increased percolation. Chemigation with this
system allows the operator the opportunity to mange nutrients, wastewater and
pesticides. For example, nutrients applied in several incremental applications
based on the plant needs may reduce ground water contamination considerably,
compared to one application during planting. Poor management may cause pol-
lution of surface and ground water. Pesticide drift from chemigation may* also be
hazardous to vegetation, animals, and surface water resources. Appropriate
safety equipment, operation and maintenance of the system is needed with
chemigation to prevent accidental environmental pollution or back/lows to water
sources.
Irrigation System, Surface and Subsurface (443): A planned irrigation system
in which all necessary water control structures have been installed for efficient
distribution of irrigation water by surface means, such as furrows, borders, con-
tour levees, or contour ditches, or by subsurface means.
Operation and management of the irrigation system in a manner which allows
little or no runoff may allow small yields of sediment or sediment-attached sub-
stances to downstream waters. Pollutants may increase if irrigation water man-
agement is not adequate. Ground water quality from mobile, dissolved chemicals
may also be a hazard if irrigation water management does not prevent deep per-
colation. Subsurface irrigation that requires the drainage and removal of excess
water from the field may discharge increased amounts of dissolved substances
such as nutrients or other salts to surface water. Temperatures of downstream
water courses that receive runoff waters may be increased. Temperatures of
downstream waters might be decreased with subsurface systems when excess
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Chapter 10: Appendix 273
water is being pumped from the field to lower the water table. Downstream tem-
peratures should not be affected by subsurface irrigation during summer months
if lowering the water table is not required. Improved aquatic habitat may occur if
runoff or seepage occurs from surface systems or from pumping to lower the
water table in subsurface systems.
Irrigation System, Tailwater Recovery (447): A facility to collect, store, and
transport irrigation tailwater for reuse in the farm irrigation distribution system.
The reservoir will trap sediment and sediment-attached substances from runoff
waters. Sediment and chemicals will accumulate in the collection facility by en-
trapping which would decrease downstream yields of these substances.
Salts, soluble nutrients, and soluble pesticides will be collected with the runoff
and will not be released to surface waters. Recovered irrigation water with high
salt and/or metal content will ultimately have to be disposed of in an environ-
mentally safe manner and location. Disposal of these waters should be part of
the overall management plan. Although some ground water recharge may occur,
little if any pollution hazard is usually expected.
Irrigation Water Conveyance, Ditch and Canal Lining, Flexible Membrane
(428B): A fixed lining of impervious material installed in an existing or newly
constructed irrigation field ditch or irrigation canal or lateral.
Irrigation Water Conveyance, Ditch and Canal Lining, Galvanized Steel
(428C): A fixed lining of impervious material installed in an existing or newly
constructed irrigation field ditch or irrigation canal or lateral.
Irrigation Water Conveyance, Ditch and Canal Lining, Nonreinforced Con-
crete (428A): A fixed lining of impervious material installed in an existing or
newly constructed irrigation field ditch or irrigation canal or lateral.
Irrigation Water Conveyance, High-Pressure, Underground, Plastic (430DD):
A pipeline and appurtenances installed in an irrigation system.
Irrigation Water Conveyance, Low-Pressure, Underground, Plastic (430EE):
A pipeline and appurtenances installed in an irrigation system.
Irrigation Water Conveyance, Pipeline, Aluminum Tubing (430AA): A pipe-
line and appurtenances installed in an irrigation system.
Irrigation Water Conveyance, Pipeline, Asbestos-Cement (430BB): A pipeline
and appurtenances installed in an irrigation system.
Irrigation Water Conveyance, Pipeline, Nonreinforced Concrete (430CC): A
pipeline and appurtenances installed in an irrigation system.
Irrigation Water Conveyance, Pipeline, Reinforced Plastic Mortar (430GG):
A pipeline and appurtenances installed in an irrigation system.
Irrigation Water Conveyance, Pipeline, Rigid Gated Pipeline (430HH): A
rigid pipeline, with closely spaced gates, installed as part of a surface irrigation
system.
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274 Chapter 10: Appendix
Irrigation Water Conveyance, Pipeline, Steel (430FF): A pipeline and appurte-
nances installed in an irrigation system.
Irrigation Water Management (449): Determining and controlling the rate,
amount, and timing of irrigation water in a planned and efficient manner.
Management of the irrigation system should provide the control needed to mini-
mize losses of water, and yields of sediment and sediment-attached and dissolved
substances, such as plant nutrients and herbicides, from the system. Poor man-
agement may allow the loss of dissolved substances from the irrigation system to
surface or ground water. Good management may reduce saline percolation from
geologic origins. Returns to the surface water system would increase downstream
water temperature.
The purpose is to effectively use available irrigation water supply in managing
and controlling the moisture environment of crops to promote the desired crop
response, to minimize soil erosion and loss of plant nutrients, to control undesir-
able water loss, and to protect water quality.
To achieve this purpose the irrigator must have knowledge of(l) how to deter-
mine when irrigation water should be applied, based on the rate of water used by
crops and on the stages of plant growth; (2) how to measure or estimate the
amount of water required for each irrigation, including the leaching needs; (3)
the normal time needed for the soil to absorb the required amount of water and
how to detect changes in intake rate; (4) how to adjust water stream size, appli-
cation rate, or irrigation time to compensate for changes in such factors as in-
take rate or the amount of irrigation runoff from an area; (5) how to recognize
erosion caused by irrigation; (6) how to estimate the amount of irrigation runoff
from an area; and (7) how to evaluate the uniformity of water application.
Landslide Treatments (453): Treatments to prevent or stabilize landslides to
protect life and property and to prevent excessive erosion and sedimentation.
Lined Waterway or Outlet (468): A waterway or outlet having an erosion-resis-
tant lining of concrete, stone, or other permanent material.
The lined section extends up the side slopes to a designed depth. The earth above
the permanent lining may be vegetated or otherwise protected.
This practice may reduce the erosion in concentrated flow areas resulting in the
reduction of sediment and substances delivered to the receiving waters.
When used as a stable outlet for another practice, lined waterways may increase
the likelihood of dissolved and suspended substances being transported to sur-
face waters due to high flow velocities.
Livestock Exclusion (472): Excluding livestock from an area not intended for
grazing.
Livestock exclusion may improve water quality by preventing livestock from be-
ing in the water or walking down the banks, and by preventing manure deposi-
tion in the stream. The amount of sediment and manure may be reduced in the
surface water. This practice prevents compaction of the soil by livestock and
prevents losses of vegetation and undergrowth. This may maintain or increase
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Chapter 10: Appendix 275
evapotranspiration. Increased permeability may reduce erosion and lower sedi-
ment and substance transportation to the surface waters. Shading along streams
and channels resulting from the application of this practice may reduce surface
water temperature.
Mole Drain (482): An underground conduit constructed by pulling a'bullet-shaped
cylinder through the soil.
Mulching (484): Applying plant residues or other suitable materials not produced
on the site to the soil surface.
Nutrient Management (590): Managing the amount, form, placement, and timing
of applications of plant nutrients.
Pasture and Hay Planting (512): Establishing and reestablishing long-term
stands of adapted species of perennial, biennial, orreseeding forage plants. (In-
cludes pasture and hayland renovations. Does not include grassed waterways or
outlets on cropland.)
The long-term effect will be an increase in the quality of the surface water due to
reduced erosion and sediment delivery; Increased infiltration and subsequent
percolation may cause more soluble substances to be carried to ground water.
Pasture and Hayland Management (510): Proper treatment and use of pasture or
hayland.
With the reduced runoff there will be less erosion, less sediment and substances
transported to the surface waters. The increased infiltration increases the possi-
bility of soluble substances leaching into the ground water.
Pipeline (516): Pipeline installed for conveying water for livestock or for recre-
ation
Pipelines may decrease sediment, nutrient, organic, and bacteria pollution from
livestock. Pipelines may afford the opportunity for alternative water sources
other than streams and lakes, possibly keeping the animals away from the stream
or impoundment. This will prevent bank destruction with resulting sedimentation,
and will reduce animal waste deposition directly in the water. The reduction of
concentrated livestock areas will reduce manure solids, nutrients, and bacteria
that accompany surface runoff.
Planned Grazing System (556): A practice in which two or more grazing units
are alternately rested and grazed in a planned sequence for a period of years, and
rest periods may be throughout the year or during the growing season of key
plants.
Planned grazing systems normally reduce the system time livestock spend in each
pasture. This increases quality and quantity of vegetation. As vegetation quality
increases, fiber content in manure decreases which speeds manure decomposition
and reduces pollution potential. Freeze-thaw, shrink-swell, and other natural soil
mechanisms can reduce compacted layers during the absence of grazing animals.
This increases infiltration, increases vegetative growth, slows runoff, and im-
proves the nutrient and moisture filtering and trapping ability of the area.
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276 Chapter 10: Appendix
Decreased runoff will reduce the rate of erosion and movement of sediment and
dissolved and sediment-attached substances to downstream water courses. No
increase in ground water pollution hazard would be anticipated from the use of
this practice.
Pond (378): A water impoundment made by constructing a dam or an embank-
ment or by excavation of a pit or dugout.
Ponds may trap nutrients and sediment which wash into the basin. This removes
these substances from downstream. Chemical concentrations in the pond may be
higher during the summer months. By reducing the amount of water that flows in
the channel downstream, the frequency of flushing of the stream is reduced and
there is a collection of substances held temporarily within the channel. A pond
may cause more teachable substances to be carried into the ground water.
Precision Land Forming (462): Reshaping the surface of land to planned grades.
Prescribed Burning (338): Applying fire to predetermined areas under conditions
under which the intensity and spread of the fire are controlled.
When the area is burned in accordance with the specifications of this practice
the nitrates with the burned vegetation will be released to the atmosphere. The
ash will contain phosphorous and potassium which will be in a relatively highly
soluble form. If a runoff event occurs soon after the burn there is a probability
that these two materials may be transported into the ground water or into the
surface water. When in a soluble state the phosphorous and potassium will be
more difficult to trap and hold in place. When done on range grasses the growth
of the grasses is increased and there will be an increased tie-up of plant nutrients
as the grasses' growth is accelerated.
Prescribed Grazing (Proper Grazing Use)(528A): Grazing at an intensity that
will maintain enough cover to protect the soil and maintain or improve the quan-
tity and quality of desirable vegetation.
Planned grazing systems normally reduce the system time livestock spend in each
pasture. This increases quality and quantity of vegetation. As vegetation quality
increases, fiber content in manure decreases which speeds manure decomposition
and reduces pollution potential. Freeze-thaw, shrink-swell, and other natural soil
mechanisms can reduce compacted layers during the absence of grazing animals.
This increases infiltration, increases vegetative growth, slows runoff, and im-
proves the nutrient and moisture filtering and trapping ability of the area.
Decreased runoff will reduce the rate of erosion and movement of sediment and
dissolved and sediment-attached substances to downstream water courses. No
increase in ground water pollution hazard would be anticipated from the use of
this practice.
Increased vegetation slows runoff and acts as a sediment filter for sediments and
sediment attached substances, uses more nutrients, and reduces raindrop splash.
Adverse chemical effects should not be anticipated from the use of this practice.
Proper Woodland Grazing (530): Grazing wooded areas at an intensity that will
maintain adequate cover for soil protection and maintain or improve the quantity
and quality of trees and forage vegetation.
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Chapter 10: Appendix 277
This practice is applicable on wooded areas producing a significant amount of
forage that can be harvested without damage to other values. In these areas
there should be no detrimental effects on the quality of surface and ground water.
Any time this practice is applied there must be a detailed management and graz-
ing plan.
Pumped Well Drain (532): A well sunk into an aquifer from which water is
pumped to lower the prevailing water table.
Range Planting (Seeding)(550): Establishing adapted plants by seeding on native
grazing land (does not include pasture and hayland planting).
Increased erosion and sediment yield may occur during the establishment of this
practice. This is a temporary situation and sediment yields decrease when re-
seeded area becomes established. If chemicals are used in the reestablishment
process, chances of chemical runoff into downstream water courses are reduced
if application is applied according to label instructions. After establishment of
the grass cover, grass sod slows runoff, acts as a filter to trap sediment, sediment
attached substances, increases infiltration, and decreases sediment yields.
Rangeland Fertilization (203): To apply the appropriate nutrients to improve the
quantity and quality of forage for livestock and wildlife.
Regulating Water in Drainage Systems (554): Controlling the removal of sur-
face or subsurface runoff, primarily through the operation of water-control struc-
tures.
Riparian Forest Buffer (Field Windbreak) (392): A strip or belt of trees or
shrubs established in or adjacent to a field.
Rock Barrier (555): A rock retaining wall constructed across the slope to form
and support a bench terrace that will control the flow of water and check erosion
on sloping land.
Roof Runoff Management (558): A facility for controlling and disposing of run-
off water from roofs.
This practice may reduce erosion and the delivery of sediment and related sub-
stances to surface waters. It will reduce the volume of water polluted by animal
wastes. Loadings of organic waste, nutrients, bacteria, and salts to surface water
will be reduced as water is prevented from flowing across concentrated waste
areas, barnyards, roads and alleys. Pollution and erosion will be reduced.
Flooding may be prevented and drainage may improve.
Runoff Management System (570): A system for controlling excess runoff
caused by construction operations at development sites, changes in land use, or
other land disturbances.
Sediment Basin (350): A basin constructed to collect and store debris or sedi-
ment.
Sediment basins will remove sediment, sediment-associated materials and other
debris from the water which is passed on downstream. Due to the detention of the
runoff in the basin, there is an increased opportunity for soluble materials to be
leached toward the ground water.
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278 Chapter 10: Appendix
Soil and Crop Water Use Data: From soils information the available water-
holding capacity of the soil can be determined along with the amount of water that
the plant can extract from the soil before additional irrigation is needed.
Water use information for various crops can be obtained from various USD A
publications.
The purpose is to allow the water user to estimate the amount of available water
remaining in the root zone at any time, thereby indicating when the next irriga-
tion should be scheduled and the amount of water needed. Methods to measure
or estimate the soil moisture should be employed, especially for high-value crops
or where the water-holding capacity of the soil is low,
Spring Development (574): Improving springs and seeps by excavating, cleaning,
capping, or providing collection and storage facilities.
There will be negligible long-term water quality impacts with spring develop-
ments. Erosion and sedimentation may occur from any disturbed areas during
and immediately after construction, but should be short-lived. These sediments
will have minor amounts of adsorbed nutrients from soil organic matter.
Stock Trails or Walkways (575): A livestock trail or walkway constructed to
improve grazing distribution and access to forage and water. This practice may be
used to reduce livestock concentrations, facilitate proper grazing use and planned
grazing systems.
Stream Channel Stabilization (584): Stabilizing the channel of a stream with
suitable structures.
Stream Corridor Improvement (204): Restoration of a modified or damaged
stream to a more natural state using bioengineering techniques to protect the banks
and reestablish the riparian vegetation.
Stream Crossing (interim): A stabilized area to provide access across a stream
for livestock and farm machinery.
The purpose is to provide a controlled crossing or watering access point for
livestock along with access for farm equipment, in order to control bank and
streambed erosion, reduce sediment and enhance water quality, and maintain or
improve wildlife habitat.
Streambank and Shoreline Protection (580): Using vegetation or structures to
stabilize and protect banks and streams, lakes, estuaries, or excavated channels
against scour and erosion.
Stripcropping, Contour (585): Growing crops in a systematic arrangement of
strips or bands on the contour to reduce water erosion. The crops are arranged so
that a strip of grass or close-growing crop is alternated with a strip of clean-tilled
crop or fallow or a strip of grass is alternated with a close-growing crop.
Structure for Water Control (587): A structure in an irrigation, drainage, or
other water management systems that conveys water, controls the direction or rate
of flow, or maintains a desired water surface elevation.
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Chapter 10: Appendix 279
Subsurface Drain (606): A conduit, such as corrugated plastic tile, or pipe, in-
stalled beneath the ground surface to collect and/or convey drainage water.
Soil water outlet to surface water courses by this practice may be low in concen-
trations of sediment and sediment-adsorbed substances and that may improve
stream water quality. Sometimes the drained soil water is high in the concentra-
tion of nitrates and other dissolved substances and drinking water standards may
be exceeded. If drainage water that is high in dissolved substances is able to
recharge ground water, the aquifer quality may become impaired. Stream water
temperatures may be reduced by water drainage discharge. Aquatic habitat may
be altered or enhanced with the increased cooler water temperatures.
Surface Drainage Field Ditch (607): A graded ditch for collecting excess water
in a field.
From erosive fields, this practice may increase the yields of sediment and sedi-
ment-attached substances to downstream water courses because of an increase in
runoff. In other fields, the location of the ditches may cause a reduction in sheet
and rill erosion and ephemeral gully erosion. Drainage of high salinity areas
may raise salinity levels temporarily in receiving waters. Areas of soils with high
salinity that are drained by the ditches may increase receiving waters. Phospho-
rus loads resulting from this practice may increase eutrophication problems in
ponded receiving waters. Water temperature changes will probably not be signifi-
cant. Upland wildlife habitat may be improved or increased although the habitat
formed by standing water and wet areas may be decreased.
Surface Drainage, Main or Lateral (608): An open drainage ditch constructed to
a designed size and grade.
Surface Roughening (609): Roughening the soil surface by ridge or clod-forming
tillage.
Terrace (600): An earthen embankment, a channel, or combination ridge and
channel constructed across the slope.
This practice reduces the slope length and the amount of surface runoff which
passes over the area downslope from an individual terrace. This may reduce the
erosion rate and production of sediment within the terrace interval. Terraces trap
sediment and reduce the sediment and associated pollutant content in the runoff
water which enhance surface water quality. Terraces may intercept and conduct
surface runoff at a nonerosive velocity to stable outlets, thus, reducing the occur-
rence of ephemeral and classic gullies and the resulting sediment. Increases in
infiltration can cause a greater amount of soluble nutrients and pesticides to be
leached into the soil. Underground outlets may collect highly soluble nutrient
and pesticide leachates and convey runoff directly to an outlet. Terraces may
increase the delivery of pollutants to surface waters. Terraces increase the op-
portunity to leach salts below the root zone in the soil. Terraces may have a det-
rimental effect on water quality if they concentrate and accelerate delivery of
dissolved or suspended nutrient, salt, and pesticide pollutants to surface or
ground waters.
Tree Planting (612): To set tree seedlings or cuttings in the soil.
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280 Chapter 10: Appendix
Trough or Tank (614): A trough or tank, with needed devices for water control
and waste water disposal, installed to provide drinking water for livestock.
By the installation of a trough or tank, livestock may be better distributed over
the pasture, grazing can be better controlled, and surface runoff reduced, thus
reducing erosion. By itself this practice will have only a minor effect on water
quality; however when coupled with other conservation practices, the beneficial
effects of the combined practices may be large. Each site and application should
be evaluated on its own merits.
Use Exclusion (472): Excluding livestock from an area not intended for grazing.
Livestock exclusion may improve water quality by preventing livestock from be-
ing in the water or walking down the banks, and by preventing manure deposi-
tion in the stream. The amount of sediment and manure may be reduced in the
surface water. This practice prevents compaction of the soil by livestock and
prevents losses of vegetation and undergrowth. This may maintain or increase
evapotranspiration. Increased permeability may reduce erosion and lower sedi-
ment and substance transportation to the surface waters. Shading along streams
and channels resulting from the application of this practice may reduce surface
water temperature.
Waste Management System (312): A planned system in which all necessary
components are installed for managing liquid and solid waste, including runoff
from concentrated waste areas, in a manner that does not degrade air, soil, or wa-
ter resources.
Waste Storage Pond (425): An impoundment made by excavation or earth fill for
temporary storage of animal or other agricultural wastes.
This practice reduces the direct delivery of polluted water, which is the runoff
from manure stacking areas andfeedlots and barnyards, to the surface waters.
This practice may reduce the organic, pathogen, and nutrient loading to surface
waters. This practice may increase the dissolved pollutant loading to ground
water by leakage through the sidewalls and bottom.
Waste Storage Structure (313): A fabricated structure for temporary storage of
animal wastes or other organic agricultural wastes.
This practice may reduce the nutrient, pathogen, and organic loading to the
surface waters. This is accomplished by intercepting and storing the polluted
runoff from manure stacking areas, barnyards andfeedlots. This practice will not
eliminate the possibility of contaminating surface and ground water; however, it
greatly reduces this possibility.
Waste Treatment Lagoon (359): An impoundment made by excavation or earth
fill for biological treatment of animal or other agricultural wastes.
This practice may reduce polluted surficial runoff and the loading oforganics,
pathogens, and nutrients into the surface waters. It decreases the nitrogen con-
tent of the surface runoff from feedlots by denitrification. Runoff is retained long
enough that the solids and insoluble phosphorus settle and form a sludge in the
bottom of the lagoon. There may be some seepage through the sidewalls and the
bottom of the lagoon. Usually the long-term seepage rate is. low enough, so that
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Chapter 10: Appendix 281
the concentration of substances transported into the ground water does not reach
an unacceptable level.
Waste Utilization (633): Using agricultural wastes or other wastes on land in an
environmentally acceptable manner while maintaining or improving soil and plant
resources.
Waste utilization helps reduce the transport of sediment and related pollutants to
the surface water. Proper site selection, timing of application and rate of appli-
cation may reduce the potential for degradation.of surface and ground water.
This practice may increase microbial action in the surface layers of the soil,
causing a reaction which assists in controlling pesticides and other pollutants by
keeping them in place in the field.
Mortality and other compost, when applied to agricultural land, will be applied
in accordance with the nutrient management measure. The composting facility
may be subject to State regulations and will have a written operation and man-
agement plan if SCS practice 317 (composting facility) is used.
Water and Sediment Control Basin (638): An earthen embankment or a combi-
nation ridge and channel generally constructed across the slope and minor water-
courses to form a sediment trap and water detention basin.
The practice traps and removes sediment and sediment-attached substances from
runoff. Trap control efficiencies for sediment and total phosphorus that qre
transported by runoff may exceed 90 percent in silt loam soils. Dissolved sub-
stances, .such as nitrates, may be removed from discharge to downstream areas
because of the increased infiltration. Where geologic condition permit, the prac-
tice will lead to increased loadings of dissolved substances toward ground water.
Water temperatures of surface runoff, released through underground outlets, may
increase slightly because of longer exposure to warming during its impoundment.
Water Table Control (641): Water table control through proper use of subsurface
drains, water control structures, and water conveyance facilities for the efficient
removal of drainage water and distribution of irrigation water.
The water table control practice reduces runoff, therefore downstream sediment
and sediment-attached substances yields will be reduced. When drainage is in-
creased, the dissolved substances in the soil water will be discharged to receiving
water and the quality of water reduced. Maintaining a high water table, espe-
cially during the nongrowing season, will allow denitrification to occur and
reduce the nitrate content of surface and ground water by as much as 75 percent.
The use of this practice for salinity control can increase the dissolved substance
loading of downstream waters while decreasing the salinity of the soil. Installa-
tion of this practice may create temporary erosion and sediment yield hazards
but the completed practice will lower erosion and sedimentation levels. The ef-
fect of the water table control of this practice on downstream wildlife communi-
ties may vary with the purpose and management of the water in the system.
Waterspreading (640): Diverting or collecting runoff from natural channels,
gullies, or streams with a system of dams, dikes, ditches, or other means, and
spreading it over relatively flat areas.
Chapter 10-281:10/98
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282 Chapter 10: Appendix
Well (642): A well constructed or improved to provide water for irrigation, live-
stock, wildlife, or recreation.
The location of the well must consider the natural water quality and the hazards
of its use in potentially contaminating the environment. Hazards exist during well
development and its operation and maintenance. Care must be taken to prevent
contamination of the aquifer from back flushing, accident, or flow down the an-
nular spacing between the well casing and the bore hole.
Water-Measuring Device: An irrigation water meter, flume, weir, or other water-
measuring device installed in a pipeline or ditch.
The measuring device must be installed between the point of diversion and water
distribution system used on the field. The device should provide a means to mea-
sure the rate of flow. Total water volume used may then be calculated using rate.
of flow and time, or read directly, if a totalizing meter is used.
The purpose is to provide the irrigator the rate of flow and/or application of
water, and the total amount of water applied to the field with each irrigation.
Wetland Restoration (657): A rehabilitation of a drained or degraded wetland
where the soils, hydrology, vegetative community, and biological habitat are re-
turned to the natural condition to the extent practicable.
Wildlife Upland Habitat Management (645): Creating, maintaining, or enhanc-
ing upland habitat for desired wildlife species.
Wildlife Wetland Habitat Management (644): Creating, maintaining, or enhanc-
ing wetland habitat for desired wildlife species.
Windbreak/Shelterbelt Establishment (380): Linear plantings of single or mul-
tiple rows of trees or shrubs established next to farmstead, feedlots, and rural
residences as a barrier to wind,
Windbreak/Shelterbelt Renovation (650): Restoration or preservation of an
existing windbreak, including widening, replanting, or replacing trees.
Chapter 10-282:10/98
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Chapter 10: Appendix 283
Appendix B: SCS Field Office Technical Guide Policy
Chapter 10-283:10/98
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284 Chapter 10: Appendix
Chapter 10-284:10/98
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/S>N United States Soil P.O. Box 2890
*/' Department ot Conservation . Washington. D.C.
Vl Agriculture Service 20013
February 12, 1990
GENERAL MANUAL
450-TCH
AMENDMENT - 4 (PART 401)
SUBJECT.: TCH - SCS TECHNICAL GUIDE POLICY
Purpose. To transmit revised Soil Conservation Service (SCS)
Field Office Technical Guide (FOTG) policy.
Effective Date. This policy is effective when received.
Background. SCS Field Office Technical Guide policy was revised
by 450-GM, Amendment 3, February 1987. As a result of numerous
comments received on that policy, the National Technical Guide
Committee (NTGC) prepared a draft revision for review by selected
states and by technical guide committees at the National
Technical Centers. Amendment 4 is the result of comments on the
draft.
Explanation. Policy transmitted by this amendment contains ""
guidance by which FOTG are established, changed and maintained.
Following are the more important changes from Amendment 3:
l. State and NTC responsibilities in Section 401.01 for
maintaining up-to-date information in technical guides have been
amplified.
2. The descriptions of the six resource concerns in Section
401.03(b)(3)(iii) have been replaced with descriptions of the
five resources: soil, water, air, plants, and animals.
3. Criteria for treatment required to achieve an RMS for each of
the five resources have been clearly stated in Section
401.03(b)(iv).
4. The process for developing criteria for treatment required to
achieve an Acceptable Management System (AMS), a new concept, has
been stated in section 401.03(b)(3)(v).
5. Explanation of the content of the National Handbook for
Conservation Practices (NHCP) in Subpart B has been revised to
remove redundant statements and clearly states responsibilities
for changes in NHCP and for issuance and review of interim
standards.
6. Section V of the FOTG, described in section 401.03(b)(5), has
been totally revised and is now named "Conservation Effects."
Guidance on effects is provided to aid in conservation planning
activities.
DIST: GM
Tne Soil Conservation Service
-------
Filing Instructions;
l. Remove and discard existing GM 450, Part 401, dated
February 1987. (Amendment 3)
2. Replace with the enclosed GM 450, Part 401, dated
January 1990.
Directives Cancelled;
1. Remove and discard National Instruction No. 450-301,
dated October 5, 1979.
WILSON SCALING
Chief
Enclosures
-------
PART 401 - TECHNICAL GUIDES
SUBPART A - POLICY AND RESPONSIBILITIES
401.00(d)(5)
401.00 General.
(a) This part states policy for establishing, changing, and maintaining technical guides.
It also establishes supporting committees for maintaining those guides.
(b) The Soil Conservation Service (SCS) is responsible for providing national leader-
ship and administration of programs to conserve soil, water, and related resources on the
private lands of the Nation. A primary goal is to provide technical assistance to decision-
makers for the planning and implementation of a system of conservation practices and man-
agement which achieves a level of natural resource protection that prevents degradation and
permits sustainable use. In cases where degradation has already occurred, the goal is to re-
store the resource to the degree practical to permit sustainable use. Technical guides provide
procedures and criteria for the formulation and evaluation of resource management systems
which achieve these goals and, when needed, for the formulation and evaluation of acceptable
management systems which achieve these goals to the extent feasible.
(c) Technical guides are primary technical references for SCS. They contain technical
information about conservation of soil, water, air, and related plant and animal resources.
Technical guides used in any office are to be localized so that they apply specifically to the
geographic area for which they are prepared. These documents are referred to as Field Office
Technical Guides (FOTGs). Appropriate parts of FOTG will be systematically automated as
data bases, computer programs, and other electronic-based materials compatible with the
Computer Assisted Management and Planning System (CAMPS) are developed.
(d) Technical guides provide:
(1) Soil interpretations and potential productivity within alternative levels of man-
agement intensity and conservation treatment;
(2) Technical information for achieving SCS's and the decisionmaker's objectives;
(3) Information for interdisciplinary planning for the conservation of soil, water, and
related resources;
(4) A basis for identifying resource management system (RMS) options and, when
needed, acceptable management system (AMS) options and components thereof;
(5) Information on effects of resource management systems, acceptable management
(450-GM,, Amend. 4, February 1990) 401-1
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Part 401-Technical Guides
401.00(d)(6)
systems, and their component practices;
(6) Criteria to evaluate the quality of RMS options, AMS options, and components
thereof;
(7) Standards and specifications for conservation practices;
(8) Information for evaluating the economic feasibility of conservation practices and
resource management system options;
(9) Information for locating and identifying cultural resources and methods to ac-
count for their significance; and
(10) Technical material for training employees.
401.01 Responsibilities.
(a) National Headquarters (NHQ).
(1) The Deputy Chief for Technology has national leadership for policy and proce-
dures for developing and using the FOTG.
(2) The Director, Ecological Sciences Division (ECS), chairs the National Technical
Guide Committee (NTGC).
(3) The NTGC makes recommendations to the Deputy Chief for Technology regard-
ing technical guide policy and procedure.
(b) National Technical Centers (NTCs).
(1) NTC directors are responsible for establishing a Technical Guide Committee
(TGC) at each NTC.
(2) The TGC provides guidance to states in developing FOTGs.
(3) NTC directors establish procedures to coordinate NTC technical review and
concurrence of state developed material that affect either policy or technical aspects
in all sections of the FOTG.
(4) The TGC coordinates NTC technical review and concurrence of state developed
material as described in (3). The NTC director will inform the state conservationist
(STC) of NTC action and comments.
(5) The TGC refers proposed changes in the National Handbook of Conservation
Practices (NHCP) to NTGC for action.
401 - 2 (450-GM, Amend. 4, February 1990)
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Subpart A - Policy and Responsibilities
(6) NTC provide states with examples of guidance documents for RMS and AMS
options, displays of conservation effects, and guidance documents developed to meet
specific program requirements. NTC has primary technical oversight
(7) NTC directors are responsible for coordination and consistency among NTC
regions.
(c) State offices.
(1) The state conservationist (STC) is responsible for the development, quality,
coordination, use, and maintenance of FOTG in his/her state.
(2) The STC will:
(i) Coordinate FOTG contents across state lines where Major Land Resource
Areas are shared to achieve reasonable uniformity between and among states; '*
(ii) Request appropriate assistance from the NTC director to prepare, revise, and
maintain the FOTG and to correlate FOTG contents, with adjoining states;
(iii) Submit to the NTC for review and concurrence all state developed materials
that affect either policy or technical aspects in all FOTG sections prior to issu-
ance;
(iv) Propose interim standards, variances, or changes in national standards to the
NTC director for action;
(v) Establish a state TGC and appoint membership;
(vi) Establish criteria for RMS and AMS with concurrence by the NTC; and
(vii) Establish procedures for maintaining up-to-date data in FOTG. All FOTG
material is to be reviewed by the designated state discipline specialist at least once
every two years. Material is to be updated as necessary to maintain technical
adequacy. Each technical guide subsection described in section 401.03(b) is to
contain a table of contents showing the issue date and the date of the last review.
(d) Area offices.
(1) The area conservationist (AC) will:
(i) Coordinate the development, use, and maintenance of FOTG in the field
offices supervised;
(450-GM, Amend. 4, February 1990) 401-3
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Part 401 -Technical Guides
(ii) Work with the specialists in the state offices to achieve high-quality FOTG;
and
(iii) Establish an area-level TGC if necessary.
(e) Field offices.
( 1 ) District conservationists (DC) will:
(i) Take the lead to develop and assemble the FOTG;
(ii) Use and maintain the FOTG in the office(s) they supervise;
(iii) Ensure that all field office technical assistance is based on FOTG contents;
(iv) Identify needed changes and/or additions; and
(v) Request specialist help to make improvements.
(2) All field office employees are responsible for identifying the need for improve-
ments and for informing the DC of those needs.
401.02 National Technical Guide Committee (NTGC).
(a) Membership. The members of the NTGC are:
(1) Director, Ecological Sciences Division (chairperson);
(2) Director, Engineering Division;
(3) Director, Economics and Social Sciences Division;
(4) Director, Soil Survey Division;
(5) Director, Land Treatment Program Division;
(6) Director, Conservation Planning Division;
(7) Director, Watershed Projects Division;
(8) Director, Basin and Area Planning Division;
(9) Director of an NTC (on a 1 -year rotation);
(10) Executive Secretary (appointed by the chairperson); and
(11) Chair of National Conservation Practice Standards Subcommittee (NCPSS)
(appointed by the NTGC chairperson).
( 12) A representative from the Extension Service will be invited to participate in
all NTGC meetings.
(b) Responsibilities.
(1) Keep national FOTG policy and procedures current by recommending policy
changes to the Deputy Chief for Technology.
401-4 (450-GM, Amend. 4, February 1990)
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Subpart A - Policy and Responsibilities
(2) Respond to requests for FOTG policy and procedure clarification.
(3) Designate members of the National Conservation Practice Standards Subcom-
mittee.
(4) Act upon recommendations from NCPSS.
(5) Coordinate policy and procedures established to automate FOTG contents and
functions in SCS operations.
(6) Create ad hoc subcommittees as necessary.
(7) Receive and act upon requests, recommendations, referrals, and suggestions
from the NTC TGC.
(c) NTGC operation.
(1) NTGC will meet quarterly and otherwise as convened by the chairperson.
(2) Materials for consideration by the NTGC will be sent to the chairperson.
(3) Minutes of each meeting will be sent to each member, the Deputy Chiefs for
Technology and Programs, and NTC directors.
(4) Matters requiring action will be acted upon within 45 days of receipt
401.03 Content of technical guides.
(a) Technical guides contain Sections I through V and appropriate subsections. Those
sections are:
(1) Section I • General Resource References;
(2) Section H - Soil and Site Information;
(3) Section m - Conservation Management Systems;
(4) Section IV • Practice Standards and Specifications; and
(5) Section V - Conservation Effects.
(b) The following are descriptions of technical guide sections and subsections:
(1) Section I - General Resource References.
This section lists references and other information for use in understanding the Meld office working
area or in making decisions about resource use and management systems. The actual references
listed are to be filed to the extent possible in the same location as the FOTG. References kept in
other locations will be cross-referenced. The following are subsections of Section I of the FOTG.
(i) Reference lists. These include handbooks, manuals, and reports commonly used in
resource conservation planning and implementation activities such as irrigation and drain-
age guides; the National List of Scientific Plant Names (NLSPN); the National Register of
(450-GM, Amend. 4, February 1990) 401-5
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Part 401 -Technical Guides
Historic Places; published soil surveys; basic water resources information on ground water
quality, surface water quality, and water quantity; recreation potential appraisals; natural
resource inventories; reports that identify such items as areas susceptible to flooding; river
basin reports; seismic zones; and documentation of useful computer models.
(ii) Cost data. General reference data on costs, such as cost lists for practice components.
(Hi) Maps. The SCS National Planning Manual (NPM), Pan 507, Exhibits 507.09, con-
tains a list of resource maps that should be included. Water quality problem areas and
areas with a potential water quality problem are to be included here.
(iv) Erosion prediction. Guidance, data, and SCS approved techniques for predicting soil
erosion are to be included here, or appropriately referenced.
(v) Climatic data. This subsection contains local climatic data needed for planning
conservation management systems and installing conservation practices, such as record low
and high temperatures; averages for such items as rainfall, length of growing season,
temperatures, wind velocities, hail incidence, and snowfall; water supply data; probability •
of receiving selected amounts of precipitation by months; and frost-free periods. Refer-
ences should be made to other climatic data in other field office documents.
(vi) Cultural (archaeological and historic) resource information. This subsection
contains general locational data and documentation suitable for inventory, checking and
recording, and conservation planning. The law states, that specific locational information,
such as site maps, is not to be available to the general public; therefore they should only be
referenced in this subsection.
(vii) Threatened and endangered species list. This subsection contains information on
species of plants and animals that are threatened and endangered and are to be accounted
for in conservation planning.
(viii) Laws. List of state and local laws, ordinances, or regulations that impact Conserva-
tion Management System development and other technical applications such as conserva-
tion practice application.
(2) Section n - Soil and Site Information.
Information from the State Soil Survey Database (3SD) will be used as the basis of this section.
The 3SD contains current information on soils and their basic interpretations as tailored from the
Soil Interpretations Records (SCS-SOI-5). Detailed interpretations of soils will be provided in
Section n by state and area specialists.
Interpretations are specific to the soils identified and mapped in the area. Map units to which the
401-6 (450-GM, Amend. 4, February 1990)
-------
Subpart A - Policy and Responsibilities
401.03(b)(2)(iii)(A)
interpretations apply are clearly identified by name, symbol(s), or both. New map unit names and
symbols resulting from reclassificarion of soils are cross-referenced to old names and symbols and
shown on a list. '
Soils are to be described and interpreted to help make decisions about use and manage-
ment of land. Soil characteristics that limit or affect land use and management are to be identified,
and soils are to be rated according to limitations, capability, suitability, and/or potential.
This information may be available in published soil surveys or in the State Soil Survey Database
(3SD). A copy of the appropriate sections of soil surveys can be included in the applicable subsec-
tions, or reference can be made to the source document maintained in the field office.
The following are subsections of Section n of the FOTG.
(i) Soils legend. This list includes the names of the soil map units and, for each unit, the identifica-
tion of interpretive groups (if any) of importance in the field office. For map units having two or
more soils in their name, interpretive groups are identified for each soil. Where appropriate, the
map unit is placed in a group that generally controls the use and management of the area.
If soil surveys of more than one vintage are used, the symbols used in each are to be identified
along with appropriate interpretive groups. For remapped areas, only the legend for the most recent
mapping is to be used.
(ii) Soil descriptions.
(A) Nontechnical soil descriptions for use with individuals, groups, and units of government
are included. Brief references to major limitations e.g., erosion or wetness, and soil potential
are a pan of each description. Basic information needed to develop these descriptions is in
the soil map unit descriptions and in the State Soil Survey Database (3SD).
*
(B) Technical descriptions of each soil series and of each soil map unit are provided in this
section or available in the field office. If such descriptions are maintained as separate mate-
rial, the source document should be listed here as a reference.
(iii) Detailed soil interpretations. These will be supplied by appropriate technical specialists for
all land uses in the field office area. Examples follow:
(A) Cropland interpretations. These include soil interpretive information needed for plant
adaptations, yield estimates, and the lists of soil map units that meet the soil requirements for
prime farmland and highly credible land. Interpretations are presented by land capability
units, credibility index, and soil map units in narrative or tabular form as appropriate. Where
land capability unit or credibility index is used, a list of all soil map units in each capability
unit or credibility index is included.
(450-GM, Amend. 4, February 1990) 401-7
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Part 401-TechnicaI Guides
401.03(b)(2)(iii)(B)
(B) Rangeland, grazed forest land, and native pasture interpretations. The required
content of range and native pasture interpretive groupings is outlined in the National Range
Handbook. All soils used as rangeland are to be placed in appropriate range sites. Range site
descriptions and condition guides for rangeland are included. Grazed forest land and native
pasture groupings include references to individual soils, grazing groups, or woodland suita-
bility groups. Interpretations may be presented by individual soil map units or by groups of
soil map units.
(C) Forest land interpretations. These are presented by individual soils or by woodland
suitability groups (WSG). These interpretations include the woodland class symbol that
denotes potential productivity for the indicator species in wood per cubic meters per hectare.
Site index and annual productivity estimates in cubic feet per acre, board feet per acre, and/or
cords per acre may also be provided for important tree species. The subclass indicates the
primary soil or physiographic characteristic that contributes to important hazards or limita-
tions in management. Site index information is also provided for important tree species.
(D) Nonagricultural interpretations. Nonagricultural uses include commercial develop-
ment, subdivision development, industrial related development, roads and other transpona-.
tion and transmission systems, and other land uses important to the area.
(E) Recreation interpretations. These include the ratings of soils for recreation uses.
(F) Wildlife interpretations. These are presented by wildlife habitat elements with descrip-
tions of each element.
(G) Pastureland and hayland interpretations. These are arranged by pastureland and
hayland suitability groups, capability units, other groupings, or soil map units.
(H) Mined land interpretations. These include interpretations which dictate the limitation
to reclamation, revegetation, and maintenance for the different types of mined land.
(I) Windbreak interpretations. These interpretations are made by individual soils or by
windbreak suitability groups (WISG). Interpretations provided by the WISG include the
soil-adapted species recommended, the predicted height growth in 20 years, and the soil-
related limitations.
(J) Engineering interpretations. These include engineering properties, indices, and soil
interpretations for engineering uses and practices.
(K) Waste disposal interpretations. These are interpretations related to the suitability of
soils for disposal of organic and inorganic wastes.
(L) Water quality and quantity interpretations. These are interpretations related to soil
properties affecting water quantity and quality problems and treatments. Included are soil-
pesticide interactive ratings and soil ratings for nitrates and soluble nutrients.
401 - 8 (450-GM, Amend. 4, February 1990)
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Subpart A - Policy and Responsibilities
(M) Hydric soils interpretations. These are interpretations related to the identification and
use of wetlands.
(3) Section m - Conservation Management Systems.
The'function of SCS is to provide technical assistance to decisionmakers to protect, maintain, and
improve soil, water, air, and related plant and animal resources. This section provides guidance for
developing resource management systems (RMS) and acceptable management systems (AMS) for a
resource area to prevent or treat problems and take advantage of opportunities associated with these
resources. This section includes a description of considerations important in conservation planning
of soil, water, air, and related plant and animal resources.
(i) An RMS achieves the goal of preventing resource degradation and permitting sustainable
use as stated in 401.00 (b). An RMS is achieved if criteria for soil, water, air, and related plant and
animal resources are met as defined in Section 401.03(b)(3)(iv). This section describes either na-
tional criteria or considerations that must be addressed in developing state criteria for achieving an
RMS that solve identified onsite and offsite resource problems using best available technology. The
concept and use of RMS is defined in the SCS National Planning Manual (NPM). RMS are not to be
confused with "conservation systems," as defined in 7 CFR Section 12.2 for treatment of highly
credible land. A conservation system for Food Security Act purposes is an erosion reduction com-
ponent of an RMS for cropland.
(ii) SCS helps decisionmakers plan and apply conservation management systems to prevent
and/or solve identified onsite and offsite resource problems or conditions and to achieve the
decisionmaker's and public objectives. SCS identifies and documents decisionmaker's objectives,
consistent with land capability and sound environmental principles, as pan of element 3 (Determin-
ing objectives) of the planning process (reference: National Planning Manual). SCS identifies and
documents resource problems or conditions as pan of element 4 (Providing resource inventory data)
of the planning process. As pan of element 6 (Developing and evaluating conservation alternatives),
information on conservation effects is used to provide suitable options for addressing the
decisionmaker's and public objectives.
(iii) The five resources are soil, water, air, plants, and animals. Each resource has several
considerations important in conservation planning. Additional considerations in a specific state may
need to be added to account for wide variations in soils, climate, or topography. A description of the
main considerations for each resource follows:
(A) Soil. Considerations for the soil resource are erosion, condition, and deposition.
[1] Erosion. This consideration deals with one or more of the following types or
locations of erosion: sheet and rill, wind, concentrated flow (ephemeral gully and
classic gully), strcambank, soil mass movement (land slips or slides), road bank,
construction site, and irrigation-induced. All of these forms of erosion that are idcnn
fied on the site to be planned need to be dealt with in developing treatment options.
(450-GM, Amend. 4, February 1990) 401-9
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Part 401-Technical Guides
[2] Condition. This consideration deals with the chemical and physical characteris-
tics of soil as related to its ease of tillage, fitness as a seedbed, and ability to absorb,
store, and release water and nutrients for plants. Aspects of this consideration will
improve soil tilth, which reduces soil crusting and compacting; optimize water infil-
tration; optimize soil organic material; enhance beneficial soil organisms and biologi-
cal activity; reduce subsidence; and minimize effects of excess natural and applied
chemicals and elements such as salt, selenium, boron, and heavy metals. This consid-
eration also deals with the proper and safe land application and utilization of animal
wastes, other organics, nutrients, and pesticides.
[3] Deposition. This consideration deals with onsite or off site deposition of products
of erosion, which includes sediment causing damages to land, crops, and property,
such as structures and machinery. This consideration also deals with safety hazards
and decreased long-term productivity. v
(B) Water. Considerations for the water resource are quantity and quality.
[1] Quantity includes:
• proper disposal of water from overland flows or seeps, both natural and man-made;
• management of water accumulations on soil surfaces or in soil profiles and vadose
zones;
• optimization of irrigation and precipitation water use;
• dealing with other problems relating to irrigation — water mounding, water supply
and distribution, increasing or decreasing water tables;
• management of deep percolation, runoff, and evaporation;
• water storage;
• management of water for wetland protection; and
• sediment deposition in lakes, ponds, streams and reservoirs, and restricted water
conveyance capacity.
[2] Quality includes:
• reducing the effects of salinity and sodicity;
• minimizing deep percolation of contaminated water which will lead to unacceptable
levels of pollutants in the underlying ground water,
• maintaining acceptable water quality;
• minimizing off site effects including ground water contamination by pesticides,
nutrients, salts, organics, metals and other inorganics, and pathogens; contamination
of surface water (streams and lakes) by sediment, pesticides, nutrients, salts, organics,
metals and other inorganics; pathogens; fecal coliform; and high temperature;
• reducing the quantity of sediment;
• improving the quality of sediment;
• ensuring that all waters will be free from substances attributable to man-caused
nonpoint source discharges in concentrations that:
"settle to form objectionable deposits;
*float as debris, scum, oil or other matter to. form nuisances;
401-10 (450-GM, Amend. 4, February 1990)
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Subpart A - Policy and Responsibilities
401.03(b)(3)(iv)(A)
•produce objectionable color, odor, taste, or turbidity;
*injure, are toxic to, or produce adverse physiological or behavior
responses in humans, animals, or plants; or
'produce undesirable aquatic life or result in the dominance of nuisance
species.
(C) Air. This resource deals with onsite and offsite airborne effects of undesirable odors,
windblown particulates, chemical drift, temperature, and wind.
(D) Plants. The considerations for the plant resource are suitability, condition, and manage-
ment
[1] Suitability includes:
• plant adaptation to site; and
• plant suitability for intended use.
[2] Condition includes:
• productivity, kinds, amounts, and distribution of plants; and
• health and vigor of plants.
[3] Management includes:
• establishment, growth, and harvest (including grazing) of plants;
• agricultural chemical management (pesticides and nutrients); and
• pest management (brush, weeds, insects, and diseases).
(E) Animals. This includes wild and domestic animals, both terrestrial and aquatic. The
considerations for the animal resource are habitat and management.
[1] Habitat includes:
•food;
• cover or shelter, and
• water.
•
[2] Management includes:
• population and resource balance; and
• animal health.
(iv) Criteria for treatment required to achieve an RMS will be established by SCS. They are to
be stated in either qualitative or quantitative terms for each resource consideration. Where national
criteria have not been established, the state conservationist will establish criteria with concurrence by
the NTC. Where state and/or local regulations establish more restrictive criteria, these must be used
in developing criteria for state and local programs. For example, some state and/or local regulations
have established criteria for offsite control of water quality.
(A) Soil. Following are the criteria for this resource:
(450-GM, Amend. 4, February 1990) 401- 11
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Part 401-Technical Guides
401.03(b)(3)(iv)(A)[l]
[1] Erosion.
• Estimated sheet and rill or wind erosion rates are reduced to the level that long term
soil degradation is prevented and a high level of crop productivity can be sustained
economically and indefinitely.
• Erosion from ephemeral or similar gullies is reduced to a level which permits
efficient fanning operations and sustains long term productivity.
• Irrigation-induced erosion is reduced to a level that sustains long term productivity.
• Other forms of erosion, such as classic gullies, streambank, roadbank, and land-
slides, that are identified as needing treatment (and are within the ability of the deci-
sionmaker to treat), are reduced to the degree necessary to protect the resources or
threatened man-made improvements.
[2] Condition.
• Soil tilth is maintained or improved;
• Crop production practices return adequate residue within the rotation cycle;
• Soil compaction by machinery, livestock, or other traffic is minimized:
• Water infiltration is optimized so as not to increase sheet and rill erosion;
• Wind forces and soil blowing are controlled below the crop tolerance level of young
seedlings;
• Toxic chemicals affecting soil and plants are controlled to levels sufficient to pre-
vent soil degradation and are below the tolerance of adapted crops;
• Application and utilization of animal wastes and other organics are at a rate that the
soil, soil microbes and bacteria, and the plant community can assimilate, degrade, or
retain the various materials.
[3] Deposition.
• Where existing or potential onsite or off site deposition problem(s) are identified, the
practices applied to the contributing land resolve the identified deposition problem(s).
• State and/or local governments may establish criteria in response to identified
deposition problems. These criteria will be used to determine the adequacy of an
RMS with regard to offsite effects. This may require-the establishment of more
401 -12 (450-GM, Amend. 4, February 1990)
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Subpart A • Policy and Responsibilities
401.03(b)(3)(iv)(B)[2]
restrictive criteria for one or more of the resources to alleviate the problem. Local
public perception of an acceptable level could be used where no standards have been
established.
• When disposal of animal wastes and other organics is needed, it shall be done in a
manner that maintains or enhances the natural resources.
(B) Water. In developing criteria for this resource, the state conservationist is to address:
[1] Quantity.
• Overland flows and subsurface water conveyed by conservation practices are safely
conducted and disposed of through acceptable outlets.
• Water system discharges going from one ownership to another ownership are not
changed from natural flow pathways unless needed land and/or water rights have
been obtained consistent with local, state, and Federal regulations.
• Water quality aspects associated with outlets are accounted for.
• Appropriate water storage requirements are in accordance with the needs of the
planned use.
• Drainage activities are consistent with SCS policy regarding wetland protection.
• For irrigated land, a minimum percentage level of efficiency is achieved or ex-
ceeded for each type of irrigation system and management, as stated in the SCS state
irrigation guide.
• For land under supplemental irrigation where adequate water supplies exist, or for
land under partial irrigation because of water deficiency or lack of seasonal availabil-
ity or frequency of availability of water, water is applied in the most effective man-
ner, so that the infiltration rate of the soil, the plant needs, and the soil water-holding
capacity are not exceeded.
• Vegetation, cropping sequences, and cultural operations are managed for efficient
use of precipitation by minimizing water losses to runoff and evaporation, thereby
inducing positive effects on the plant-soil moisture relationship, on ground water
recharge, and on water yield downstream.
[2] Quality.
• Sediment movement is controlled to minimize contamination of receiving waters.
(450-GM, Amend. 4, February 1990) 401 - 13
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Part 401-Technical Guides
401.03(b)(3)(iv)(B)[2]
• Percolation below the root zone is managed to minimize contamination of the
percolating water and to minimize the negative effects on production.
• Water used for salt leaching and plant temperature modification is applied to mini-
mize adverse effects.
• Acceptable water temperature is maintained.
• Irrigation water and natural precipitation are managed to minimize the movement of
nutrients, pesticides, sediment, salts, and animal wastes to offsite surface and ground
water.
• Water-based uses, such as aquaculture enterprises and water-based recreation
facilities maintain or improve environmental quality.
• Where surface or ground water nutrient and/or pesticide problems or potential
problems exist, the selection of appropriate nutrients or pesticides and the riming,
chemical forms, and rate and method of application reduce adverse effects. The use ••
of pesticides and nutrients with high potential for polluting water are avoided where
site limitations, such as slope, depth to ground water, soil, and material in die vadose
zone or aquifer could allow that potential to be realized Soil-pesticide interactive
ratings to identify potential problem situations from surface runoff and/or leaching
are used according to FOTG guidelines. Alternative practices or other pest control
methods (mechanical, cultural, or biological) or integrated methods are recommended
where site limitations exist that increase the probability of degrading water supplies,
either below the surface or downstream.
• Agricultural chemical containers and chemicals (including waste oil, fuel, and
detergents) are used, handled, and disposed of in compliance with Federal, state, and
local laws.
(C) Air. Criteria established by the state conservationist are to address the following onsite
and offsite considerations:
• Airborne participates from agricultural sources do not cause safety, health, machin-
ery, vehicular, or structure problems.
• Local and state regulations are followed in minimizing undesirable odors from
agricultural sources.
• Air movement and temperatures are modified when necessary using appropriate
vegetative or mechanical means.
• Chemical drift from the application of agricultural chemicals is controlled by adher-
ence to local and state application recommendations and product labels.
401-14 (450-GM, Amend. 4, February 1990)
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Subpart A • Policy and Responsibilities
401.03(b)(3)(iv)(D)
(D) Plants. Criteria established by the state conservationist are to address the following
considerations:
• Plants on all land uses are used, maintained and improved to achieve acceptable
production levels to meet conservation, environmental, decisionmaker, and public
objectives.
• Nutrient applications for any land use are based on plant nutrient requirements,
production requirements, soil test recommendations, soil fertility, soil potential
limitations, water budget, and the types of practices planned Nutrients from all
sources (animal waste, crop residue, soil residual, commercial fertilizer, atmospheric -
fixed) are considered when calculating the amount of nutrients to apply. Timing,
method, and rate of application, and chemical forms of nutrients to be applied are
taken into consideration in planning practices.
• Pesticide applications for any land use are applied according to the label recommen-
dation and federal, state, and local regulations.
• On Cropland, crops are grown in a planned sequence that meets conservation,
production, and decisionmaker objectives; and weeds, insects, other pests, and dis-
eases are adequately treated.
• On Hayland, dominant native or introduced plant species are appropriate for the
forage, agronomic, or commercial use; well adapted to the site; and their stand den-
sity is maintained or improved.
• On Native Pasture, herbaceous plants are properly grazed, forage value rating is
medium or better, vigor is strong and is commensurate with overstory canopy.
• On Pastureland, dominant plant species are appropriate for the use, adapted to the
site, and their stand density is adequate and productivity is maintained or improved.
• On Rangeland, the plant community is managed to meet the needs of the plants and
animals in a manner to conserve the natural resources and meet the objectives of the
decisionmaker. As a general rule, rangeland in poor or fair ecological range condi-
tion is managed for an upward range trend, and rangeland in good or excellent eco-
logical range condition will be managed for a static or upward range trend. In some
special situations, poor or fair ecological range condition could be managed for a
static range trend to meet special objectives of the decisionmaker as long as there is
no degradation of the soil resource.
• On Forest Land, trees are well distributed, vigorous, relatively free of insects,
disease, and other damage, and the density of the stand is within 25% of forest stand
density guide spacing on a stems-per-acre basis for the particular forest types. Forest
Land shall be protected from wildfires and erosion. Forest Land that is grazed shall
(450-GM, Amend. 4, February 1990) 401-15
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Part 401 -Technical Guides
401.03(b)(3)(iv)(D)
also be managed to meet the needs of the forage plants, the animals, and the objec-
tives of the decisionmaker.
• On Wildlife Land, Recitation Land, and Other Land, adapted or native plants are of
sufficient quantity and quality to improve or protect the defined resource.
• On Urban Land uses, soil cover is maintained using suitable plants or other cover to
keep soil erosion within acceptable limits, minimise runoff, and manage infiltration.
(E) Animals. Criteria established by the state conservationist are to address the following
considerations:
• The adaptation, kinds, amounts, distribution, health, and vigor of livestock and
wildlife are appropriate for the site.
• Adequate quality, quantity and distribution of food are provided for the species of
concern.
• Adequate quantity, quality and distribution of wildlife cover for the species of
concern are provided. Domestic animals are provided adequate shelter as needed.
• Adequate quantity, quality and distribution of water are provided for the species of
concern.
• The decisionmaker's enterprise and the balance between forage production and
livestock needs are appropriate.
• Domestic livestock are managed in a manner that meets the needs of the ecosystem,
the animal, and that accomplishes the goals and objectives of the decisionmaker.
• Animal wastes and other organic wastes are managed according to an animal waste
management plan developed according to SCS standards. Minimum quality criteria
are met when the animal waste management plan is applied. Where surface and
ground water problems exist from organic waste, bacteria, pathogens, microorgan-
isms, or nutrients, special design considerations for each component will be necessary
to eliminate further contamination of runoff or leachates.
(v) An AMS will be established for a resource area in the event that social, cultural, or eco-
nomic characteristics of the area prevent the feasible achievement of an RMS. An AMS is
achieved when soil, water, air, and related plant and animal criteria for the related resource use are
established at the level which is achievable in view of the social, cultural, and economic characteris-
tics of the resource area involved.
(A) Social, cultural, and economic considerations are used to establish the level of natural
resource protection obtainable and may constrain the resource criteria used in formulating an
401-16 (450-GM, Amend. 4, February 1990)
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Subpart A - Policy and Responsibilities
401.03(b)(3)(vii)(A)
RMS. Criteria for treatment required to achieve in AMS will be established by SCS. They
are to be stated in either qualitative or quantitative terms for each resource consideration .
The state conservationist will establish criteria with concurrence by the NTC. Some of these
criteria are prescribed by law or statute; e.f.. the National Historic Preservation ACL Others
are developed through an onsite assessment of social, cultural, and economic factors which
define the reasonable and practical degree to which the resource criteria can be achieved.
Where regional, state and/or local regulations establish more restrictive criteria, these must
be used.
(B) The following criteria are applied to determine the practical limits of resource protection
within a resource area and temper the resource criteria to be used in the formulation of an
AMS.
(1) Social
• Public health is maintained or improved.
• Treatment level is compatible with community characteristics.
• Treatment level is compatible with clientele characteristics.
(2) Cultural
• Protection of cultural resources is consistent with CM 420, Pan 401.
(3) Economic
• Treatment level reflects the ability to pay that is representative of the area.
• Inputs required for conservation treatment are readily available.
• Conservation treatment is consistent with government program participation.
(vi) Additional considerations useful in the planning process to screen or select suitable con-
servation treatments for individual dedsionmakers may include legal, social, cultural, eco-
nomic, aesthetic, management, and other factors. These are integral to the planning process and
are discussed in the National Planning Manual and are displayed in Section V.
(vii) Applications of RMS and AMS Criteria
(A) Several factors may affect the actual level or degree of treatment achieved at a point in
time or that is required to be achieved by the decisionmaker. Without legal constraints, the
differing cultural, social or economic situation of a decisionmaker usually determines the
degree of treatment planned or attained at any point in time. Where an RMS or AMS is not
attainable during the present planning effort, the progressive planning approach in NPM
501.04 (d) may be used to ultimately achieve planning and application of an RMS or AMS.
Progressive planning is the incremental process of building a plan on pan or all of the plan-
ning unit consistent with the decisionmaker's ability to make decisions over a period of time.
The progression on individual planning units is always toward the planning and implementa-
tion of an RMS.
(450-GM, Amend. 4, February 1990) 401-17
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Part 401-Technical Guides
401.03(b)(3)(vii)(B)
(B) Legislated programs usually have varying authorities and qualifying criteria that may
require more or less treatment than RMS or AMS criteria. An example is legislated practices
for improving water quality. In this case, the related program manual will establish the
criteria to be achieved. These applications must be coordinated across county and state lines
and should be for the period of time specified in the law or in the related policies and proce-
dures.
(C) The opportunity for establishing an RMS to achieve the non-degradation and sustainable
use goal should be evaluated when ownership, land use, or cropping system changes, or
when new technology becomes available.
(D) Decisionmakers may desire to plan treatment in addition to that required to meet RMS
or AMS criteria to enhance resource conditions or to serve secondary or tertiary uses or
objectives. This additional treatment may include conservation practices or management that
contribute to further improvement of water quality; increased production, drainage, or irriga-
tion; enhancement of cultural and environmental values, wildlife habitat, or aesthetics; or
improved health and safety.
(viii) RMS, AMS, or other guidance documents will be developed by major land use in the -.
field office area and placed in Section in of each FOTG.
(A) Only enough guidance documents to show examples of the RMS and AMS options to
treat the most common identified resource problems for each locally applicable major land
use will be developed. NTC will provide specific examples of format for guidance to states
in the preparation of guidance documents. Guidance documents are to be developed by
states for each FOTG using the NTC format Guidance documents are to have concurrence of
the NTC. NTC directors are to coordinate formats across NTC boundaries.
(B) Guidance documents will present a reasonable number of alternative combinations of
practices and management that will meet the criteria for solving resource problems common
to that land use.
(C) In developing guidance documents, the effects that alternative practices and combina-
tions of practices and management have on the five resources and on the social, economic,
and cultural considerations are to be used. For each guidance document developed, a display
of effects of the conservation system should be included in Section V. Guidance on the
development and display of effects is provided in Section 401.03(b)(5).
(D) Guidance documents may need to be developed to meet specific program requirements,
in which case they are to be clearly labeled to show the program(s) or provision(s) of law to
which they apply. These guidance documents may describe management actions in addition
to conservation practices that can be carried out to achieve these program purposes.
(ix) Conservation practices are to be installed according to SCS practice standards and
specifications. Practice standards and specifications are the same for both RMS and AMS.
401-18 (450-GM, Amend. 4, February 1990)
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Subpart A - Policy and Responsibilities
401.03(b)(5)(ii)
(4) Section IV - Practice Standards and Specifications
(i) This section of FOTG contains conservation practice standards and specifications.
(ii) The first item of Section IV is an alphabetical list of conservation practices used by the field
office, followed by the practice standards and specifications in the same order. This list will include
the date of preparation or revision of each standard, supplement, specification, and interim standard
in effect. This list will also show the date of the last review. This list will be revised and reissued
each time a change is made in a conservation practice standard, supplement, or specification. See
section 401.01(c)(2)(vii).
*
(iii) Practice standards establish the minimum level of acceptable quality for planning, designing,
installing, operating, and maintaining conservation practices. Standards from the National Handbook
of Conservation Practices (NHCP) and interim standards are to be used, and will be supplemented by
states as needed.
(iv) Practice specifications describe requirements necessary to install a conservation practice so that
it functions properly. For most practices in the NHCP, it is necessary to prepare state specifications
to fit local soil and climatic conditions. Specifications include some or all of the following: major
elements of work to be done; kind, quality, and quantity of materials to be used; essential details of
installation; and other technical instructions necessary for installing and maintaining the practice.
(v) See Part 401 - Subpart B for policy and procedural details for standards and specifications.
(5) Section V - Conservation Effects
(i) The purpose of this section is twofold:
(A) The first purpose is to provide a repository of data on the effects of conservation activi-
ties. Such data are an important part of technical reference material used by SCS and deci-
sionmakers in planning conservation actions. SCS determines the effects of conservation
treatments in order to help formulate and facilitate the identification of suitable conservation
management systems to protect the resource base and to address the decisionmaker's and
society's social, cultural, and economic objectives. The concept of using conservation effects
in the decisionmaking process (CED) is elaborated in the National Planning Manual.
(B) The second purpose of this section is to serve as a source of appropriate procedures and
methods for collecting, analyzing, and displaying conservation effects data:
•r
(ii) Conservation effects information will typically include the resource setting (i.e., soil, slope,
etc.), the specific conservation treatments applied, the kinds, amounts, and timing of actions under-
taken by decisionmakers in their operations, and the expected outcome in terms of solving resource
problems and meeting social, cultural, and economic objectives.
(450-GM, Amend. 4, February 1990) 401- 19
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Part 401-TechnicaI Guides
401.03(b)(5)(ii)(A)
(A) Effects of conservation may be expressed in either narrative or quantitative terms that
represent factual data on experienced or expected results of the specified conservation treat-
ment as applied to the resource setting. Effects of conservation will normally be expressed as
a condition or stage of the factors associated with a specified conservation action. For
example, typical effects could be: a corn yield of 110 bushels per acre; a USLE erosion rate
of 4 tons per acre; irrigation efficiency of 60%; or "a significant reduction in ephemeral gully
erosion will occur with this treatment." "Impacts" is a closely related term. An impact is a
measure of the change between the stage or condition of one treatment alternative to another.
Guidance on the use of effects information in the conservation planning process is contained
in the National Planning Manual.
(B) To the extent possible, conservation effects information will include conservation treat-
ments on the five resources and their considerations as described in Section in above.
[1] Examples of effects of conservation treatment on the five resources include but
are not limited to:
• Expected effect on sheet and rill, wind, or ephemeral gully erosion.
• Indicators or measures of soil conditions, such as tilth, compaction, and infiltration.
• Where applicable, indicators of soil deposition.
• Measures or indicators of effects on quality and quantity of surface or subsurface
waters, such as chemical runoff as influenced by the conservation system.
• Effects on plant conditions and management, such as expected status of range
conditions with the indicated range conservation actions.
• Measures of conservation effects on wild and domestic animals, including animal
waste uses and effects on the resource base.
• Indicators of effects on air, such as airborne particulates, odors, and chemical drift
[2] Effects information will also include management, social, cultural, and economic
information. Factors such as cost, client acceptability, and physical changes to cul-
tural resource sites associated with the specific conservation treatment component are
to be identified. Included, for example, would be:
• Tillage requirements, labor inputs, quantity and costs of inputs, net economic
returns, experienced yields, risk management requirements, operation and mainte-
nance requirements, time requirements, cultural resources (archaeological and historic
properties), length of life of practices, health and safety, aesthetics, and community
effects.
401-20 (450-GM, Amend. 4, February 1990)
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Subpart A • Policy and Responsibilities
401.03(b)(5)(iv)(B)
(C) Information developed on conservation effects will vary significantly in scope
and detail depending on the resource conditions in the local area as well as upon the
needs for technical reference materials to carry out conservation activities in that
location.
(iii) Section V of the FOTG should contain summaries of effects data relevant to the field office
area. As a minimum, Section V should contain a display of the important effects for decisionmaking
for each of the RMS and AMS developed and inserted in Section IJL The display should be cross
referenced with cropping system, soil map units, and other descriptions of the resource setting and
conditions (e.g., precipitation, slope, etc.) that the RMS or AMS was formulated to address in that
field office. The format of the display should be easily understandable so as to make the information
valuable as ready reference material for the conservation planner and decisionmaker to facilitate
planning and decisionmaking. The display will show the degree of resource protection achieved.
(A) Options may be evaluated by simply comparing the differences in the effects of the
options.
(B) NTC will provide specific examples of format guidance to states for recording and
displaying conservation effects data.
(C) Collection of data on conservation effects is a long term effort to be undertaken as pan of
the followup element in the planning process. Initial efforts may provide effect information
for only the most common situations. Over time, additional resource situations and treatment
alternatives will be examined to add depth and breadth to the available conservation effect
information.
(D) Information on conservation effects may be refined or updated over time as needed in the
local area. The data on conservation effects should be useful to field office personnel in
identifying suitable conservation treatment applicable to the area, and serves as technical
reference materials when working with decisionmakers in the conservation planning process.
(See National Planning Manual Section 508.01).
(iv) Data on conservation effects may be developed by following two general approaches:
(A) The observation and documentation of the experiences of cooperators. Typically, con-
servationists will make observations of conservation treatments applied by one or more
decisionmakers in the first or second year following the application and record the effects ex-
perienced. This data can be recorded in conservation field notes and be entered into CAMPS
databases. Effects information may also be available from conservation field trials, univer-
sity research plots, or other trials in the area.
,
(B) Models of processes impacted by conservation actions can be used to simulate the physi-
cal, agronomic, or other effects of treatment systems. Actual results or graphs summarizing
results could be developed by state staffs and provided to field offices for inclusion in FOTG.
Appropriate models or references to the appropriate models may be stored in FOTG Section
V to facilitate use in collecting and analyzing conservation effects data.
(450-GM, Amend. 4, February 1990) 401 - 21
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Part 401-Technical Guides
401.03(b)(5)(v)
(v) Data relating effects of conservation practices on the five resources may be displayed in tabular,
narrative, or matrix form. This will be useful in developing RMS or AMS for inclusion in FOTG
Section III.
401-22 * • (450-GM, Amend. 4, February 1990)
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SUBPART B — NATIONAL HANDBOOK
OF CONSERVATION PRACTICES
401.10 Purpose. 401.12
This subpart sets forth SCS policy for establishing and maintaining a National Handbook of Conser-
vation Practices (NHCP). It also includes directions for variances, changes, interim standards, and
adaptations of standards to state and local conditions.
401.11 Content
(a) The NHCP establishes a national standard for each conservation practice, including:
(1) The official name, definition, code identity, and unit of measurement for the
practice;
(2) A concise statement of the scope, purposes (including secondary purposes),
conditions where the practice applies, and planning considerations for the practice;
and
(3) Criteria for the practice.
(b) For some conservation practices, the NHCP also establishes items for inclusion in
state-developed specifications.
(c) The NHCP contains an index of national standards, including:
(1) The practice name and unit
(2) The SCS technical discipline leader responsible for each practice.
(3) The date of the current standard.
(4) The code number of the standard.
401.12 National Conservation Practice Standards Subcommittee (NCPSS) of
National Technical Guide Committee (NTGC).
The National Conservation Practice Standards Subcommittee (NCPSS) of NTGC coordinates and
updates the NHCP. The NTGC designates subcommittee members and acts on recommendations
from NCPSS.
(450-GM, Amend. 4, February 1990) 401 - 23
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Part 401-Technical Guides
40L13(a)(l)
401.13 Practice standards and specifications.
(a) Practice standards establish the minimum level of acceptable quality of planning,
designing, installing, operating and maintaining conservation practices.,
(1) NHCP standards are to be used directly within a state, or state supplements can
be added as necessary. Because of wide variations in soils, climate, and topography,
state conservationists may need to add special provisions or provide more detail in the
standards. State laws and local ordinances or regulations may dictate more stringent
criteria.
*
(2) The official practice name, definition, code identity, and unit of measurement are
established nationally and are not to be changed. Generally, the statement of scope,
purpose, and conditions where a practice applies can be used directly.
(b) Practice specifications establish the technical details and workmanship for the
various operations required to install the practice and the quality and extent of the materials .
to be used.
(1) Specifications enumerate items that apply when adapting the standard to site
specific locations, such as considerations of site preparation and protection; instruc-
tions for use of materials described in the standard; or guidance for performing
installation operations not directly addressed in the standard. Statements in the
specifications are not to conflict with the requirements of the standard.
(2) Items to be included in state-developed specifications for a limited number of
conservation practices are contained in the NHCP. Specifications for practices are to
be developed by states or NTCs and. are to consider the wide variations in soils, cli-
mate, and topography present in the various states. State developed specifications
must be approved by the appropriate discipline specialist and the state conservation-
ist. Specifications are to meet the requirements of state laws and local ordinances or
regulations.
(c) National Technical Centers (NTCs) review and concur in supplements to NHCP
standards and specifications prepared by a state for use within that state to ensure confer-
mance with NHCP and consistency among states.
401 - 24 (450-GM, Amend. 4, February 1990)
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Subpart B-National Handbook of Conservation Practices
401.16(c)
401.14 Variances.
Only the directors of the Engineering and/or Ecological Sciences Divisions can approve variances
from requirements stated in the NHCP except that approval authority for variations in channel
stability requirements has been delegated to the heads of engineering staffs at the NTC (see NEM
210 Section 501.32). Any other request for a variance is to be submitted to the NTGC and is to
include recommendations of the appropriate NTC Director. The NTGC will refer die request to the
appropriate division for action. Variances, when granted, are for a specific period of time or until
the practice standard to which they pertain is revised, whichever is shorter. Variances will include
any requirements for monitoring, evaluation, and reporting needed to determine whether or not
changes in practice standards are necessary.
401.15 Changes in the National Handbook of Conservation Practices (NHCP).
(a) The NTGC will consider and recommend proposed changes in the NHCP to the
Deputy Chief for Technology. Changes will be made by numbered handbook notices issued
by the Deputy Chief for Technology.
(b) Each NHCP standard is to be formally reviewed by the NCPSS at least once every
five years from the date of issuance or revision to determine if the standard is needed and up-
to-date. If revisions are needed, the revised standard will establish the current minimum level
of acceptable quality for planning, designing, installing, operating, and maintaining conserva-
tion practices.
(c) The NTC reviews all state proposed changes to NHCP and sends recommendations
for approval or disapproval to NTGC. Review and approval of technical content of proposed
changes is to be made by the Director, Engineering Division, or the Director, Ecological Sci-
ences Division. Review and approval of format with respect to inclusion of items listed in
Section 401.11 are to be performed by NTGC.
401.16 Interim standards.
(a) Interim standards are prepared by states or NTC to address problems for which
there is no existing standard.
(b) Interim standards are to be approved by the NTC Director.
(c) Interim standards are to be issued for a period not to exceed 3 years. The NTC
director can extend the period for further evaluation at the end of this period, and after an
analysis of practice performance using the interim standard.
(450-GM, Amend. 4, February 1990) 401.- 25
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Part 401r Technical Guides
. (d) Interim standards will be evaluated by NTC Technical Guide Committees at the
end of the 3-year period and, if appropriate, recommendations made to the NTGC for inclu-
sion in the Nation?! Handbook of Conservation Practices.
(e) Hie notice of approval of each interim standard will provide instructions to states
regarding eYCbudion of practice performance.
(!) NTC Erectors are to send information copies of all interim standards and evalu-
ation reports to WTGC.
401- 2& (450-GM, Amend 4, February 1990)
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