BEST MANAGEMENT PRACTICES
FOR
AGRICULTURAL NONPOINT SOURCE CONTROL
•
I. ANIMAL WASTE
North Carolina Agricultural Extension Service
Biological and Agricultural Engineering Department
North Carolina State University
Raleigh, North Carolina
In Cooperation With:
Agricultural Stabilization and Conservation Service, USDA
Economic Research Service, USDA
Extension Service, USDA
Soil Conservation Service, USDA
Environmental Protection Agency
North Carolina Agricultural Research Service
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STATE-OF-THE-ART REVIEW OF
BEST MANAGEMENT PRACTICES FOR AGRICULTURAL
NONPOINT SOURCE CONTROL
I. ANIMAL WASTE
for the project
RURAL NONPOINT SOURCE CONTROL WATER QUALITY
EVALUATION AND TECHNICAL ASSISTANCE
USDA Cooperative Agreement - 12-05-300-472
EPA Interagency Agreement - AD-12-F-0-037-0
PROJECT PERSONNEL
DeAnne D. Johnson Project Assistant
Jonathan M. Kreglow Extension Specialist
Steven A. Dressing Extension Specialist
Richard P. Maas Extension Specialist
Fred A. Koehler Principal Investigator
Frank J. Humenik Project Director
Biological & Agricultural Engineering Dept.
North Carolina State University
Raleigh, North Carolina 27650
William K. Snyder USDA-SCS Participant
Lee Christensen USDA-ESS Participant
EPA PROJECT OFFICER USDA PROJECT OFFICER
James W. Meek Fred :;. Swader
Implementation Branch Extension Service
Water Planning Division Natural Resources
Washington, D.C. 'Washington, D.C.
nUGUST 1932
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EXECUTIVE SUMMARY
Agricultural nonpoint sources (NPS) are major contributors of pollution
to the nation's lakes, rivers and streams. Animal waste NPS inputs are
usually traced to land application sites or to small feedlots. Pollutants
from manure can cause algal blooms, fish kills and unpleasant odors; contami-
nate drinking water and be a potential source of disease. Concern for im-
proving and/or maintaining water quality has necessitated the development of
mechanisms for controlling NPS pollution. This document will identify and
discuss the state-of-the-art in Best Management Practices (BMPs) for control-
ling NPS inputs from livestock and poultry production wastes.
Presently, several Rural Clean Water Program (RCWP), Model Implementation
Program (MIP) and Agricultural Concervation Program-Special Water Quality (ACP)
projects across the United States are designed to demonstrate the effectiveness
of various control mechanisms for abatement of agricultural nonpoint source
water quality problems. In many cases, programs have been hindered in their
efforts to achieve water quality goals by a lack of information on the cause-
effect relations between BMPs and water quality. Data from these research
efforts may expand current assessments of the applicability of individual BMPs
and BMP systems as water quality control mechanisms.
The literature supports the conclusion that the key components of an
animal utilization BMP system are proper rate, in conjunction with soil and
manure nutrient testing, timing and method of animal waste land application
for controlling livestock inputs into natural waters and for more efficiently
utilizing the plant nutrients. Rates should be determined from the soil and
manure nutrient results and crop requirements. Heavy rates have been shown to
cause excessive nitrate-nitrogen leaching to ground or subsurface water sources
and phosphorus accumulation in the upper soil profile where losses through erosion
can occur. Manure should be applied in either the spring or summer when the crop
can effectively utilize the nutrients. Fall application of manure should be
minimized in regions with sandy soils and mild winters where winter crop nutrient
uptake is reduced and leaching can occur throughout the year. Winter applica-
tions to frozen or snow covered ground should especially be avoided to prevent
nutrient and organic losses during rainfall or snowmelt events. The manure
should either be broadcast and immediately incorporated or applied by liquid
injection to reduce runoff and ammonia volatilization losses.
The pollutant loads from small feedlots can be several times greater than
those from properly managed land application sites. The diversion of non-polluted
surface and building roof runoff from feedlots and the use of vegetative filter
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strips to treat feedlot runoff have been found to be excellent BMPs. Pasture
management must also be maintained to avoid water quality problems. Management
practices which prevent nutrient, bacteria and sediment contamination of re-
ceiving waters include restricting animals from these waters and rotational
grazing to avoid destroying grass cover.
While a good deal of research has been completed regarding manure ap-
plication and its effects on water quality, most studies have been only on a
plot scale. Plot studies permit analyses of specific practices and mechanisms
but may not fully represent conditions in a real world situation. Water quality
benefits and other impacts resulting from the implementation of animal waste
BMPs and BMP systems on an areawide basis still remain largely unknown. Data
from the RCWP, MIP, and ACP projects may help characterize these unknowns by
allowing the determination of cause-effect relationships and the cost-effective-
ness of BMPs and/or BMP systems for improving water quality on a watershed scale.
The following are conclusions and recommendations regarding best manage-
ment practices and their components for controlling the inputs from animal wastes
in surface and ground waters.
1. Soil testing on cropland should be done yearly to determine
whether the nitrogen is being used effectively, whether
salinity problems exist, whether certain elements are at
toxic levels, and whether an increase of one element has
reduced the availability of another.
2. Manure nutrient analysis should be made just prior to land
application so that nitrogen and phosphorus contents can be
matched with crop requirements.
3. Rates of application should be based on crop nitrogen and
phosphorus needs. Excessive rates of application result in
nitrate-nitrogen leaching into groundwater sources, and
phosphorus accumulating in the upper soil profile and being
susceptable to erosion.
4. Timing of application should be just prior to or during
periods of maximum crop nutrient uptake such as either spring
or summer when crops can utilize most of the nutrients.
When applying wastes in the fall, up to 50% of the total
nitrogen can be lost through decomposition and leaching.
Winter manure applications have also shown large nutrient
losses; up to 86% of the nitrogen and 94% of the phosphorus
applied during the winter season can be lost in a single
rainfall or snowmelt runoff event. If fall and winter
applications can not be avoided, manure rates should be
applied to a vegetative cover crop, thus, reducing runoff
losses.
m
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5. Method of application should be either by broadcasting
and immediate incorporation or by liquid injection, thus
avoiding losses by ammonia volatilization and by surface
runoff.
6. Vegetative filter strips should be used as a treatment
for feedlot and dairy wastewater runoff. Filter strips
have been found to reduce the nitrogen, phosphorus and
COD in animal waste runoff by 77%, 94% and 96%, respective
7. Rangeland management should include restriction of pastured
animals from lakes or other impoundments and streams, and
rotational grazing to prevent grass cover reduction.
IV
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CONTENTS
Executive Summary ii
Figures viii
Tables x
Preface xi i
1. Introduction 1
2. Animal Waste Management 10
Animal Waste Uses 10
Land Application 10
Management Considerations 17
Preliminary Application Procedures 18
Soil testing 18
Manure Nutrient Analysis 18
Other Considerations 18
Rate of Application 21
Timing of Application 25
Methods of Application 32
Conventional Practices 33
Other Practices 33
Feedlots 35
Unconfined Pastured Animals 38
Summary 39
vi
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CONTENTS (continued)
3. Factors in the Economic Evaluation of Waste
Management Systems
Economic Concepts and Procedures ............................... 41
Principle of Diminishing Returns ............................ 42
Fixed and Variable Costs .................................... 44
Opportunity Costs ........................................... 44
Budgeting [[[ 45
Amortization ................................................ 45
Southeastern Dairy Example ..................................... 47
Estimating Nutrient Value of Manure ......................... 47
Estimating Costs and Benefits ............................... 50
References [[[ 50
4. Research Needs ................................................. 52
5. Current Research ............................................... 54
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FIGURES
Number page
1 Observed range of total nitrogen concentrations from nonpoint
sources 5
2 Observed range of total phosphorus concentrations from nonpoint
sources 6
3 Fed beef production in U.S 11
4 Fed hog production in U.S 12
5 Dairy cows on farms in U.S 13
6 Layers in production in U.S 14
7 Commercial broiler production in U.S 15
8 Land Resource Regions 16
9 Land resource regions with literature references and
projections indicating nitrate leaching or toxic nitrate
accumulations in the forage due to excessive animal waste
appl ication rates 24
10 Land resource regions with literature references and
projections indicating excessive phosphorus accumulations
on the soil surface due to excessive animal waste application
rates 26
11 Land resource regions with literature references and projections
indicating where salt accumulation has been a problem or has
been shown the potential to be a problem from excessive animal
waste appl ication rates 27
12 Land resource regions with literature references and
projections indicating the areas where application of
animal wastes is a BMP 28
VI 1 1
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FIGURES (continued)
Number Page
13 Land resource regions with literature references and
projections indicating the areas where application of
animal wastes during spring and fall is a BMP 31
14 Land resources regions with literature references and
projections indicating incorporation of animal waste
during or immediately after application as a BMP 34
15 Land resource regions with literature references
and projections indicating split application of
animal wastes as a BMP 36
16 Land resource regions with literature references and projections
indicating filtration strips for treating feedlot runoff
and milking parlor wastewater as a BMP 37
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TABLES
Number page
1 Ranges of BOD and COD Concentrations for Various
Untreated Wastes 2
2 Comparative Magnitude of Some Nonpoint Sources 4
3 Sources of Nitrogen and Phosphorus on a National and
Watershed Scale 8
4 Nitrogen Losses in Handling and Storage 19
5 Summarization of Various Animal Waste Nutrient Contents 20
6 Fertilizer Requirements and N:P:K Ratios for Selected
Crops in Ohio and North Carolina 22
7 Animal Waste Nutrient Values and N:P:K Ratios 23
8 Volatilization Losses Associated with Application Methods 32
9 Hypothetical Relationship Between Nitrogen Application
Rates and Corn Yield 43
10 Partial Budget Format for Evaluating Waste Management
Systems, Single Enterprise Operation 46
11 Capital Amortization Table 48
12 Partial Budget Analysis of Waste Management Options, 75-cow
Dairy Herd, Southeast 51
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PREFACE
There are currently many programs and projects across the country for
reducing nonpoint source pollution from agricultural activities. Public and
private monies are being spent to implement agricultural Best Management
Practices (BMPs) for improving water quality. To assess these many efforts
on a nationwide basis, a joint USDA-EPA project, "Rural Nonpoint Source Con-
trol Water Quality Evaluation and Technical Assistance," has been established.
This undertaking, commonly known as the National Water Quality Evaluation
Project, will assess the water quality and socioeconomic effects of BMP use
in the rural sector.
This document identifies and discusses the state-of-the-art in Best
Management Practices for controlling nonpoint source pollution inputs from
livestock and poultry production wastes. Emphasis was given mainly to the
utilization of animal waste as a crop nutrient, as well as the treatment
of runoff from feedlots and milking parlor facilities using vegetative
filter strips. Storage structures were only given reference for a comparison
of nutrients available at application.
The scope of the literature reviewed for this document was restricted
to published documents with supporting data. Two computer-based files, the
Southern Water Resources Scientific Information Center (SWRSIC) and AGRICultural
OnLine Access system (AGRICOLA), were used for a large portion of the liter-
ature retrieval. Much additional information was obtained through citations
follow-up, and interpretive insight was solicited from NCSU professionals.
XI 1
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SECTION 1
INTRODUCTION
In the past several years, there has been more awareness of the
pollutional inputs agriculture has contributed to the nation's waters. This
awareness was addressed in 1972 by the Federal Water Pollution Control Act
amendments, commonly known as Public Law 92-500. This law established as a
national goal the restoration of lakes, rivers and streams of the nation to
fishable and swimmable conditions, where practicable and attainable, by 1983.
One of the key areas addressed by PL 92-500 in Section 208 is the problem of
nonpoint sources (NPS). Nonpoint sources (NPS) generally are diffuse and dis-
charge pollutants to waterways by dispersed pathways. Agricultural NPS pol-
lutants are the result of runoff from cropland, grassland, range, forest, and
animal production areas. The quantity and quality of the runoff depends markedly
on land use patterns and practices as well as watershed climatology and physio-
graphy (50).
The impact of agricultural runoff on the nation's waters has been well
documented. One national study on nonpoint source stream nutrient levels con-
ducted on 928 NPS impacted watersheds (62) determined that streams draining
agricultural watersheds had, on the average, higher nutrient concentrations than
those draining forested watersheds. Mean concentrations of both total phosphorus
(Pj) and total nitrogen (NT) were nearly nine times greater in streams draining
agricultural lands than in those draining forested areas. The inorganic nitrogen
made up a larger percentage of the total nitrogen concentrations in these agri-
cultural area streams, increasing from about 18% in streams draining forested
areas to almost 80% in streams draining agricultural watersheds. A study con-
ducted in the Missouri River Basin (50) identified agricultural operations as a
major contributor of nonpoint source pollution, reporting that agricultural pro-
duction was positively correlated with instream concentrations. Studies conducted
in the Piedmont and Coastal Plain regions of North Carolina support these con-
clusions, finding that streams draining predominately agricultural watersheds
had higher nitrogen (N) and phosphorus (P) runoff concentrations than forested
areas (31). Areas with the highest nitrogen and phosphorus concentrations were
also found to have the highest levels of livestock production. In a character-
ization study of 30 Delaware lakes, most were found to have nitrogen:phosphorus
concentration ratios of greater than 15 to 1 (indicating they were phosphorus
limited), with at least 97% of the nitrogen entering these lakes from agricul-
tural nonpoint sources (74).
Animal waste has been found to be a major constituent of the agricultural
nonpoint source pollution problem in some areas of the country. Livestock wastes
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entering Lake Tholocco in Alabama have caused elevated bacteria counts, some-
times high enough to restrict contact recreational uses (42). Eutrophic con-
ditions in the near shore areas of Lake Michigan have been attributed to animal
waste nutrients entering from the Lower Manitowoc River watershed in Wisconsin
(49). Nutrients from animal waste runoff entering St. Albans Bay in Vermont
(84) has significantly contributed to the occurance of major algae blooms and
extensive growth of aquatic macrophytes. Nonpoint source animal manure problems
are usually traced to (leaching or runoff from) land application sites, to
(runoff losses from) small feedlots, or to (nitrate leaching from) abandoned
feedlots.
The potential pollutants of concern in manure are the oxygen-demanding
organic matter, plant nutrients, infectious agents and salts, and can lead to
turbidity, taste and odor problems in a water body (7, 23, 33, 41,102). These
contaminants may be either leached to groundwater or transported to surface
waters via runoff.
Organic matter serves as a substrate for aerobic bacteria when it enters
a receiving stream and is usually measured in terms of Biological Oxygen Demand
(BOD) or Chemical Oxygen Demand (COD). The high BOD or COD associated with
livestock waste runoff is capable of rapidly depleting the oxygen supply typi-
cally found in a stream or lake system, resulting in fish kills and severe dis-
ruptions of other aquatic life (41). Also nutrients are released as organic
matter is biodegraded. The rate of biodegradation is dependent upon the type
of organic material and the type of micro-organisms assimilating it. Decompos-
ing organic matter also contributes color, taste, and odor problems in public
water systems utilizing surface sources (17). Table 1 gives a range of BOD
concentrations in various wastes (6,108 ).
TABLE 1. RANGES OF BOD AND COD CONCENTRATIONS FOR
VARIOUS UNTREATED WASTES (6,108 )
Source
BOD
(mg/1)
COD
(mg/1)
Domestic sewage 100-300 400-600
Dairy cattle manure 25,600 68,200-168,000
Beef manure - 72,900-258,000
Swine manure 27,000-33,000 25,000-176,400
Chicken droppings 24,000 100,000-255,100
Sheep manure - 162,100-351,700
Excessive levels of nutrients in surface waters can cause algal blooms,
fish kills, odors and increased turbidity (7, 103). Nutrients can also be
leached through the soil profile to groundwater. The two nutrients of most
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concern from a water quality perspective are nitrogen and phosphorus. Data
indicate that large quantities of total nitrogen and total phosphorus are as-
sociated with animal manure (Table 2). Animal wastes can contribute nitrate
concentrations in excess of drinking water standards (Figure 1) and phosphorus
concentrations in excess of what has been determined to stimulate aquatic growths
(Figure 2).
Manurial nitrogen is primarily in the organic and ammonium forms. Organic
nitrogen (Org-N) is released by microbial decomposition in the form of ammonia.
Runoff generally contains only trace amounts of ammonia. The ammonia cations
(NH4+) are held tightly by soil and organic colloids and are thus immobile in
the soil solution (53), but can be transported by erosion processes (13). In
well structured and aerated soils ammonium is oxidized by bacteria to nitrite
(N02-N) and then to nitrate (NO_-N). Nitrates are water soluble and will move
through the soil profile if not utilized by plants (41, 43, 57,94 ,109 ). The
primary mechanism for nitrate leaching is the mass flow of the soil solution
(94, 99 ). Nitrate loss is mainly a function of soil type, management practices,
rainfall amount and intensity, and other climatic factors (34,78,94).
Loss of nitrate-nitrogen from land receiving manure is a concern from both
production and water quality perspectives. Farmers incur greater expense when
they apply additional fertilizer to replace nitrogen leached beyond the root
zone. Furthermore, nitrate can pose a health problem as it flows through the
soil profile to groundwaters (26, 43, 51, 57,99 ). The maximum permissible
NOo-N concentration in domestic water supply is 10 mg/1 (26, 66). Nitrate it-
seff is not toxic at this concentration, but its reduction product nitrite can
react with hemoglobin in the bloodstream to impair oxygen transport in warm-
blooded animals. This condition of methemoglobinemia can be hazardous to in-
fants younger than three months (66). A major focus of the Conestoga Headwaters
RCWP project in Pennsylvania is the nitrate contamination of water resulting
from the heavy animal loads generated by high density livestock production
(17).
Nitrogen forms can also contribute to accelerated eutrophication in stream
and lakes. Plants can assimilate both nitrate and ammonium-nitrogen (NH^-N)
for conversion to protein (66). Total nitrogen concentrations as low as 1 to
2 mg/1 have been associated with algal blooms.
Animal wastes contain phosphorus in both organic and inorganic forms with
the inorganic form predominant (21, 53). Phosphorus in the soil readily reacts
with available calcium, iron and aluminum to form insoluble compounds or be ad-
sorbed onto soil particles (53); thus, surface runoff is the general mode of P
transport (21, 26, 51). In studies on silty clay loam soils of Northern Alabama
more than 95% of the phosphorus was lost with .sediment (11). Other researchers
found similar results on silt soils in Iowa, where on the average 82% of the
phosphorus was transported by sediment (13). Since loss of phosphorus is related
to soil loss, sediment control practices should reduce P runoff (80).
Phosphorus as phosphate (PO.-P) is one of the major nutrients required
for plant nutrition and has been linked to the accelerated eutrophication
of streams and lakes (108). Concentrations in excess of 25 yg/1 occurring
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Source
*Lower Limit for Algal Blooms
*Maximum Level for Domestic Water Supply
*Precipitation-U.S.
*Precipitation-OH
*Precipitation-Coastal DE
*Precipitation-MN
*Forested-OH
*Forested-OH
*Forested-MN
*Silvi cultural Piedmont-VA
*Agri cultural Piedmont-VA
*Agricultural Watersheds-Coastal DE
*Farmland-OH
*Upland Native Prairie-MN
*Grassland (Rotational Grazing)-OK
*Grassland (Continuous Grazing)-OK
*Grassland (Rotational Grazing)-TX
*Grassland (Continuous Grazing)-TX
*Land Applied Dairy Manure-WI
*Land Applied Dairy Manure-WI
*Land Applied Dairy Manure-MN
*Land Applied Dairy Manure-SC
*Land Applied Dairy Manure-AL
*Land Applied Dairy Manure-MN
*Seepage from Stacked Manure-U.S.
*Seepage from Stacked Manure-WI
*Feedlot Runoff-U.S.
*Feedlot Runoff-Great Plains Region
*Dairy Barnyard Runoff-VT
*Dairy Barnyard Runoff-NY
Total N
mg/1 kg/ha/yrf
10
0.73-1.27
2.0 -2.8
0.54-0.89
1.1-1.8
1.1-3.2
0.90-3.11
1.52-1.64
2.58-3.25
0.64
0.94
13. 2-62. 3§
10. 3-11. 85
1800-2350
1315-2641
920-2100
3000-17,500
78-3953
5.6-10.0
12.8
44.6-45.4
2.1
2.59-4.61
2.7
4.4
14.4-15.7
5.1
1.0
1.47
6.84
4.0
2.8-8.0
11. 8-16. 65
0.8-3.2
2.8-3.7
100-1600
Total P
mg/1 kg/ha/yr1"
0.025
0.02-0.04
0.011-0.042
0.011-0.020
0.04-1.20
0.12-0.19
0.10-0.60
0.020-0.023
0.56-0.83
1.29-1.32
0.04
0.07
1.8-4.9
7.5-8.9
190-280
51-156
290-360
47-300
7-255
8.5-39.5
0.05-0.10
1.45-1.48
0.10
0.04
0.08-0.14
0.08
0.28
0.54
0.39-0.46
0.06
0.13
0.89
3.24
0.8
0.4-1.7
8.2-13.5
0.5-0.6
10-620
Reference
66
66
45
93
73
81
93
105
81
10
10
73
93
96
61
61
82
82
59
18
113
67
47
111
45
19
45
16
51
2
Normalized to precipitation of 76 cm/yr
*Surface Runoff
5NOj-N
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•DRINKING WATER STANDARD FOR NITRATE-NITROGEN
Ref. 66
\/ / / >l
Ref. 45, 93
PRECIPITATION
Ref. 10, 93
FORESTED
IX X X 7 A GRASSLAND
Ref. 61, 82 I
AGRICULTURAL LAND
Ref. 10, 93
FEEDL
V /
Ref.
' X XJ
67, 113
LAND APPLIED MANURE (NO,-N)
o
SEEPAGE FROM STACKED MANURE E3
_OT
1 1 1
O.I 1 10
RUNOFF
IX X X X X X X
Ref. 16, 45, 51
1
100
Ref. 19, 45
X X X X X
1
1000
X X XJ
1
10,00
TOTAL NITROGEN CONCENTRATION (mg/l)
Figure 1. Observed range of total nitrogen concentrations from nonpoint sources.
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cr>
U— LOWER LIMIT FOR ALGAL BLOOMS (0.025 mg. P/l )
Ref. 66
I ...
\S /A PRECIPITATION
| Ref. 45,81
\/ ////// / / / 7 / /( FORESTED
Ref. 10, 81 , 93
Y / 7 7 7 / / / / / /\ GRASSLAND
Ref. 61, 82
\//////S 7 A AGRICULTURAL LAND
Ref. 10, 93
IX / / /A LAND APPLIED MANURE
Ref. 67, 113
SEEPAGE FROM STACKED MANURE
Ref. 19, 45
FEEDLOT RUNOFF V / / / / / / / / /\
Ref. 2, 16, 45, 51
I
0.01
I
O.I
I
I
I
100
TOTAL PHOSPHORUS CONCENTRATION (mg/1)
Figure 2. Observed range of total phosphorus concentrations from nonpoint sources.
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at spring overturn in lakes and reservoirs have been found to stimulate
excessive or nuisance growths of algae and other aquatic plants. These algal
blooms can reduce the aesthetic quality, making water bodies less desirable for
swimming, fishing, and boating. Algal growths can also impart undesirable tastes
and odors to the water and interfere with water treatment. When large masses of
algae and other aquatic plants die, the dissolved oxygen in the water decreases
and certain toxins are produced, both of which can cause fish kills (66).
Phosphorus seldom contaminates groundwater, with concentrations generally
less than .05 mg/1 (71). However, soils have a finite capacity for fixing
phosphorus and if heavy applications of manure exceed this adsorptive capacity,
elevated concentrations of phosphorus in the runoff and leachate may result (21).
Leaching into groundwater is also possible if manurial phosphorus is applied to
sandy soils where adsorption sites are not readily available.
Animal wastes can carry pathogens to any swimming or drinking waters
they impact (41). These wastes are sources of bacteria and viruses that can
infect man and animals, and create outbreaks of disease in the aquatic environ-
ment (66). The World Health Organization estimates that more than 150 diseases
are transferable between animals and humans (41). Although waterborne diseases
are relatively rare in this country, increasing emphasis on water-based recre-
ation creates new opportunities for this mode of infection. The log mean of
200 fecal coliform bacteria per 100 ml is the limit recognized as being safe
for bathing purposes. Fecal coliform levels serve as an indicator of the micro-
bial pathogen levels in a water source (66).
Bacteria stored in lagoons or applied to soil die off rapidly (108). Other
sources found that when dairy manure slurry was pumped through irrigation sprink-
ler equipment, the median total coliform and fecal coliform levels of ground-
water underneath the manure application site were well within the permissible
criteria for raw surface water for public supplies (8). Thus, little public
health hazard would appear due to livestock wastes (108) unless disposal is di-
rectly into a water supply.
Salt contents associated with animal wastes result from high salt content
in animal rations. The excess salts pass through the animals and remain in the
manure (41). If this manure is then applied to fields at high rates, consider-
ably higher salt concentrations may be found on these fields versus those with-
out applied manure doo). A soil salt problem can exist when soluble salts ac-
cumulate in the soil solution in excess of the exchangeable fraction that the
soil can handle. Salts can be leached from the soil surface by rainfall, caus-
ing ground and surface water pollution 26,41,35). Salts (i.e. dissolved solids)
are objectionable in drinking water because of possible physiological effects,
unpalatable mineral tastes, and higher costs associated with metal corrosion or
additional water treatment (66). Some of the physiological symptoms caused by
high salt intake include laxity from sodium sulfate and magnesium sulfate, en-
hancement of cardiac disease due to sodium and the adverse effects sodium has
on women with toxemia associated with pregnancy. Sodium frequently is the
principal component in dissolved solids, and although specific levels for water
supplies have not been established, it is recommended that sodium levels for
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those people on salt restricted diets not exceed 20 rng/1- For people on
moderately salt restricted diets, levels should not exceed 270 mg/1.
High concentrations of salts in the plant root zone resulting from high
rates of animal waste application can reduce crop yields (57). The amount of
salt accumulation that can cause yield decreases is dependent upon crop salt
tolerance. Germination can also be affected by manurial salinity. On loam
soils in Southern California, salt sensitive spinach and radishes, when fertil-
ized with dairy manure, had germination reductions of 25% and 50% respectively
(1).
A 1975 survey estimated that 112 million tons of manure are being pro-
duced annually by livestock and poultry industries. Presently, 60 million
tons are being applied directly to farm land with the remainder available for
collection and application to other lands (98 ). Although on a national scale
the contribution of animal waste as a fertilizer is small, within a watershed
manure can be one of the major nutrient sources (Table 3.)and thus a major con-
tributor of pollutants (86).
TABLE 3. SOURCES OF NITROGEN AND PHOSPHORUS ON A
NATIONAL AND WATERSHED SCALE
Source
Commercial
Fertil izer
Fixation
Manure
Plant Residues
Precipitation
Totals
National
% Nitrogen
45.9
20.3
6.8
16.9
10.1
100.0
% Phosphorus
76
0
14
10
0
100
Wisconsin
% Nitrogen /
8.5
10.3
35.9
38.5
6.8
100.0
Watersheds
'o Phosphorus
32
0
48
20
0
100
Adopted from: Stewart, B.A., Woolhiser, D.A., Wischmeier, W.H., Caro, J.H.
and M.H. Frere, "Control of Water Pollution from Cropland, Volume II, A
Manual for Guideline Development," USDA, EPA; EPA-600/2-75-026b, 1975.
With the large amount of animal manure available and the tendency to apply
wastes on adjacent land, proper management of animal waste is essential to
prevent impairment of water quality.
The International Reference Group on Great Lakes Pollution from Land Use
Activities (PLUARG) found that mismanagement of animal wastes was a key factor
in water quality problems associated with the Great Lakes region. Mis-
management practices were found to include lack of proper storage facilities
and the spreading of manure on frozen soils close to drainage systems. Un-
controlled discharge of wastes from livestock and poultry confinement operations
into water sources has also been associated with Great Lakes water quality
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degradation (33).
Small feedlots may also be major sources of pollutants when runoff is
not controlled. In the New York Model Implementation Program (MIP) project
West Branch of the Delaware River, phosphorus from barnyard runoff was found
to be responsible for the eutrophication of the Cannonsville Reservoir (2).
These are only a few examples of water quality impairments caused by
agricultural nonpoint source inputs. Concern for improving and/or maintain-
ing water quality has necessitated the development of mechanisms for con-
trolling NPS pollutants. The intention of this report is to identify and
discuss the state-of-the-art in Best Management Practices (BMPs) for control-
ling inputs from livestock and poultry production wastes.
-------
SECTION 2
ANIMAL WASTE MANAGEMENT
Livestock production occurs in every state, however, these livestock
industries tend to be concentrated according to climate, feed availability
proximity to market, etc. Beef production is most concentrated in the
central region, hog production in the Corn Belt region, dairies in the Great
Lakes and northeast regions, and layers and broilers in the east and southeast
regions of the continental United States (Figures 3-7) (106). This regional-
ization of animals to specific areas of the nation also regionalizes where an-
imal wastes may be used as the primary source of fertilizer for cropland, and
may also be a predominant contributor to water pollution.
Due to either geoclimatic or hydro!ogic differences, best management
practices (BMPs) for applying animal wastes may also tend to be regionalized.
For the purposes of this discussion, BMPs will be described in terms of
their regional and/or national applicability. Regions designated by the SCS
Land Resource Regions map (Figure 8) will be used for the purpose of area
identification.
ANIMAL WASTE USES
The utilization of animal waste while minimizing pollution of ground-
water and surface water systems is the management operation of most concern.
Some established practices for disposal of animal wastes (44) are as follows:
1) land application as a fertilizer and soil conditioner.
2) land application as supplemental water for crop production.
3) re-use of liquids to flush and transport manure.
4) re-use of processed solids as bedding or litter-
5) as a supplemental energy source.
6) re-use as a feed for livestock.
LAND APPLICATION
Increases in production of livestock and poultry in larger, more special-
ized confinement operations has resulted in large quantities of manure being
10
-------
HEAD (1000)
P«V«1 - _ _
»•••! IKK!
£»••! 1001
E?3 1241-1550 0 311-620
00 981-1240 D 156-310
[H 621-930 CH 0-155
Figure 3. Fed beef production in U.S. (Jan. 1, 1976)
Adopted from: White et al . (106).
-------
ro
HEAD (1000)
010 3901
EH 3121-3900 H 781-1560
H0 2341-3120 EH] 391-780
H 1561-1230 D O-290
Figure 4. Fed hog production in the U.S. (number on farms, Dec. 1, 1975)
Adopted from: White et al. (106)-
-------
Figure 5. Dairy cows on farms in U.S. (Jan 1, 1976)
Adopted from: White et al. (106).
-------
BIRDS (1,000,000)
00 15.6
£3 12.5-15.6 H 8.1-6.3
DD 9.4-12.5 ED 1.5-3.1
H 6.3-9.4 D 0-1-5
Figure 6. Layers in production in the U.S. (Dec. 1, 1976)
Adopted from: White et al. (106).
-------
BIRDS (1,000,0(50)
501
401-500
301-400
201-300
td 101-200
D 51-100
1 0-50
Figure 7. Commercial broiler production in U.S. (1976)
Adopted from: White et al. (106).
-------
LEGEND
A Northwestern Forest, Forage and Specialty Crop Region
B Northwestern Wheat and Range Region
C California Subtropical Fruit, Truck and Specialty Crop Region
D Western Range and Irrigated Region
E Rocky Mountain Range and Forest Region
F Northern Great Plains Spring Wheat Region
G Western Great Plains Range and Irrigated Region
H Central Great Plains Winter Wheat and Range Region
I Southwest Plateaus and Plains Range and Cotton Region
J Southwestern Prairies Cotton and Forage Region
K Northern Lake States Forest and Forage Region
L Lake States Fruit, Truck and Dairy Region
M Central Feed Grains and Livestock Region
N East and Central Farming and Forest Region
0 Mississippi Delta Cotton and Feed Grains Region
P South Atlantic and Gulf Slope Cash Crops, Forest and Livestock Region
R Northeastern Forage and Forest Region
S Northern Atlantic Slope Diversified Farming Region
T Atlantic and Gulf Coast Lowland Forest and Crop Region
U Florida Subtropical Fruit, Truck Crop and Range Region
Figure 8. Land Resource Regions (83).
16
-------
produced in high concentrations. Coupled with the high cost of petroleum-
based fertilizers, the use of animal wastes as an economic alternative to
commercial fertilizer has increased. Proper management of these wastes is
necessary to prevent water pollution.
Manure applied to cropland not only supplies nutrients, but also im-
proves soil tilth, reduces runoff rates and improves soil infiltration. Reddy
et al. (72) found that animal wastes add organic matter to the soil while also
reducing runoff and increasing infiltration. Gilbertson et al. (26) found
that surface applications of 6.7 metric tons ormore (dry weight)per hectare can re-
duce soil loss from sloping land by 50 to 80 percent. Because sediment is a
major transport vehicle for phosphorus and organic nitrogen (86, 101 ) manure
applications may substantially reduce nutrient transport to runoff waters
while increasing the infiltration and water holding capacities of some soils.
Mathers and Stewart (54) found that beef feedlot manure increased the soil
organic matter and hydraulic conductivity on clay loam soils in Texas. A
related study (56) found that rates of 22 and 67 metric tons per hectare per
year of beef feedlot manure incorporated into clay loam soils increased water
intake by 10 to 15 percent, while the amount of runoff decreased. Long et al.
(47) found that 45 metric tons per hectare per year of dairy manure on sandy
loam soils decreased runoff either by increasing the water holding capacity
or increasing the infiltration rate of the soil. Land application of animal
wastes should be executed according to Best Management Practices (BMPs) so that
immediate runoff is eliminated, odor suppressed and quantities of limiting ma-
terials not exceeded (32). To accomplish this, the rate, timing and method of
manure application are essential factors to be considered (41).
Management Considerations
Preapplication and application losses differ greatly between individual
manure management systems (103)- Factors (87) which affect the nutrient con-
tent of the animal waste and their eventual availability to plants are:
1) the method of waste collection and storage-
2) the length of time waste is stored.
3) the amount of feed, bedding and/or water added.
4) the time and method of field application.
5) the soil characteristics.
6) type of production and/or housing facilities-
7) climate.
The form in which animal wastes are applied varies with the type of
management system. Most animal manures are in either a solid, liquid or slurry
form. Solid manure will have a solids content of about 15 to 25;.', and liquid
manure will have zero to 4% solids, with the slurry form lying in between (26).
The handling of manure from barnyard lots as a solid is the least expensive
17
-------
method of disposal and is the most practical for small production systems (7).
This method, however, requires more labor input. Most liquid systems require
less labor but are more capital intensive.
The type of handling and storage system chosen will determine the amount
of nutrients lost before land application. A breakdown of average losses to
expect from different systems (65) is given in Table 4. Losses of phosphorus
(P) and potassium (K) range from five to twenty percent for all systems ex-
cept the open lot and lagoon waste handling systems where losses can reach up
to seventy percent for P and sixty percent for K. Losses can be reduced if the
feedlot is covered and manure is stored in a manure pack or deep compost pit
(51, 87).
Preliminary Application Procedures
When using animal wastes as a substitute for commercial fertilizer,
several preliminary steps should be taken before actual application. These
steps are soil testing, nutrient analysis and site selection.
Soil Testing --
Periodic soil testing is recommended on all cropland where wastes are to
be applied to determine fertilizer needs. Testing should be done for nitrate
and ammonia (where available), and salt, in addition to standard soil tests to
determine whether nitrogen is being used effectively, whether salinity problems
exist, whether certain elements are present at toxic levels, and whether an in-
creased concentration of one element (such as phosphorus) has reduced the avail-
ability of another (zinc) to plants. Frequent tests (at least annually) are
needed on soils receiving large amounts of wastes in order to monitor the bal-
ance of nutrients in the soil (26, 41, 87).
Manure Nutrient Analysis --
An essential action in providing a fairly exact estimate of the amount
of manurial nitrogen applied should be manure analysis just prior to land ap-
plication (85> 1°9). Differences in nutrient values are dependent on animal
species, the digestibility, protein and fiber contents of the feed ration, the
animal age, the animal environment, and manure handling system (26, 44). Data
compiled from research on land application of animal wastes are summarized in
Table 5. It can be seen that nitrogen and phosphorus contents within a given
species of animal can be highly variable, thus emphasizing the need for
nutrient analysis for proper application rates. When applying liquid wastes,
proper agitation or mixing is necessary to insure a uniform application of
nutrients (87).
Other Considerations —
Matching nitrogen and phosphorus rates with crop requirements will not
always prevent surface and groundwater pollution. Additional considerations
include water infiltration rate, water holding capacity, texture and total
exchange capacity of the soil to determine whether animal waste can be safely
18
-------
TABLE 4. NUTRIENT LOSSES IN HANDLING AND STORAGE (65)
^———^—^—^——^^——^—^^——^-^^
System
Dry Stock (with bedding and roofed storage)
Earth Storage
Lagoon-Flush System
Tear Drop Flush System
Above Ground Tank
Scraped and Placed in Above Ground Tank
Daily Spread
Slatted Floor (manure stored beneath in pit)
Open Shed with Paved Lot
o
Open Paved Lot
o
Covered Paved Area
Approximate
N2
20-403
75-40
70-80
65-80
15-30
15-30
15-356
15-30
30-50
40-60
15-30
% Nutrients
P
5-204
5-20
50-70
50-70
5-15
5-15
5-20
5-10
20-40
20-40
5-15
Lost1
K
5-204
5-20
30-60
30-60
5-15
5-15
5-20
5-10
30-50
30-50
5-15
Animal Species
Dairy
Dairy
Dairy and Swine
Beef
Dairy
Beef and Swine
Da i ry
Beef and Swine
Beef
Swine
Swine
Values do not consider losses of nutrients in the application process on the soil surface or within the soil profile.
2
Fifteen percent nitrogen loss assumed first day while manure is on the floor or alley that is from the time it is
excreted until collection.
Assumes 40% loss if manure is top loaded, 20% loss if loaded from a pipeline below stack. This concept applies also
to earth storage and above ground storage tanks.
Value at higher end of range represents losses by seepage.
Injected into the bottom of the tank.
A 15% loss is assumed if manure can be hauled and spread daily, with sufficient bedding used to retain liquids. Up
to an additional 20% loss can occur if manure must be stored due to inclement weather conditions.
^Manure is collected and applied twice a year. Values do not consider nutrients retained by a grass filter or a runoff
storage pond.
n
Manure is collected in a gutter and then placed in a tank.
19
-------
TABLE 5. SUMMARIZATION OF VARIOUS ANIMAL WASTE NUTRIENT CONTENTS
Species
of
Manure
Poul try
Dairy
Beef
Beef
Dairy
Dairy
Dairy
Beef
Swine
Manure
form
During
Application
Solid
SI urry
Solid
Solid
Slurry
Slurry
Liquid
Slurry
Liquid
Nitrogen
Concentration
(kg/mt)***
44*
18*
15*
16*
4.9**
4.9**
2.9**
7.8**
2.8**
Phosphorus
Concentration
(kg/mt)***
17*
3.9*
5.7*
2.2*
1.2**
0.9**
1.1**
1.6**
0.8**
Reference
15
47
52
58
40
18
59
57
89
*Based on Dry Basis
**Based on Wet Basis
***! kg/mt=0.5 1b/t
-------
applied. Distances to streams, ditches and other water sources must be
considered if animal wastes are surface applied and not immediately incor-
porated. In addition to water quality problems, excess applications of animal
wastes can cause agricultural problems. Cattle have been known to develop fat
necrosis, grass tetany and nitrate toxicity after grazing on fescue pastures
heavily fertilized with poultry litter (34,92,107). Poor stands and reduced yields
caused by toxic levels of ammoria and salts in the plant root zone have also
been well documented (1, 14, 54).
Rate of Application
Studies have shown that to avoid groundwater and surface water contami-
nation and possible crop damage, rates of application should be only enough
to supply crop needs (11,13, 87, 91, 92 ). The application rate for animal
wastes should be based on crop requirements, the nutrient pool of the soil and
the nutrient value of the manure. Fertilizer requirements and N:P:K ratios for
selected crops from Ohio and North Carolina (4, 60) are given in Table 6. Re-
ported animal waste nutrient values (44) and N:P:K ratios are given in Table 7.
Nitrogen is found to be the limiting nutrient for crops where the plant re-
quirement N:P:K ratio equals or exceeds the livestock manure N:P:K ratio (e.g.
swine manure (1:1:1) applied to small grains in Piedmont North Carolina (1:2:1)).
Thus, rates should be based on nitrogen, using commercial fertilizer to supply
additional phosphorus and potassium. Phosphorus is found to be the limiting
nutrient where the N:P:K ratio of manure is less than the requirement ratio for
the crop (e.g. beef cattle manure (1:2:3) applied to corn in Coastal Plain
North Carolina (3:1:2)). Thus, rates should be based on the phosphorus content
of the manure.
Nitrate-nitrogen is the form most available to crops, and also is very
water soluble. If applications supply more nitrate than the crop can use, the
excess can move down through the soil profile and become a potential pollutant
to groundwater (53,94 ). Nitrate leaching from over application of nutrients
has been well documented. Scarsbrook (so) found that when 168 kg N/ha was
applied to corn in the Coastal Plain (region P), most of the nitrogen could be
found in the corn plant with little remaining in the soil. Where 336 kg N/ha
was applied to corn, large amounts of nitrogen remained in the soil and thus
were available to leaching. Significant accumulation of total nitrogen and
nitrate was found in clay loam soils in the high plains of Texas when mas-
sive inputs of nitrogen in the form of feedlot wastes were made (69). Nitrate
accumulations at a depth of 180-210 cm were approximately seven times those
found in plots receiving no manure. Mathers et al. (55) found applications
of 22 mt/ha of feedlot waste to clay loam soil planted to grain sorghum re-
sulted in only small increases in soil nitrate with none moving below two meters,
but when rates exceeded 22 mt/ha, nitrates accumulated in the top two meters of
soil with some movement to depths of six meters. A related study (54) reported
that with application rates of 67, 134 and 268 mt/ha on Texas clay loam soils
planted to a corn-wheat rotation, excess amounts of nitrate accumulated in the
lower soil profiles. Evans et al. (25) found that applying heavy rates of
cattle and swine manures to corn on silt soils in Minnesota resulted in exces-
sive amounts of nitrate moving below the root zone. Applying dairy manure at
21
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TABLE 6. FERTILIZER REQUIREMENTS AND N:P:K RATIOS FOR SELECTED CROPS IN (4,60) IN OHIO AND NORTH CAROLINA
CROP
Corn
Corn
Corn
Pasture (Fesque)
Pasture (Bluegrass)
Small Grains
Small Grains
Small Grains
Sorghum
Soybeans
Soybeans
Soybeans
NORTH CAROLINA
N
134
140
134
168
67
22
45
22
90
-
-
-
P2°4 K2°
(kg/ ha)
45 45
112 56
45 90
45 90
163 84
45 45
90 45
22 45
90 90
45 45
90 45
45 90
Soil Type
Organi c
Piedmont
Coastal Plain
All
All
Organic
Piedmont
Coastal Plain
Piedmont
Organic
Piedmont
Coastal Plain
N:P:K
3:1:1
3:2:1
3:1:2
4:1:2
1:2:1
1:2:2
1:2:1
1:1:2
1:1:1
0:1:1
0:2:1
0:1:2
OHIO
N P204* K20** Expected Yield N:P:K
(kg/ha)
129 56 67 7.53 mt/ha (120 bu/ac) 2:1:1
90 22 - 4.5 mt/ha (2T/ac) 4:1:0
45 90 50 3.4 mt/ha (50bu/ac)wheat 1:2:1
129 56 73 - 2:1:1
50 101 3.4 mt/ha (50bu/ac) 0:1:2
ro
r\i
* Based on soil test of 280 kg K and C.E.C. of 20.
** Based on soil test of 28 kg P
P
-------
45 mt/ha annually on sandy loam soils of Alabama was found to increase the nitrate
in the soil profile (47). Approximately 200 kg N/ha was found accumulated in
the 90 cm profile of the soil and subject to leaching. Jackson et al . (36)
found large increases in nitrate-nitrogen in the profile of sandy loam soils
of Georgia when large rates of broiler litter were applied to the surface of
tall fescue sod. After two years of applying 538 mt/ha of broiler litter,
only 17% to 31% of the nitrogen still remained in the manure residue on the
soil surface, leaving approximately 68% unaccounted for. This rate of applica-
tion killed much of the fescue; thus, none of the nitrogen was taken up by the
crop and was lost either by leaching or denitrification.
TABLE 7. ANIMAL WASTE NUTRIENT VALUES AND N:P:K RATIOS
Animal
Type
Bedding
or Litter
Total
N
Available
N P205 K20
i \,~ /™+ \
N:P:K
V i\y/ nit i
Swine
Beef
Cattle
Dairy
Cattle
Poultry
No
Yes
No
Yes
No
Yes
No
Yes
5
4
10.5
10.5
4.5
4.5
16.5
28
3
2.5
3.5
4
1.5
2.5
13
18
4.5
3.5
7
9
2
2
24
21.5
4
3.5
11.5
13
5
5
17
17
1:2:1
1:1:1
1:2:3
1:2:4
1:1:3
1:1:3
1:2:1
1:1:1
Adopted from: Livestock Waste Facilities Handbook, Midwest Plan Service,
Iowa State University, Ames, Iowa, 94 pp., 1975.
Crop yields can decrease and/or toxic accumulations of nitrate in
forage can be reached if applications of manurial nitrogen are excessively
high. Carreker et al. (15) reported that when rates of 44.8 mt/ha of poultry
manure were applied to corn, yields were decreased. Data show that the heavy
applications increased the difficulty of corn seedling establishment. Evans
et al. (25) found that although corn yields were not affected by applying
high rates of cattle and swine manure, considerable amounts of nitrate were
found in the stover, sometimes at levels exceeding recommended limits (3000 ppm)
for feeding directly to cattle.
Areas where high application rates of animal wastes resulted or could
be projected to result in either nitrate leaching or toxic accumulations of
nitrates in the forage are given in Figure 9. This should emphasize the
need for controlling the amount of nitrogen applied, and that proper rate of
manurial nitrogen application is a BMP for these areas.
Although applications of animal manure can be regulated by the nitrogen
requirements to preclude leaching and groundwater contamination, the phosphorus
in the animal waste must be accounted for and thus application above the
phosphorus requirements of the selected crop avoided (21). The phosphorus
that is not used can accumulate on the upper surface layers of the soil pro-
23
-------
ro
Figure 9. Land Resource Regions with literature references (///) and projections (:::) indicating
nitrate leaching or toxic nitrate accumulations in the forage due to excessive animal
waste application rates.
-------
file and be lost in surface runoff events (7).
Research has shown that high rates of animal waste can lead to large
amounts of phosphorus in the upper layers of the soil profile (14). Cummings
et al. (20) reported more than a two-fold increase in extractable phosphorus
after two years of applying swine lagoon effluent at a rate of 563 kg/ha.
Most of this increase in phosphorus occurred in the top 36 cm of the sandy
loam soil.
Poultry manures can contribute increases in the soil phosphorus even
at relatively low rates. Hileman (29) reported that low application rates
of broiler litter (19 mt/ha) caused increases in extractable phosphorus on
silt loam soils down to a depth of 30 cm. In a 10-county North Georgia area,
soil samples taken from farmers' pastures (15 cm depth) in which poultry
manure was used as a fertilizer were reported to contain 90% more phosphorus
than soil samples taken from pastures fertilized with commercial fertilizers
(37).
Areas where phosphorus accumulations have occurred from large application
rates of manure are illustrated in Figure 10. Most of the area that is
marked is potentially erosive and could possibly transport phosphorus with
sediment.
Soil salinity can become a problem if excessive applications of manure
are made. Salts can affect seed germination, cause inefficient use of plant
elements and thus reduce yields, and can be leached to groundwater sources
(1,66,89).Areas where salts from animal wastes have been a problem, or where
the potential of a problem has been found to exist from heavy manure applica-
tions are illustrated in Figure 11.
When using an animal waste as a fertilizer, both the nitrogen and
phosphorus contents should be matched with the crop requirements. Any ad-
ditional nutrient requirements should then be met using supplemental commercial
fertilizer. Areas where applying the proper rate of manure has been found or
is projected to be a Best Management Practice to maintain water quality are
represented in Figure 12.
Timing of Application
Timing of the application must be considered to effectively reduce po-
tential water pollution and increase plant nutrient uptake efficiency. Climate,
animal species, waste handling methods, and crop type can affect the timing of
application. In areas that are warm throughout much of the year, such as in
the Southern Coastal Plain, organic-nitrogen and ammonium-nitrogen can be
rapidly converted to NO^-M, in less than 20 days in some instances (68). Man-
urial nitrogen applied Tn the fall or winter seasons can be leached away be-
fore the following growing season. It has been reported that 50% of the avail-
able nitrogen in swine and poultry waste was mineralized in three to six
weeks, while beef manure needed up to 18 weeks (70). Careful consideration
should be given to the species of animal manure used in order to be assured
that plant nutrients are available when they are most needed. The crop's
sensitivity to ammonia should also be taken into account when determining
25
-------
ro
cr>
Figure IQ. Land Resource Regions with literature references (///) indicating excessive phosphorus
accumulations on the soil surface due to excessive animal waste application rates.
-------
ro
Figure 11. Land Resource Regions with literature references (///) indicating where salt accumulation
has been a problem or has been shown the potential to be a problem from excessive animal
waste application rates.
-------
ro
CO
Figure 12. Land Resource Regions with literature references (///) and projections (:::) indicating
the areas where application of animal wastes at recommended rates is a BMP.
-------
application time. Animal wastes with high ammonia concentrations have been
shown to inhibit seed germination and decrease yields when applied too close
to the planting date (1,108 ).
Most research agrees that the optimum time for applying animal wastes
is shortly before or as close to planting time as possible (87,91). Some
research has shown that plants in their dormancy stage cannot recover enough
nutrients before they have been leached out of the root zone and thus fertili-
zation should be done after the root system has been established (30, 94, 104).
Top dressings of liquid manure by irrigation onto standing crops not sensitive
to ammonia during early growth stages has been found to be beneficial. Carlile
(14) reported that applying swine wastes to one month-old corn in the Southern
Coastal Plain region did not cause plant damage or reduce the corn yields.
Yields were found to be comparable to those obtained from commercial fertilizer
applications. Other research in the Coastal Plain region (region P) indicates
that spring is the optimum time for animal waste application to cropland. Ap-
lications of poultry wastes on tall fescue plots in South Carolina were reported
only beneficial in the spring and late summer-early fall periods (67). Soil
tests in October of 1978, taken from an area where high rates (672 kg/ha/yr of
manurial-N) were applied to Kentucky fescue, showed approximately 248 kg/ha of
nitrate-nitrogen through the 90 cm soil depth. An additional 168 kg/ha of
nitrate-nitrogen was added in December 1978. When soil tests were again taken
in March 1979, only 70 kg/ha of nitrate-nitrogen remained in this profile just
past the active root zone. While it was not possible to know the exact amount
lost by leaching, 250 kg/ha was conservatively estimated. This indicates that
applying nitrogen when the crop is no longer in an active growing period (late
fall and winter) will result in nitrate leaching. A related study (14) re-
ported that when fall applications of swine waste were made to loam soils in
North Carolina only 50% of the nitrogen remained available for the following
growing season. Losses to manurial nitrogen were thought to be caused by
denitrification or leaching. These losses were not evident when applications
were made in the spring.
The previous research indicates that the application of animal wastes
during spring or active plant growth periods at recommended rates is a Best
Management Practice.
The application of animal wastes to snow-covered ground is a problem
of particular importance to the northern regions of the United States. While
it may be more convenient to apply waste in late fall or winter after harvest-
ing is completed, up to 50% of the total nitrogen can be lost through decompo-
sition and leaching, thus increasing water pollution potential (14).
Heavy losses of organic matter and nutrients can occur through surface
runoff when manure is spread on frozen ground, snow-covered fields, or prior
to heavy rainfall during winter periods (12, 51, 108). Areas receiving manure
during the winter and subject to snowmelt runoff have been reported to result
in significantly higher nitrogen and phosphorus losses compared to those areas
receiving applications during the summer and fall (38). When manure is applied
to frozen ground, losses of up to 20% and 17%, respectively, of applied nitrogen
29
-------
and phosphorus in early spring runoff have been reported (39, 113).
Klausner et al. (40) reported that when 100 mt/ha of dairy slurry was
field spread during a single snowmelt event in New York state approximately
45.6 kg/ha of inorganic nitrogen and 8.9 kg/ha of total soluble phosphorus
were lost in the runoff. This accounted for 85.7% of the nitrogen and 93.6%
of the phosphorus lost under this application rate for the entire winter period
of January 1 through March 31. Animal waste rates of 35 mt/ha and 200 mt/ha
that were applied 10 days before the snowmelt also showed significant losses
of inorganic nitrogen and soluble phosphorus. Results showed that 35 mt/ha
could be applied safely to frozen ground if it were then covered with snow
before a thaw period resulted.
Minshall (59) examined the application of dairy manure to the silt loam
soils in southern Wisconsin and found that up to 20% of the nitrogen and 13%
of the phosphorus could be lost in spring runoff when applications were made
on frozen ground. In a similar study ( 10]), dairy manure was surface applied
to Wisconsin loam soils in late fall. When grab samples of snowmelt runoff
were taken in March, P concentrations were almost 23 times the concentrations
of the control (unmanured) area.
There have been reports, however, that applying animal wastes to frozen
ground has improved water quality. Young and Mutch!er (112) found that when
applying 44.8 mt/ha of solid dairy waste on frozen plowed soil in Minnesota,
soil losses were reduced 100% and runoff reduced up to 80% when compared with
unmanured control areas. Data indicated that the total nitrogen loss was not
significantly increased by the manure application. Nutrient losses were thought
to be less when manure was applied on top of the snow versus when the manure
was covered with snow. Snowmelt runoff generally occurs from underneath the
snowpack, therefore manure under the snow is in contact with the runoff water
and can be transported away. A related study (111) reported that application
of manure to frozen soil eliminated soil losses due to snowmelt runoff. Soil
loss on the manured plots averaged 10.9 mt/ha compared to 20.5 mt/ha and 16.5
mt/ha of soil for unmanured and natural runoff areas. Since most of the nu-
trient losses were associated with soil loss, the total nutrient loss from
manured plots was reduced. Witzel et al. (110) reported that nutrient losses
from winter and spring runoff of four small watersheds in Wisconsin were the
same even though some of the watersheds had winter spread manure while some
did not.
Manure application during the fall and winter seasons in the Northern
regions does not appear to be a BMP. In isolated instances manure applied
to snow-covered or frozen ground can provide a mulch for reducing runoff
and thus reduce the nutrients carried in runoff waters. However, this ap-
pears to be the case only when manure is handled in the solid form. Application
of manure in the fall and winter to regions that have potential to leach nutrients,
are poorly drained or have high water tables is not considered a BMP. The areas
where the spring or summer application of animal wastes is considered or pro-
jected as a BMP based on research data are denoted in Figure 13.
30
-------
Figure 13. Land Resource Regions with literature references (///) and projections (:::) indicating
the areas where application of animal wastes during spring or summer periods is a BMP.
-------
Methods of Application
Methods of applying animal wastes (87, 108) are:
1) broadcasting only
2) broadcasting followed by plowdown or discing
3) knifing or injection
4) irrigation-
The application method is dependent on the manure moisture content. Manure
in the liquid form can usually be spray applicated with an irrigation system
(5). Manure in slurry form can be spray irrigated but is more often broadcast
or soil injected by a liquid manure spreader. Waste slurries should be ap-
plied to the soil surface in such a manner that utilization and degradation by
plants and soil bacteria can be accomplished while soil and water pollution are
minimized (79). Manure can be handled in the solid form by either drying or
by the adding of bedding (straw, wood chips). Bedding, in addition to its
adsorption properties, helps reduce volatilization losses of nitrogen (28).
Volatilization of ammonia can occur if manure is left exposed for long
periods of time (26), with as much as 80% of the ammonia being lost shortly
after land application (70). Will rich et al. (109) reported that when fresh
manures with nitrogen contents greater than 2% are left on the soil surface
for several days, as much as 50% of the total nitrogen can escape to the atmos-
phere as free ammonia. Losses were greatest from warm, relatively dry soils.
Wind and low humidity may also increase the amount of losses that can occur
(3). Although the amount of volatilization that can be expected is variable,
estimated losses associated with different application methods are given in
Table 8 (44).
TABLE 8. ESTIMATED VOLATILIZATION LOSSES ASSOCIATED WITH APPLICATION METHODS
Method of
Application
Broadcast
Broadcast and immediately
cultivated
Knifing
Sprinkler irrigation
Type of
Waste
Solid
Liquid
Solid
Liquid
Liquid
Liquid
Average N
Volatilization Loss %
21
27
5
5
5
25
Adopted from: Livestock Waste Facilities Handbook. Midwest Plan Service,
Iowa State University, Ames, Iowa, 94 pp., 1975.
32
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Conventional Practices —
Safley et al. (75) compared the crop performance between areas receiving
surface-broadcasted swine manure slurry and areas where manure was injected.
The injection method gave the highest corn yields at both rates of manure
tested (168 and 336 kg N/ha). Yields at the 168 kg N/ha rate were comparable
to yields produced from similar nitrogen rates of commercial fertilizer.
Broadcast manure at this rate produced only 80% of the yield of that obtained
from the commercial fertilizer treatment. The broadcast manure, however, had
not been incorporated, thus losses could be linked to ammonia volatilization
and surface runoff.
Lowest nutrient losses and best crop yields can be attained when manure
is incorporated into the soil before it dries (28). Immediate incorporation
of solid manure minimizes losses to the air and allows soil micro-organisms to
decompose the waste sooner, thus allowing nutrients to become available sooner.
When manure slurry is incorporated, losses to air and runoff, as well as odors,
are minimized (87).
Patni (64), in a three year study, examined the effects of large-scale
plowdown of liquid dairy, sheep and poultry manure slurries on the physical
quality of drainage water from a 594 hectare watershed. No noticeable effects
on water quality were detected from the usage of manure as a fertilizer. Mon-
itored results showed the volatile fraction in the nonfilterable material in
the drainage water of the manured area was practically the same as the water
from a chemically fertilized area and non-cultivated area within the watershed.
The reasonably good physical quality of the drainage water could be attributed
to management factors of immediate plowdown of the manure into the soil fol-
lowing application, rotation of fields for manure applications and applications
made away from stream banks.
Research shows that incorporation or injection of animal wastes can
eliminate losses of nitrogen through erosion and volatilization while increas-
ing crop yields. Regions where incorporation has been documented or is pro-
jected to be a BMP are shown in Figure 14.
Other Practices --
Other practices have been investigated to obtain maximum crop yields with
minimum pollutional effects. One practice is location of the application in
relation to the plant. Hensler et al. (28) found that liquid manure slurry
knifed midway between the rows and applied four to six inches beside the rows
resulted in somewhat larger yields than where the manure was surface applied
or plowed under.
Long et al. (46) reported that when manure was applied at rates of 45
mt/ha annually in split applications, higher nitrate levels in the runoff were
recorded compared to that of non-manured areas, though the values were still
below the criteria for drinking water sources. No differences in the nitrate
content of the groundwater could be detected. Yields also tended to be lower
on the manured areas than on those of the controlled areas.
33
-------
OJ
-p.
Figure 14. Land Resource Regions with literature references (///) and projections (:::) indicating
incorporation of animal waste during or immediately after application as a BMP.
-------
Quisenberry (67) reported on applying dry and slurry dairy manure at
rates of approximately 235 kg/ha of manurial nitrogen to sandy loam soils
in single and split applications. No noticeable differences appeared in the
N runoff from single versus dual applications of the dry manure. However, the
percentage of phosphorus in the runoff was higher for the single versus the
dual application of the liquid manure slurry. Results also indicated that
nutrient losses were slightly less when wastes were applied as a solid as
opposed to a slurry.
Split applications of animal wastes are a BMP when applied to grasses where
runoff is reduced or when injected as a side dressing for row crops. Split ap-
plications are ineffective if applied to bare ground where a crop is not avail-
able to immediately utilize the nutrients. Areas where split application of
manure is projected to be a BMP are given in Figure 15.
FEEDLOTS
There is potential for leaching and runoff losses when animal waste is
exposed to weathert> The magnitude of pollution from feedlots can be several
times that of land application sites (38). Under an open lot system almost 50%
of the phosphorus and 40% of the potassium can be lost to runoff and leaching
(87). Losses of nitrogen are usually in the form of ammonia and nitrates (27).
These losses are especially important if the nutrients are getting to receiving
streams via surface runoff.
The criteria for determining if a feedlot is a point source of pollution
are established under the National Pollutant Discharge Elimination System
(NPDES). Point source feedlots must have a permit which stipulates the amounts
and conditions under which the lot effluent can be discharged. Small feedlots
which are classified as nonpoint sources, however, can also contribute signifi-
cant amounts of pollutants to ground and surface waters (16, 53). Thus, small
feedlot operators should also incorporate some type of effluent control or
treatment into their waste management system.
Vegetative filters are systems in which areas such as pastures, grassed
waterways or even cropland are used for treating feedlot runoff or dairy parlor
wastes by settling, filtration, dilution, adsorption of pollutants, and in-
filtration . These filters usually have either channelized or overland flow.
Channelized flow systems (i.e. graded terrace channel or grassed waterway)
concentrate the flow to a relatively narrow channel. Overland flow systems al-
low flow of uniform depth over the disposal area (97).
Research has shown that filtration strips are very effective in treating
animal waste runoff on most regions in the continental United States (Figure
16). Bingham et al. (9) found that buffer strips seeded with a mixture of
reed canary, redtop and fescue on clay loam soils in the Coastal Plain removed
77°; of the TKN, 94% of the total phosphorus, and 96% of the COD from applied
poultry waste. In the corn belt region, Dickey and Vanderholm (21) examined
two systems consisting of a dairy and a beef operation both using an overland-
flow filtering system, and a beef and swine operation both using channelized
35
-------
GO
01
Figure 15. Land Resource Regions with literature references (///) and projections (:::) indicating
split application of animal wastes as a BMP.
-------
OJ
Figure 16. Land Resource Regions with literature references (///) and projections (:::) indicating
filtration strips for treating feedlot runoff and milking parlor wastewater as a BMP.
-------
flow systems. All systems had a settling facility that reduced concentrations
about 75%. The channelized systems, however, required almost five times the
length of the overland-flow systems in order to obtain equivalent reductions
in concentration. Edwards et al. (24) examined the effectiveness of a settling
basin-grass filter system for treating beef feedlot wastes in eastern Ohio.
Concentrations of total solids, COD and BOD were markedly reduced by the settling
basin. Potassium, ammonium-nitrogen and phosphorus concentrations also showed
reductions when filter strips were incorporated into the system. Young et al.
(ll2) examined four types of vegetative buffer strips for reducing feedlot
runoff. These strips consisted of corn, orchard grass, sorghum-sudan grass and
oats. The corn buffer strip was found to have the greatest amount of reduction
in solids and runoff at 86% and 82%, respectively, followed by orchard grass
at 66% and 81%, sorghum-sudan grass at 82% and 61%, and oats at 75% and 41%.
Total nitrogen and total phosphorus associated with the solids were also reduced
for all treatments an average of 93% and 92%, respectively. Concentrations of
TN, NH4-N, TP and PO.-P in the runoff were also reduced 67%, 71%, 67% and 69%,
respectively. Significant reductions in coliform organisms in the runoff water
were also seen after the runoff passed through the vegetative strips.
Filtration strips have also been found very economical in treating milking
parlor wastes (63). These wastes can consist of water used for washing, rinsing
and sanitizing milking equipment and storage tanks as well as wastewater generated
in the milking operation and the cleaning of the parlor (48). When milking
parlor wastes are passed through a grassed filter, much of the pollutant load
can be trapped on the surface of the vegetation and biodegradation can take
place.
Overland Flow systems appear to be more effective than channelized flow
systems for removal of pollutants from runoff (93). Because of the concentrated
flow that occurs in channelized systems, vegetative kill sometimes results,
limiting the effectiveness of this system. Effectiveness of both systems can
be limited by daily heavy loadings. Where loadings of this nature are antici-
pated, a second filter area for periodic system recovery and drying is recom-
mended (93). Settling basins can also reduce the amount of solids in the
effluent, thus reducing the amount of vegetative kill.
The type of filter treatment system chosen and the degree of treatment
achieved will depend on the soil type, soil texture and size of the treatment
area, consistency and rate of discharged effluent to be treated, and the treat-
ment frequency and time of year.
UNCONFINED PASTURED ANIMALS
The contribution that pastured livestock will make to nonpoint source
pollution is dependent upon the stocking density, length of grazing period,
average manure loading rate, manure spreading uniformity by grazing livestock,
disappearance of manure with time and their distance from a water body (90).
Documented cases of pollution resulting from the fecal deposition of livestock
to pasture and rangeland are limited. Often, the only water quality change
that can be definitely discerned is elevated counts of indicator bacteria (75).
38
-------
A literature review conducted by Khaleel et al . (38) determined that most of
the pollution that was associated with livestock on pasture or rangeland
resulted from overgrazing. It was found that as livestock overgrazed an area,
grass cover was reduced and soil erosion was allowed to take place, resulting
in the loss of sediment bound nutrients. Lack of a grass cover was also found
to increase runoff and to decrease the effectiveness of vegetative filtering,
thus allowing more animal waste pollutants to reach receiving bodies of water
(75, 77)-
Most recommendations for pasture management to maintain water quality
pertain to the maintenance of a grass cover to prevent soil erosion and re-
strict runoff volumes. Grazing programs should be tailored to the soil
vegetation, topography, hydrogeology and microclimate of the particular site.
Animals should be restricted from critical areas such as highly erodible areas
or water bodies (i.e. streams, ponds, etc.). Stocking rates should be such,
that the pasture or rangeland is not converted from a grazing area to a hold-
ing area. Pasture feeding areas should be as far removed from water courses
as possible and should be periodically rotated in order to allow the denuded
areas around the feed bunk to recover.
SUMMARY
The most effective way to obtain maximum nutrient benefits from manure
and avoid potential pollution problems is by applying manure at the agronomic
rates determined for the crop. The rate to apply can best be determined by
soil and manure nutrient testing. It has been demonstrated that rates of manure
can have different concentrations of nutrients depending on the animal species,
ration fed, and the type of storage and handling system used. Thus, it is es-
sential to have the manure analyzed to assure that proper amounts are applied.
Both the nitrogen and phosphorus contents of the manure should be matched with
the crop requirements. Any additional nutrient requirements should be met
using commercial fertilizer as a supplement to avoid over application. Ap-
plication of the waste should be when the crop can most effectively use the
nutrients. This appears to be in the spring and summer seasons. If application
is to be made before planting, time should be allowed (generally two to four
weeks) for applied ammonium-nitrogen to mineralize, thus avoiding problems with
seed germination. Fall and winter applications of animal wastes should be re-
stricted to those areas where cover crops can utilize the nutrients. Fall ap-
plications allow some of the manurial nitrogen to be converted to nitrate and
lost by leaching. Winter applications can result in significant losses of
nitrogen and phosphorus in surface runoff during periods of rainfall or snow-
melt.
The most effective practice for reducing pollution from small feedlots
is to divert water from flowing through the feedlot and thus preventing much
of the solid and liquid pollutants from being carried in the runoff. Feedlots
with excessive amounts of runoff should consider some type of treatment system.
One of the more cost-effective methods of treatment is a combination settling
basin-vegetative filter strip. Filter strips have also been found to be ef-
fective in reducing the amount of solids and liquid nutrientsin milking parlor
39
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wastes. When daily heavy loadings are anticipated, a second filter area for
periodic system recovery and drying should be used to improve system effective-
ness.
Pasture management to maintain water quality should include animal
restriction from critical areas, such as erodible areas and water bodies, as
well as rotational grazing and maintenance of low stocking rates to prevent
overgrazing.
40
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SECTION 3
ECONOMICS
OF WASTE MANAGEMENT SYSTEMS1
Increased environmental regulations, rising energy costs, and
increased fertilizer costs are providing new incentives and pressures for
farmers to rethink their attitudes towards waste management. The costs
involved in proposed changes are requiring an increased awareness and use
of economic principles. Questions about the costs and nutrient savings
of alternative manure handling technologies need to be answered in a
consistent evaluation framework.
The decisionmaking process requires technical information available
from diverse sources. Sources of information include county extension
agents, local universities, equipment dealers, agricultural engineers,
the Soil Conservation Service (SCS), and other Federal agencies with
agricultural waste management expertise.
After farmers collect information on the most pertinent technical
solutions, they still must decide which is the most appropriate and
economical for their operations. Many factors affect the decision to
undertake proposed changes, including the length of an individual farmer's
planning horizon, availability and costs of capital, and type of farming
operation. The main factor which influences the selection process is
the net cost of each proposed system—that is, the total cost less the
value of nutrients realized from the system amortized over the expected
lifetime of the system. An important factor in this decisionmaking
process is the extent to which manure can be used as a productive resource
rather than treated as a waste product.
ECOMOMIC CONCEPTS AND PROCEDURES
Livestock and crop production involves a continual series of
farm-level decisions. One of the most important decisions is how to
organize the available resources to maximize profits. In crop agriculture,
resource inputs typically include land, seed, fertilizer, water, labor,
and capital. Outputs include products such as corn, wheat, or hay. In
This section was prepared by Dr. L. A. Christensen, Economic Research
Service, U.S. Department of Agriculture (USDA), Athens, Georgia.
41
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livestock production, resource inputs include labor, grain, roughages,
proteins, minerals, and equipment, including those for manure handling and
management. Outputs include milk, meat, and poultry products.
A farmer's decisionmaking process in organizing inputs for production
may be very structured, or it may be little more than an intuitive judgment.
Regardless of the method, the decisionmaker can usefully employ economic
concepts such as the principle of diminishing returns, the principle of fixed
and variable costs, and the concept of opportunity costs. These concepts
can be incorporated into relatively simple tools for economic analysis, such
as a complete budget or a partial budget.
Principle of Diminishing Returns
The concept of diminishing returns represents a physical relationship
and simply states that after some point each additional unit of input adds
less to total output than the previous unit. In more formal terms, the
law of diminishing marginal physical returns states that as the amount of
a variable input is increased, with the amount of other fixed inputs
held constant, a point is reached beyond which marginal product declines.
The basic physical relationships between inputs and outputs stated in this
law of diminishing returns is extremely useful in economic analysis. When
respective prices are assigned to the output (for example, corn) and to the
input (for example, nitrogen), the outputs and inputs are expressed in
the same term—namely, dollars. Expressing the relationship in this manner
aids in deciding how much fertilizer to apply. One has only to find the
nitrogen application rate where profit is greatest—that is, where the
total revenue exceeds the total cost by the largest amount. This application
rate occurs when the value of the additional yield is equal to the additional
cost of producing that yield. A greater application rate of nitrogen will
cost more than it returns.
The data in table 9 illustrates the principle of diminishing returns.
Maximum physical production is 146 bushels per acre, where 200 pounds of
nitrogen are applied. However, with the respective prices of corn and
nitrogen at $2.20 per bushel and at 16 cents per pound, only 160 pounds
would be applied to obtain a 144-bushel yield. Additional nitrogen appli-
cations would cost more than the value of the additional yield.
A few generalizations are appropriate, relative to diminishing
returns. First, excessive input of a single resource, such as fertilizer,
pesticides, water, labor, or seed, will result in reduced profit and
output. Second, not only are the revenues lost and the costs increased,
but in the case of inputs such as fertilizer and pesticides, the potential
for environmental degradation increases with heavier application rates.
Excessive and poorly timed application of fertilizer may mean not only
lost profit to the farm operation but also a cost to society in the form
of diminished water quality-
42
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TABLE 9. HYPOTHETICAL RELATIONSHIP BETWEEN NITROGEN APPLICATION RATES AND CORN YIELD I/
Bushels
per
acre
81
105
124
w 137
144 2]
146 3_/
143
Value of 1
total a<
yield
Hnl 1 a r<;
178.20
231.00
272.80
301.40
316.80
321.20
314.60
i/alue of
Jditional
yield
--
52.80
41.80
28.60
15.40
4.40
-6.60
Total pounds
and cost of
nitrogen
__
40 6.40
80 12.80
120 19.20
160 25.60
200 32.00
240 38.40
Cost of
additional
nitrogen
n/-> 1 Tare
—
6.40
6.40
6.40
6.40
6.40
6.40
Change
in net
revenue
--
+46.40
+35.40
+22.20
+9.00
-2.00
-13.00
Not applicable.
\l Corn priced at $2.20/bushel; nitrogen at $0.16/pound.
2J Profit-maximizing yield.
3/ Maximum physical yield.
-------
Fixed and Variable Costs
Two other important concepts in the evaluation of animal waste
management systems are fixed and variable costs. Definitions of fixed
and variable costs are based on the time frame under consideration. With
a longer planning horizon, more and more fixed costs become variable.
Fixed costs represent costs that are incurred annually regardless of the
level of production, such as depreciation, taxes, insurance. In contrast,
variable costs fluctuate with the production level. Examples are labor,
energy, and feed costs.
Specification of fixed and variable costs depends on the time frame
under consideration. Both fixed and variable costs are associated with
any given production year. However, in deciding whether or not to pro-
duce, decisionmakers consider only variable costs. As long as a production
enterprise will yield sufficient revenues to cover variable costs and a
portion of the fixed costs, production should continue. The alternative
of idling the resources would result in no revenues being generated to
offset the fixed costs.
As the time span increases, the producer is able to make changes,
whereas in the short run the producer has fewer alternatives and becomes
locked into a particular production activity. In a longer planning period,
some of the previously fixed costs become variable costs and in the very
long run, all costs become variable. In other words, over a long enough
planning period, fixed assets can be completely depreciated or abandoned.
An important point to remember is that there are tradeoffs between
fixed capital and variable capital resources such as equipment and labor.
Capital can usually be readily substituted for labor. However, once
capital is invested in durable equipment, the tradeoffs become difficult
and are almost impossible in the short run. Consequently, as farmers buy
more equipment to reduce labor, their flexibility for meeting changing
economic conditions is reduced.
Opportunity Costs
Farmers continually seek to use their limited resources in the most
productive manner. Applying the concept of opportunity costs insures that
resources are used in the most economically efficient manner. The
opportunity cost is the income or return foregone by using a resource
somewhere other than for its most profitable purpose. Profits will be
greatest when each unit of land, labor, and capital is used where it
will add the greatest return. Stated differently, optimum use of limited
resources exists when resources are organized such that any change in the
organization of capital, labor, or acreage inputs will reduce income.
44
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The opportunity costs principle can be demonstrated with an example
from hog production. A hog producer who has been applying manure on corn
fields receives an offer of $5 a ton from a neighbor. The producer figures
that $3 a ton can be cleared after a deduction for transportation costs.
Sale of 200 tons would return $600, but it would take $700 worth of
commercial fertilizer to replace the hog manure and still maintain production
levels. By selling the manure, the producer incurs a $700 opportunity cost.
As the return from selling the manure was $600, there would be a net loss
of $100 due to foregone opportunities.
Budgeting
Two forms of budgeting can be used for incorporating economic concepts
into problem analysis—complete budgeting and partial budgeting. Complete
budgeting refers to a total accounting plan for whole farm or for all de-
cisions in a single enterprise. For example, complete farm budgeting would
estimate all crop and livestock producing methods, costs, and returns. It
would include all viable alternatives for the farm organization. Many farm
management decisions affect only a small portion of the entire farm operation
and do not require all the information for a complete farm budget. Farmers
can use partial budgeting to evaluate only those operations or input levels
that will be affected by the decision.
Partial budgeting is the most common and the simplest form of budgeting
for economic decisionmaking. The crucial element in preparing a partial
budget is identifying the items that change due to an adjustment. For example,
a livestock operator considering changing waste management systems is un-
likely to make a complete change in livestock enterprise. Feed costs,
veterinary bills, building costs, and machinery and equipment costs not
associated with waste management will remain unchanged. However, the costs
of waste disposal may well change, as might the cost of producing crops if
the manure is spread on the land. Thus, these items should be included in
the partial budget. Similarly, if an adjustment in the system increases
the amount of nitrogen available from manure, then the use of commercial
fertilizer might also be examined in the partial budget.
In evaluating alternative investments, farmers can set up partial
budgeting to identify the returns and costs for each alternative. Then
they can identify the differences in costs between alternatives. Table
10 presents an example of a partial budget format. This format can be
modified to fit a variety of situations, but it illustrates the changing
costs and returns to consider in partial budgeting.
Amortization
A livestock producer evaluating an investment in waste handling
equipment wants to know the annual cost of repaying the initial investment.
Using the total amount of the investment, the life of the investment, and
the cost of money (interest rate), the producer can determine the annual
45
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TABLE 10. PARTIAL BUDGET FORMAT FOR EVALUATING WASTE MANAGEMENT SYSTEMS,
SINGLE ENTERPRISE OPERATION
Item Cost
Dollars I/
Additional capital outlays:
New manure control structures 15,000
New manure handling equipment 10,000
Subtotal 25,000
Salvage value (if any) 5,000
Fixed investment to be amortized at 12-percent interest
for 10 years 20,000
Annual ownership costs:
Annual amortized cost (principal and interest),
$20,000 x 0.1770 3,540
Taxes 200
Insurance 200
Total annual ownership costs 3,940
Annual operating costs:
Labor 500
Fuel 150
Electricity 50
Chemicals 0
Total annual operating cost 700
Total annual costs 4,640
Benefits:
Increased value of residues from new handling
system (if any) 0
Total new annual cost increase (decrease) 4,640
I/ Dollar values are presented only to help the reader follow the budget
format; they do not reflect actual costs of any waste management system.
46
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payment to repay the investment and include it in the budget development.
The producer can use the amortization factors presented in table 11
to determine this annual repayment amount. An example would be determining
the annual costs to repay a $4,000 loan to purchase a liquid manure spreader.
Assuming the loan is to be repaid in 5 years and that the cost of money is
10 percent, an amortization factor of 0.2638 is taken from table 11.
Multiplying the investment ($4,000) by the amortization factor (0.2638)
gives the annual repayment amount, or $1,055. This is the annual payment
necessary to repay the amount borrowed, plus interest.
SOUTHEASTERN DAIRY EXAMPLE
The economic tools discussed previously are applied in an example
based upon a 75-cow milking herd in the Southeast. Technical and
economic information were drawn from numerous sources. Prices used are
representative of 1978-79.
The region has a hot and humid climate. The ground almost never freezes
Average annual precipitation varies between 50 and 60 inches. Typically,
cows are kept in confinement in loafing sheds and milked in a parlor. Manure
is scraped, hauled, and spread daily. Over the years, some dairy farmers
have started to switch to liquid systems with lagoons. Lagoons are usually
dewatered by use of high pressure pumps combined with an irrigation system.
With a lagoon system, barns can be cleaned with either an automatic flush
system or a pressure hose system.
Our example focuses on changes in the waste handling system for
the loafing area and milking parlors. A dairy farmer wants to compare a solid
handling system with a liquid handling system, particularly their respective
requirements for investment and labor. As the farmer is interested only
in comparing alternative waste handling facilities, the costs of other com-
ponents of the loafing shed need not be evaluated. Thus, the comparison
will focus on the following options:
1. Solid-waste handling system, with daily scraping, hauling,
and spreading;
2. Liquid-waste handling, with daily scraping, holding tank
storage, tank hauling, and injection; and
3. Liquid-waste handling, with twice-daily automatic flush
system, lagoon storage, and cropland irrigation.
Estimating Nutrient Value of Manure
Manure production from the 75-cow dairy is estimated at about
1,574 tons per year. A 1,400-pound dairy cow produces 0.57 pounds of
nitrogen, 0.23 pounds of PpOq> and 0.46 pounds of ICO per day. Total annual
nutrient production from tne 75-cow milking herd is approximately 15,600
pounds of nitrogen, 6,290 pounds of P205> and 12,590 pounds of K20.
47
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TABLE 11. CAPITAL AMORTIZATION TABLE
Year
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Interest rate
5
1.0500
.5378
.3672
.2820
.2310
.1970
.1728
.1547
.1407
.1295
.1204
.1128
.1065
.1010
.0963
.0923
.0887
.0856
.0828
.0802
.0780
.0760
.0741
.0725
.0710
.0696
.0683
.0671
.0660
.0650
6
1.0600
.5454
.3741
.2886
.2374
.2034
.1791
.1610
.1470
.1359
.1268
.1193
.1130
.1076
.1030
.0990
.0954
.0924
.0896
.0872
.0850
.0830
.0813
.0797
.0782
.0769
.0757
.0746
.0736
.0726
7
1.0700
.5531
.3810
.2952
.2439
.2098
.1856
.1675
.1535
.1424
.1334
.1259
.1196
.1143
.1098
.1059
.1024
.0994
.0968
.0944
.0923
.0904
.0887
.0872
.0858
.0846
.0834
.0824
.0814
.0806
8
Dollars
1.0800
.5608
.3880
.3019
.2505
.2163
.1921
.1740
.1601
.1490
.1401
.1327
.1265
.1213
.1168
.1130
.1096
.1067
.1041
.1018
.0998
.0980
.0964
.0950
.0937
.0925
.0914
.0905
.0896
.0888
(percent)
9
I/
1.0900
.5685
.3950
.3087
.2571
.2229
.1987
.1807
.1668
.1558
.1470
.1396
.1336
.1284
.1241
.1203
.1170
.1142
.1117
.1096
.1076
.1059
.1044
.1030
.1018
.1007
.0997
.0988
.0981
.0973
10
1.1000
.5762
.4021
.3155
.2638
.2296
.2054
.1874
.1736
.1628
.1540
.1468
.1408
.1358
.1315
.1278
.1247
.1219
.1196
.1175
.1156
.1140
.1126
.1113
.1102
.1092
.1083
.1074
.1067
.1061
11
1.1100
.5839
.4092
.3223
.2706
.2364
.2122
.1943
.1806
.1698
.1611
.1540
.1482
.1432
.1391
.1355
.1325
.1298
.1276
.1256
.1238
.1223
.1210
.1198
.1187
.1178
.1164
.1163
.1156
.1150
12
1.1200
.5917
.4164
.3292
.2774
.2432
.2191
.2013
.1877
.1770
.1684
.1614
.1557
.1509
.1468
.1434
.1405
.1379
.1358
.1339
.1322
.1308
.1296
.1285
.1275
.1266
.1259
.1252
.1247
.1241
See footnote at end of table.
48
-------
TABLE 11. (continued)
Year
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Interest rate
13
1.1300
.5995
.4235
.3362
.2843
.2502
.2261
.2084
.1949
.1843
.1758
.1690
.1634
.1587
.1547
.1514
.1486
.1462
.1441
.1424
.1408
.1395
.1383
.1373
.1364
.1356
.1350
.1344
.1339
.1334
14
1.1400
.6073
.4307
.3432
.2913
.2572
.2332
.2156
.2022
.1917
.1834
.1767
.1712
.1666
.1628
.1596
.1569
.1546
.1527
.1510
.1495
.1483
.1472
.1463
.1455
.1448
.1442
.1437
.1432
.1428
15
1.1500
.6151
.4380
.3503
.2983
.2642
.2404
.2228
.2096
.1992
.1911
.1845
.1791
.1747
.1710
.1680
.1654
.1632
.1613
.1598
.1584
.1573
.1563
.1554
.1547
.1541
.1535
.1531
.1526
.1523
16
Dollars
1.1600
.6230
.4453
.3574
.3054
.2714
.2476
.2302
.2171
.2069
.1989
.1924
.1872
.1829
.1794
.1764
.1740
.1719
.1701
.1687
.1674
.1664
.1654
.1647
.1640
.1634
.1630
.1626
.1622
.1619
(percent)
17
I/
1.1700
.6308
.4526
.3645
.3126
.2786
.2550
.2377
.2247
.2147
.2068
.2005
.1954
.1912
.1878
.1850
.1827
.1807
.1791
.1777
.1765
.1756
.1747
.1740
.1734
.1729
.1725
.1721
.1718
.1715
18
1.1800
.6387
.4599
.3717
.3198
.2859
.2624
.2452
.2324
.2225
.2148
.2086
.2037
.1997
.1964
.1937
.1915
.1896
.1881
.1868
.1858
.1848
.1841
.1834
.1829
.1825
.1821
.1818
.1815
.1813
19
1.1900
.6466
.4673
.3790
.3270
.2933
.2698
.2529
.2402
.2305
.2229
.2169
.2121
.2082
.2051
.2025
.2004
.1987
.1972
.1960
.1950
.1942
.1935
.1930
.1925
.1921
.1918
.1915
.1912
.1910
20
1.2000
.6546
.4747
.3863
.3344
.3007
.2774
.2606
.2481
.2385
.2311
.2253
.2206
.2169
.2139
.2114
.2094
.2078
.2065
.2054
.2044
.2037
.2031
.2026
.2021
.2018
.2015
.2012
.2010
.2008
_!/ Each factor is the amount of money (in dollars) that must be repaid
annually per dollar borrowed to repay a loan at the respective interest
rate and in the number of years.
49
-------
Nutrient losses occur in the collection, storage, and land application
phases of management. Good manure management can help minimize losses
and simultaneously protect the quality of streams and lakes.
Estimating Costs and Benefits
Table 12 summarizes estimated costs and returns for the three systems
considered. The estimated volume of manure was approximately 51,000 cubic
feet (75 cows x 1.85 x 365). Approximately 152 hours of labor were required
to load, haul, and spread this manure with a 220-cubic foot spreader, assum-
ing a travel distance of 2,500 feet (option 1). If a 3,000-gallon tank
spreader is used, approximately 61 hours of labor are required (option 2).
The fuel requirements for hauling and spreading are 434 gallons for option
1 and 463 gallons for option 2. An additional 0.5 gallon of fuel per day
is assumed for scraping, tractor startup, and idling on those days when
manure is hauled and spread—an additional 185 gallons for option 1 and an
additional 100 gallons for option 2. Option 1, the conventional scrape,
haul, and spread solid manure system, is the least costly alternative, if
one ignores the impact of environmental costs or regulations. The higher
costs of options 2 and 3 are due to the higher investment requirements and,
in the case of option 3, to the greater loss of nutrients.
If the dairy farmer's only constraint is to minimize investment cost
and labor, option 1 is the system to select. However, option 3's waste
handling system requires 62 fewer labor hours annually than does option 1's.
The dairy farmer must decide whether the labor savings is worth the added
investment. If the opportunity cost of going to the liquid flush system
is divided by the labor saved (($4,167 - $2,633) 7 63), one can see that
the labor savings comes at a cost of $25.75 per hour. It would clearly be
less costly to select option 1 and hire the additional labor at a going
rate of $3.50 per hour. However, there are environmental benefits (reduction
pollutant runoff) associated with options 2 and 3 that the farmer must
consider in making the final selection.
REFERENCES
1. Christensen, L.A., J.R. Trierweiler, T.J. Ulrich,
and M.W. Erickson. 1981. Managing animal wastes:
guidelines for decisionmaking. USDA/ERS-671.
2. Gilbertson, G.B. et al. 1979. Animal waste utili-
zation on cropland and pastureland--a manual for
evaluating agronomic and environmental effects.
Section 1 and 6. USDA/SEA and EPA/ORD, USDA Utilization
Report, No. 6.
3. White, R.K. and D.L. Forster. 1978. A manual on
evaluation and economic analysis of livestock waste
management systems. The Ohio Agricultural Research
and Development Center and the Ohio State University,
EPA-600-2-78-102.
50
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TABLE 12. PARTIAL BUDGET ANALYSIS OF WASTE MANAGEMENT OPERATIONS,
75-COW DAIRY HERD, SOUTHEAST
Item
Option 1 I/ Option 2 I/ Option 3 _!/
Additional capital outlays:
Manure spreader 3,200
Tractor scraper 500
Front-end loader 2,000
Spreader tank (3,000 gal.)
Injectors (2)
Holding tank
Flush tanks (2)
Earthen lagoon
Traveling gun irrigator
High pressure centrifugal pump, with chopper
1,000-ft. aluminum pipe
Subtotal 5,700
Less salvage value 1,245
Investment for amortization at 12 percent
for 7 years 4,455
Annual ownership costs:
Fixed investment x amortization factor
(0.2191) 976
Dollars
500
7,000
1,200
6,300
15,000
4,155
10,845
2,376
2,500
5,500
5,000
5,000
5,000
23,000
9,250
13,750
3,013
Annual operating costs:
Labor at $3.50/hr. 2/
Fuel and lubricants 3/
Repair and maintenance 4/
Total annual operating costs
Increase in annual costs
Value of nutrients in manure
Net change in annual costs
745
712
200
1,657
2,633
3,026
-393
424
647
225
1,296
3,672
3,494
+178
529
125
500
1,154
4,167
1,545
+2,622
— = Not applicable.
17 Option 1 solid-waste handling, daily scraping, hauling and spreading; option 2
= liquid-waste handling, daily scraping, holding tank storage, hauling, and injection;
option 3 = liquid-waste handling, twice-daily automatic flush system, storage pond,
cropland irrigation.
27 The 213-hr, labor requirement for option 1 is based on 152 hrs. (app. table 9), plus
an additional 60 hrs. assumed for scraping and miscellaneous activities; the 121 hrs.
for option 2 are based on 61 hrs. (app. table 9), plus 60 additional hrs; option 3
uses 151 hrs.
_3/ Fuel use is assumed to be 619 gal. for option 1, and 563 gal. for option 2. Costs
are based on $l/gal., plus 15 percent for lubricants and oil. Energy costs for
option 3 are estimated to be $125.
4/ Repairs for options 1 and 2 are based on appendix table 8, plus $75 assumed for
scraper repairs. Repair costs for option 3 are assumed to be about $500.
51
-------
SECTION 4
RESEARCH NEEDS
Extensive research has been done in the area of animal waste utilization,
The rates and times of application that are most effective in utilizing nutri-
ents in crop production and thus reducing pollution potential have been well
documented in most regions of the country. More information is still needed
on the effectiveness of different methods of application of crop nutrient
utilization and nutrient availability. Some research has been done on split
and band application of manure, but results are too contrasting and too few
to regionally determine their effectiveness. Comparison studies conducted across
the country on application methods would more clearly determine which practices
appear to have merit and in which regions they are applicable. Economic in-
formation on the usage of manure as a fertilizer is also needed. Research in
the past has dealt with animal manure as waste product with some nutrient value,
but as petroleum-based fertilizers increase in cost, the storage and handling
of manure as a substitute fertilizer is becoming more cost-effective.
Many practices are now being used to treat or reduce nonpoint source
loading to receiving waters, such as lagoons, settling basins and terraces.
These practices are efficient but entail high costs. Thus, more research
should focus on cultural practices, such as controlled manure applications,
which are more effective and efficient than controlling runoff.
More research data are still needed to determine the seasonal effective-
ness of vegetative strips in treating animal waste effluent. Questions still
remain on the limitations these strips may have during winter conditions in the
northern states. Research on the long term effects on soil and ground water
under these filters is also needed.
There are few research data on the loadings of organics and pathogens
from land application areas. Evidence for transmission of disease from
animals to humans via nonpoint source inputs to water bodies is limited.
Indicator organisms which better describe actual health hazards to humans
are needed as well as a better characterization of survival rates in land
application systems for pathogens known to be transmissible from livestock
to humans.
Organic matter in runoff from feedlots has been found to result in low
oxygen problems in lakes and streams, as well as fish kills. The contribution
of organic materials from application sites to receiving bodies however, has
not been well documented. Research is needed to determine the significance
52
-------
of organic matter from land applied animal wastes.
Most of the research examined in this report has dealt with plot studies
designed to analyze specific practices and the mechanisms under which certain
events occur, but do not give a true picture of conditions on a watershed
basis. Water quality benefits attributed to BMPs or BMP systems and the impact
resulting from their implementation still remain largely unknown. Many vari-
ables are introduced when larger, more complexed systems are used. By applying
these practices on a series of watersheds across the nation, more knowledge of
their effectiveness can be gained.
The International Joint Commission (32) has stated that more information
is needed in relating costs of agricultural BMPs to incremental water quality
benefits. To do this, a well thought-out, systematic approach to water quality
monitoring and BMP implementation is needed.
Better information on animal waste BMPs and BMP systems will allow more
cost-effective planning and implementation of agricultural nonpoint source
control projects to achieve water quality goals.
53
-------
SECTION 5
CURRENT RESEARCH
Presently, U.S.E.P.A. and U.S.D.A. are jointly funding several water-
shed projects across the nation to evaluate the effectiveness of agricultural
nonpoint source control practices. These watershed studies are intended to
evaluate animal waste BMP systems on a watershed basis and their cost-
effectiveness for improving water quality. Some projects, however, have been
hindered in their efforts to achieve program goals because either a sound
monitoring strategy has not been developed or critical areas have not been
adequately identified. Thus, the quality of the evaluation that can be made
will be dependent upon these variables.
The Lower Manitowoc River watershed in Wisconsin is a major source of
the phosphorus entering the near shores of Lake Michigan. Livestock wastes
have been estimated to contribute 52% of the P loading. The goal is to re-
duce the phosphorus entering the watershed by 50% and to improve the overall
river water quality to a good rating as indicated by the Hilsenhoff Biotic
Index. This is to be accomplished by installing 274 barnyard runoff control
and manure storage and handling practices, in conjunction with various crop-
land erosion management practices within the watershed. This project will be
used to determine the effectiveness runoff and manure handling BMPs have on
improving water quality.
Phosphorus from agricultural nonpoint sources has resulted in algae
blooms and prolific growth of rooted aquatic plants in the St. Albans Bay
area, Vermont. These undesirable water conditions have resulted in periodic
closing of the beaches to swimming as well as impaired use of the Bay water
for drinking, water skiing and fishing. Manure from barnyards and waste ap-
plication areas has been identified as a significant source of phosphorus.
BMPs for reducing the amount of animal and milkhouse waste entering the Bay
will include construction of waste handling structures and filtration strips,
as well as developement of a management system for land application of manure.
Data from this project will be used in determining the effectiveness of manure
handling BMPs and grass filtration strips on improving water quality.
Animal wastes are a large contributor to the water quality impairment
of Lake Tholocco in Alabama. High bacteria counts have been a major problem,
as well as high turbidity and sediment deposition. The goal is to attain 85%
treatment in reducing fecal coliform concentrations and sediment loads enter-
ing the lake. Animal waste BMPs that will be used to attain this goal include
construction of waste storage structures, utilization of animal wastes as a
54
-------
fertilizer and filtration strips for treatment.
Tillamook Bay in Oregon is an important producer of fish and shellfish
with oyster production alone accounting for $1.5 million annually. Large
concentrations of livestock, primarily dairy cows, has caused contamination
of the Bay with excessive fecal coliform bacteria levels. A 70% reduction of
the fecal coliform is expected by implementing BMPs such as collection and set-
tling basins, as well as diversions, channels, waterways and landshaping.
Double Pipe Creek watershed in Maryland is approximately 110,000 acres
in size, with 66% of the land area in cropland and 12% in pastureland. A
major pollutant identified is fecal coliforms from animal operations. The goal
is to reduce fecal coliform counts to levels which meet state standards by in-
stalling 115 animal waste management systems. These systems include improving
animal waste storage, and incorporating diversions, filter strips, waterways
and other land management practices into farm systems.
The Double Pipe Creek and Tillamook Bay projects will be used in deter-
mining a regional comparison of the effectiveness that similar animal waste
BMPs have on reducing fecal coliforms and improving the overall water quality.
High animal stocking rates in excess of two units per acre has resulted
in high nitrate and coliform levels in the groundwater and eutrophic river
conditions in Pennsylvania's Conestoga Headwaters project. Project goals
are to develop and implement Water Quality Improvement Plans on 75% of the
400 critical farm units, thus reducing the nutrients and coliforms entering
the river. Animal waste BMPs that are to be implemented include storage
structures, filtration strips and utilization of animal waste as a fertilizer.
Results will be used in determining animal waste BMPs effectiveness in re-
ducing ground and surface water pollution.
The West Branch of the Delaware River watershed in New York has been
identified as a contributor of nutrients (mainly phosphorus) into the
Cannonsville Reservoir, a public water supply for New York City. These
nutrients have caused excessive growths of algae, limiting the reservoir's
use to certain seasonal periods. Barnyard and field spread manure runoff
have been cited as a major contributor of the P load. One of the objectives
of the project is to install animal waste management practices on farms as
deemed appropriate, giving full consideration of the more cost-effective
methods for achieving water quality improvement.
Results from the RCWP and MIP projects will aid in evaluating BMPs for
controlling pollutants from animal production units from a BMP systems approach
while also determining BMP applicability on a regional scope. Information on
BMP costs versus the water quality improvements obtained will help determine
the cost-effectiveness of these practices. It appears that animal waste manage-
ment is playing an important role in many of these projects and although im-
provements in water quality from specific BMPs may not be seen, results from
BMP systems implementation should be observed. The final analysis of all in-
formation gathered from specific practices should fill in some of the present
knowledge gaps and help develop a better understanding of the BMP systems ap-
proach for improving water quality.
55
-------
REFERENCES
1. Adriano, D.C., Chang, A.C., Prah, P.P. and R. Sharpless, "Effect of
Soil Application of Dairy Manure on Germination and Emergence of
Some Selected Crops," Journal of Environmental Quality, 2(3):396-399,
1973. '
2. "Agricultural Nonpoint Source Control of Phosphorus and Sediment -
A Watershed Evaluation," West Branch of the Delaware River Research
Plan, 90 pp., 1980.
3. Agricultural Waste Management Field Manual, USDA, Soil Conservation
Service, 1975.
4. Ajgrgnomy Guide, Cooperative Extension Service, Ohio State University,
Bulletin 472, Agdex 100, 97 pp., 1981.
5. Albin, R.C., "Handling and Disposal of Cattle Feedlot Waste,"
Journal of Animal Science. 32(4) :803-810, 1970.
6. Barker, J.C., Personal Communications, Department of Biological and
Agricultural Engineering, North Carolina State University, Raleigh,
North Carolina.
7. Barker, J.C., "The Effects of Surface Irrigation with Dairy Manure
Slurries on the Quality of Ground Water and Surface Runoff,"
Ph.D. thesis, 1973.
8. Barker, J.C. and J.I. Sewell, "Effects of Surface Irrigation with
Dairy Manure Slurries on the Quality of Groundwater and Surface
Runoff," Transactions of the ASAE. 16(4):804-807, 1973.
9. Bingham, S.C., Overcash, M.R. and P.W. Westerman, "Effectiveness
of Grass Buffer Zones in Eliminating Pollutants in Runoff from
Waste Application Sites," ASAE paper no. 78-2571, 34 pp., 1978.
10. Bliven, L.F., Humenik, F.J., Koehler, F.A. and M.R. Overcash
"Dynamics of Rural Nonpoint Source Water Quality in a Southeastern
Watershed," Transactions of the ASAE, 23(6):1450-1456, 1980.
11. Bradford, R., "Nitrogen and Phosphorus Losses from Agronomy Plots
in North Alabama," Environmental Protection Technoloav Series
EPA-660/2-74-033, 1974.
56
-------
12. Burwell, R.E., "Nutrient Loss Research," ARS-NC-57:28-34, 1977.
13. Burwell, R.E., Schuman, G.E., Heinemann, H.G. and R.G. Spomer,
"Nitrogen and Phosphorus Movement from Agricultural Watersheds,"
Journal of Soil and Water Conservation, 32(5):226-230, 1977.
14. Carlile, B.L., "Animal Waste Management in High Water Table
Soils," In: Livestock Waste: A Renewable Resource, Proceedings
of the 4 tin I n ter n at i on a 1 Sympos i urn on Livestock Wastes, ASAE,
St. Joseph, Michigan, pp. 156-158, 162, 1980.
15. Carreker, J.R., Wilkinson, S.R., Box, J.E. Jr., Dawson, R.N.,
Beaty, E.R., Morris, H.D. and J.B. Jones, Jr., "Using Poultry
Litter, Irrigation and Tall Fesque for No-Till Corn Production,"
Journal of Environmental Quality, 2(4) :497-500, 1973.
16. Clark, R.N., Gilbertson, C.B. and H.R. Duke, "Quantity and Quality
of Beef Feedyard Runoff in the Great Plains," In: Managing Live-
stock Wastes, Proceedings of the 3rd International Symposium on
Livestock Wastes, ASAE, St. Joseph, Michigan, pp. 432-436, 1975.
17. "Conestoga Headwaters Rural Clean Water Program," Project Appli-
cation, Lancaster County, Pennsylvania, 1981.
18. Converse, J.C., Bubenzer, G.D. and W.H. Paulson, "Nutrient Losses
in Surface Runoff from Winter Spread Manure," Transactions of the
ASAE, 19(3):517-519, 1976.
19. Converse, J.C., Cramer, C.O., Tempas, G.H. and D.A. Schlough,
"Properties of Solids and Liquids from Stacked Manure," In: Managing
Livestock Wastes, Proceedings of the 3rd International Symposium
on Livestock Wastes, ASAE, St. Joseph, Michigan, pp. 432-436, 1975.
20. Cummings, G.A., Burns, J.C., Sneed, R.E., Overcash, M.R. and
F.J. Humenik, "Plant and Soil Effects of Swine Lagoon Effluent
Applied to Coastal Bermudagrass," In: Managing Livestock Wastes, Pro-
ceedings of the 3rd International Symposium on Livestock Wastes,
ASAE, St. Joseph, Michigan, pp. 598-601, 1975.
21. Dickey, E.C. and D.H. Vanderholm, "Performance and Design of
Vegetative Filters for Feedlot Runoff Treatment," In: Livestock
Wastes: A Renewable Resource, Proceedings of the 4th International
Symposium on Livestock Wastes, ASAE, St. Joseph, Michigan, pp. 257-
260, 1980.
57
-------
22. "Double Pipe Creek-Westminster" RCWP Application, Maryland, 1980.
23. Dunigan, E.P., Phelan, R.A. and C.L. Mondart, Jr., "Surface Runoff
Losses of Fertilizer Elements," Journal of Environmental Quality,
5(3):339-342, 1976.
24. Edwards, W.M., Owens, L.B., Norman, D.A. and R.K. White, "A Settling
Basin-Grass Filter System for Managing Runoff from a Paved Beef
Feedlot," In: Livestock Wastes: A Renewable Resource, Proceedings
of the 4th International Symposium on Livestock Wastes, ASAE, St.
Joseph, Michigan, pp. 265-273, 1980.
25. Evans, S.D., Goodrich, P.R., Munter, R.C. and R.E. Smith, "Effects
of Solid and Liquid Beef Manure and Liquid Hog Manure on Soil
Characteristics and on Growth, Yield and Composition of Corn,"
Journal of Environmental Quality, 6(4):361-368, 1977.
26. Gilbertson, C.B., Norstadt, F.A., Mathers, A.C., Holt, R.F., Barnett,
A.P., McCalla, T.M., Onstad, C.A. and R.A. Young, "Animal Waste
Utilization on Cropland and Pastureland: A Manual for Evaluating
Agronomic and Environmental Effects," EPA-600/2-79-059, 1979.
27. Hansen, R.W., Harper, J.M., Stone, M.L., Ward, G.M. and R.A. Kidd,
"Manure Harvesting Practices: Effects on Waste Characteristics
and Runoff," EPA-600/2-76-292, 1976.
28. Hensler, R.F., Olsen, R.J., Witzel, S.A., Attoe, O.J., Paulson, W.H.
and R.F. Johannes, "Effects of Method of Manure Handling on Crop
Yields, Nutrient Recovery and Runoff Losses," Transactions of the
ASAE, 13:726-731, 1970. ~" ' "
29. Hileman, L.H., "Response of Orchardgrass to Broiler Litter and
Commercial Fertilizer," Arkansas AEA Report Series 207, 18 pp.,
1973.
30. Hills, F.H., Broadbent, F.E. and M. Fried, "Timing and Rate of
Fertilizer Nitrogen for Sugarbeets Related to Nitrogen Uptake
and Pollution Potential," Journal of Environmental Quality,
7(3):368-372, 1978. ~~
31. Horney, L.F., Koehler, F.A. and F.J. Humenik, "North Carolina 208
Water Quality Survey Results," ASAE paper no. 79-2504, 1979.
58
-------
32. Humenik, F.J., "Swine Waste Characterization and Evaluation of
Animal Waste Treatment Alternatives," Water Resources Research
Institute, Report No. 61, 1972. ~~~
33. International Reference Group, "Summary Review of Pollution From
Land Use Activities," International Joint Commission, 65 pp., 1975.
34. Jackson, W.A., Asmussen, I.E., Mauser, E.W. and A.W. White,
"Nitrate in Surface and Subsurface Flow from a Small Agricultural
Watershed," Journal of Environmental Quality, 2(4):480-482, 1973.
35. Jackson, W.A., Leonard, R.A. and S.R. Wilkinson, "Land Disposal
of Broiler Litter - Changes in Soil Potassium, Calcium and Magnesium,"
Journal of Environmental Quality, 4(2) :202-206, 1975.
36. Jackson, W.A., Wilkinson, S.R. and R.A. Leonard, "Land Disposal
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