jglll^ JOURNAL OF SJOIL AND WATER H •
Conservation
: ; • :" i : ; :
Nutrient Management
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Supplement to the Journal of Soil ;and Water Gpnseri/ation Volume 49 No. 2
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This special issue of the Journal of Soil and Water Conservation on
nutrient management was prepared with support from the U.S.
Environmental Protection Agency (EPA) under Cooperative
Agreement 820524-01-0; Project Officer, Anne Weinberg. Articles
presented herein do not necessarily reflect the views of EPA.
Mention of commercial products or publications does not consti-
tute endorsement, or recommendation for use by EPA.
This is a special supplement to the March-April 1994 issue of the
Journal of Soil and Water Conservation.
The Journal of Soil and Water Conservation and this supplement are
published by the Soil and Water Conservation Society,
7515 Northeast Ankeny Road, Ankeny, Iowa 50021.
For additional copies of this publication, contact SWCS at the address
above, or at (515) 289-2331 or 1-800-843-7645.
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CONTENTS
Preface.
General Introduction
Why nutrient management? 3
Lynn JR. Shuyler
Nutrient management, an integrated component
for water quality protection 5
Lynn JR. Shuyler
You need to start with the soil:
The Soil Conservation Service experience 7
Robert R. Shaw
Keeping agriculture viable: Industry's viewpoint 8
B. C. Darst and L. S. Murphy
EPA's perspective—you need to protect
water quality 14 •
Thomas E. Davenport
Understanding the Basics
Understanding the nutrient cycling process 16
/. F. Power
Understanding the nutrient management process 23
Douglas B. Beegle and Les E. Lanyon
Minimizing surface water eutrophication from
agriculture by phosphorous management 30
T. C. Daniel, A. N. Sharpley, D. R. Edwards, R. Wedepohl,
and]. L. Lemunyon
BMPs
Best management practices meeting
water quality goals 39
/. Watson, E. Hassinger, K. Reffruschinni, M. Sheedy, and B.
Anthony
Tools to aid management:
the use of site specific management 43
'S. Kincheloe
Nitrogen testing for optimum management 46
D. H. Sander, D. T. Walters, andK. D. Frank
Managing Animal Wastes
Agricultural waste management planning 53
William H. Boyd P.E.
Best management practices for livestock production 57
L. M. So/ley, Jr. P.E.
Methane production from animal wastes 62
Andrew G. Hashimoto, Thorn G. Edgar, and Hiroshi Nakano
Proper animal manure utilization 65
Alan L. Sutton
Coastal Zone Act Reauthorization Amendment of
1990 (C21ARA)
Nutrient management measure to be implemented
in the coastal zone 71
Anne C. Weinberg
A new approach to runoff—state coastal nonpoint
pollution control programs 72
AnnBeier, Steven Dressing, and Lynn Shuyler
State/Regional Experiences
California's experience with a voluntary approach
to reducing nitrate contaminationof groundwater:
The Fertilizer Reasearch and Education
Program (FREP) ..77
Jacques Franco, Stephan Schad, and Casey Walsh Cady
A local agency's approach to solving the difficult
problem of nitrate in groundwater (Nebraska) 83
Ron Bishop
Nutrient management legislation in Pennsylvania 85
Douglas B. Beegle and Les E. Lanyon
Evolution of nutrient management in the
Chesapeake Bay region 88
Russ Perkinson
Nutrient management in Idaho 90
R. L. Mahler
Innovative local dealer nutrient management
programs—how they work 93
John E. Gulp
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On April 20~22> 1993, about 300
people involved in nutrient manage-
ment programs, representatives from
federal, state, and local governments,
producers, agribusiness represen-
tatives, academics, and representatives
of other interest groups met in St.
Louis, Missouri, to learn about effec-
tive approaches to nutrient manage-
ment. This was the first such National
Agricultural Nutrient Management
Conference sponsored by the Conser-
vation Technology Information Center
(CTIC) and others. The papers pre-
sented at this conference are contained
in this special issue of the Journal of
Soil and Water Conservation, published
by the Soil and Water Conservation
Society.
The conference was organized to
address concerns that significant
portions of our nation's coastal waters,
ground water, and inland surface
waters are either impaired or threat-
ened by excessive nutrient levels.
Improved nutrient management is
recognized by experts.and practition-
ers nationwide as a solution for water
quality problems and as a means by
which producers can enhance both
yields and profits. Also, federal, state,
and local programs and regulations
have increasingly focused on efficient
nutrient management as an essential
tool for preventing nonpoint source
water pollution.
The conference was designed to
assist local and state program man-
agers in planning effective nutrient
management programs and to provide
the best current information for
efficient field-level nutrient manage-
ment. Lessons learned, technical
information, and ways to overcome
obstacles to good nutrient manage-
ment were presented at the con-
ference. In addition, there was a
hands-on workshop where conference
participants went through the steps
necessary to develop a nutrient
management plan on a farm.
A very encouraging sign at the
conference was that conference
participants were almost unanimously
in agreement on the need for nutrient
management programs. Thus, much of
the discussion at the conference
focused on how to develop such
programs, how to deliver nutrient
management plans to individual
farmers, and on different technical
approaches.
The Conservation Technology Infor-
mation Center (CTIC) would like to
thank all those who came to St. Louis.
They made the conference a great
success because they were eager to
share their knowledge, energy, and
insights. CTIC also extends special
thanks to our cosponsors for their
hard work in organizing and promot-
ing the conference. The cosponsors
were a diverse group: the Conser-
vation Technology Information
Center; U.S. Environmental Protection
Agency; USDA Extension Service;
Foundation for Agronomic Research;
National Association of Conservation
Districts; National Pork Board;
National Pork Producers Council;
Potash and Phosphate Institute; USDA
Soil Conservation Service; Soil and
Water Conservation Society; and the
Tennessee Valley Authority.
In addition, we would like to thank
the members of the Conference
Steering Committee, and the Soil and
Water Conservation Society for
publishing the proceedings.
These conference proceedings are
intended as a detailed reference tool.
We hope they will prove valuable,
both to conference attendees and to
anyone interested in developing a
nutrient management program or
improving an established program.
We encourage you, the reader, to
contact the authors .of the papers and
other conference attendees and to
continue to build the partnerships we
need to develop strong nutrient
management programs to protect
water quality while maintaining
profitability. We at CTIC enthus-
iastically support the need for
developing effective nutrient manage-
ment programs and will continue to
provide our support.
Jerome C. Hytry
Executive Director, Conservation
Technology Information Center
2 JOURNAL OF SOIL AND WATER CONSERVATION
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INTRODUCTION
Why nutrient
management?
Lynn R. Shuyler
In order to begin to answer the
question "Why nutrient man-
agement?" we need to address
another question, "What have we
done in the past?"
In the past, we viewed management
of the land and land based resources
as soil and water conservation
management. This was the correct
view to take "when soil erosion and
water volumes were our only
concerns. In the past these were just
about our only concerns and therefore
the things we viewed as really
important. It has only been in the very
recent past that we have broadened
our view and begun to include
interests of other people and to treat
them with the same concern as we
had for soil and water conservation
many years ago.
It has been less than 30 years since
many managers and resource planners
became concerned about the envi-
ronment to any real degree. During
Lynn R. Shuyler is the nonpoint source
coordinator at the U.S. Environmental
Protection Agency Chesapeake Bay Program,
Office, Annapolis, Maryland 21403.
this time, society began to voice
concerns about the state of the
environment and depletion of natural
resources such as coal, oil, and natural
gas. These events demanded change
from those who work with natural
resource planning and management.
The message was to expand our
tunnel vision, to look at all aspects of
our resource use program, and to
bring it all together into a true
resource management plan for a field,
a farm, but more importantly for the
land user, the farmer. While it is very
important that we expand our
thinking, our planning, and our
management, it is also important that
we not lose sight of what we started
with, soil and water conservation. The
old concerns and old issues are just as
important today as any of the new
concepts that some rush to embrace.
These must be given equal status with
the new and must not be forgotten.
As we expand our concerns and
begin to plan and manage new
concepts, we face new problems,
some of which need solutions before
we can effectively move forward. The
list of real and perceived problems is
quite long and could force us back
into tunnel vision or into a shotgun
approach, as we look for solutions.
Neither of these approaches is
acceptable today. We must move
forward with the implementation of
total resource management, while at
the same time refining the practices
that we have to use and continue to
look for new and better practices or
better uses for existing practices. The
real fear that we all should have and
where real mistakes can be made is
when we evaluate the problems in a
-watershed and begin to develop
solutions for that watershed. In the
past we have only seen our part of
the problem and developed solutions
for that portion. This is not enough
today.
Today we must evaluate and
pinpoint what the real problems are—
ground water, surface water, air, soil
erosion, wildlife losses, or any of a
number of other items. Once the
overall problems are defined,
solutions can be crafted for all sources
of problems, including nonpoint
sources, point sources, air sources,
and natural sources. Solutions can
have cost estimates attached to them,
which then become part of the
political, economic, and technical
tradeoffs to select the proper mix of
solutions for the area and its
problems. The trend today in many
projects has been to develop stacks of
plans to implement solutions, many
different plans developed by many
different planners not communicating
with each other. Our society cannot
and "will not stand for this type of
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 3
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planning and implementation today.
Society demands, and should be
given, one overall integrated plan for
the area, one plan that recognizes the
conflicts of solutions and laws, one
plan that allows all implementing
agencies to work together, and one
plan that has a single point of contact
for each land owner, business owner,
and the general public. As the
planning process moves down the
chain to smaller basins, to sub-basins,
to farms and fields, the one-plan
concept must hold. All of these plans
and implementation must be based on
the least costly, best available
technology that passes the political
test to be accepted by the affected
party and still solve the original
problems. Many planners are working
toward this end today and we all
should be moving in that direction in
the near future.
Agricultural management plans
should contain one common element,
nutrient management. Why is it so
important? It is the only element of a
plan that can really manage nitrogen.
It is the least costly of all components
of the plan. It does not require much,
if any, change in equipment. It has the
potential to be an economic plus for
the farmer. Although it is good and
good for you, it can be hard to sell—it
is too simple and it calls for a change
in thinking on the part of
management. The concept of nutrient
management should be applied to
land that has erosion control practices
applied to it and to land that receives
additional nutrients from any outside
source, such as animal manure,
sludge, and/or commercial fertilizer.
What should nutrient management
accomplish? Nutrient management
should reduce soluble nutrient trans-
port and provide enough nutrients to
produce a realistic crop yield. If these
conditions are met, nutrient manage-
ment will help protect groundwater
resources, reduce nitrogen loadings
into streams and estuaries, and bal-
ance the nutrient needs of the crop.
Nutrient management should accomp-
lish the following goals:
• maintain production at realistic
yield goals,
• allow environmental conditions to
improve, and
• provide for the wise use of all
available sources of nutrients.
Nutrient management must allow
commercial suppliers of nutrients to
stay in business, not only as
commercial sources of nutrients, but
also as providers of assistance in the
form of nutrient management plan
development, and in some cases, as
brokers for other sources of nutrients
such as animal manures and/or
sludge.
Some people strongly believe that
nutrient management means a
reduction in the amount of
commercial fertilizer purchased and
that it will put fertilizer dealers out of
business if nutrient management plans
are widely used. This belief is
inaccurate; it is not true and this is not
the intent of nutrient management. It
is true that in the majority of cases
nutrient management plans will call
for less total nutrients than are now
being used on the field. The plan
must ensure that the proper nutrient
balance is obtained and that the needs
of the crop are met. We cannot afford
to over-fertilize just to keep a dealer
in business. We cannot afford to
waste the natural resources required
to produce, transport, and apply
something we did not need in the first
place, something that has the potential
to harm the environment.
Nutrient management provides an
opportunity for private sector business
to sell a service, deliver the necessary
nutrients to fulfill the needs of the
client, and keep the client from
polluting the environment. If such a
service is provided, it should take
little, if any, advertising to keep that
farmer as a paying client. Therefore, if
any part of the industry is impacted it
might be only the advertising portion.
This is not to make light of the
impact that wide-spread nutrient
management could have on agri-
cultural business interests in some
areas. This is why we need to explore
ways to involve, fertilizer businesses in
all aspects of the nutrient management
concept, finding ways for them to
recover the cost of plan development
if they choose to offer the service.
There are many good reasons for
nutrient management. It saves
resources and reduces pollution. It is
the most important component of a
resource management plan and it is
one of the most effective ways of
managing nitrogen. It could increase
the producer's profit margin.
However, there are many problems
that must be overcome before we can
sit back and proclaim that nutrient
management is a success. We do not
have enough people in the field to
deliver nutrient management to all the
land area that should be using it.
Government is not going to be able to
provide the service at any cost.
Government staffing is being reduced,
so we can no longer look to the
"agent" to solve our planning
problems. The bulk of nutrient
management planning must be
delivered by the private sector as a
profit-making venture.
How can this be done if publicly
funded planners are in competition
with the private sector? We must find
ways to ensure that the private sector
is paid a fair price for such work. At
the same time, we must assure the
farmer and the environmental agency
that the planners are certified, and
qualified to develop plans that will
work for everyone.
Do we really need to do nutrient
management? Yes! It is the cheapest
way to reach our pollution reduction
goal. While this paper is focused on
nitrogen, the nutrient management
concept can be used for any limiting
element or nutrient. What is being
controlled or limited with these plans
will differ as different problems
present themselves. Some sources of
nutrients will have different com-
ponents that could limit their use. For
example, animal wastes could have
very high total salts and need to be
restricted on certain soils, or the
phosphorus rate may be too high for
some soils when the manure is
applied at a nitrogen rate. The metal
content of some sludge could cause
concern, limiting the amount that
could be applied to a field.
Much will depend upon the
problem being solved, the source of
the nutrients, the soil, the climate, and
the crops being grown in the overall
rotation. Each area of the country will
encounter different problems that can
be addressed with nutrient manage-
4 JOURNAL OF SOIL AND WATER CONSERVATION
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ment planning. There are enough
problems and opportunities to keep
all of us busy for years with research
to improve the concept, with plan
development to help the land
manager, and with program manage-
ment to ensure that all players
(consultant, dealers, and government)
are treated fairly and that the land
manager is given the best possible
plan. This will not be an easy task,
but we must do this or some other
group will tell agriculture how much
to use and where to use it, through
laws or rule making. Agriculture does
not need that—agriculture is well
organized enough to do what is right
and to do it now. Q
Nutrient
management, an
integrated
component for
water quality
protection
Lynn R. Shuyler
Is nutrient management ready to be
integrated into water quality pro-
tection? The answer to that
question is yes, but the real question
is "are we as planners and users ready
to integrate nutrient management into
our management systems?" I think
most of us here today [at the National
Agricultural Nutrient Management
Conference] would have a positive
answer to that question. But if we
were the average farmer, I do not
think we would be very positive in
our response to nutrient management
and using it in our management
system unless we had a good data-
base on which to make the decision.
Lynn R. Shuyler is the nonpoint source
coordinator at the U.S. Environmental
Protection Agency Chesapeake Bay Program
Office, Annapolis, Maryland 21403.
As water quality and nutrient
management professionals, we can
analyze different water quality
problems and develop strategies to
address such questions as these:
• Are we dealing with surface water?
If so, is it fresh or saline, or as
with most estuaries, both?
• Is ground water our concern? Is it
a source for surface water? Is it a
drinking water source or not?
• What are the pollutants of
concern, N, P, and/or total salts?
• What are the sources of pollutants
causing this water quality
problem? Are the sources of the
pollutant background soil loads,
commercial fertilizer, added
organic wastes (animal manure or
treatment plant sludge),
atmospheric deposition?
In most cases it will be a
combination of some, if not all, of
these.
As professionals in this field we can
evaluate large or small scale water
quality problems and propose the
necessary actions and goals required
to solve the problems, thereby
allowing regional or area specific
strategies to be developed to attain
the goals.
When we develop strategies or
action plans for water quality
restoration and protection, the
concept of nutrient management must
be the focus of our plan or strategy.
Nutrient management is a prime
example of pollution prevention—it
requires a close examination of the
farm operation, the "farm manu-
facturing process" being used, and
attempts to optimize the inputs to
accomplish a reduction of the
undesirable outputs. When we think
of nutrient management in a process
engineering context, we see that it is
not something new and that it has
been used very successfully in other
areas of pollution control. For
example, the phosphate bans for
certain types of soap in the
Chesapeake Bay basin have greatly
reduced the phosphate loads into the
Bay without upgrading the treatment
plants or increasing the cost of oper-
ation of the plants. The bans have
increased the cost to the home owner
a little, but given the difference in the
cost of removal and the cost of
prevention, there is no contest.
If nutrient management is to
become an integrated component of
water quality protection, it must also
become an integrated component of
the existing programs that are active
on the land. These include U.S.
Department of Agriculture Soil Con-
servation Service (USDA-SCS) total
resource management planning, state
and local land use planning, and
operation requirements, and the soon-
to-be-implemented Coastal Zone
Management NFS (nonpoint source)
program. I believe nutrient manage-
ment as a concept can be integrated
into these existing activities today. I
also believe most programs managers
know the benefits of nutrient manage-
ment and are interested in imple-
menting it on agricultural lands.
The concept of nutrient manage-
ment is very simple. If a nutrient is
not applied, then it is still in storage
or in the bag and not on the land
where it would be available to move
with soil particles or water. Some
have incorrectly focused discussions
regarding nutrient .management on
reducing the amount of commercial
fertilizer applied to the land. This is
not correct. Nutrient management is a
balancing of the nutrient needs of a
crop with the nutrient resources avail-
able to the producer. In some cases it
will require changes in the mix of
nutrient sources used on the field.
If a limiting nutrient concept is used
to determine the application rate of
organic sources, and the limiting
nutrient is phosphorus, there may be
a great increase in the amount of
commercial fertilizer applied to
provide the correct nitrogen balance
for the crop. The point is, there are no
hard and fast rules about what
nutrient management is or is not. The
only common thread is that it is a
process that considers the following:
• source of nutrient
—manure, sludge, commercial,
residual from crop and previous
applications
• type of crop and realistic yield goal
• soil productivity
• weather
• previous history of land and
producer
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 5
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• environmental hazards of the land
As nutrient management is used
throughout the nation we will learn
more about how it works, the
economics of using it, the water
quality benefits, and the acceptance of
the farmer to the practice. Some
specific questions or areas that need
answers or at least more data are the
following:
• What is the cost or savings to
producer?
• Can yield be sustained over time?
• Is the practice mining nutrients
from the soil and will the practice
destroy the soil in later years?
• Is nutrient management likely to
reduce soil nutrient content during
periods when nutrients are most
subject to movement or loss from
the field?
• Will the practice reduce the
nutrient load to ground water?
• Will the practice reduce the
nutrient load to surface water? and
• What is the time frame for these
reductions to happen?
Some of these questions have been
answered here [at the nutrient
management conference] this week;
others must await further research and
study. The important point is that we
have learned a great deal about this
practice over the years. We have
learned enough to recommend it
strongly to farmers and land users
across the country. We know that
nutrient management is the most
effective water quality practice that we
have for controlling N, and it allows
us to consider the limiting nutrient
concept for all situations.
I do not believe that we need to
wait for more information before we
move forward with the implement-
ation of nutrient management. I
believe that we know enough to
deliver this most useful tool as part of
a program to the land managers in
this country.
Many people want to make nutrient
management mandatory across the
U.S. Several states have considered
mandatory nutrient management in
legislative sessions in the past few
years. So far none have enacted a
fully operational requirement yet, but
it is only a matter of time before it
happens. I hope that you, the nutrient
management professionals, will be
active in ensuring that the technical
concepts of nutrient management are
correctly included in any new laws or
regulations. Mandatory nutrient
management seems to be a great idea;
using the available nutrient sources
correctly should reduce the cost of
nutrient for the user, should allow the
production of a realistic yield, and
should be good for the environment.
If it is all of these things then why do
some people want to make it man-
datory? I think the short answer to this
question is that people just don't trust
us. Or they know that not all farmers
will do the right thing, even if it is
better than what they are now doing.
This is because farmers are just like
the rest of the population: we do not
all do what is correct all of the time!
I believe that nutrient management
on agricultural land should be
required to receive any form of
government assistance. This would
include federal assistance for con-
servation/water quality practices,
assistance from the commodity pro-
grams, federal crop insurance, and
operational and land loans from
federal agencies. At the state and local
level nutrient management should be
required to receive state funded
assistance for conservation/water
quality practices, and to be considered
an agricultural activity for state and
local tax purposes. I also believe that
nutrient management, as we know it,
can be delivered to the urban sector
for turf managers and home owners.
How can we deliver a nutrient
management program that is effective
in doing all of the things that we have
been told it can do? Is it the
responsibility of government to do it?
The answer is yes and no. If nutrient
management is part of a strategy to
reach a goal, then the jurisdiction
responsible for reaching the goal must
see that all required actions are taken
to reach the goal. In this example the
state water quality agency might want
assurances that nutrient management
as a practice is being delivered
according to some specifications. It is
common knowledge that neither
federal or state government is likely to
have the funding to support the large
number of nutrient management
specialists required for full coverage
of a program. I believe that nutrient
management is a concept that can and
should become part of the private
sector's service to land users. This can
take the form of private consultants
and/or staff of fertilizer sales outlets. It
makes no difference who writes a
plan, how much or how little it costs,
as long as it follows the concepts and
specifications required for the area.
Planners should be responsible for
their work. In the case of nutrient
management, license by the state
seems reasonable, since someone or
some agency needs to be able to
remove bad actors if a problem is
found. Maryland has such a licensing
law and has just finished the first
testing cycle. A large number of
people (about 130) were interested in
taking the test, and about 80 of those
who took the test passed it.
As a result of this new state law,
Maryland will have many more nutri-
ent management planners operating in
the state this year, a mix of private
consultants, fertilizer dealers, and
government agency personnel, all
working from the same knowledge
base and developing similar plans.
This should help Maryland meet a
large acreage goal over the next few
years.
We as professionals in this field can
make a difference. We must make this
happen if agriculture and the environ-
ment are to coexist and people are to
enjoy the standard of living that we
now have. Nutrient management is a
critical part of the solution to most, if
not all, of our agricultural NFS
problems and we must use it
effectively for the benefit of all. Q
6 JOURNAL OF SOIL AND WATER CONSERVATION
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You need to start
with the soil: The
Soil Conservation
Service
experience
Robert R. Shaw
Let me share, from two perspec-
tives, how the U.S. Department
of Agriculture's Soil. Conservation
Service (SCS) is addressing nutrient
management: first, how SCS currently
is aligning its technology to fit soils
and nutrient management into an
ecosystems approach to resource
conservation; and second, where we
are going from here in terms of our
capability to deal with a conservation
systems approach to nutrient manage-
ment.
Before looking at the ecosystems
approach, let me mention that we are
struggling with exactly what to call it.
We have tried "total resource
planning" as well as "ecosystem
planning." But the bottom line is this:
what environmental concerns compel
us to do and what computers allow us
to do is to help agriculture move in
the direction of a holistic approach, an
ecosystem approach to conservation
planning.
This direction we are taking in SCS
is based on three factors. The first is
the need for balance between
economics and ecology. Second is the
proliferation of national, state, and
local policy moving toward resource
protection and sustainability. The third
factor is the need to ensure that
environmental aims are incremental to
give agriculture time to adjust.
But in establishing the basis for
change in the direction of nutrient
management and other environ-
mentally sound practices, we know
that there is one key factor: the soil.
You have to know your soil. You
Roberts. Shaw is the deputy chief for
technology, USDA Soil Conservation Service,
Washington, D.C. 20013-
have to know its natural fertility, its
capacity to hold the nutrients that are
applied, its pH, and its structure,
which affects how water and air move
through it.
For that reason, one of the ways
that SCS is aligning itself for an
ecosystems approach is by reassessing
our soils database. Although that
database is extensive, it needs further
development. Some of the information
needed for water quality and nutrient
planning was not considered
important at the time many of our soil
surveys were conducted.
For example, in planning for
groundwater protection, we need
information about the area below the
root zone—the "vadose" zone. A
wealth of information about the
vadose zone is available, but for the
most part, it exists in well-drilling logs
that are scattered around in various
state agency files and in formats that
are largely incompatible with our
computer system.
We are funding a small project in
Michigan that will rate aquifer
vulnerability by using SCS's STATSGO
(state soils map) database and
digitized well logs. If this proves
successful, we should have a tremen-
dous opportunity to cooperate with
other groups in augmenting soils data
and increasing our knowledge of how
nutrients move to groundwater. We
also are trying to expand our soils
database by using small samples to
establish relationships between
known information and needed
information and then derive what is
needed.
But that is not all we are doing to
align nutrient management with
ecosystems management.
• We have revised the SCS field
office technical guides to include
the five natural resources—soil,
water, air, plants, and animals,
plus human considerations. The
technical guide is a compilation of
technical materials tailored to local
conditions. It guides SCS field
people in the advice they give to
their customers.
• We are helping with new practice
standards involving nutrient and
pesticide management,
composting, chemical loading, and
mixing facilities to deal with
commercial agri-chemicals.
• We have cooperated on producing
evaluation procedures that address
potential pollution from the
farmstead.
• We have embarked on the huge
task of automating the best
available technology so that our
employees can help our customers
plan and carry out their
conservation systems at the field,
farm, and watershed level.
As to SCS's capability to deal with
fixture needs, let me put this, in the
context of how SCS has had to
respond to environmental objectives
in farm policy. I am talking primarily
about the conservation requirements
of the Food Security Act of 1985 and
the Food, Agriculture, Conservation,
and Trade Act of 1990.
SCS has long had the technology to
address the erosion control aspects of
the law. But we have had to make
adjustments to meet the tremendous
•workload and to deal with the quasi-
regulatory nature of the conservation
compliance requirements. One of the
adjustments we have had to make is
to focus our attention almost entirely
on single-purpose planning for
erosion control. We have had very
little time to devote to a more holistic,
comprehensive approach in conser-
vation planning.
Where are we headed? I believe
that the future of the Soil Conser-
vation Service hinges on public
decisions as to a number of issues,
especially issues dealing with the
reconciliation of environmental and
economic values, with water manage-
ment being the biggest issue. There is
a question of how profitability and
economics will factor in to the
environmental equation. What will the
role be for incentives? What will the
role be for regulation? Does it matter
whether we have regulation or
incentives?
Whatever direction society takes,
SCS has a responsibility to deliver
automated technology' and to train the
workforce in this technology. Essential
to this task are our computer
technology, our databases, and our
geographic information system (GIS)
technology. More and more, we see
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 7
-------
the importance of our role as "value
add-ers" and as customizers of
resource information. You can see
that in what we are building toward—
common data standards, shared data-
bases, compatible hardware platforms
for computer linkage with allied
agencies, and remote access.
The next leap forward is to take our
computer systems from a primarily
textual kind of system to a graphic
and spatially oriented system. That is
an important step toward the
technology world we envision. And it
is a logical step, when you consider
that 80 percent of SCS data is spatial
or geographic data. This, of course,
brings us fully into the world of
geographic information systems.
That is the approach we are taking.
For agri-chemicals, we are working
with the research community and
others to build an automated multi-
tiered process for analyzing agri-
chemical use and assessing the
impacts of alternative choices. Each
successive tier provides more detailed
answers, but also requires more
resources to implement. Therefore, we
only move on to the next tier—or
level of analysis—when we are not
confident that environmental risk is
low. At each tier, we look at site sen-
sitivity based on soil properties, slope,
depth to groundwater, and proximity
to surface water. The concept is to
move to a more technologically inten-
sive tier only if the prior tier indicates
that a problem exists.
The technology is available for
prescription farming—using different
application rates of seed, pesticides,
nutrients, water, and cultivation
methods by soil and site conditions.
The big question is how can the
industry—meaning all sectors, ranging
from the federal government to
private consultants—help standardize
this information so that it is readily
available and affordable to all who
need it?
For detailed analysis, there are
many tools available. We have begun
by evaluating six of the models that
we felt had the greatest potential for
providing guidance in agri-chemical
management, especially for water
quality protection.
When we started this evaluation we
thought we would find the one best
model that would do the complete
job. Instead we found that each model
does something unique, even though
there may be overlap with other
similar models. We have settled on
two that will enhance planning at the
watershed level (AGNPS and
SWRRBWQ), three that are field or
point specific (EPIC, GLEAMS, and
NLEAP), and one for a pesticide
screening model.
Now we are working toward
• automating the pesticide and
nutrient management screening
procedures;
• "decomposing" the technology
found in comprehensive water
quality simulation models into
objects relating to water and
atmospherics, soils and geologic,
biological, and chemical
processes;
• constructing a model "assembler"
that will integrate objects as
needed to simulate water quality
effects;
• minimizing user inputs by a
graphical user interface and GIS
technology; and
• developing SCS water quality
simulation tools for two levels of
resolution—hydrologic unit scale
for area, state, and national offices
and field scale for field offices.
These are our challenges for the
future as I see them.
• It is imperative that we continue
moving into ecosystem manage-
ment—a more comprehensive,
holistic approach to conservation
planning. We have to start our
planning with the basic resources:
soil, water and air. Small water-
sheds (traditionally no bigger than
250,000 acres [101,175 ha]) are the
largest scale at which we should
attempt this for now, but at some
time in the future, we will have to
move to watershed management
that addresses bigger areas.
• To support a holistic approach, we
still have a lot to do to enhance
our information base so that it can
be consistently applied in eco-
system planning and management.
We need to move toward integrated
natural resource decision-support
systems. To that end, we must
• move rapidly in supporting spatial-
ly oriented computer systems,
• strengthen and build partnerships
and alliances needed to meet the
challenges ahead,
• accelerate the development of
user-friendly interfaces for many
complex research findings and
models,
• be able to identify critical areas
based on biological and other
natural resource data, and
• deliver services that are technically
consistent in different regions of
the nation.
Again, our goal is to build an inte-
grated, geographically based tech-
nology information system that is
sustainable and responsive to SCS
requirements and customer expecta-
tions. I believe we are on the thresh-
old of an exciting new chapter in total
resource planning and management. Q
Keeping
agriculture viable:
Industry's
viewpoint
B. C. Darst and L, S. Murphy
Webster's II New Riverside University
Dictionary defines "heritage" and
"viability" as follows:
• Heritage—something passed down
from preceding generations;
tradition.
• Viability (viable)—capable of
success or ongoing effectiveness;
practicable.
Production agriculture could be
described as a practicable tradition,
because it is, at least in part, tradition.
It is also practicable. Further, it links
B.C. Darst is executive vice-president of the
Potash and Phosphate Institute and president
of the Foundation for Agronomic Research,
Norcross, Georgia, 30092-2821. L.S. Murphy
is senior vice-president of the Potash and
Phosphate Institute, Manhattan, Kansas
66502.
8 JOURNAL OF SOIL AND WATER CONSERVATION
-------
the past, present, and future as
perhaps no other industry in the
history of humankind. A piece of that
linkage can be seen across today's
America, as we re-evaluate crop rota-
tion, use of cover crops, residue man-
agement, alternative methods of pest
control...myriad practices, some adapt-
ed by previous generations and others
which will be used by farmers of the
future.
A part of the viability of production
agriculture has been nutrient manage-
ment. As we learned to put back into
the soil its nutritional wealth, which
we exported to our dinner tables,
urban friends, and world neighbors,
production agriculture began to build
toward sustainability. Mined-out fields
were no longer abandoned, requiring
that virgin sod be plowed.
The lessons learned from the Dust
Bowl, coupled with thousands of
research studies showing the merits of
proper crop fertilization and other
new production technology, catalyzed
the fusing of conservation and
agronomic best management practices
(BMPs). The results have been
outstanding. Consider what has
happened in the last half-century (.12).
• The ratio of farms per American
citizen has fallen from 1:15 to
1:120.
• The number of people fed by the
American farmer has increased
from about 20 to more than 120.
• Corn and peanut yields have
quadrupled; wheat and soybean
yields have more than doubled,
cotton yields have tripled.
That's not the end of the story.
Yields of most of our common
agronomic crops are projected to
double in the next 40 years (79.
Americans can be fed, exports will be
boosted, and the environment will
benefit, because tens of millions of
acres of our most fragile land can be
returned to permanent cover. Sound
nutrient management will be a major
part of that scenario.
Nitrogen, phosphorus, and the
environment
All the 16 essential nutrients
required for food, feed, and fiber
production are , alSft protective ._of the
environment. They promote a more
vigorous, healthy crop. They reward
the farmer with greater profits; they
help conserve and protect our soil
and water resources in several ways,
by (2£>
« promoting more massive root
systems,
« providing quicker canopy devel-
opment and ground cover to
lower the impact of rainfall and
reduce runoff and erosion,
» supporting the production of more
residue, both above and below
ground, to stabilize the soil,
« improving water use efficiency, and
• increasing crop resistance to
stresses—drought, pests, heat, and
cold.
Essential crop nutrients play a vital
role in supplying us with food and in
protecting the environment. However,
in some cases, they can pose an
environmental risk without proper
management. The two nutrients most
often associated with environmental
risk are nitrogen and phosphorus.
This paper deals largely with con-
cerns about nitrogen and phosphorus
and with their management. It should
be understood, however, that for both
economic crop production and envi-
ronmental protection, the nutrient
management principles addressed
with regard to nitrogen and phos-
phorus apply to all essential nutrients.
Nitrogen. When nutrient manage-
ment is discussed in some quarters, it
is equated to reduced per-acre rates of
commercially produced fertilizer,
particularly nitrogen. The assumption
seems to be that there is a direct
relationship between fertilizer nitrogen
use and environmental damage. Facts
do not bear that out, however.
Many studies have shown a positive
relationship among appropriate use of
nitrogen fertilizers, profitable crop
production, and soil and water con-
servation. Others have demonstrated
that nitrate-nitrogen (hereafter referred
to as nitrate-N) occurrence in ground-
water and surface water is a natural
phenomenon. Still other studies have
identified significant contents of
nitrate-N in groundwater, long before
nitrogen fertilization was a common
practice. Selected examples follow.
In the early 1960s, nitrate-N
accumulation in plants and water
was of major concern. Several
studies attempted to correlate this
problem with the use of nitrogen
fertilizers. However, research in
the midwest U.S. at that time
indicated little evidence that nitro-
gen fertilizers were responsible for
or related to high nitrate-N levels
in water or in plants under normal
conditions (18, 19).
• Research in Nebraska, evaluating
the relationship between fertilizer
use and water quality, resulted in
the discovery of large amounts of
geologic nitrate-N within the deep
loess mantle stretching across the
central and southwestern areas of
the state. The accumulation was
encountered at about 20 ft (6 m)
and continued below depths of 90
ft (27 m). Levels of 25 to 45 ppm
nitrate-N are common, but values to
87 ppm have been measured (4).
• In a recent Ohio survey, repre-
senting 34,000 rural residences
from 276 counties in 15 states,
results showed that nitrate-N in
excess of 10 ppm—EPA
standard—occurred in only 3-8
percent of the wells tested.
Minimal nitrate-N contamination
was found in many areas of inten-
sive row crop agriculture, while
areas of more extensive contam-
ination occurred in agricultural
and non-agricultural regions (2).
• A Texas survey showed that
nitrate-N levels exceeding the EPA
standard were prevalent in water
supplies in the 1890s, more than
50 years before nitrogen fertilizer
was widely used in that state. In
fact, the percentage of water wells
exceeding the EPA standard in the
1896-1950 period was 9.93, com-
pared to 7.65 for the 1971-1990
period (.13, 14)-
• According to a 1992 report, nitrate-
N levels in the Des Moines River
in 1945 were nearly identical to
today's levels. In 1945,
commercially-produced fertilizer
accounted for about 0.3 percent of
the total nitrogen used by crops in
Iowa; today it accounts for about
two-thirds of the total (.9).
To say that nitrogen fertilization is
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 9
-------
Table 1. Increasing P rates improved wheat yields and N use
efficiency.
N
75
75
75
75
Treatment. Ib/A
Pads
0
20
30
40
Grain yield,
Ib/A
35
53
60
70
Plant N
composition, %
3.67
3.69
3.70
3.97
N removal
in grain, Ib/A
49
70
80
92
Soil test: Phosphorus, Very low. Nitrogen and P knifed preplant. Nitrogen removal based on
actual measurements.
Table 2. Commercial N use in the U.S., 1980-82 vs. 1989-91.
Years
Commercial N use,
million tons/year
1980-82
1989-91
11.4
11.1
ruining surface and groundwater
quality is no more accurate than to
data that it has no effect. There are
some risks to adding nitrogen to the
soil, whether the source is commer-
cially produced nitrogen or an organic
such as animal manures.
Rather than argue right or wrong,
the best course of action is to link
nutrient management with other BMPs
for crop production systems that
reward the farmer financially and
protect our soil and water resources.
Where die two cannot be reconciled
because the plant/soil/water system is
too fragile, the land should be
returned to permanent cover. Even
then, however, there is no guarantee
that natural processes such as the
mineralization of organic matter or the
leaching of geologic nitrate-N will not
introduce nitrate-N into groundwater
systems. In fact, they will. In many
cases, nitrate-N produced by the
mineralization of organic matter is
more likely to leach to soil depths
below the root zone than that from
fertilizer nitrogen, which is applied
near the time the crop uses it (3, 15).
Research has shown that organic
matter can release as much as 100
Ibs/acre (112 kg/ha) of nitrogen in
less than four months during the
summer, in areas with no crop residue
or low nitrogen residue. C5)
Phosphorus. Phosphorus is asso-
ciated with water quality primarily
through the eutrophication of lakes,
bays, and non-flowing water bodies.
Many sources, including sewage,
industrial wastes, detergents, fertil-
izers, soil erosion, animal manures,
and plant residues contribute to
phosphorus in water.
Eutrophication is a natural process
which has been going on since the
beginning of plant and animal life on
earth. All of the coal, peat, and muck
bogs in the world were created by it.
The state of Minnesota alone has
more than 7.5 million acres (3 million
ha) of peat bogs containing 6.8 billion
tons (6 billion metric tons) of peat, of
which approximately 5.5 million tons
(5 million metric tons) is phosphorus.
That phosphorus originated from soil
erosion and the decomposition of
plants and animals (17, 23).
Soil erosion is the major pathway
by which phosphorus is lost from
agricultural soils. When erosion is
reduced by agronomic and conser-
vation BMPs, phosphorus loss is
minimized. Leaching of phosphorus
through soils into groundwater is
limited because of the strong bonding
reactions of phosphorus with soil
compounds and soil particles. Phos-
phorus has a very low water solu-
bility, but natural weathering of soil
minerals and rocks does contribute
small amounts to surface waters.
Terraces, contour ridges, grass
waterways, and buffer strips are
examples of structural techniques for
erosion control. Any of these
conservation practices which reduce
soil erosion will also reduce phos-
phorus losses. Conservation tillage
systems such as no-till, minimum till,
and ridge till are also effective in
cutting erosion losses and are practical
and economical methods for farmer
implementation.
Some research has shown that
phosphorus concentration can be
higher in runoff from fields under
conservation tillage than from those
with more intense tillage. The reason
for this is that phosphorus is released
from decaying plant residues on the
soil surface (as well as other factors).
But total phosphorus loss is much
lower because conservation tillage is
so effective in reducing runoff.
Nutrient management and soil and
water conservation
The control of nitrogen and
phosphorus losses is best achieved by
adopting BMPs which include and
combine both conservation and
agronomic management. Agronomic
BMPs include the use of proper
fertilizer rates, timing, placement,
nitrogen stabilization, nutrient balance
and proper irrigation practices, variety
or hybrid selection, etc.
An example of a nutrient manage-
ment practice that can have direct,
positive effects on nutrient use effi-
ciency, crop yield, and the envi-
ronment is the use of nitrification
inhibitors in preplant nitrogen appli-
cations for corn. Nitrification inhibitors
such as nitrapyrin slow bacterial
conversion of ammonium-N to nitrate-
N. Ammonium-N is rather stable in the
soil, so potential leaching losses are
minimal. In a seven-year Iowa study,
nitrogen use efficiency was improved
and yields were increased by as much
as 16 bushels per acre with nitrapyrin
in preplant nitrogen applications (6).
With better nitrogen utilization, less
would be left in the soil after the
cropping season to leach with winter
precipitation.
Research data from across North
America emphasize the positive effects
of adequate amounts of all nutrients
on the ability of crops to utilize
available nitrogen. In Kansas wheat
10 JOURNAL OF SOIL AND WATER CONSERVATION
-------
research, grain yields and nitrogen
removed in the grain increased with
phosphorus fertilization (.ZO). Results
are summarized in Table 1. Nitrogen
utilization improved with adequate
phosphorus because of the more
extensive root system resulting from
better overall nutrition. In this case,
nitrogen removed in the grain was
actually higher than applied nitrogen
rates, indicating that additional
nitrogen had been supplied either by
carry-over nitrate-N or mineralized
organic matter. The net effect was less
nitrate-N remaining in the soil for
possible leaching into groundwater.
The first step toward achieving
optimum nutrient use efficiency is to
establish realistic yield goals—those
yields which are attainable, offer
acceptable economic return to the
farmer, and which are most protective
of soil and water resources. Produc-
tion history, cost/price benefits, soil
testing (soil fertility levels), and
management capability of the farmer
are factors which should be consid-
ered in setting yield goals.
Once realistic, attainable yield goals
have been set, nutrient management
(and other production management)
can be put in place to support eco-
nomic, environmentally-protective
crop production.
Nutrient management—nitrogen.
Nitrogen is the plant nutrient most
often deficient in non-legume crops.
Its availability to crops such as corn,
cotton, and wheat is essential to
sustainable crop production. Its use in
excess is detrimental to both the
economic well-being of the farmer
and the environment. The North
American farmer is making more
efficient use of nitrogen fertilization,
as measured by several indicators.
Since the beginning of the 1980s,
nitrogen fertilizer consumption has
levelled off, as shown in Table 2 (22).
During the. 1980s, crop yields
continued to climb, while principal
crop acreage was reduced by the
Conservation Reserve Program (CRP)
and Acreage Reduction Program
(ARP). The rate of nitrogen applied
per acre remained fairly constant. This
Table 3. Examples of nitrate-N leaching potential from various
sources.
Research site and
source of N
Nitrate-N content in soil,
parts per million (ppm)
Michigan State University
No N added
Commercial N
Animal manure
Alfalfa plowed down
University of Maryland
Poultry manure
(Aug to Dec)
(Nov to May)
Commercial fertilizer
(Aug to Dec)
(Nov to May)
10
49
62
18 (monthly avg.)
42 (monthly avg.)
15 (monthly avg.)
15 (monthly avg.)
fact is in contrast to claims that there
have been rapid increases in use.
Of the approximately 17 million
tons (15 million metric tons) of nitro-
gen applied to U.S. crops each year,
about two-thirds is commercial fertil-
izer nitrogen, with the remainder
coming from various other sources, as
shown in Figure 1 (22).
Non-commercial sources of nitrogen
will continue to be necessary in crop
production. Predicting their role in the
future would be impossible without
knowing how government trade
policy, regulation, and legislation will
affect farmer practices. What is
known, however, is that all nitrogen
sources impact on nitrate-N content in
the soil and, therefore, the potential
for contamination of groundwater, as
shown in Table 3 (22).
Long-term research in Oklahoma,
beginning in 1969, showed that
nitrogen sources do not differ when
evaluating residual nitrogen (amount
not used by the crop). Scientists state
that "regardless of the source, nitrate-
N will accumulate in subsurface
horizons if (your) nitrogen fertilization
rate exceeds the amounts recom-
mended" (J).
Results also showed that soil nitrate-
N levels, measured at 6-inch (15-cm)
intervals to a depth of 10 feet (3 m),
were the same when fertilizer was
applied to meet yield requirements of
wheat as those where no nitrogen
fertilizer was applied. The conclusion:
If the recommended nitrogen rates
64
|H Commercial N
|^\1 Legumes & Crop Residues
I I Animal Manures
• other
21
12
Figure 1. Percentages of total N
applied to U.S. cropland by
source.
300-1
Optimum N
rate = 160lb/A i
200
Figure 2. Nitrogen rate and P
application effects on nitrate-N
accumulation in the soil over a
30-year period (corn, Kansas
research).
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 11
-------
800
600-
400-
(200) -
(400) -
(600) -
(800)
Net Addition
Net Removal
76
78
1 I
80
I i I i I i I i [ r
82 84 86 88 90
Year
Figure 3. Net phosphate removal by corn and soybeans in the midwestern U.S., 1976-1992.
92
Table 4. Phosphate uptake by some common crops.
Crop
Alfalfa
Coastal bermudagrass
Corn
Cotton
Grain sorghum
Oranges
Peanuts
Rice
Soybeans
Tomatoes
Wheat
Yield
level
8 tons
8 tons
160bu
1, 000 Ib lint
8,000 Ib
540 cwt
4,000 Ib
7,000 Ib
60 bu
40 tons
60 bu
P2Os taken
in total crop
120
96
91
51
84
55
39
60
58
87
41
up
, Ib
Note: Phosphorus content of fertilizer is expressed as "PsOs" equivalent, even though no PzOs
as such occurs in fertilizer materials. The PiOs designation is a standard expression of
relative P content.
established by the Oklahoma State
University soil testing program are
followed, results suggest that there
will be no risk of environmental
contamination (f).
Nitrogen management, both com-
mercially-produced and from other
sources, is being researched and
improved constantly. As a result, use
efficiency by agronomic crops is
increasing. In 1992, for example, the
U.S. average corn yield was 131-plus
bushels per acre (8,223-plus kg/ha),
with an average nitrogen application
rate of 127 pounds per acre (142
kg/ha). That translates into a use
efficiency of 1.07 bushels of corn per
pound of applied nitrogen, extending
a record of improved use efficiency
that goes back to the mid-1980s, and
representing the highest nitrogen use
efficiency on corn in the last quarter
of a century.
What does the future of nitrogen
management hold? Several manage-
ment tools are now available and
more are being developed that will
improve crop nitrogen use. These
include
• More precise timing of nitrogen
fertilization, including split
applications, so the growing crop
has the nitrogen available when it
is needed, leaving less remaining
in the soil where it can pollute
groundwater
• Nitrogen soil tests, which will
more accurately measure nitrogen
available for crop use, allowing for
fertilizer nitrogen application rates
that meet but do not exceed crop
needs
• Nitrogen stabilization through the
use of special coatings or nitri-
fication inhibitors which hold the
nitrogen in the root zone until the
crop can take it up and use it
• Site specific nitrogen fertilizer
applications, made possible with
the use of variable rate field
equipment, computers, and
satellite tracking
• Balanced fertilization, using
adequate levels of other essential
nutrients with nitrogen to enhance
nitrogen use efficiency, resulting in
more profitable crop production
12 JOURNAL OF SOIL AND WATER CONSERVATION
-------
and the protection of soil and
water resources. Figure 2 shows
how balanced fertilization—using
phosphorus (phosphate) with
nitrogen——minimized nitrate-N
accumulation in the soil. When
phosphate was applied at 40
pounds per acre (45 kg/ha) and at
the optimum nitrogen rate of 160
pounds per acre (179 kg/ha),
residual nitrate-N levels after 30
years were comparable to those
.when no nitrogen was applied.
However, when too much nitro-
gen was applied, even with phos-
phorus, residual nitrate-N levels
were significantly higher. In this
30-year Kansas study, corn yields
were also increased by an average
of 24 bushels per acre per year
with phosphorus (.76). Both the
farmer and the environment
benefitted from balanced
fertilization.
Nutrient management—phosphorus.
Phosphorus is one of the three major
nutrients, along with nitrogen and
potassium, required in crop production.
It is essential to normal crop growth;
no other nutrient can be substituted
for it in plant physiology. Most crops
take up rather large amounts of
phosphorus, as shown in Table 4
(.20).
Until the late 1970s, farmers in the
Corn Belt (Midwest) were building
soil nutrient levels, including phos-
phorus. Since 1980, however, farmers
have removed more phosphorus in
corn and soybean harvests than they
have been applying. In 1992, mid-
western farmers applied only 75
percent of the phosphorus their corn
and soybeans removed. Since 1984,
they have 'mined' 3.9 million tons (4
million metric tons) of phosphate
from their soils. This total reflects the
deficit for phosphate fertilizer appli-
cation relative to removal. Figure 3
shows that since 1980, phosphate
removal has exceeded the amount
added back every year except 1980,
1983, and 1988, all drought years (8).
Soil testing is a valuable tool
available for farmers to use in
assessing crop nutrient needs. It is site
specific and can be combined with
other management practices to
formulate economically efficient and
environmentally, friendly fertilizer
recommendations. A common miscon-
ception among those not in tune with
production agriculture is that farmers
have built their soil tests for phos-
phorus (and potassium) to the point
that fertilization is no longer needed.
Soil test summaries show that is not
true. There are many soils across
North America which test medium or
less in soil phosphorus fertility that
are responsive to fertilizer application.
Table 5 illustrates that point (.20).
In addition, research is showing
frequent crop responses to starter
fertilization, even on soils which test
high or very high in fertility.
Traditionally, little if any response
would be expected from the crop
being fertilized. Farmers were
encouraged to apply nutrients at rates
to offset crop removal in order to
maintain the soil's productivity.
However, -with today's higher
yielding crop hybrids and varieties,
conservation tillage, and other new or
improved management practices,
nutrient management is changing.
Unplowed soils with residue cover
stay cooler and wetter during early,
initial crop growth. Applied fertilizer
nutrients concentrate in the upper few
inches of soil. The crop itself
contributes to this stratification of
fertility. All these factors tend to
reduce the crop's ability to take up
nutrients early in the growing season.
As a result, rooting patterns change.
Crops explore a lesser volume of soil
for water and nutrients. Yields suffer.
Starter fertilizers place high
concentrations of nitrogen, phospho-
rus, potassium, and other nutrients
close to the young crop's developing
root system. They help the crop over-
come stresses such as low temper-
atures, wet soil conditions, and soil
compaction. Understanding how
limited young plant root systems are,
one can see why concentrating high
levels of nutrients in the root zone can
boost early growth and increase the
crop's yield potential. Research across
North America is showing the
benefits. An example of how starter
phosphorus fertilizer can affect corn
yield and maturity (grain moisture) is
shown in Table 6 (.11).
As new technology is discovered
through research, phosphorus fertil-
izer management will become more
efficient. With conservation and
agronomic BMPs, more phosphorus
will go into the production of food;
less will be lost through erosion.
A look to the future
As we look to the future for
direction in keeping production
agriculture viable, we would be well
served to glance over our shoulders,
to back-breaking labor, low crop
Table S. Soil test summaries for selected states and Canadian
provinces.
State or
province
Phosphorus soil test summary,
percent testing medium or less
Alabama
Iowa
Nebraska
Ohio
Oklahoma
Ontario
Pennsylvania
65
44
69
32
52
52
56
Table 6. Phosphorus starter fertilizer increased corn yield and
reduced soil moisture, even on a soil with a very high soil test.
Treatment
Yield,
bu/A
Grain
moisture, %
Without P
WithP
122
145
26.8
24.3
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 13
-------
yields, and disease- and insect-
infected fruits and vegetables. Further,
we must face the pressures of feeding
a growing world population. The
earth is now inhabited by more than
5.3 billion people. That number is
expected to grow to 6.1 billion in the
next seven years, and to more than
8.0 billion by the year 2025.
The effects of population pressures
on the ever-shrinking land area
available to food production continue.
On a per-capita basis, the world had
about 0.42 agricultural acre (0.17 ha)
in 1980, down to 0.37 acre (0.15 ha)
in 1998. If forecasters are correct, we
will have only 0.32 acre (0.13 ha) per
person available to production
agriculture at the end of this century.
A much debated subject today is the
sustainability of agriculture. Some
argue that agriculture should revert to
'yesteryear,' to low input farming to
achieve true sustainability. Nutrient
use would be one of the inputs cut
back, particularly the use of commer-
cially produced fertilizers. Those
familiar with nutrient requirements of
high yield crops understand, however,
that feeding the world will require
larger amounts of inputs, including
nutrients.
Now and in the future, the
definition of sustainability—viability—
must include a statement on enhanced
productivity to meet increasing
demands of the world's growing
population and its per capita income.
More intensive production will require
greater amounts of plant nutrients.
Our concern should not be how
much, or how little, nitrogen, phos-
phorus, and other essential nutrients
are applied to the soil, but how,
when, where, and why they are
applied. To be able to answer the
questions thus implied, we must look
to agricultural scientists. Their
research clearly shows that when
nutrients are managed to build and
maintain soil fertility, long term
productivity can be sustained. Further,
tomorrow's production agriculture can
go hand-in-hand with environmental
protection.
It is not enough, though, for
production agriculture to be econom-
ically, technically, and environ-
mentally sustainable. It must also be
socially and politically sustainable.
Consumers, elected and appointed
officials, and others must be better
informed, so that decisions relative to
agricultural policy can be based on
scientific fact, not emotion.
On one hand, consumers and
special interest groups must under-
stand that food production will never
be risk-free. The potential for nitrate-N
leakage into groundwater or phos-
phorus enrichment of surface waters
exists now and will in the future. On
the other hand, the farmers must
continue to grow crops and livestock
in ways that protect our soil and water
resources. A critical part of tomorrow's
production agriculture will be efficient
nutrient management.
Production agriculture has changed
and continues to change, mostly for
the better. It is viable today and will
be tomorrow. Our well-being as a
world society depends on it.
REFERENCES CITED
1. Anonymous. 1992. Accumulation of
ammonium and nitrate in soils cropped to
continuous wheat. Fertilizer Checks,
Oklahoma State University, Stillwater.
2. Baker, D.V. 1992. Nitrate in private water
supplies: Building local data bases. Better
Crops 76(3):6-9.
3. Black, A.L., and A. Bauer. 1991. USDA-
ARS, Mandan, North Dakota. Personal
communications.
4. Boyce, J.S., et al. 1976. Geologic nitrogen
in Pleistocene loess of Nebraska. J.
Environ. Qual. 5(l):93-96.
5. Cabrera, M.L., and D.E. Kissel. 1988.
Potentially mineralizable nitrogen in
disturbed and undisturbed soil samples.
Soil Sci. Soc. Am. J. 52:1010-1015.
6. Christensen, R.H., andJ.R. Huffman. 1992.
Response of com to preplan! applications
of nitrogen and to nitrogen plus
nitrapyrin. J. Prod. Agric. 5(3):352-358.
7. Darst, B.C. 1993. Crop fertility research
highlights. Solutions 37(3):32-35.
8. Anonymous. 1993. Fertilizer and
Agricultural Review. IMC Fertilizer Group,
Inc., Mundelein, 111.
9. Keeney, D. 1992. Nitrate in the Des
Moines River: Not a new problem? Leopold
Letter 4:10-11. Iowa State University,
Ames.
10. Leikam, D.E., et al. 1978. Effects of
methods of nitrogen and P application
and P rate on winter wheat. Kansas
Fertilizer Research Report of Progress
343:27-29.
ll.Moncrief et al. 1991. A report on field
research in soils. University of Minnesota
Blue Book. p. 313-316.
12. Nelson, W.L. 1985. Agronomic Programs
in North America for 50 years. Better
Crops 69(2):10-15.
13. Pennington, H.D. 1989. Nitrogen fertilizer
use: Its impact on Texas groundwater.
Better Crops 73(4):20-21.
14. Pennington, H.D. 1990. Nitrogen fertilizer
and nitrogen technology's impact on
Texas groundwaters. Texas Agricultural
Extension Service. Soil, Plant and Water
Testing Lab., Texas A&M University,
College Station.
15. Powlson, D. 1988. Long-term nitrogen
studies at Rothamsted. Arable Farming.
July. p. 2.
16. Schlegel, A., and K. Dhuyvetter. 1992.
Phosphorus boosts long term corn and
sorghum yields, reduces soil nitrate
carryover. Better Crops 76(l):l6-19.
17. Sharpley, A.N. 1985. Phosphorus and
eutrophication. In: Proc. Plant Nutrient
Use and the Environment Symposium. The
Fertilizer Institute. Washington, D.C. p.
247-270.
18. Smith, G.E. 1965. Nitrate problems in
waters related to soils, plants and water.
Missouri Agricultural Experiment Station
Special Report 55:42-45. University of
Missouri, Columbia.
19. Smith, G.E., et al. 1964. Nitrate problems
in plants and water supplies. Division of
Fertilizer and Soil Chemistry, American
Chemical Society. Chicago, 111.
20. Potash & Phosphate Institute. 1992. Soil
Fertility Manual. Chapter 4: Phosphorus.
Norcross, Ga.
21. Potash & Phosphate Institute. 1992. Soil
Fertility Manual. Chapter 10: Plant nutri-
ents and the environment. Norcross, Ga.
22. Potash & Phosphate Institute. 1992. Ten
facts affecting nitrogen use for sustainable
agriculture and nitrate in groundwater.
Norcross, Ga.
23. Wadleigh, C.H. 1968. Wastes in relation to
agriculture and forestry. U.S. Department
of Agriculture Miscellaneous Publication
No. 1065. p. 112. Q
EPA's perspective—
you need to
protect water
quality
Thomas E. Davenport
Avast majority of the nation's
water resources are degraded
by nutrients. Nutrients are the
leading cause (55 percent) of
impairment for estuaries and coastal
Thomas E. Davenport is chief of Watershed
Management Unit, U.S. EPA Region 5,
Chicago, Illinois 60604.
14 JOURNAL OF SOIL AND WATER CONSERVATION
-------
waters, the second leading cause in
lakes (32 percent) and rivers (28
percent). Phosphorus and nitrogen
compounds from diffuse nonpoint
sources are most often cited by states.
Nutrient management is not just an
agricultural issue. There are seven
major sources of nutrients:
• Commercial fertilizer
• Manure production and disposal
• Municipal and industrial treatment
plant sludge
• Municipal and industrial effluent
• Legumes and crop residues
• Irrigation water
• Atmospheric deposition
In addition, there is not just one
problem associated with excessive
nutrients in water. The major problem
associated with excessive nutrients,
particularly phosphorus in freshwater
and nitrogen in salt-water, is the
exacerbation of eutrophicatio'n prob-
lems in our lakes, rivers, and' bays.
Eutrophication is a natural-process but
the problem is elevated, by nutrient
loadings resulting from human inputs,.'- ;
This accelerates eutrophication,
degrading water quality more quickly.
In addition, nitrogen in the form of
ammonia is toxic to freshwater fish
and nitrate is a concern in drinking
water from either surface or ground-
water sources.
It is important to note that there is
not one specific answer to the
question of how to deal with excess
nutrients. A general answer is the Best
Utilization of Business and Biological
Assets (BUBBA) approach. This
approach recommends managing
nutrients in a manner that doesn't
adversely effect the environment. In
plain terms, it means put on only
what is needed, when it is needed,
and in a form and by a method that
ensures the nutrients will be fully
utilized by the crop. Some nutrients
will be lost through various processes,
but users should focus on minimizing
those losses. There is a vast array of
methods for determining what is
needed, when it should be applied,
and how; with this information,
individual nutrient management plans
can be developed according to
BUBBA.
Since nutrient problems impact
bodies of water and are not specific to
individual fields, the problems of
excessive nutrients must be dealt with
on a watershed basis. Unless it is
related to a spill, this cumulative
problem must be handled collectively
by addressing all causes of the water
quality problems, not just agriculture.
It is well known that the condition of
a body of water is a reflection of its
entire watershed use and man-
agement.
When dealing with nutrient related
water quality problems, two basic
issues emerge: economics and envi-
ronment. Economics relates to the
landowner or operator's probability of
making a profit. Environment issues
break down into two types of prob-
lems: acute and chronic. Acute
problems are those that need to be
dealt with right away, such as fish
toxicity and nutrient levels that exceed
daily drinking water standards.
Chronic problems are related .to
eutrophication and what it does to the
water resource over time. Eutro-
phication causes taste, odor, and
•aesthetics problems, causes fish
populations to change, and con-
tributes to winter kills in many lakes
due to dissolved oxygen depletion.
Solutions must incorporate both
economics and the environment.
There are two levels to deal with
the nutrient problem: at the individual
source level or geographic (statewide)
level. At the individual level, selling
the solution is the preferred approach
because linking field economics with
environmental benefit leads the
individual to buy into the solution.
MAX, an economic tillage computer
program, is being modified to relate
profit to water quality concerns and
benefits. This will be a useful tool for
dealing with individual fields.
At the geographic or statewide
level, programs usually need to be a
combination of information/education,
technical and financial assistance, and
in some cases, mandatory regulations.
Regulations are not always necessary;
the voluntary approach has worked in
some cases, such as with the Great
Lakes Water Quality Agreement.
Several states in the Great Lakes Basin
had to reduce phosphorus loading to
Saginaw Bay, Lake Erie, and Lake
Ontario. Without regulation, Indiana
met its phosphorus load reduction
goal for Lake Erie and Michigan met
its goal for Saginaw Bay. These
achievements were the result of a
combination of cropland erosion
control, nutrient management, and
animal waste management practice
implementation.
However, the mandatory regulatory
approach will become more predom-
inant due to the Coastal Zone Act
Reauthorization Amendments (CZARA)
nonpoint source requirement. CZARA
requires states with coastal zone
authority to develop and implement a
coastal nonpoint source program. The
purpose of this program is to support
the implementation of specific man-
agement measures, for individual
sources including cropland and
livestock operations. These new state
coastal nonpoint source programs
must include enforceable policies and
mechanisms to ensure the manage-
ment measures are-implemented.
Region 5 of the Environmental Pro-
tection Agency is encouraging all of
its states to use these management
measures statewide, not just in the
coastal zone. These measures make
sense in both economic and envi-
ronmental terms. One of the prin-
ciples guiding this approach is that
restoring 'water resources that have
been impaired by nutrients is
extremely costly. It is more cost
effective to prevent the problem than
to fix it after it occurs, and these
management measures help do that. Q
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 15
-------
Understanding the
Basics
L
Understanding the
nutrient cycling
process
/. F. Power
Nutrient cycling involves the
transformation and availability
of nutrients from many
sources. Good soil management
consists of regulating nutrient cycling
in such a manner that nutrient
requirements of the growing crop are
met but not greatly exceeded at each
stage of crop growth. This is accom-
plished by creating a soil micro-
environment (air, water, temperature,
and substrate availability within soil
pores) through proper choice of
management practices that controls
the rate of nutrient cycling and
availability as dictated by crop needs.
Nutrient transformations, especially N
and to a lesser extent P, result from
soil microbial activity within soil
pores, and are therefore mediated by
the microenvironment existing within
these pores. Through choice of tillage
J,F. Poioer is a research leader, USDA-
Agiiciiltural Research Service, University of
Nebraska, Lincoln 68583.
and crop residue practices, cropping
systems, fertilizer practices, and
related decisions, the farmer exercises
some degree of control over the soil
microenvironment and thus affects the
transformation, availability, and
potential loss of nutrients from the
soil. While we currently have knowl-
edge of many of the processes
involved and factors affecting these
processes, integration of all factors
into an efficient management system
remains very difficult and empirical.
Development of an artificial intelli-
gence system will be required to best
integrate these myriad factors for all
situations.
Nutrient cycles involve the
transformations and availability of
nutrients from many sources. Modern
agricultural production practices have
emphasized the widespread use of
fertilizers as a source of nutrients to
supplement biological sources made
available through nutrient cycling.
Within a generation, this approach has
increased grain yields dramatically.
This change has also resulted in
planting less land to legumes and
perennials, thereby increasing the area
available for grain production. As a
consequence of these developments,
total grain production in many nations
has increased many-fold. This has
provided a means by which many
nations are now able to meet their
food needs for an expanding
population.
This expansion in grain production
capability through use of fertilizers has
not been without its problems,
however. There is evidence that over-
fertilization has increased the con-
centration of many plant nutrients in
both surface and ground water (33,
39), creating a potential health hazard,
and reducing utility of many water
bodies. There is also a possibility that
greatly increased use of N fertilizers
world-wide in the last several decades
may be responsible for at least part of
the increased ^O concentrations in
the atmosphere (75, thereby depleting
stratospheric ozone concentrations.
This allows more ultraviolet light to
reach the earth's surface, and
increases potential for skin cancer.
Also N fertilizers are largely depen-
dent on fossil fuels for their manu-
facture, and consequently deplete a
non-renewable resource. Collectively,
these and other associated problems
raise the question of the sustainability
of a system highly dependent upon
intense fertilizer inputs. Does such a
system jeopardize the conservation of
soil, water, air, and energy resources
for future generations?
Fortunately there are other sources
of essential plant nutrients beside
fertilizers. Plant-available N is derived
by biological N2 fixation, loose
16 JOURNAL OF SOIL AND WATER CONSERVATION
-------
mineralization of native soil organic N,
and mineralization of N contained in
crop residues, manures, sludges, and
other organic wastes. Likewise plant-
available P can be obtained not only
from acid-treated phosphates, but also
from rock phosphates and other
natural P-containing minerals, soil
organic matter, crop residues,
manures, and other organic wastes,
and from secondary minerals in soils.
Available K and other nutrients can be
obtained from many similar sources.
Because of the many sources that
may contribute to the availability of a
nutrient, much of the science of crop
production is involved with con-
trolling the rate of release of nutrients
from all 'sources in a manner that
enables the plant to have a sufficient
but not excessive supply of the
nutrient at all phases of growth.
Usually an excessive supply results in
leakages from the soil-crop systems,
and these leakages not only reduce
economic returns, but also often end
up as pollutants of air and water.
Controlling nutrient availability is
complicated by the fact that the crop
requirement for a given nutrient
constantly changes throughout the
growth cycle. Achieving synchrony
between crop requirement and
nutrient availability is further
complicated by variations in tem-
perature, soil water content, soil
aeration, and many soil properties
(30). Consequently, controlling nutri-
ent cycles through management
practices is a difficult assignment.
Inherent
Soil
Properties
Nutrient
Transformations
Figure 1. Flow chart relating bioiic and abiotic factors to soil
ecology and nutrient uptake (30).
The agricultural ecosystem
The effects of inputs into farming
systems on changes in the soil
environment, nutrient availability, and
subsequent plant growth are shown
schematically in Figure 1. For a given
soil and climate input, each with its
inherent properties and characteristics,
the producer controls the soil envi-
ronment through the selection of
management practices. Soil environ-
ment factors of most concern are air
(oxygen) and water regimes, soil
temperature, and substrate availability.
The farmer makes and executes a
series of management decisions each
year—choice of tillage practices, crop
residue management, irrigation and
fertilization practices, crops grown
and cropping sequences, manuring
and green manuring, weed and pest
control, harvesting technique, and
others. These decisions for a given
soil in a given climate result in unique
combinations of aeration, water
availability, temperature distribution,
and availability of substrates (espe-
cially soluble C utilization by
microorganisms and plant-available
nutrients for uptake by plant roots).
The preceding parameters of the
soil environment, which are estab-
lished as a result of management
decisions, regulate to a large extent
the chemical reactions and biological
niches that occur in the soil. Chemical
reactions are concerned with pre-
cipitation-solubility relations (phase
changes), as well as alterations of
chemical forms or species. For
example, as the soil dries, many
inorganic elements precipitate out of
soil solution as solubility limits of the
various salts are reached (.22).
Biological niches or habitats
determine the kind and numbers of
living organisms in the soil. These
organisms in turn affect plant root
activity and. microbial activity. Soil
microbial and faunal activity largely
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 17
-------
determine the rates of decomposition
of fresh organic matter and the avail-
ability of nutrients immobilized in
organic form. Soil microorganisms live
and function predominantly within the
pores of the soil. These pores are also
occupied by the water and air con-
tained in a volume of soil. Conse-
quently, one would expect that the
better farm management decisions
would be those in which water, aera-
tion, and microbial activity are near
the optimum combination that pro-
motes the amount of biological activ-
ity needed to mobilize the nutrients
required by the crop at that time.
The chemical and biological activity
of the soil regulates, to a large degree,
the nature and extent of nutrient
transformations that occur (see Figure
1). In addition, changes in water and
aeration regimes may result in oxi-
dation-reduction reactions that convert
certain elements from plant-available
to unavailable forms (Fe, Mn, and
others). Also, salt concentration of the
soil solution (salinity) increases as soil
water content decreases, and at suffi-
Table 1. Relative quantity, turnover rate, and availability of various
soil organic nitrogen components of prairie soils (6).
Fraction
Plant residues
Living
Dead
Microbial biomass
Labile organic
nitrogen
Resistant N
Total Soil N
%
6
4
5
65
20
Half-life
Yr
0.3
1.2
36.0
990.0
Mineralizable N Pool
%
68.3
31.3
0.4
Table 2. Effect of fallow tillage practices for winter wheat
production on several soil properties and microbial biomass (9,
10).
Bulk density
mg m~3
Soil water, V/V
Water-filled
pore, %
Hydraulic
conductivity,
mm ha"1
Total N, %
Organic C, %
NH'«-N, kg ha'1
NO3-N, kg ha'1
PMN, kg ha'1 (a)
Microbial bio-
mass(b)
No
0-75 mm
1.29
0.28
54
32.0
0.124
1.08
4.6
5.1
52.1
1.53
Till
75-150
1.30
0.30
65
21.9
0.103
0.77
5.2
7.1
45.9
0.97
Sub Till P
' 0-75 mm
1.25
0.24
45
33.0
0.114
1.00
4.0
5.4
47.6
1.36
75-150
1.38
0.28
62
10.1
0.101
0.75
3.8
10.4
50.8
0.98
0-75 mm
1.25
0.22
43
19.4
0.104
0.85
3.5
4.6
43.9
1.00
low
75-150
1.31
0.27
56
15.4
0.101
8.3
4.2
13.5
47.9
1.00
a Potentially mineralizable N by autoclaving
b Relative to plow treatment
ciently high concentrations it can
affect all biological activity by altering
the osmotic potential.
Finally, as indicated in Figure 1, all
factors discussed ultimately affect
plant growth and activity. Soil envi-
ronment directly affects productivity,
including plant root growth and
development, nodulation, mycorrhizal
infections, and meristematic activity in
the crown (especially for gramineous
species). Thus, the kind and mag-
nitude of nutrient transformations that
ultimately result from management
decisions affect the availability of
plant nutrients and subsequent plant
growth. This is especially important
for N since N availability is so closely
tied to soil microbiology.
Sources of nitrogen
Because of the dominance of N
nutrient cycling and uptake, major
emphasis is placed on it in this paper.
The primary sources of N used in crop
production originate from soil organic
matter, residual inorganic N, biological
dinitrogen fixation, atmospheric depo-
sits, crop residues, manures, other
organic wastes, and fertilizers. Relative
importance of these sources varies
widely in different years, locations, or
cropping systems. As suggested by the
flow diagram given in Figure 1, all
sources must be managed in order to
obtain economically profitable crop
yields without experiencing unaccept-
able losses to the environment.
In many soils, soil organic matter is
often a primary source of plant
available N and other nutrients. Most
of this N is immobilized as proteins
and other nitrogenous compounds,
often as components of dead micro-
bial cells or sorbed on clay surfaces.
This N is made available to a growing
plant only through microbial degrad-
ation (mineralization) (.29). Usually
organic N comprises some 6 to 10
percent of the total soil organic
matter. Often about 3 percent of the
soil organic N pool is mineralized
during a growing season. Thus a soil
with 2 percent soil organic matter, 8
percent N in the soil organic matter
component, and bulk density of 1.33
Mg m~3 may mineralize approximately
18 JOURNAL OF SOIL AND WATER CONSERVATION
-------
96 kg N ha'l annually in the upper 15
cm of soil. Consequently in a fertile
soil, mineralization of indigenous soil
organic N is usually a major source of
plant-available N (.38).
Soil organic N is not homogenous,
but rather is composed of readily
labile, slowly labile, and resistant
components. Chemical, physical, and
functional characteristics of these
components have been studied
frequently (6, 43). Readily labile
components have a turnover rate
measured in weeks or months, slowly
labile in months and years, and
resistant in decades or centuries. Most
N in soil organic matter is in the
resistant form, with a much smaller
fraction in the slowly labile forms.
Only a few percent is in the readily
labile pool, but this pool constitutes
most of the N mineralized during the
course of the growing season (Table
1). Nitrogen immobilized in microbial
biomass may account for a large part
of the readily labile pool (2.9). The
resistant pool, while relatively inert,
plays a major role in creating and
maintaining the soil physical condition
(.41).
Residual soil inorganic N consists of
ammonium (NO^ and nitrate (NO^)
remaining in a soil after harvest of a
crop or mineralized prior to planting
the next crop. Often much of the
residual inorganic N originates from
excess applications of fertilizers and
manures (.38). This N, while readily
available to the next crop, is also sub-
ject to loss by leaching or denitri-
fication before or shortly after planting
the next crop. Levels of inorganic soil
N can usually be controlled through
management practices if the practices
used syn-chronize N availability with
N uptake by the crop (39). Existing
levels of residual inorganic soil N are
frequently measured by soil testing
prior to planting a crop in order to
determine quantity of fertilizer or
manure required by the next crop
(soil testing).
Mention should be made of the
non-exchangeable ammonium frac-
tion. This N is trapped in inter-lattice
spaces in 2:1 clays and is more
strongly attached to clay particles than
exchangeable ammonium. While this
N fraction is generally considered to
be unavailable to crop plants, there is
considerable evidence from -^N
studies that an equilibrium exists
between concentrations of exchange-
able and non-exchangeable ammo-
nium (3, 27). Because non-exchange-
able ammonium may account for well
over 1,000 kg N per ha in the upper
meter of some soils with 2:1 clays,
even a small rate of .conversion of this
N pool to plant-available forms could
account for an appreciable part of the
N requirements of a crop. Much more
research is needed to understand the
kinetics and role of non-exchangeable
N in plant nutrition.
Atmospheric sources of N consist
primarily of wet and dry deposition
and gaseous ammonia absorption
from (or released to) the atmosphere
(19). The wet and dry deposition
includes the various atmospheric
oxides of N that are oxidized to nitrate
and washed out of the air by precip-
itation, plus ammonia absorbed on
particulate matter. Except for highly
industrialized areas or near confined
livestock operations, most measure-
ments of wet and dry deposition are
in the 10 to 20 kg N ha"1 annual
range. Most of this N is in plant-
available forms.
Ammonia is a highly volatile
compound, and may be emitted
directly from the soil following
fertilization with urea or anhydrous
ammonia. Also animal wastes emit
NHj gases, as do a number of
industrial processes. Consequently
high atmospheric NHg values are
often found near feedlots or industrial
areas. Another major source of
atmospheric NHj is from the anaer-
obic decomposition of organic matter,
such as from swamp or rice paddies.
In recent years there has been
increasing evidence that well fertilized
crop plants also emit NH^ through
their stomata during the maturation
process (21, 28). Some studies suggest
that as much as 25 percent of the total
N taken up by a crop may be emitted
by this means. Ammonia in the
atmosphere is readily washed out by
rain. Also if a plant is deficient in N, it
may directly absorb atmospheric NHj
through its leaves. Thus, most NHj
gases emitted into the atmosphere are
usually returned to the soil or crop
within a few kilometers.
Crop residues are another major
source of plant nutrients. In the
United States, the quantity of nutrients
returned to the soil in crop residues
approximates that added as fertilizers.
Essentially all the N returned in crop
residues is in organic form so it must
be mineralized by microbiological
activity before becoming available for
uptake by the next crop. Rate and
efficiency of the mineralization
process depends upon many factors—
soil temperature and water regimes,
C/N ratio of the crop residues, residue
placement, particle size, and other
factors (32, 36). Crop residues vary
widely in C/N ratio, with higher
values for residues from grain crops
and generally lower values from
legumes. If the C/N ratio is greater
than about 30, little or no net N
mineralization will occur. Tillage
practices often regulate the rate at
which N in crop residues is miner-
alized, with fastest mineralization
occurring when residues are incor-
porated into the soil (plowing,
disking).
Cropping systems largely control
the quantity and composition of crop
residues available to manage (If).
Monocultures of grain crops provide
only high C/N residues that contribute
relatively little directly to the supply of
plant-available nutrients (labile pool).
They may, however, contribute
appreciably to the slightly labile and
resistant soil N pools (Table 1),
appreciably influencing soil physical
conditions and indirectly influencing
microbial activity (7, 26). On the other
hand, use of legume cover crops or
legume-based crop rotations provides
a variety of crop residues varying
greatly in composition. Gupta and
Germida (18) concluded that micro-
bial (especially fungal) biomass
responds rapidly to management
practices, affecting macroaggregation
(over 1 mm [0.04 in] diameter) more
than microaggregation.
In many regions animal manures,
sewage sludges, and other organic
wastes also contribute greatly to the
cycling of plant available nutrients.
Again composition (C/N ratio) of
these organic materials can vary
widely, affecting rate of decompo-
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 19
-------
sition, availability of nutrients, and
stability of soil aggregates. With
livestock production systems, except
for dairying, only a small part of the N
fed to the livestock is physically
removed in the livestock product sold
from the farm (.42). However much of
the N in livestock wastes is commonly
lost to the atmosphere by ammonia
volatilization (and possibly denitri-
fication) because the manures are not
properly handled (38)- It frequently
happens that with intense livestock
enterprises, the area available for
economically suitable manure disposal
is limited, resulting in manure over-
loading of the land. In such instances,
high concentrations of nitrates in
associated surface and ground waters
often result (.25).
Microbial transformations
Water, temperature, aeration, and
substrate availability are the primary
parameters governing microbial
activity in soils. Water is often a
dominant factor. These parameters
therefore affect transformations of N
and, to a large extent P, because most
of the N and an appreciable part of
the labile P in a soil are derived from
the biological decomposition of
organic matter (.12). Linn and Doran
(23) have shown that such biological
processes as N mineralization, nitri-
fication, and CC>2 production increase
as the percentage of the soil pores
filled with water (water-filled pore
space) increases to about 60 percent
(Figure 2). At higher values, rates of
these aerobic processes decrease
while rates of anaerobic processes
(i.e., denitrification) increase. The 60
percent water-filled pore space (also
60 percent saturation) approximates
water content at field capacity for
most soils. From this, then, it is
apparent that, as a soil dries to below
field capacity, the potential rate of
conversion of organic forms of N to
plant-available (inorganic) forms
decreases. Consequently, the rate at
which indigenous organic N is miner-
alized and made available for crop
growth decreases as the soil dries.
Mineralization of N from organic
forms to soluble nitrate (NOjj) N is a
two-step process. First, heterogeneous
groups of soil organisms hydrolyze
the proteins and amino acids in the
organic fraction of the soil to produce
ammonium N (NH|). The ammonium
N is then oxidized by select groups of
bacteria (Nitrosomas, Nitrococcus,
Nitrobacter) to nitrite and then to
nitrate forms (.4). Because bacteria are
generally more sensitive to water
deficits than are fungi, the bacteria-
dependent nitrification process (NHJ
to NOj to NOj) may essentially cease
to operate in a dry soil, whereas the
ammonification step (organic N-NH|),
accomplished predominantly by more
drought-tolerant fungi, may still
proceed. For this reason, it is not
unusual to find appreciable accumu-
lations of ammonium N in soils after
prolonged dry periods. This ammo-
nium N is rapidly nitrified when the
soil is again exposed to an environ-
ment conducive to activity of nitrifying
organisms (35).
With alternative wetting and drying
of a surface soil, especially in summer
or following an irrigation, appreciable
denitrification can occur under some
conditions. Aulakh et al. (2) showed
that considerable N could be lost from
a no-till summer fallow field in
Saskatchewan. Warm soil temper-
atures, coupled with a temporary
reduction of water-filled pore space
for a few days after a summer rain or
an irrigation may create conditions in
the soil favorable for denitrification
(.46). Also, wetting of the soil after
incorporation of green manures may
result in appreciable denitrification
(2).
Water availability also has a similar
effect on the rate of mineralization of
organic sources of P, as well as for
other nutrients present in organic
forms. For many soils, especially those
on which manuring, green manure,
reduced tillage, or other such prac-
tices are employed, organic matter
may be the major source for plant-
available P and some micronutrients.
Management practices
As indicated several times in the
preceding pages, nutrient cycling in
agricultural ecosystems can be
regulated to a significant extent by the
soil and crop management practices
employed. It should be pointed out,
however, that there are limits to the
degree of control possible, and that
management techniques suitable for
one set of soil, climate, and cropping
conditions may be entirely unsatis-
factory in another situation.
Several of the more common man-
agement practices used to control the
cycling and availability of nutrients
from various sources include cropping
systems, tillage (crop residue) man-
agement, fertilizer and manuring
practices, timing of cultural practices,
irrigation, and others. Cropping
practices affect not only the quantity
of nutrients removed in the harvested
crop and the quantity of crop residues
returned to the soil, but also com-
position of the crop residues returned,
time of the year they are returned, soil
water regimes, and to some extent soil
temperatures. Thus, cropping systems
can greatly affect the availability of
nutrients from the crop residues
returned, as well as the rate of miner-
alization of indigenous soil N (37).
Quantity of nutrients applied as
fertilizer is often altered by cropping
practices.
The use of legumes in a cropping
system often increases the quantity of
N returned in crop residues and may
also increase total N uptake by crops
during a cropping cycle (3£>. Rotating
a seed legume such as soybean
[Glycine max (L.) Merr.] with a cereal
grain such as corn (Zea mays L.)
usually results in greater cereal yields
and greater N uptake and removal in
the combined seed harvests of the
two crops than would occur with a
monoculture (44). Such a rotation
results in more N being returned in
crop residues, and only half as much
fertilizer N is used as with a corn
monoculture. Varvel and Peterson
(45) showed that such a crop rotation
often reduces residual soil nitrates
after harvest, thereby reducing
potential for nitrate leaching.
If a forage legume is used in a crop
rotation, somewhat similar effects on
N availability and use is often
observed (44). Doran et al. (11)
showed that, compared to a grain
monoculture, a legume-based rotation
20 JOURNAL OF SOIL AND WATER CONSERVATION
-------
AERATION LIMITING
Ammonirication
& Respiration
10
20
80
100
30 40 50 60 70
% WATER-FILLED PORE SPACE
Figure 2. Relationship between several aerobic and anaerobic microbial processes and the
percentage of water-filled pore space (23).
resulted in increased microbial bio-
mass N and potentially mineralizable
N. Similar results have been reported
when a green manure cover crop such
as hairy vetch (Vicia villosa L.) was
used with a grain monoculture (11,
16).
Choice of tillage and crop residue
management practices is also a major
factor regulating availability of nutri-
ents from many sources. The net
effect of crop residue management on
N availability and utilization depends
on many factors. In addition to tillage
practices (degree of residue incorpo-
ration), these factors include N con-
tent of the crop residues (C/N ratio),
time of year (precipitation and tem-
perature regimes), quantity of
residues, and to some extent, soil
properties.
Crop residue management practices
(achieved primarily through choice of
tillage practice) greatly influence the
cycling of nutrients from crop residues
(9). By incorporating residues with
plowing or disking, decomposition
and nutrient cycling are more rapid.
Frequently conditions are ideal for
microbial activity for several days after
incorporation. This results in a flush of
microbial growth and rapid disap-
pearance of crop residues. However,
tillage that leaves the soil surface
without residues results in rapid soil
drying, greatly diminishing microbial
activity. At the other extreme, no-till
systems leave crop residues on the
soil surface where much slower rates
of microbial degradation occur. The
surface mulch also reduces'evapo-
ration losses, thereby enabling this
slower rate of microbial activity to
proceed for a longer period. As a
consequence, by the end of the
season there may be little difference
between no-till and bare tillage
systems in total quantity of N and
other nutrients mineralized (.Iff).
However, those nutrients mineralized
with the no-till system may be better
synchronized with the nutrient needs
of summer-grown crops, so are
utilized more effectively. On the other
hand, with bare tillage nitrate is
formed early in the season and
accumulates in the soil before it is
needed by such crops, thereby
increasing risk of loss by leaching or
denitrification.
These effects of tillage practices on
N availability result because of the
changes in microbial habitat that
different types of tillage create. Doran
(9, 10) has shown that plowing, in
comparison to no-till, usually results
in fewer microorganisms and less
microbial activity in the surface 0 to
75 mm (0-3 in) soil, but that this trend
is sometimes reversed at lower soil
depths (Table 2). Also while popu-
lations of all classes of organisms are
usually increased in the surface soil of
no-till, increases are particularly great
for anaerobic or facultative organisms.
This probably results because the
microenvironment with no-till is
cooler and generally less aerobic than
with plowing (Table 2). Follett and
Peterson (15) showed that concen-
trations of available N and several
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 21
-------
other nutrients were also greater near
die surface of no-tilled than in bare-
tilled soils.
Considerable research in recent
years on the use of cover crops has
shown that method and time of year
of killing and incorporating the green
manure residues also greatly affects
the relative availability of N from
many sources. Frye et al. (16) and
others have shown that leaving
herbicide-killed cover crop residues
on the soil surface followed by no-till
corn production is an acceptable
practice in the southeastern United
States. However in cooler, more
northern regions, Power, Doran, and
Koerner (34) found that N in cover
crop residues left on the soil surface
for no-till failed to mineralize in time
to be utilized by the following corn
crop. On the other hand, N in cover
crop residues incorporated by tillage
did mineralize and was used by the
corn crop.
Of course, fertilizer practices also
affect nutrient availability and use by
crops. Included are choices of fer-
tilizer carriers, times of application,
method and placement, and use of
inhibitors and coatings to regulate
conversions, transformations, dis-
solution, and related factors. There are
a number of books that discuss many
of the factors controlling availability
and utilization of fertilizers (.14, 20,
40). The general philosophy on
fertilizer N usage is to determine or
estimate N availability from all other
sources, estimate N requirement of the
crop, and apply sufficient fertilizer N
to meet any deficit that might exist
between these two numbers. Usually
some form of soil testing is used to
estimate amount of N that will be
available from residual inorganic soil
N plus that mineralized from soil
organic matter (5). In situations where
a forage legume has been plowed
down or where manures have been
added, credits are given for additional
available N originating from these
sources. Gilbertson et al. (17) devel-
oped guidelines for calculating
fertilizer N credits for manure
applications.
Fertilizer management is critical for
controlling nitrate pollution of surface
water and especially groundwater.
Any residual fertilizer nitrate-N
remaining in the soil profile after crop
harvest can potentially be leached
beneath the crop root zone before the
next crop is planted and develops an
extensive rooting system. Thus it is
important to apply no more fertilizer
N than is required by the crop,
especially in situations where leaching
is likely during this non-crop period.
These problems and their conse-
quences have been discussed by
many (33, 38, 39).
Summary
Nutrient management for agri-
cultural production is a highly
complex and poorly understood
process. While this paper has pointed
out several of the paramount factors
affecting availability of uptake of
nutrients from a multitude of sources,
it has not addressed other factors
involved or provided much quan-
titative information on the integration
aspect. While deficiencies in knowl-
edge required for N management are
apparent, we have hardly mentioned
the other nutrients involved in crop
production. Likewise the multitude of
feedbacks and biocontrol mechanisms
involved in these biological systems
have hardly been mentioned, mainly
because we know so little about them.
Thus it is evident that while this paper
attempts to summarize knowledge on
the management aspects of nutrient
cycling, we realize the woeful
inadequacies that still exist.
Research to date has developed
many of the principles involved in the
cycling, managing, and integrating of
nutrient sources for crop production.
As outlined in this paper, we have
learned much about the various
sources of crop-available nutrients,
how they are transformed by soil
microbial activity, and how we can
manage, to some extent, these trans-
formations. This body of knowledge is.
great and it continues to grow. We are
also making progress on the quan-
tification of the cycling processes. A
good example is the recent recog-
nition that percent water-filled pore
space is a good predictor of type and
intensity of soil microbial activity (13,
24). As we continue to accumulate
knowledge of this type, we will better
be able to develop a much more
integrative approach in managing N
and other nutrients in agricultural
enterprises.
Integration of these complex inter-
actions will eventually be achieved
through computer simulation model-
ing. Actually an artificial intelligence
system will be needed because the
matter is so complex with so many
feedbacks and other control mecha-
nisms involved. Add to this the liter-
ally millions of combinations of soils,
crops, weather patterns, management
practices, and time scales involved in
agricultural production, and simu-
lation modeling is obviously the only
realistic approach to acquiring a com-
prehensive understanding and pre-
dictive capability. Fortunately some
progress toward this goal has been
made in the last decade (8), and we
can be optimistic that we will advance
rapidly toward this goal in the future.
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Am. J. (In press.) Q
Understanding the
nutrient
management
process
Douglas B. Beegle and Les E. Lanyon
Traditionally, nutrient manage-
ment has attempted to optimize
the economic return from
nutrients used to produce a crop. The
main emphasis was on the expected
crop response to added nutrients. In
practice however, manure has not
always been applied to optimize plant
nutrient use. Under contemporary
circumstances manure may be applied
so that nutrients are in excess of plant
Douglas B. Beegle is an associate professor of
agronomy and Les E. Lanyon is an associate
professor of soil fertility in the Department of
Agronomy, The Pennsylvania State University,
University Park 16802.
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 23
-------
needs, so that the nutrients are not
available for crop growth at the
optimum time, or so that they are
released into the air or water. These
nutrient losses have prompted
concerns about the impact of existing
nutrient management on environ-
mental quality. Leaching of excess
nitrogen through the soil can increase
groundwater nitrate to levels that can
adversely affect the health of young
children and young livestock. Surface
movement of nitrogen and phos-
phorus in runoff increases concen-
trations of these nutrients in surface
waters, potentially leading to eutro-
phication and changes in aquatic
wildlife. The problems that we have
with nutrient pollution are not solely
the result of mismanagement by
farmers but have been influenced by
the evolution of our agricultural
systems with no accounting for the
costs of changes in environmental
quality. Managing nutrients to address
environmental concerns will mean
more than just eliminating poor
management. It will require changes
in our agricultural systems. Many
innovative management approaches
and supportive social policies will be
necessary to reconcile a highly
productive, intensive agriculture with
environmental protection.
Farm nutrient flows
Plant nutrient management deci-
sions deal primarily with the flow of
plant nutrients to, from, and within
farms. Characterizing various patterns
of farm organization can be helpful in
understanding nutrient management
issues and in addressing practically all
activities associated with the nutrient
management process for crop produc-
tion and environmental protection.
This is especially true in evaluating
the nutrient management situation on
individual farms. A major goal of
nutrient management for crop produc-
tion and environmental protection is
the balance between agronomic crop
requirement and the supply of nutri-
ent available on the farm. Based on
the evaluation of material movement,
approaches to nutrient management
can be developed that are sensitive to
specific farm situations and the
existing strategies of farm man-
agement.
Three representative examples of
farm nutrient flow are illustrated in
Figure 1. The managed pathways of
nutrient flow on a modern cash-crop
farm are shown in Figure la. Nutrients
come on to this farm in fertilizers and
other materials that are applied
directly to the fields. Crops harvested
from the fields take a fraction of the
applied nutrients with them. When the
crops are sold the nutrients the crops
contain leave the farm. There is a
direct connection between the flow of
nutrient and the agronomic or
economic performance of a farm with
this pattern of organization. Trad-
itional economic and agronomic
incentives can then be effective in
guiding nutrient use on these farms
for crop production (and farm
production) and for environmental
protection. Of course, the managed
nutrient paths illustrated are not the
only ones nutrients can take.
Significant losses from fields can occur
if nutrients are over-applied compared
to the crop utilization or if nutrients
are otherwise allowed to be lost from
the fields. The cost of practices that
increase efficiency of utilization
and/or reduce nutrient losses on a
cash-crop farm can be at least partially
offset by decreased cost in purchased
fertilizer to offset the nutrient losses.
Crop and livestock farms tradi-
tionally have been viewed as pro-
ducing animals or animal product
outputs that result from the almost
exclusive use of on-farm resources. A
large proportion of the plant nutrient
in the crops produced as feed for the
animals are returned to the farm fields
in manure from the animals. Never-
theless, fewer nutrients will be
returned to the fields in the manure
than were harvested in the crop, so
the efficient return of nutrients to the
fields is critical to maintain crop
production (and farm production) on
such a farm. With uniform manure
distribution, nutrients are unlikely to
be lost to the environment under
these nutrient-poor conditions.
Changes in management are therefore
unlikely to be necessary to protect the
environment on these farms.
The ready availability of fertilizers
since the 1950s has made it possible
to offset the losses of plant nutrients
in animal production and manure
handling from a traditional "self-
sufficient" farm. If the nutrients
previously available on the farm were
inadequate to meet potential crop
productivity, fertilizer and other plant
nutrient inputs to the fields not only
offset the losses of nutrients from the
farm, they made it possible to build
soil fertility to achieve greater
potential crop production. This is the
familiar nutrient response to fertil-
ization that was so important to the
rapid, widespread adoption of fertil-
izer by farmers.
Also, off-farm feeds can either be
produced on another nearby farm and
transported by the farmer to the farm
where the animals are housed or they
can be purchased commercially
through a feed company and deliv-
ered to the farm. A key factor on
modern crop and livestock farms is
that the manure produced by the
animals no longer must be spread on
the fields where the crops were
produced to maintain crop or animal
production. The plant nutrients in the
feed inputs can offset the losses of
nutrients from the farm in the animal
products or the manure handling
losses as fertilizer did on the tradi-
tional farm. Accounting for all sources
of plant nutrients being applied to
fields becomes an important manage-
ment activity to protect the environ-
ment from negative impacts associated
with the overapplication of nutrients
to crop fields. The on-farm resources
on a modern crop and livestock farm
with ruminant animals can be sup-
plemented with fertilizer inputs
directly to the fields and with off-farm
feeds or other animal input. The
resulting pattern of organization
(Figure lb) is significantly different
from a traditional crop and livestock
farm or a modern cash-crop farm.
While conditions have changed in
agriculture so that intensified animal
production supported by off-farm feed
is possible, the changes are not just in
the amounts of nutrients flowing to,
from, and within the farms. The
concentration of animals in larger
facilities results in more manure in
24 JOURNAL OF SOIL AND WATER CONSERVATION
-------
limited areas. The distance and
amount of manure to be hauled can
increase substantially if the nutrients
are to be spread uniformly over
potentially suitable crop areas. The
farmer will generally be responsible
for the costs of this additional manure
hauling.
Since farms with this pattern of
organization sell primarily animal
products, farm performance can be
different from the magnitude or
efficiency of crop performance. Farm
performance depends on the animal
husbandry skills of the farmer and the
utilization of off-farm production
inputs, not just success in crop
production. On a farm organized this
way the decisions about plant nutrient
use in the fields are not as sensitive to
the economic or agronomic criteria of
crop production as on the modern
cash-crop farm.
Trends in animal housing and the
success of crop production on cash-
crop farms in specialized geographic
regions have made it possible to
concentrate large numbers of non-
ruminant animals, such as poultry or
hogs, on small land areas. Most, if not
all, of the feed necessary for these
animals can be economically trans-
ported to the farm where the animals
are housed. Even though these farms
may produce crops for off-farm sale,
the land areas involved can be quite
limited since the focus of the man-
agement activity is on animal pro-
duction (Figure Ic). The cash-crop
farm and the intensive modern live-
stock farm are connected by the flow
of feed. However, nutrients in this
flow often do not cycle back from the
livestock locations to the areas of crop
production. Breakdown of the nutrient
cycle is a significant feature of the
nutrient management situations
encountered on these farms.
The difference between nutrient
management on the cash-crop farm
and the modern crop and livestock
farm •with non-ruminant animals is
that the application of nutrients to the
fields on the crop and livestock farm
is not closely related to the major
production activity of the farm: selling
animals or animal products. The field-
based economic and agronomic
incentives that can be effective for
managing nutrients on a cash-crop
farm, and that will also minimize
negative environmental impacts, are
not as significant on the intensive
livestock production-oriented farm.
Further, field-based agronomic prac-
tices may be of limited effectiveness in
utilizing the total quantity of nutrients
on the farm because of the small land
area that is necessary for animal
housing. It is very likely that plant
nutrient management to protect envi-
ronmental quality cannot be accom-
plished solely on the farm where the
animals are housed. Successful man-
agement of nutrients to protect the
environment will depend on support
from off-farm people and organ-
izations. Neighbors with land for
manure application could cooperate
by providing land for manure distri-
bution. Off-farm organizations may
deal with manure hauling to locations
where the manure can be used direct-
ly or transformed into another product
such as compost.
The nutrient management process
Since nutrients are transferred to,
from, and within farms with the
movement of almost all common farm
materials, such as crops, animals, and
manure, nutrient management gener-
ally involves decision-making about a
wide range of farm operations. These
management decisions are made as
frequently as several times a day to as
seldom as once every five years or
.more. Decisions may deal with day-to-
day details, such as spreading manure
on a specific field on a particular day,
or with the long-range future of an
entire farm, such as the decision to
build a manure storage unit. Nutrient
management is an ongoing repetitive
farm process with several key
activities (Figure 2).
Since nutrient management is
ongoing, an initial assessment of the
farm and the potential environmental
impacts of the existing farm oper-
ations is an effective starting place in
many situations. Nutrient management
need not start with a plan. In the
assessment the approximate nutrient
balance of individual fields, groups of
fields that are treated similarly, or
a. Cash Crop Farm
c. Intensive Poultry Farm
Figure 1. Nutrient flows on
representative farm types.
even the whole farm can be deter-
mined depending on the purpose of
the assessment. The outcome of the
assessment can be used as the basis
for selecting options for farm nutrient
management to protect the environ-
ment while producing crops and
animals. The extent of nutrient man-
agement assistance required to change
farm operations will also be influ-
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 25
-------
enced by the type and extent of the
options to be incorporated.
Nutrient management options can
be specific practices, such as incor-
porating field-applied manure soon
after application, identifying other
landowners who may be interested in
having manure spread on their fields,
or more far-reaching possibilities, such
as postponing a planned expansion of
the livestock housing facilities on the
farm. The assessment and the options
selected can be the basis for many
decisions that will be made in the
development of a farm nutrient man-
agement plan.
Implementation of a nutrient man-
agement plan involves both the actual
activities called for in the plan plus
the appropriate recording of those
activities so that the effectiveness of
plan implementation can be assessed.
The success of the management plan
can be evaluated in a repeat of the
original assessment.
Changes in management will gener-
ally involve a transition period from
the existing to the "improved" man-
agement. The change in management
could involve the adoption of new
practices or require new financial
arrangements to deal with the costs of
implementation. The transition period
can be of different lengths on different
farms depending on the current status
of the farm and the extent of the
changes required. For those farms that
successfully negotiate the transition,
following nutrient management guide-
lines for crop production and environ-
mental protection may simply become
a. part of normal farm operations in
the future unless the farm operations
(or environmental expectations)
change significantly.
The nutrient management process
can be applied at the strategic,
tactical, and operational levels of
management, although tactical levels
may be the most common point of
off-farm technical input. At the strate-
gic level management decisions are
made by the top management of the
farm regarding long term goals and
strategies for the operation. Examples
of strategic decisions include whether
to expand the livestock operations or
not, or whether to acquire more land
or reduce livestock numbers to
achieve nutrient balance on the farm.
A very broad cross-section of infor-
mation is used at this level of decision
making. Most of the input for strategic
decision making comes from outside
the farm. Information on markets for
expanded production, availability .of
labor, or regulations regarding nutri-
ent management would be examples
of the type of information used in
making strategic decisions. Thus,
nutrient management goals are sub-
stantially shaped by the conditions in
the surroundings of the farm, not by
the actual resources or activities on-
farm. If new expectations for farm
performance are to be implemented,
exploring the natural and social
conditions within which farms must
function can be more fruitful than the
development of detailed practices.
Practices will follow from water
quality protection strategies, but
practices will not mandate strategies.
At best, prescribed practices will only
be adopted by farmers for whom the
practices are consistent with their
strategies or those who are compelled
to adopt them. With the difficulty in
enforcing water quality protection
standards for nonpoint source pol-
lution, emphasizing and rewarding
transformations in farm strategies may
be the most effective approach to
change.
Nevertheless, most nutrient manage-
ment promotion for water quality
protection emphasizes the tactical
level of management. The time-frame
for tactical decision making is usually
from a few months to a few years.
This management deals primarily, but
not exclusively, with site-specific
information about the farm. It is
intended to implement the broad
strategies outlined in strategic man-
agement. The farm nutrient manage-
ment plan, in which specific nutrient
allocation decisions are made for the
farm, is the most common example of
this level of management. When the
tactical plan is the primary mechanism
for implementing nutrient manage-
ment for environmental protection,
the possibility and consequences of
accommodating the potentially dif-
ferent strategic goals of the farmer and
society in the plan must be recog-
nized. For instance, a farmer may not
voluntarily adopt a complete nutrient
management plan if the environmental
protection features require contra-
dictions with the goals of production,
technology, or lifestyle that are
embedded in his/her strategies. Or, if
a plan is agreed upon that is on the
surface consistent with the environ-
mental protection goals and the
farmer's goals, discretionary decisions
will tend to favor any competing
farmer goals so that implementation
may be inadequate for the envi-
ronmental goals.
The operational level is the most
detailed level of management. At this
level the tactical plan is actually
implemented and decisions are made
about specific tasks to be performed
by the farm labor force. For example,
the tactical plan may call for certain
fields to receive manure at a given
rate this year. The operational man-
ager will decide on any given day
who will spread manure using what
equipment and on which field. This
type of decision making is generally
short term and requires in addition to
a tactical plan, timely, very site-
specific information such as weather
forecasts, soil conditions, and avail-
ability of labor and equipment. Record
keeping is also an important role of
the operational manager. Good
records of what is actually imple-
mented on the farm are crucial for
sustaining the management process.
These records provide the basis for
subsequent assessment of the tactical
plan implementation. Discrepancies
between the plan and the actual
performance can be evaluated and
different management options may be
selected for inclusion in the next
iteration of tactical plan development.
Information from the tactical assess-
ment based on these records is useful
to the strategic manager for evaluating
progress toward achieving the strate-
gic environmental and production
goals of the farm.
A farm production strategy assess-
ment especially for crop and livestock
farms in a production setting like
Pennsylvania can be illustrated using
either animal density on the farm or
off-farm feed used on the farm for the
animals and nitrogen fertilizer appli-
cations to corn. An assessment matrix
26 JOURNAL OF SOIL AND WATER CONSERVATION
-------
and management option relationships
based on these criteria can be used by
farmers or technical support prac-
titioners to assist in the nutrient
management process for environ-
mental protection and farm produc-
tion (Table 1). From this simple
assessment the strategic decision
maker can evaluate factors such as the
pollution potential of the operation,
whether there is likely to be adequate
land available for environmentally
sound manure nutrient utilization, the
type and extent of management
assistance required for environmental
protection, and possible economic
implications of nutrient management
for environmental protection for the
farm.
Different tactical nutrient manage-
ment plans will be developed depend-
ing on the preceding assessment of
the farm. Low intensity farms are
those where there is not enough
manure generated on the farm to
supply the total crop nutrient needs.
Tactical plans to ensure adequate crop
production and environmental protec-
tion for farms in this group would
incorporate practices to maximize
nutrient use efficiency on the farm.
The environmental impact of any
practices selected is likely to be
nominal except where there is cur-
rently gross mismanagement. Conse-
quently, changes in operations on
these farms would have a small
beneficial effect on the environment.
While a formal nutrient management
plan for environmental protection may
not be required for this group, the
possibility exists for positive economic
benefits to the farmer based on more
efficient nutrient utili2ation from
manure that could be offset by the
reduced costs of previously-utilized
fertilizer. Nutrient management plans
on these farms will use soil tests and
manure analysis to assure distribution
and timing of manure applications to
maximize nutrient availability from the
manure and minimize the purchase of
commercial fertilizer. Examples of
practices that would be appropriate
on this group of farms include spring
application of manure, immediate
incorporation of manure, use of cover
crops to scavenge nutrients, no
manure spreading on legumes, and
Figure 2. A schematic of the nutrient management process
illustrating the four activities.
manure storage.
Medium intensity farms are those
that generally generate enough
manure to meet the total crop nutrient
needs. Tactical plans to ensure
adequate farm production and envi-
ronmental protection would incor-
porate practices to maximize environ-
mentally-safe nutrient utilization on
the farms in this group. If there is
enough or more than enough nutri-
ents on the farm to meet the crop
requirements, efficiency will likely be
a secondary concern. The major
concern will be safely using all of the
manure produced. Intense manage-
ment will be needed to provide the
most favorable economic situation
while protecting the environment.
There is good potential for envi-
ronmental benefits from improved
management on these farms. Generally
the economic impact of nutrient
management for environmental pro-
tection on these farms will be small.
Changes in the overall farm manage-
ment, such as altering the cropping
system, may be necessary strategic
decisions on this group of farms. At
the tactical level a detailed manure
management plan will probably be
necessary on these farms and will be
based on nutrient balance rather than
crop response. Most farmers in this
group will probably want to take
advantage of technical assistance from
public agencies and/or private consul-
tants in developing and implementing
a nutrient management plan. The plan
will use soil tests and manure analysis
in conjunction with appropriate man-
agement practices to match as closely
as possible nutrients available in
manure with crop needs over the
entire rotation. Practices such as
spreading manure on legumes and not
incorporating manure are examples of
management options that may be
appropriate for this group.
On high intensity farms, animal
manure production often significantly
exceeds total crop nutrient needs.
Tactical plans to ensure adequate farm
production and environmental protec-
tion for this group of farms will
involve determining the maximum
amount of manure that can be safely
utilized on the farm. A substantial
amount of detailed field by field
nutrient management planning will
not usually be necessary. In most
cases the available land and the high
residual nutrient levels in the soil may
severely restrict on-farm use of
manure. This group of farms has the
highest potential for negative impacts
on the environment. Alternative off-
farm uses for the excess manure will
need to be explored. In most
instances this will mean locating a
market for the manure and arranging
the logistics of transportation and
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 27
-------
Table 1. Nutrient management assessment and management
options based on the potential for available soil nitrogen balance.
Criteria Category 1
Farm Characteristics I Assessment1)
Animal density Low
(Animal units/acre routinely manured) (<1 .25/A)
Feed source On-farm
(% Off-farm)* (<50%)
Non-manure nitrogen applied
Nitrogen fertilizer use Low to moderate
(Ibs/A on corn) (<50to150)
Category 2
High
(1.25-2.25/A)
Combination
(50-80%)
Low to high
(<50to>150)
Category 3
Very high
(>2.25/A)
Off-farm
Low to high
(<50to>150)
Management Considerations for Environmental Protection
Adequate land available for manure
spreading
Manure balance
Nonpoint source pollution potential
Assistance for:
Field by field
Nutrient management planning
Assistance for:
Nutrient management
implementation
Source of nutrient management
options
Manure management strategy
Manure management system
Economics of manure management
Yes
Deficit
Low
Usually
Balanced
Low to high
Low to moderate Moderate to high
Low to moderate Moderate to high
On-farm
On-farm
efficiency
Yes
On-farm
On-farm
high utilization
Yes
+ or-
No
Excess
Very high
Low
High
Off-farm
Off-farm distribution
of excess
Yes
"Feed purchased or grown on land not routinely manured.
appropriate use. Appropriate nutrient
management plans should be devel-
oped for the farms where the manure
is ultimately utilized. In many cases,
unless a favorable marketing arrange-
ment can developed, implementing
improved nutrient management on
this group of farms will have a
negative economic impact on the
farm. Assistance from public agencies
and private consultants, manure
brokers, and manure haulers will be
critical to improve nutrient manage-
ment for environment protection.
Unfortunately, this is an area of
nutrient management that is not
currently well developed.
Farm nutrient management
planning
Each farmer is currently involved in
nutrient management. Each farmer
currently has a nutrient management
plan. Many of these informal or formal
plans focus on providing nutrients for
crop production. Some of these
existing plans will also achieve
environmental protection goals.
Where it has been determined that a
farm has a high potential for
environmental impact from on-farm
nutrient management or that imple-
mentation of an existing plan does not
adequately protect the environment,
formalizing the plan to manage all
nutrient sources for crop production
and environmental protection can be
an effective approach to reconcile the
multiple interests of society in nutrient
management. Implementation of
nutrient management plans for crop
production and for protecting environ-
mental quality will be most successful
if the plan emphasizes modifications
of the farmer's current management to
meet evolving environmental expec-
tations rather than coming up with a
completely new plan that may bear
little relationship to the farmer's
existing management. This is why
having a good assessment of the
current strategy and/or ongoing
nutrient management activities is so
essential to achieving new nutrient
management goals.
Nutrient management includes the
use of manure and other nutrient
sources to meet plant nutrient needs.
It takes into account nutrient needs
throughout the crop rotation, realistic
expected crop yields, site limitations,
existing soil nutrient levels, and
timing, placement, and amounts of
additional nutrients applied to the
fields. Information required to
develop these plans will vary among
farms, but will likely include crop
acreage, crop field histories, measured
harvests or crop yield checks, amount
of manure generated based on the
livestock or poultry number and size
and handling facilities, amount and
kind of manure applied per acre,
amount of purchased fertilizer applied
per acre, soil test results and recom-
mendations, manure analysis, and
manure spreader calibration.
Once the net nutrient needs have
been determined for individual fields
or crop groups, the areas to be spread
should be prioritized for manure
applications. The highest priority
fields to receive manure should be
those determined to have the lowest
residual nutrient concentrations, those
in which the crop to be grown has the
greatest nutrient needs, and those in
which detrimental environmental
effects will be minimized (no sink-
holes, not a floodplain, gentle slopes,
soils with low leaching potential, etc.).
All remaining fields are ranked in
descending order. Table 2 summarizes
the factors that must be considered
during the field prioritization process.
After fields have been prioritized,
available manure is allocated to fields
based on their ranking. The manure
application priority does not deter-
mine the actual sequence of manure
spreading on the fields. This oper-
ational decision is based on such
factors as cropping plans, soil condi-
tions, weather, time available, etc. at
the time the manure is being spread
28 JOURNAL OF SOIL AND WATER CONSERVATION
-------
within the context of the tactical plan.
The prioritization of fields simply
indicates that when all of the manure
has been spread, the high priority
fields will have received manure
rather than the low priority fields.
The nutrient nitrogen (available or
total) or phosphorus, used as a prior-
itizing criterion for manure appli-
cation, will significantly affect manure
allocation. Manure application rates to
nonlegume crops based on available
nitrogen are likely to be greater for a
particular year than if the rates are
based on phosphorus, especially if the
crop is harvested as grain. If phos-
phorus requirements for a crop
sequence including crops that will not
receive manure are used as the basis
of the manure application, higher
rates may be possible than if based on
available nitrogen. If the nutrient
content of the manure exceeds the
annual crop requirements of available
nitrogen or phosphorus for the
planned crop sequence, options must
be developed to deal with the excess
manure. For instance, the nutrient
management plan may be altered to
include more intensive crop produc-
tion through doublecropping, different
crop selections or harvesting methods
(whole plant vs. grain), or improved
crop management leading to higher
crop yields. Or, options to export
manure from the farm can be identi-
fied. Since nutrient management is an
integral part of the total farm oper-
ation, there may also be options
available in the management of the
farm animals. These would include
changes in the protein or phosphorus
concentration of the animal rations, in
the components of the animal ration
to enhance the efficiency of utiliz-
ation, or in facilities management to
decrease the amount of nutrients in
the manure.
It is not likely that it will be
practical for a farmer to apply the
exact manure rates calculated to
balance the crop nutrient require-
ments for each field. However,
calculating the balanced rates will
provide a guide for the maximum
amount of manure that should be
applied. For practical operations, the
calculated rates can be used to group
fields and to determine the appro-
Table 2. Field prioritization of manure applications.
Categorized by priority-nutrient:
Crop N needs
N requirement
and residual N
P soil test level
and K soil test level
High priority
for manure
N-requiring crops
Low priority
for manure
Non-N requiring crops
Highest N requirement Lowest N requirement
Lowest residual N Highest residual N
Lowest P level
Lowest K level
Highest P level
Highest K level
Categorized by environmental considerations:
Proximity to Water bodies
Sinkholes
Flood plains
Soil limitations Leaching potential (soil hydrologic group)
Erodibility and runoff (degree of slope)
Land cover Presence of a growing crop, crop residue or cover
Practical limitations Distance to manure source
Neighbor concerns
Land tenure
priate rate or rates to apply. Finally,
the nutrients to be applied in manure,
based on the selected application
rates, must be compared to the nutri-
ents required by the crops. Deficien-
cies will need to be corrected with
nutrients from other sources.
Performance vs. BMPs
The motivations for farmers to
change their nutrient management
practices are many. The reasons may
be economic, social, or personal
preference, to name a few. As society
demands more accountability from
farmers, there will likely also be
regulatory motivations. There are two
approaches to environmental regula-
tion. One approach is to specify what
should be done on all farms as a
recipe for nutrient management. Lists
of required standard practices or best
management practices (BMPs) such as
specifying times, rates, and methods
of manure application for all farmers
is an example of this approach.
Although this approach is relatively
simple to administer, it does not
accommodate, specific conditions of
particular farming operations or the
nature, interests, abilities, or local
conditions of individual farmers.
Neither does this approach address
needed changes in the current
structure of agriculture. Closely speci-
fying particular farming practices can
also limit innovation by farmers and
farm advisors in finding ways to deal
with new requirements for crop pro-
duction and environmental protec-
tion. Specific practices are character-
istic of the operational or tactical level
of management. Social expectations of
farming for both farm production and
environmental protection may be best
represented as strategic goals, not
operational specifications. Thus, rather
than attempting to achieve complex
goals by specifying detailed manage-
ment (or behavior), alternatives that
are consistent with the site-specific
character of farming should be
considered.
Such an approach to farm nutrient
management would emphasize perfor-
mance criteria for farmers to meet as
part of their farm management and
generate an incentive structure to
recognize that performance. Perfor-
mance criteria are outcomes to be
achieved through nutrient manage-
ment such as nutrient balance for the
farm fields. These criteria are not lists
of specific activities or BMPs that all
farms must follow, but rather they are
targets that are established and
farmers and their advisors are given
the freedom to develop and imple-
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 29
-------
ment a plan integrating any practices
or BMPs that are appropriate. There
would be no official list of standard
BMPs but rather a wide range of
activities conducted on individual
farms in order to meet the expec-
tations. Carefully established outcomes
can promote solutions to meet the
environmental challenges faced by
farmers based on local conditions
while stimulating innovation at the
same time. Success of this approach is
predicated on the ability to deliver
appropriate technical support. Clearly
defined, measurable outcomes are
essential to this approach to nutrient
management. Incentives for meeting
the performance criteria would rein-
force the approach to farming that is
consistent with the strategic goals of
society. If the incentives that are
currently in place are not revised,
promoting nutrient management to
protect the environment is not likely
to be accepted by those producers
who need to make the greatest
changes to meet environmental
requirements. If the current incentives
were adequate for environmental
protection it is unlikely that we would
have the environmental problems in
the first place. Teaming performance
criteria with incentives could entice
those who might not otherwise
participate to do so. Q
Minimizing
surface water
eutrophication
from agriculture
by phosphorous
management
T.C. Daniel, A.N. Sharpley, D.R.
Edwards, R. Wedepobl, andJ.L.
Lemunyon
~f~~\ unoff from agricultural land is
1-^ one of the major sources of
JL Vnonpoint source (NFS) pollu-
tion. In recent reports to Congress,
USEPA identified agricultural NFS
pollution as the major source of
stream and lake contamination pre-
venting attainment of the water quality
goals identified in the Clean Water Act
(5-€>. Nutrients from agricultural
nonpoint sources have been identified
as the main cause of cultural eutro-
phication .in freshwater inland lakes of
the U.S. and an important source of
nutrients to estuaries, affecting 57 and
18 percent of impaired lakes and
estuaries, respectively (57). With
increasing amounts of phosphorus (P)
control being required of point source
discharges, agricultural NPSs of P are
an increasing national concern. In
most cases, noxious aquatic weed
growth results from the addition of
excessive amounts of nitrogen (N) and
P (24). Concentrations of 0.3 and 0.01
mg L"l for inorganic N and P,
respectively, have been identified as
critical levels expected to promote
noxious aquatic plant growth in lake
T.C. Daniel is a professor in the Department
of Agronomy and D.R. Edwards is an
associate professor in the Department of
Biological and Agricultural Engineering,
University of Arkansas, Fayetteville 72701.
A.N Sharpley is a soil scientist with USDA-
Agricultural Research Service, Durant,
Oklahoma 74702. R. Wedepobl is a lake
management specialist with Wisconsin
Department Natural Resources, Madison
53707. J.L. Lemunyon is an agronomist in the
USDA-Soil Conservation Service, Fort Worth,
Texas 76115.
water (35, 59). Phosphorus is the
single most important nutrient to
manage for controlling accelerated
eutrophication in freshwater lakes
(55). Although N may occasionally be
limiting to algae during certain
periods of the year, for example,
when the total N to total P ratio is less
than 15:1, P is still most often the
nutrient of concern. Controlling P
inputs to lakes is much easier than
controlling N sources, as certain blue-
green algae are capable of fixing
atmospheric N. It is important to note
that even when algal growth is limited
by N, P load reduction can result in
improved water quality if the load
reduction is sufficiently large to drive
the lake or reservoir to P limitation. In
estuaries, both P and N are often
limiting nutrients, with P being the
limiting nutrient in the upper, fresh-
water dominated portions and N in
the more marine dominated regions
(.8).
The relative importance of P and N
to the productivity of free-flowing
waters is less well understood.
Bothwell (4) showed that although
there was a relationship between peak
areal biornass.of periphyton com-
munities in streams and P concen-
trations, P was not limiting when
dissolved P (DP) concentrations
exceeded 0.03 to 0.05 mg L"1-levels
exceeded in all but the most oligo-
trophic streams.
This paper will provide background
information on the forms and sources
of P, the importance of minimizing P
in surface waters, procedures for
identifying P-sensitive water bodies,
and management approaches that
limit P loss.
Phosphorus chemistry of soil and
runoff
Phosphorus occurs naturally in soil
at levels between 300 and 1,200 mg
kg"-'-, although amounts can vary from
100 to 2,500 mg kg"1. The wide
variation in soil P content is a function
of parent material, texture, and
management factors such as the rate
and type of P applied and soil culti-
vation. These factors also influence
the amount of P in inorganic and.
30 JOURNAL OF SOIL AND WATER CONSERVATION
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organic forms. In most soils, 50 to 90
percent of the P is inorganic, con-
sisting of iron and aluminum phos-
phates in acidic soils and calcium
phosphates in alkaline soils. Most
inorganic P forms are so insoluble that
only a small fraction (< 10 percent) is
available at any one time for plant
uptake.
The major portion of soil organic P
is in stable fulvic and humic com-
pounds. More labile organic P forms,
such as glycerophosphates, phospho-
sugars, phospholipids, and nucleic
acids can be mineralized by microbial
activity. Although less than 5 percent
of soil organic P is usually mineralized
annually, in some cases this supplies
sufficient P for plant growth.
Plants absorb inorganic P from soil
solution, the level of which is deter-
mined by adsorption and desorption
of labile iron, aluminum, and calcium
phosphates; dissolution of more sol-
uble mineral forms of recently applied
P; and mineralization of organic P..
Adsorption of P by soil occurs rapidly
and because of the high binding
energy between soil and P, adsorption
tends to dominate desorption. Thus, a
general decrease in plant-available P
occurs after P Is applied. As the labile
form of P is depleted by plant uptake,
it is slowly replenished by inorganic P
desorption, organic P mineralization,
crop residue decay, and applied fer-
tilizer or manure.
The loss of soil P in runoff occurs in
dissolved and sediment-bound or
particulate forms (Figure 1). The
standard procedure to separate dis-
solved and particulate forms in runoff
is by filtration through a 0.45/J.m pore
diameter membrane filter. Dissolved P
is comprised mostly of orthophos-
phate which is immediately available
for algal uptake (33, 60). However,
variable amounts of organic and
colloidal P less than 0.45/J-m may pass
through the filter and-be hydrolyzed
or dissolved by the strong acidic
medium of the molybdate-blue proce-
dures used for P analysis. Amounts of
dissolved organic P are. normally small
with 90 to 95 percent DP actually
bioavailable (i.e., algal available) (.22,
50).
Sediment P includes P sorbed by
soil particles and organic matter
eroded during runoff and constitutes
the major portion of P transported
from conventionally tilled land (75 to
95 percent). Runoff from grass or
forest- land carries little sediment and
is dominated by dissolved P. Sediment
P can provide a variable but long-term
source of P to aquatic biota. Sharpley
et al. (46) found that from 10 to 90
percent of P associated with sediment
runoff was bioavailable and varied as
a function of watershed management.
The first step in the movement of
dissolved P in runoff is the desorp-
tion, dissolution, and extraction of P
from soil crop residues, fertilizer, and
manure (Figure 1). These processes
occur as rainfall interacts with a thin
layer of surface soil (< 2 cm) before
leaving a field as runoff (.40). Once in
runoff water, dissolved P can be
resorbed by runoff sediment. In runoff
from no-till or pasture, the sediment
load is generally so low that little
dissolved P is adsorbed by suspended
-^sediment. Under.these conditions,
losses of dissolved P can exceed
losses in runoff from conventional
tilled fields with higher erosion.
Rainfall that does not run off per-
colates through the soil profile where
sorption by P-deficient subsoils results
in low dissolved P concentrations in
subsurface flow.
As P is sorbed by soil material,
erosion determines, sediment P move-
ment (Figure 1). Sources of. sediment
P in streams include eroding surface
.soil, plant material, stream banks, and
channel beds. Where there is perma-
nent vegetative .cover, such as forest
or pasture, the primary source of
sediment is from stream bank erosion.
This sediment will have characteristics
similar to the subsoil material of the
area which is often of low P content.
During detachment and movement of
sediment in runoff, the finer-sized
fractions of source material are
preferentially eroded. Thus, the P
content and reactivity of eroded
particulate material is usually greater
than source soil (.4T).
As P moves to a lake by stream
flow, there is generally a progressive
decrease in P load by water dilution
and sediment deposition. However, P
often becomes more algal available as
it moves from the edge of a field to a
lake as a result of these chemical and
physical processes.
P sources and management
considerations
Phosphorus is supplied to crops
through application of both commer-
cial fertilizer and animal manure. For
both P sources, runoff losses are
generally greatest in the short-term
(one to three runoff events) following
application with the amount of fer-
tilizer P lost in the runoff generally
less that 5 percent of that applied.
Commercial fertilizer. Loss of P in
the runoff from cropland is influenced
by the rate, time, formulation, and
method of fertilizer application. The
severity of the runoff-producing event
and amount of surface cover also
influence P loss. A clear relationship
exists between P application rate and
method and amount of P transported
in the runoff. In a field and laboratory
study, Romkens and Nelson (37)
demonstrated a linear relationship
between the amount of P added as
fertilizer and runoff P loss. Baker and
Laflen (2), using simulated rainfall,
confirmed this work and further
.demonstrated the effect of fertilizer
placement on runoff P transport.
Concentrations of DP in the runoff
from areas receiving broadcast appli-
cations of P fertilizer averaged 100
times higher than the runoff from
areas receiving similar rates of P that
were point-injected below the soil
surface. Time of P application also
influences the amount ultimately
transported in the runoff. Generally,
.one or two runoff events account for
the majority of the P lost in the runoff
(62). If these runoff events coincide
with recent application of P, regard-
less of the form of P, then the amount
of P transported in the runoff is
expected to be higher than if P
applications were made during times
of low runoff probability (15). For
example, Burwell et al. (6) in a
watershed study demonstrated that P
loss in Missouri was greatest during
the planting season; a time consistent
with the most intense rains, P appli-
cation, and minimum crop cover.
There is no intrinsic reason for
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 31
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DeSorption
Dissolution
Extraction
Mineralization
- «•, of soil P--.
Infiltration
and
percolation
Total runoff
(dissolved and sediment P)
Zone of interaction
_ <2cm
Figure 1. Processes involved in the transport of dissolved and sediment P in runoff.
long-term management of commercial
fertilizers to lead to problems assoc-
iated with accumulation of soil P.
Commercial fertilizers allow producers
the flexibility to tailor the fertilizer
treatment to the specific needs of their
crop, soil, and weather conditions.
Application of P at rates consistent
with crop needs will prevent over-
application of P and subsequent
accumulation and is in the economic
interest of the producer. Poorly
managed application of commercial
fertilizers, however, has the potential
for causing accumulation of soil P and
thus for promoting increased P loss.
Pierzynski et al. (34) examined several
midwestern soils and attributed soil
test P (STP) levels of 218 and 246 mg
kg"1 in a Plainfield sand (Wisconsin)
and Blount silt loam (Illinois),
respectively, to addition of com-
mercial fertilizer.
Animal manure. While row-crop
production in the Corn Belt can result
in contamination of surface waters
with sediments, nutrients, and pest-
icides (.20), Duda and Finan (.11}
showed that the greatest potential for
accelerated eutrophication occurs in
geographic regions of intense animal
production. Regions that coincide with
intense animal manure production are
especially susceptible to eutrophi-
cation for several reasons. Efficiency
of operation requires confinement of
large numbers of animal units and
ultimately the production of large
volumes of manure. The nutrient
value of fresh animal manures aver-
ages approximately 4.3 percent N, 1.4
percent P, and 2.2 percent K (.1). The
nutrient content of slurry or liquid
manures will be diluted considerably.
Losses of N can occur during storage
and land application, further diminish-
ing the nutrient content of manures.
Both long- and short-term P losses
are of concern in the context of
manure application. The greatest
potential for short-term (the first one
to three storms following application)
P loss occurs when the manures are
surface-applied, in which case P loss
is directly proportional to P applica-
tion rate (12, 13, 14)- Runoff P con-
centrations during storms that occur
soon after application can be quite
high; Edwards and Daniel (12, 13, 14)
measured total P (TP) concentrations
of 22, 29, and 12 mg L'1 in the first
storm following application of poultry
litter, poultry manure, and swine
manure, respectively. Large propor-
tions of TP in runoff from areas
receiving animal manures can be in
the dissolved form and available for
algal uptake (12, 13, 14, 29).
Generally manure is land applied
with application rates based on N with
no consideration given to the amount
P in the manure. Animal manures are
normally applied at rates sufficient to
meet N needs of the receiving crop.
Since animal manures have an aver-
age N:P ratio of 3:1 (16), and major
grain and hay crops use N and P at a
ratio of approximately 8:1 (64), excess
P is supplied when manure is used to
meet all the N needs of the crop. If
application rates are adjusted for N
losses via processes such as volatil-
ization and denitrification, the excess P
applied can be significantly greater.
For example, if manure is used to
meet the N needs for fescue produc-
tion in northwest Arkansas, an excess
of 40, 37, and 17 kg ha'1 of P will be
applied using poultry, swine, or dairy
manure, respectively (1, 19, 53).
32 JOURNAL OF SOIL AND WATER CONSERVATION
-------
Elevation of STP levels. Long-term
application of fertilizer P at rates
exceeding those of crop removal has
resulted in elevated levels of STP,
especially in areas where long-term
land application of manure has been
practiced. For example, in Wisconsin
the average STP level for all soil tested
was 48 mg kg"1 and for coarse
textured soils, used for intensive
vegetable production the average STP
level was 72 mg kg"-'- (7). In
Delaware, 65 percent of the soils
tested were considered in the high
range (.47). Several midwestern soils
were examined by Pierzynski et al.
(.34) and elevated STP levels were
attributed to the addition of commer-
cial fertilizer. Dairy manure appli-
cation has contributed to 200 mg kg"1
STP levels in Wisconsin (27).
Unfortunately, once high STP levels
have been reached, considerable time
is required for noticeable depletion.
McCollum (26) estimated that without
further additions of P, eight to 10
years of cropping corn (.Zea mays L.)
or soybean [Glycine max (L.) Merr.]
would be required to reduce P levels
in a Portsmouth sand from 54 mg kg"1
STP (Mehlich-III) to 20 mg kg"1.
Relationship between soil P and
runoff P. The P content of surface soil
directly influences the loss of P in
runoff. In fact, a highly significant
linear relationship was observed
between the soil test P (STP as Bray -
1 P) content of surface soil (1 cm [0.4
in]) and the dissolved P concentration
in runoff from cropped and grassed
watersheds in Oklahoma (Figure 2)
(.44). A similar dependence of the
dissolved P concentration in runoff on
the level (Bray-1) of STP was found
by Romkens and Nelson (37) for a
Russel silt loam in Illinois (r2 = 0.81),
on a Tokomaru silt loam in New
Zealand by Sharpley et al. (45) (r2 =
0.98, 0.1 M NaCl extractable soil P),
and on water extractable soil P (r2 =
0.61) of 17 Mississippi watersheds by
Schreiber (.39).
Vaithiyanathan and Correll (5§)
observed that the loss of P in runoff
from forested and cropped watersheds
in the Atlantic coastal plains was
closely related to soil P content (r^ =
0.96). In fact, the high organic P con-
tent of the forest soils (331 mg kg"1;
70 percent of total P) contributed to
the high organic P loss in funoff,
while the high inorganic P content of
the cropped soils (486 mg kg"1; 75
percent of total P) resulted in a higher
inorganic P loss. Other studies have
also demonstrated the close depen-
dence of P loss in runoff upon surface
soil P content (3, 35, 36", 5f).
Other factors that affect the loss of
P in runoff include depth of surface
soil that interacts with runoff water,
the concentration of sediment in
runoff, and runoff volume. Few mech-
anistic models have been developed
to quantify these factors, so simpler,
empirical models have been pro-
posed. Using simulated rainfall,
Sharpley et al. (43) investigated the
effect of these factors on P transport
in runoff. Eventually, an equation
describing the kinetics of soil P
desorption was proposed to predict P
transport in runoff (42). Using this
equation, Sharpley and Smith (42)
were able to demonstrate close
agreement between predicted and
measured soluble P concentration in
the runoff from long-term watershed
studies. Other researchers have
recognized the essential role of soil P
concentration in developing methods
to estimate P losses. Storm et al. (.48)
used a modification of the equation of
Sharpley and Smith (42) and
described particulate P loss as directly
proportional, within a particle size
class, to soil P concentration in a
combined soluble/particulate P
transport model. Wendt and Alberts
(53) used similar methods to estimate
transport of P adsorbed to soil
particles and incorporated isotherms
to account for adsorption/desorption
dynamics. Soil P concentration was an
integral input to the physically-based
P transport model developed by
Novotny et al. (3£>- Comprehensive
hydrologic/water quality models such
as EPIC (55), CREAMS (2/) and
AGNPS (57) estimate losses of P as
directly proportional to P concen-
tration in the upper layer of soil.
Priority water body selection
Identification of P-sensitive water
bodies. Recently there have been
several management efforts involving
federal, state, and local governments
in cooperation with individual citizens
to manage NFS problems (6T). Of
note was a recommendation to target
limited financial and technical
resources on the most valuable and
impaired watersheds, with additional
priority on projects having strong local
support.
The development of clear water
quality objectives is essential.
Individual lakes or reservoirs will
respond differently to the same phos-
phorus loads because of morpho-
logical differences related to depth,
water residence time, and degree of
stratification. Additionally the principal
use desired of a particular water body
will vary and will affect the "desired"
inland lake phosphorus concentration
and loadings. Lakes used principally
for water supply, swimming, and
multi-purpose recreation will benefit
from low phosphorus loadings. Lakes
principally used for fish production
may benefit from a moderate degree
of fertility (32).
Approaches to developing priorities
vary from state to state. Wisconsin,
which has an ongoing NFS priority
lakes and watershed program, utilizes
. an iterative process to identify lakes
needing nonpoint source controls.
Lakes in Wisconsin are grouped into
two classes based on their sensitivity
to phosphorus. Of the 15,000 iden-
tified inland lakes in Wisconsin,
approximately 1,400 were targeted for
phosphorus control. The principle
criteria used were (a) lakes had to be
greater than 10 ha (25 acres) in size to
be reflective of their relative value to
the state's tourism and recreation
base, (b) lakes had to have flushing
rates fewer than six times per year to
separate them from riverine systems in
which phosphorus is of lesser con-
cern, and (c) lakes had to be deep
enough to stratify. This last criterion
was used to identify lakes in which
internal phosphorus cycling occurs
and for which most of the commonly
used empirical, Vollenweider-type
models were developed.
To further screen lakes for possible
selection as a NFS control project a
point system is used to rank lakes.
Included in this ranking are factors
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 33
-------
which determine the degree to which
(a) the lake's water quality is
threatened; (b) the lake is able to
respond or to be protected from
threats if best management practices
are implemented; and (c) the lake is
valued as a resource. Finally, high
ranking lakes are selected by a
nomination process for inclusion into
the NFS priority lakes and watershed
program.
Once selected for a project, an
iterative process is used to set
achievable water quality goals for the
individual lake. The most stringent
best management practices (BMPs) are
then implemented in the watersheds
of those lakes considered excep-
tionally valuable and extremely sensi-
tive to phosphorus loadings. Those
less susceptible or those having desig-
nated uses more compatible with
higher phosphorus loadings will have
a lesser degree of critical sites or lands
identified for implementation of NFS
BMPs.
As Wisconsin's program has
evolved it has become evident that
there is a need to target and prioritize
nutrient management actions within a
watershed and focus on individual
farms to be reflective of the needs of
the receiving water bodies. As
indicated earlier, application standards
for animal manure have typically been
N driven to be reflective of ground
water contamination concerns.
Similarly, control of sediment has
been a priority resulting in the use of
conservation tillage practices which
then often require incorporation of
manure or fertilizer to minimize runoff
potential. Finally, individual farm
management plans are then devel-
oped using sediment, N, and P as
priorities.
Identification of critical areas in
priority ivatersheds. Because P trans-
port is controlled most effectively at
the origin of the excess P, the next
management step (after determining
that a critical water body is P limited)
should be to identify regions within
the contributing watershed in which P
transport reduction strategies will be
most effective. These regions should
subsequently be the primary focus of
efforts to reduce P inputs to the P-
sensitive water body by implemen-
tation of BMPs. Direct, indirect, and a
combination of direct and indirect
methods may be used to target
regions for implementation of man-
agement options to reduce P losses
from the point of origin.
Direct critical region identification
refers to systematic monitoring of
water body tributaries to determine
relative P contributions from the
various subbasins. With judicious
selection of monitoring station loca-
tions, direct monitoring can identify
subbasins contributing high P loads.
The most apparent advantage of this
approach is that subsequent decisions
regarding where to focus remedial
measures will be based on data rather
than subjective considerations or
surrogates to observed data. The
disadvantages to direct critical region
identification are the resources and
time involved. Effective monitoring
stations are expensive to establish and
operate, and sample analysis costs can
be quite high. Monitoring costs will
increase directly with the size of the
monitored watershed and the critical
region resolution desired. In addition,
several years' time can be required to
obtain meaningful information due to
the highly variable nature of NFS
pollution occurrence. The resource
requirements of direct monitoring for
critical area identification are likely the
main reason that this method is not
widely used except in large water-
sheds.
Critical region identification is
currently performed most often via
indirect methods. The principle
underlying indirect methods of critical
region identification is to obtain a
spatial representation of some index
of P export; the operative assumption
is that the P transport index selected is
a reasonable surrogate for observed
data. The criteria for critical area
identification vary considerably in
terms of complexity. Examples of
relatively simple screening criteria
include animal manure application
rate, dilution, distance to nearest
receiving water, and combinations of
factors (.10, 28, 68). Other reported
screening criteria include factors such
as existing facilities and attitude of the
owner/operator (52). Heatwole and
Shanholtz (18) reported on a proce-
dure to rank the relative contributions
of sites as a function of animal
manure application rate and estimated
delivery to nearest receiving water.
Advances in geographic information
systems (GIS) technology have been
extremely valuable in processing the
multitude of data required to
meaningfully characterize the P contri-
bution potentials of subregions of
watersheds. The latest advance in use
of indirect methods to identify critical
regions has been the linkage of spatial
data on P transport factors with
hydrologic/water quality simulation
models (P, 17, 30, 66). Distributed
parameter models can estimate P
export at the field scale, and use of
GIS technology to construct the model
input database can help alleviate
some of the practical difficulties
inherent in distributed parameter
models. Indirect methods of critical
region identification can be less
expensive and time-consuming than
direct methods and will thus probably
become increasingly common with
advances in prediction accuracy of
hydrologic/water quality models. The
dependence of critical region identi-
fication on some degree of derived
data is probably the largest limitation
to indirect methods. Until indirect
methods are shown to give results
similar to what would be obtained
from direct monitoring, healthy
skepticism as to whether a particular
region is indeed critical may be
justified.
A combination of direct and indirect
methods can combine the best attri-
butes of the two approaches to critical
area identification. Limited observed
data can be used to calibrate a
hydrologic/water quality simulation
model, and the model can then be
executed on the basis of GIS-assisted
input to identify regions likely to have
particularly high P export. Although
an uncalibrated simulation model
might adequately reflect relative
differences in P export from various
regions, calibration is essential to
accurate estimation of amounts of P
transport.
Once critical hydrologic areas have
been identified, the landowner,
producer, and field staff need to
assess the soil, hydrology, and man-
34 JOURNAL OF SOIL AND WATER CONSERVATION
-------
agement of individual fields to deter-
mine specific fields that have the
potential for P loss. A field level
assessment tool has been developed
(23) that uses easily attainable soil,
hydrologic, and management infor-
mation. Using this assessment of the
soil, topography, soil test levels of P,
and management practices, a relative
ranking procedure can be used to
identify those fields that have the
highest potential for producing off-site
movement of P. Through this proce-
dure, a numerical value—or P index—
is assigned to each field. The process
also indicates potential problem areas
such as excessive erosion or manure
application rates.
Management options for reducing
Plosses
Where lakes, reservoirs, or estuaries
are the primary water bodies of
concern, programs minimizing eutro-
phication from agricultural NFS
pollution should emphasize limiting P
inputs to surface water. In Florida,
water quality management programs
dealing with NPS pollution have
focused on P (.25). In Holland, the
national strategy for minimizing NPS
pollution, especially eutrophication
due to animal wastes, is to limit entry
of P into both surface and ground
water C5).
Because STP and runoff P concen-
trations are related, a critical level of
STP exists that results in runoff which
is, on average, sufficiently high in P to
cause eutrophication. State and federal
water quality management agencies
are attempting to identify these "cut-
off levels" of STP above which no
additional P should be added. Cut-off
levels for soil P, along with influential
chemical properties such as clay and
organic matter content, need to be
identified for bench-mark soils. Once
identified, these levels could be a
valuable tool for identifying potential
P related problems associated with
excess applications of either animal
manure or commercial fertilizer.
Developing management practices
that are sequentially enacted as the
STP level increases toward the cut-off
level would slow down the process of
0.6
O
E
Q
LU
0.4
0.2
0.0
Cropland
90
10 20 30 40 50
SOIL TEST P (kgP ha'1)
Figure 2. Effect of soil test P on the dissolved P concentration of
runoff from several Southern Plains watersheds (44).
restricting P application.
The first step in proper manure
management is to view manure as a
valuable resource that can be utilized
to advantage.. Alternative uses of
manure should be pursued along with
methods of increasing the bulk
density and N content of the manure,
encouraging the transport of manure
from manure-rich to manure-deficient
areas. However, until such methods
are perfected and expanded, the
predominant method of utilization will
remain land application.
All fields do not contribute equally
to the P load of a lake or reservoir.
Therefore, if the same management
practice is implemented on two
different fields, the effectiveness in
reducing the P load will differ. The P
indexing procedure is designed to
identify and rank fields for imple-
mentation of management practices.
For fields with a low to moderate P
index rating, flexibility exists, and a
wide range of management practices
is available. Generally these practices
are designed to reduce runoff, which
is the major transport mechanism for
P, and because of this they also
control erosion in the process. For
fields with a high P index, especially
those with high STP levels, the same
practices apply but less flexibility
exists and more stringent approaches
may be required.
Fields with low to moderate P
indexes. Many management options
are available for reducing P losses in
the short-term following application,
and all have been demonstrated to be
effective under some circumstances.
Options such as injection of P sources,
when appropriate, can reduce the
concentration of P near the soil
surface. Other management options
such as no-till farming, vegetative filter
strips, terracing, winter cover crops,
and contour farming can reduce
transport of P in particulate form by
reducing erosion. Strategies which
reduce runoff from treated areas, such
as tile drainage and impoundments,
can be effective in reducing loss of DP
as well as sediment P. Measures such
as timing P application to avoid
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 35
-------
occurrence of intense storms and
application of chemical amendments
to precipitate P may also be effective
in reducing P losses shortly after
application, but the effectiveness of
such practices needs to be better
defined.
Fields with high P indexes and STP
levels. The best P management plan is
to prevent surface soil accumulation
of P in the first place. Soil testing
should be an integral part of P
management to ensure that soil P
levels are high enough for adequate
yields and that the manure or fertilizer
is applied only to fields that are P
deficient, avoiding those with exces-
sive P or those that have the potential
for excessive P. If commercial fertilizer
is the predominant long-term method
of supplying plant nutrients, then the
composition of the fertilizer can be
structured to supply only the
necessary amount of N and P. This
approach is flexible and cost-effective
to the producer. When animal
manures are used as a nutrient source,
less flexibility exists and a combi-
nation of manure and commercial
fertilizer should be used to supply the
nutrients required by the crop.
Manure can be used to supply all the
P required and a portion of the N
needs, with the remaining N require-
ment being supplied by commercial
fertilizer. When STP levels are
between high and the cut-off level,
manure application rates should be P-
rather than N-based.
Cost-effective practices. Large-scale
implementation of management
options to reduce P loss is best
approached by first constructing a
framework for assessing the relation-
ship between implementation costs
and water quality benefits. While it is
relatively easy to define the costs of a
management practice, it is difficult to
quantify the benefits that will be
derived. Assessment of management
practice effectiveness is difficult
because of dependence of effective-
ness on site-specific variables, and an
all-inclusive database is lacking.
Rigorous mathematical simulation
models can be used to estimate
management option effectiveness, but
issues regarding data input require-
ments and output accuracy should be
resolved before depending solely on
models. If the effectiveness of a
practice for reducing P loss from
application sites can be defined, then
this edge-of-field effectiveness should
be translated into effects on the P-
sensitive water body. This translation
is best accomplished using simulation
models that address edge-of-field P
transport dynamics, channel flow
dynamics, and the dynamics of the P-
sensitive water body. A notable
example of this type of combined
model was developed by Summer et
al. (.49). Assuming that the first two
challenges can be surmounted, there
must be a relationship established
between quality of the P-sensitive
water body and some measure of
value, so that costs and benefits are
defined on a common basis. This
might be the most difficult component
in a framework for assessing
management plans, since the value
associated with a given level of
quality in the P-sensitive water body
depends on the use of the water
body. If the water body is used solely
as a water supply, then assessing its
value might be relatively straight-
forward. If the water body is used for
multiple purposes such as fishing,
boating, and other uses, then the
concept of value depends on intan-
gibles and can be very subjective.
Remediation of impacted water
bodies is often accomplished with
expenditures of limited cost-shared
public monies. Plans to improve the
quality of P-sensitive water bodies
thus need to focus on obtaining
maximum benefits from limited public
resources. To accomplish this goal,
implementation plans to reduce P
loading to the P-sensitive water body
should initially focus on regions
identified as critical. Identification of
an "optimal" plan can be rather
laborious, depending on the size of
the area in question and on the array
of potential management practices
under consideration. A systematic
procedure for plan development,
however, will ensure that only the
most effective management practices
are implemented and that these
practices will be implemented in
locations that are most appropriate.
Use of public monies to implement
management practices without regard
to effectiveness or where little water
quality improvement is likely is a
questionable public policy and will
not maintain or generate broad public
support.
Summary
Transport of solutes in agricultural
runoff is of increasing national
concern. While several pollutants are
carried in the runoff, P is deemed
especially important because it is the
nutrient limiting growth of aquatic
vegetation in most surface waters.
Runoff losses of P are generally less
than 5 percent of that applied with the
bulk of the loss occurring in one or
two events following land application.
Loss of P in runoff occurs in dissolved
and sediment-bound or particulate
forms. Sources of runoff P include
commercial fertilizers and animal
manures, and the amount contained in
runoff is directly influenced by
management practices such as rate,
method, and time of application.
Runoff losses from manure are a
particular concern in regions where
confined animal operations exist in
proximity to surface water bodies
sensitive to P inputs. Soil test P levels
are increasing nationally and a
relationship exists between the
amount of P in the soil and that
contained in the runoff. This relation-
ship requires further definition and
"cut-off STP levels" need to be iden-
tified.
Limited financial and technical
resources should be targeted on those
water bodies deemed valuable and
most likely to respond to implemen-
tation of BMPs within the watershed.
State water quality management
agencies need to develop clear water
quality objectives for lakes/reservoirs
based on intended use. Methods for
identifying and prioritizing P-sensitive
water bodies must be perfected and
demonstrated. Once P-sensitive •water
bodies are known, it is necessary to
identify hydrologically active areas or
"hot spots" in the watershed requiring
BMPs. A variety of practices exist that,
when implemented, can maintain high
surface water quality especially for
36 JOURNAL OF SOIL AND WATER CONSERVATION
-------
traditional row-crop agriculture. Less
flexibility exists with land application
of manure, especially on fields with
elevated STP levels. Soil testing should
be an integral part of manure man-
agement. Land application strategies
for manure should be based on N to
protect the ground water with equal
consideration given to P for protection
of surface waters.
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38 JOURNAL OF SOIL AND WATER CONSERVATION
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BMPs
Best management
practices meeting
water quality
goals
/. Watson, E. Hassinger, K.
Reffruschinni, M. Sheedy, and B.
Anthony
In Arizona, legislation was enacted
in 1986, referred to as the Arizona
Environmental Quality Act (2), to
protect both surface and ground water
quality from point and non-point
contamination sources. A portion of
the legislation addresses agricultural
activities. It states that "the director
shall adopt by rule agriculture general
permits consisting of best manage-
ment practices for regulated agricul-
tural activities." The director, in this
statement, refers to the director of the
Arizona Department of Environmental
/. Watson is an Extension water quality
specialist, E. Hassinger is an assistant in
Extension, K. Keffruschinni is an assistant in
extension, andM. Sheedy is a research
specialist at the Maricopa Agricultural Center,
University of Arizona, Maricopa 85239. B.
Anthony is resident director at the Campus
Agricultural Center, University of Arizona,
Tucson, 85719.
Quality (ADEQ), a department in the
state, newly created by the legislation.
Historically, the Arizona Environ-
mental Quality Act was the legislative
outgrowth of a response to an initia-
tive petition produced on water
quality issues. The initiative petition
would have required the placing of
water quality issues on the November
1986 ballot. However, water users in
Arizona were concerned that water
legislation might be drafted that
'would reflect the restrictive nature
apparent in the pesticide regulations
in neighboring California. Faced with
the probability of a water quality
initiative, the water user interests
began searching for a viable alter-
native. Since the extremes embodied
in the initiative could not be effec-
tively argued against (due to the
emotionally charged nature of the
public debate) from a technical or
scientific perspective, and since
unrestricted discharge was unaccept-
able to all parties, a solution was
sought in a permitting program.
A Blue Ribbon Commission had
been appointed by then Governor
Bruce Babbitt. This commission spent
much of the second half of 1985
debating and negotiating the various
issues to be included in the proposed
water quality legislation. Early in these
proceedings, nitrogen fertilizers and
pesticides were separated as topics
and assigned to separate subcom-
mittees, as were other topics. The
nitrogen fertilizer subcommittee con-
ducted their negotiations from the
perspective that "agriculture has no
substitute for nitrogen fertilizers."
Although this concept was not
uniformly accepted in the public
sessions before the Governor and the
entire committee, it was not seriously
challenged.
In January 1986, a draft copy of
legislation entitled the "Arizona Water
Quality Protection and Restoration
Act" was produced. This draft, which
was subsequently known as Hawke I
to identify the legislator who was
responsible for its introduction,
introduced the aquifer protection
permit procedures in the form of
individual permits. However, it
became apparent that the cost as well
as administrative and enforcement
components of the program would be
exceedingly burdensome to the state
if developed in the individual permit
format. In response, a general permit
program was developed which estab-
lished an enforcement framework for
a large group of similar users to
follow in meeting the requirements of
the law.
The concept of best management
practices (BMPs) was also introduced
in early January 1986. This concept
was derived from the Federal Clean
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 39
-------
Water Act as found in the Environ-
mental Protection Agency's rules and
regulations. Since the BMP concept
was a practical, fact-driven approach,
it was particularly well suited for and
adaptable to agriculture. The BMP
concept also provided for the
establishment of a level of partici-
pation and self-governance for
Arizona agriculture. In addition, the
BMP concept allowed site-to-site or
farm-by-farm flexibility, while provid-
ing a degree of control acceptable to
proponents of the initiative petition.
The Arizona Environmental Quality
Act mandates that BMPs for regulated
agricultural activities be adopted by
rule. Complications arose, however,
when an attorney general's opinion
indicated that all BMPs adopted by
rule, are rules, and thus must all be
implemented by every producer
(whether or not die combined appli-
cation was rational). For example, if
land levelling, high efficiency sprinkler
irrigation systems, and drip irrigation
systems were all considered best
management practices in rule to
provide efficient irrigation water
application, every producer would be
required to use all three methods
concurrently to comply with the law.
In attempting to develop the BMP
program for regulated agricultural
activities, this provision was found to
be unacceptable. Furthermore, the
rule-making process is complex,
burdensome, and time consuming. In
the best of circumstances rules require
12-18 months to finalize. The vesting
of technical practices in rule elimi-
nated the essential component of
flexibility for successful development
of an acceptable, effective, and imple-
mentable program. This constraint
was overcome when the recom-
mended BMPs for regulated agricul-
tural activities were redefined as
general goal statements, rather than
specific practices, which were then
adopted as rules. In this respect,
Arizona's BMPs for regulated agricul-
tural activities became program goal
statements as well as rules that must
be implemented. These statements not
only provided direction and purpose
for the program, but also incorporated
flexibility into the program.
The best management practices for
nitrogen fertilizer use in Arizona
agriculture follow.
BMP 1—Application of nitrogen
fertilizer shall be limited to that
amount necessary to meet projected
crop plant needs.
BMP 2—Application of nitrogen
fertilizer shall be timed to coincide as
closely as possible to the periods of
maximum crop plant uptake.
BMP 3—Application of nitrogen
fertilizer shall be by a method
designed to deliver nitrogen to the
area of maximum crop plant uptake.
BMP 4—Application of irrigation
water to meet crop needs shall be
managed to minimize nitrogen loss by
leaching and runoff.
BMP 5—The application of irri-
gation water shall be timed to mini-
mize nitrogen loss by leaching and
runoff.
BMP 6—The operator shall use
tillage practices that maximize water
and nitrogen uptake by crop plants.
Similar requirements exist for
confined animal feeding operations
(e.g. dairies and feed lots).
Guidance practices (at one time
referred to as alternative technologies)
have become the specific methods
which operators use to achieve the
goals as stated in the best manage-
ment practices and thus maintain their
general permits. Since guidance prac-
tices are not incorporated into rule
they can be readily modified to keep
pace with changing agricultural prac-
tices and technology. Thus, guidance
practices are practices that most agri-
cultural scientists and engineers would
recognize as BMPs. The following
practices are examples of guidance
practices for nitrogen fertilizer BMP 1.
G.P. 1.1—Sample and analyze soils
for residual nitrate content.
G.P. 1.2—Test irrigation water for
nitrogen content and for compatibility
with ammonia containing nitrogen
sources applied using fertigation.
G.P. 1.4—Use application equip-
ment which has been properly cali-
brated.
G.P. 1.7—Use slow-release nitrogen
fertilizers.
G.P. 1.8—Use appropriate plant
tissue analysis procedures with annual
and perennial crops to guide nitrogen
fertilizer applications.
Compliance
For rules to be effective, they must
be enforceable. Regulated agricultural
activities must be conducted so as to
meet Arizona's BMP rules. Any
operation found out of compliance
can be required to cease operation
until an individual permit to operate is
obtained. The process required to
obtain an individual permit is so
expensive due to required environ-
mental assessments, and so lengthy
(six months to a year—if everything
proceeds in a timely fashion), that it is
likely the operation will become
insolvent before the individual permit
is obtained. Furthermore, any agri-
cultural operation that is found out of
compliance is not able to access
Agricultural Stabilization and Conser-
vation Service (ASCS) cost share funds
to improve their operation to assist
them in compliance. The message for
Arizona's agricultural producers, then,
is implement BMPs to maintain your
general permit at all costs.
The guidance practices used to
implement the BMP rules are also a
key mechanism that ADEQ has at its
disposal to verify compliance with the
law. An agricultural producer can be
required by the Department to verify
implementation of BMPs. The only
rational means to do so is to produce
records indicating the use of appro-
priate guidance practices. Further, if
water quality problems exist in a
locale that are attributable to agricul-
tural activities, departmental staff can
require the implementation of guid-
ance practices that they determine are
necessary to effectively protect water
quality.
The Arizona Department of Water
Resources (ADWR) has the respon-
sibility for regulating the use of
groundwater in the state. One of its
mandates focuses on reduction of
water use by agriculture. Although
legislation provides for substantial
penalties for noncompliance, it has
seldom been necessary for the agency
to mete out such penalties, since they
have developed a strong educational
program targeting growers. They also
have substantial interaction with
growers and irrigation district man-
agement through advisory committees
40 JOURNAL OF SOIL AND WATER CONSERVATION
-------
and special projects. The success of
this program, as with the BMP
program, is not judged on the basis of
number of fines levied, but by the fact
that few compliance actions have
been necessary. Success in the BMP
program must be measured, not in
numbers of operations closed for
noncompliance (for such actions
actually identify program failure if
frequently needed), but in terms of
compliance rates while maintaining
the economic viability of the industry
and the economies of the rural com-
munities dependent upon agricultural
productivity for orderly growth.
Community support
In order for any program to work
effectively, various constituencies
must be confident that their concerns
are taken into account. The private
environmental organizations must be
satisfied that the regulations will
effectively protect water quality; the
regulatory agency staff must have
clear guidelines and mechanisms
available to evaluate compliance; the
regulated community must be con-
vinced that it is important to comply.
While no legislation is ideal, the
Arizona Environmental Quality Act
and subsequently promulgated rules,
have included these three entities.
Their concerns are reflected in the
form of the legislation and the
regulations. Not only is the legis-
latively mandated standard stringent
(aquifer protection, with all ground-
water aquifers presently protected for
drinking water), but the imple-
mentation mechanisms and compli-
ance standards are practical, fact
based, verifiable, and enforceable.
Further, the method for compliance
verification, on-site visits by ADEQ
staff to operations located in areas
with groundwater quality problems,
provides a mechanism for meaningful
dialogue between regulatory agency
staff and members of the regulated
community, prior to the need for
compliance actions, such as cease and
desist orders. This provides water
quality protection without disrupting
the economy of the local community
dependent upon agricultural viability.
Technical inconsistencies
Arizona's legislation has some
problems that should be recognized
and addressed by others considering
agricultural regulation for water
quality protection. The nitrogen
regulations are based on BMPs, which
basically address the issue of mass
emissions of nitrogen to groundwater.
The pesticide regulations focus on
concentrations below the root zone
and in groundwater. In the unsatu-
rated zone (vadose zone) between the
soil surface and groundwater, the two
criteria (mass emissions and concen-
trations) frequently are inversely
related (.5). The legislation is based on
the assumption that research exists
that accurately measures nitrogen and
pesticide losses under management
practices employed. As attested to by
the recent emphasis by the U.S.
Department of Agriculture and the
U.S. Environmental Protection Agency
to fund research regarding impacts of
agricultural management practices on
groundwater quality, this presumption
is erroneous. The (unscientific) legal
interpretation of the legislation by the
state attorney general's office that all
BMPs apply to all sites somewhat
weakened the ability to incorporate
by rule a concise list of acceptable
practices. It also required substantial
effort on the part of the regulatory
agency staff and the regulated com-
munity to find meaningful BMPs that
permitted effective and rational
implementation of the legislation.
A recent research project report (4)
on cotton in Arizona indicated that
attempting to increase field irrigation
efficiencies (an often-stated BMP)
beyond a certain level resulted in
yield reductions. Further, the differ-
ences in nitrate nitrogen losses
between treatments were not statistic-
ally different due to field soil hetero-
geneity. Pratt et al. (3) found that the
amount (usually the focus of BMPs) of
nitrate nitrogen lost to drainage waters
from agricultural fields was poorly
correlated with the concentration
(usually the focus of regulatory com-
pliance programs) of nitrate nitrogen
in those same waters. These examples
highlight the need for care in selecting
economically sustainable BMPs, as
well as in identifying effective BMPs.
For example, to state simply that a
producer should improve the irri-
gation efficiency by 10 percent would
result in yield losses in the case of
some, and in inconsequential water
quality changes in the case of others
with extremely low efficiencies.
Further, the specific examples of
inconsequential improvement in water
quality or yield losses would taint the
program and bring its credibility into
question.
Sustainability
The title of this paper is in some
ways a misnomer. People meet water
quality goals, practices don't. Effective
goals are those that individuals have
for themselves, not for others. Goals
that are advocated for others create
frustration on the part of all con-
cerned. The regulatory agency can
have desires for compliance by the
regulated community, but can only
have meaningful goals for themselves,
not for the regulated community.
Goals, by definition, cannot be
statements of what another will
accomplish but of what the goal-
setting entity will accomplish. On the
other hand, a water quality protection
program can be evaluated as success-
ful in the agricultural community
when individual members of the
agricultural community have estab-
lished goals for their operations that
are consistent with water quality
protection. The distinction is abso-
lutely critical; otherwise the standard
to evaluate the success of such a
program will be a moving target
depending upon who (media person-
alities, local officials, state officials,
agribusinesses, farm operators, regu-
latory agency staff—the list can be
substantial) is establishing the criteria
at a particular time. Thus an evalu-
ation of the effectiveness of a water
quality protection program for
agriculture must account for what
practices are implemented when "no
one is looking." The nature of
Arizona's implementation process
(with its budget constraints) relies
heavily on voluntary compliance by
the majority in the regulated com-
NUTEIENT MANAGEMENT SPECIAL SUPPLEMENT 4l
-------
munity (as it must if it is to be
sustained in the future) with focused
efforts by regulatory agency staff on
problem locations and individuals
who disregard the regulations.
Since grower response is such a key
element to on-farm adoption of BMPs,
it is helpful to ask what criteria are
considered important by growers. We
offer three that we consider critical.
First, practices must be environ-
mentally effective. If they cannot be
shown to be an improvement (envi-
ronmentally) over conventional prac-
tices presently employed, there is no
scientific rationale for recommending
them. This seems obvious, but fre-
quently practices are espoused today
for which no solid evidence exists
regarding their effectiveness for
environmental protection. To ignore
this criteria is analogous to the
situation in the 1950s and 1960s in
which pesticide recommendations
were made that were based upon the
best judgment of "the pros" at the
time for the purpose of controlling an
important environmental problem.
Today, many question the wisdom of
some of those recommendations,
because other environmental conse-
quences were not considered. If we
fail to obtain solid evidence regarding
benefits of recommended practices,
we risk not only criticism by future
generations for not considering the
consequences of such practices, but
(even worse) we seriously risk recom-
mending a placebo that makes the
patient feel better without effectively
addressing environmental conse-
quences.
Second, practices should be econo-
mically beneficial. For a change to be
sustained on a primarily voluntary
basis, there should be negative
economic impacts of non-imple-
mentation. A speeding ticket is a clear
example of a negative economic
impact. A fine for non-compliance
with BMPs is another example. The
problem with the ticket and fine is
that they require enough regulators
that a large percentage of those out of
compliance will be caught. One only
needs to travel the nation's highways
to see the ineffectiveness of monitor-
ing speeding (an activity that is much
easier to monitor than compliance
with environmental guidelines) when
the regulated or monitored commu-
nity remains unconvinced that main-
taining the legal speed is in their best
economic interests. Other social and
economic pressures apparently are
greater than the risk of getting caught
and fined. Analogously, the risk of
detection and fine may not be
adequate to achieve a high degree of
compliance with environmental regu-
lations such as mandated BMPs.
Therefore, the implementation of
BMPs must be economically and
socially beneficial to the regulated
community.
Third, practices should be easily
adaptable: Practice changes requiring
substantial capital investment will be a
hard sell. Even in cases in which a
member of the regulated community
invests in a capital intensive change, it
does not necessarily follow that the
simultaneous implementation of
important management changes will
ensue. Often, capital intensive
changes have no substantial impact
without the concurrent adoption of
management changes. A prime ex-
ample of this exists in Arizona. Cases
can be cited in which substantial sums
of money were invested in improved
irrigation delivery structures, but the
irrigation practices remained un-
changed. Consequently, the expected
savings in water costs •were not
realized, until the practices changed.
A similar example would be purchas-
ing new fertilizer equipment, then
operating it without calibration.
Educational programs
In an effort to judge grower
response to BMPs, Cooperative Exten-
sion in Arizona surveyed producers in
two of the major agricultural counties
of the state, Final and Maricopa. The
Final county survey (f) was conduc-
ted in 1991, and some of the results
are presented here. We found that
only about 60 percent of the growers
responding to the survey were aware
of BMPs being mandated. Of those
aware of BMPs, most were using plant
and irrigation management practices
that would be identified in Arizona as
acceptable guidance practices (e.g.
soil testing for nitrogen, plant tissue
testing for nitrogen, irrigation sched-
uling with real time weather data, etc.)
for the purpose of meeting BMPs.
The low percentage of respondents
who were aware of state mandated
BMPs was somewhat surprising since
the survey followed two years of
media attention, a state level grower
advisory committee effort to include
grower concerns in the BMP for-
mation, and combined agricultural
industry, cooperative extension, and
ADEQ meetings about BMPs. It was
clear that some key elements must be
missing from the educational endeav-
or to find such a low awareness level,
after such a high profile effort. At least
three missing elements of the edu-
cational program were identified. First,
a clear demonstration of environ-
mental need and benefit was missing.
Solid data did not exist that clearly
supported that specific agricultural
practices were degrading groundwater
quality, or more importantly, that
alternative practices would protect
groundwater quality to an extent
greater than already existed. A second
missing element was a "buy in" by
county extension personnel and SCS
county staff. In general, a conviction
did not exist that there was an
agriculturally created water quality
problem. Without supporting scientific
evidence, there was no compelling
reason for these educators and
technical support staff to encourage
BMP adoption. A third missing ele-
ment was the lack of local on-farm
demonstrations of practices that were
known to reduce the potential for
degradation of groundwater quality.
In response to these needs, coop-
erative extension has initiated on-farm
demonstrations highlighting the
possibility of water and nutrient losses
below the crop root zone, with a
particular emphasis on early season
losses. The ADEQ has funded a
demonstration and research project on
BMPs through the University of
Arizona Cooperative Extension and
Experiment Station, and two Hydro-
logic Unit Area projects were initiated
in the state as cooperative efforts
between Cooperative Extension, SCS,
and ASCS. The Arizona Departments
of Environmental Quality, Water
42 JOURNAL OF SOIL AND WATER CONSERVATION
-------
Resources, and Agriculture have
participated in the planning of these
two projects. A substantial contri-
bution has been made to these
projects from individual agricultural
cooperators, advisory committee
members, and irrigation districts, as
•well. The agricultural community
involvement is characterized by a
desire to define the problem specific-
ally and promote effective solutions.
There is a strong desire that the
regulatory process be consistent with
scientific findings. It is hoped that the
interaction of the regulated commun-
ity with the regulatory, educational,
and technical assistance organizations
will enhance the understanding and
adoption of effective and sustainable
practices that protect water quality.
Summary
A successful regulatory program is
often evaluated in terms of how many
citations were handed out or how
many fines were imposed. In truth, a
successful program accomplishes its
mandates in a manner that maintains
economic viability and builds a
sustainable base of support. To do so,
it must be conducted by staff who are
scientifically competent, who can
develop confidence in their credibility
by a number of constituencies, and
•who are provided with the necessary
tools (including budgetary support) to
implement the program. The regulated
community must be involved in
appropriate aspects of the program to
maintain the program's visibility. The
key ingredients in all aspects of a
successful program are individuals;
individuals in a regulatory agency
•who can make a program •work in
spite of political maneuvering in
legislative bodies and in their agency
or other agencies; individuals in the
regulated community who are willing
to take the bull by the horns and
become proactive for the good of
their industry; and individuals to
provide education and technical
assistance who are willing to deal
with the problems of helping the
regulated community implement
needed practices. Arizona has been
fortunate to have the involvement of
such individuals in the development
of its BMP program. Its long term
viability and success will depend
primarily upon the commitment of the
state's citizens and their elected
representatives to make the program
work.
There are some negative aspects of
the legislation and BMP program.
Many of the members of the agricul-
tural community would consider
Arizona's Environmental Quality Act
of 1986 to have been so divisive that it
should not be recommended as a
model for other states to use. The
nature of the process by which it was
formulated created many of the
inconsistencies within the legislation.
Legislative oversight, or the lack of it,
can be a problem. Agency directors
(and there have been three in six
years) have difficulty obtaining legis-
lative attention to funding require-
ments, except when a last minute
budget is being fought over.
The challenge to educational and
technical assistance agencies has been
and will continue to be to develop
meaningful programs that are both
scientifically correct and consistent
•with regulatory requirements. Stan-
dard practices and data interpretation
methods need to be developed
against which other practices and
result interpretations can be com-
pared. When technical inconsistencies
between the BMP program and the
pesticide program appear, the goal of
minimizing groundwater pollution will
necessarily drive the educational
effort. However, this can result in
mixed signals to the regulated com-
munity. Strong interaction between
the regulated community, the regula-
tory agency, the technical assistance
agencies, and the educational agen-
cies will be important to prevent mis-
understandings and misconceptions.
REFERENCES CITED
1. Anthony, B.R., J. Watson, R. Gibson, S.
Stedman. 1992. Agricultural producer
survey results: Casa Grande-Coolidge
Hydrologic Unit Area Project. University
of Arizona Extension Bulletin No.
192031. University of Arizona. Tucson.
2. Arizona Revised Statute 49-247. 1987.
Arizona Revised Statutes Annotated,
1987 Special Pamphlet. Title 49. The
Environment. West Publishing Company,
St. Paul, Minn. 207 pp.
3. Pratt, P.p., J.W. Biggar, F.E. Broadbent,
D.D. Focht, J. Letey, L.J. Lund, A.D.
McLaren, D.R. Nielsen, L.H. Stolzy, P.R.
Stout, K.K. Tanji. 1979. Nitrate in
effluents from irrigated lands. Final
report to the National Science Founda-
tion. May 1979. National Science Founda-
tion, Washington, D.C., Engineering and
Applied Science. U.S. Department of
Commerce, National Technical Infor-
mation Service, PB-300 582. 810 pp.
4. Sheedy, M., and J. Watson. 1992.
Irrigation efficiencies, nitrogen applica-
tions and lint yields of upland cotton
grown at the Maricopa Agricultural
Center, 1991. In: J. Silvertooth (ed.) The
1991 Arizona Cotton Report. Series P-91,
1992. University of Arizona Extension
Bulletin. University of Arizona. Tucson,
Ariz. pp. 92-95.
5. Watson, J., and M. Yitayew. 1988. Mass
flux versus concentration: A regulatory
dilemma. American Society of Agricul-
tural Engineers, 1988 International
Winter Meeting, Chicago, 111., Dec. 13-16,
1988. Paper No. 88-2647. (ASAE), St.
Joseph, Mich. Q
Tools to aid
management: The
use of site specific
management
S. Kincheloe
Best management practices
(BMPs), maximum economic
yields (MEY), and sustainable
agriculture are terms that should be
part of your vocabulary. In the proper
context, BMPs, MEY, and sustain-
ability are not terms in conflict. On
the contrary, BMPs lead to MEY and
MEY leads to sustainability, both
environmentally and economically.
Put another way, the primary
objective of a sustainable, efficient
agricultural system is to provide an
economical, safe supply of high
quality food and fiber, with adequate
and responsible protection of the
environment. It is this combination of
S. Kincheloe is the director of agronomic
services, IMC Fertilizer, Inc., Mundelein,
Illinois 60060.
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 43
-------
productivity and responsibility that
most accurately describes the term
"sustainable agriculture."
What are best management prac-
tices? Best management practices are
those practices that have been proven
in research and tested through farmer
implementation to give optimum
production potential, input efficiency,
and environmental protection. A BMP
for one location is not necessarily the
same for another—they vary for
different crops, soils, and climates.
BMPs are very site specific. Past
research, farmer experience, and
knowledge of uncontrollable factors,
such as soil and climate, are valuable
tools in arriving at the BMP recom-
mendation for each particular site.
BMPs involve both soil conservation
and agronomic practices. It is the
combination of these BMPs that
assures a highly efficient and produc-
tive cropping system, one that
preserves the soil for future gener-
ations. Most scientists agree that
farmers must build a system of BMPs
or refine the current system to be both
profitable and the best possible
steward of the soil.
Best management practices must be
site specific for each field—even areas
within those fields. General categories
of practices are usually recommended,
but within these categories, each
farmer must develop the most efficient
use of inputs.
Here are examples of BMP cate-
gories:
Cultural practices
• Variety/hybrid selection
• Crop rotation
• Intercropping
• Conservation tillage
Pest management
• Use of resistant cultivars
• Use of pest management dynamics
• Integration of techniques
• Integrated pest management
Water management and
conservation
• Scheduling irrigation
• Eco-farming/moisture harvesting
• Crop selection
Sound fertility programs
• Soil and plant tissue testing
• N credit for legumes/residues
• Placement/timing/rate
• Use of residues/manures/sludge
One BMP that is generally recog-
nized as environmentally sound is soil
testing. It will continue to be extreme-
ly important that farmers base their
fertility programs on a good soil
testing program.
Most of these examples are not
new. The idea is simply to maximize
the efficiency of all inputs and man-
age steps to produce the highest yield
at maximum profit, which in turn
enhances environmental stewardship.
MEY is achieved through the use of
BMPs and precision management.
This includes using the latest agro-
nomic technology for each productive
cropping system. Dedicated produc-
tion agronomists have put together
the kinds of technology that give
greater consistency to high yields.
This "reproducibility" has given
confidence that efficient new MEY
systems which lower unit production
costs are real today and will be
improved tomorrow. The most striking
feature of each MEY system devel-
oped is the need to integrate all
controllable inputs at optimum levels
for the crop and site. When using
MEY technology, farmers should add
soil conservation practices which best
fit their particular situation. Together,
these two objectives give farmers the
best opportunity to increase profits in
an environmentally responsible
manner.
By definition,, sustainable agriculture
is a production system of BMPs that
properly utilizes inputs, both those
produced on the farm and those
purchased externally, in the most
efficient, responsible manner to
improve productivity and maximize
profitability (MEY) from a farming
operation, while minimizing any
adverse effect on the environment.
Recent applications of technology
have offered profound progress in
achieving MEY and sustainability.
Through the integration of off-the-
shelf innovations, the implementation
of MEY can be enhanced. Some of
these innovations are computers,
radio receivers, global positioning
satellites, and intensive soil testing.
The integration of these and other
components into a production system
for greater efficiency has resulted in a
number of different terms to describe
it. Some terms are precision farming,
computer aided farming, variable rate
technology, farming by the foot, and
site specific management. The follow-
ing discussion should provide an
overview of this management process
called site specific management.
Research has documented that wide
yield variations routinely occur in
fields that have always received the
same inputs. Much of the variability is
due to different soil types. However,
significant variability is found within
soil types. This is true because human
activities have had a more profound
effect on nutrient level variability than
the natural, inherent variability of soil
type. Growing economic and environ-
mental concerns are causing some
farmers and researchers to take a
closer look at individual fields when
applying inputs.
Recent production developments
have focused on the benefit of
dividing a field into small units for
more intensive, site specific manage-
ment. This procedure is called the grid
sampling approach. The field is sub-
divided into small cells of about 2.5
acres (1 ha). Soil sample cores are
collected within the cell and consol-
idated for analysis. The soil samples
are summarized and nutrient manage-
ment maps created. With this
approach, it is recognized that nutri-
ents such as nitrogen, phosphorus,
and potassium vary independently of
soil type, map units, and of each
other. Fertilizer rates and chemicals
then are varied based on the nutrient
management maps developed.
The major advantage of the grid
system is that it considers both the soil
type and field history differences.
Another advantage of the grid system
is that the intensive soil sampling
provides the best soil testing program
most farmers have ever had.
Intensive soil testing is at the heart
of this system. Individual soil samples
are taken from each grid of approx-
imately 2.5 acres (1 ha). The soil test
results are entered into computer
mapping software. The computer is
used to develop digitized field maps
by combining grids with similar
nutrient levels. At this point, fertility
management is possible on a more
site specific basis. The fertilizer rate
44 JOURNAL OF SOIL AND WATER CONSERVATION
-------
can be varied according to the
nutrient maps using manual methods
such as spot spreading, double
spreading, and manually manipulating
the controls on spreaders.
Even more important today is the
pressure being placed on the agri-
cultural community to develop high-
tech, innovative procedures to replace
more traditional farming techniques.
The concept of site specific manage-
ment (or variable rate technology,
computer aided farming, precision
farming, or whatever the term used to
describe the concept) does address
the current issues of the day compre-
hensively. By understanding the
characteristics of a field in detail and
relating these features by geographic
location, the farmer can focus on
areas that need attention and treat
them according to yield potential.
Yield potential is shown through soil
types and the nutrient grid maps.
Successful implementation of site
specific management relies on the
farmer treating each soil type or each
grid area individually instead of
treating the entire field as a single
management unit. Obviously this shift
in management approach can lead to
increased productivity because a field
is farmed according to the potential of
each small grid area.
Innovative farmers are beginning to
break away from traditional produc-
tion practices. Space-age ideas and
equipment and computer and com-
munication systems are helping
farmers move into these high-tech
methods of crop production, achiev-
ing maximum economic yields and
reducing potential environmental
impact. Dead reckoning and radar gun
systems mounted on field equipment
have been particularly useful in
establishing the sampling grids.
Likewise, they have been helpful in
positioning equipment in the field.
However, even more sophisticated
technology is being used. It is called
Global Positioning Satellite systems.
Global Positioning Satellite systems
have the greatest potential for use in
positioning fertilizer spreaders and
other farm equipment in the field at
exactly the same location, time after
time. Another feature is that exact
geographic locations can be deter-
mined at any time as the equipment
moves across the field.
Global positioning systems are a 24-
hour, worldwide, all-weather network
providing precise navigation infor-
mation to earth-based computer
systems within meters of its target.
GPS, as it is called, is a U.S. govern-
ment navigation system operating
from a constellation of 24 satellites.
Used primarily for government activ-
ities, this highly accurate positioning
system is now open to civilian use.
Because of its precise positioning of
both moving and stationary objects,
the system can be used to provide the
missing link in agricultural input
applications—the capability to pos-
ition farm equipment precisely in the
field relative to the digitized soil
nutrient maps, maps developed from
intensive grid sampling.
The satellites send radio signals at
precise intervals. Receivers on the
ground measure the delay of signals
from four or more satellites. With the
aid of computers and these radio
signals, the distances and relative
positions are calculated. The net result
is fertilizer spreader trucks with radio
receivers and computers that can
update their position as frequently as
every second. This location infor-
mation is combined with compu-
terized fertility field maps to adjust
fertilizer applications by varying the
mixtures and rates.
The use of variable rate fertilizer
spreaders or "blend on the go"
spreaders enables this concept to
work. These spreaders, with onboard
computers and radios, have up to six
compartments of different dry fertilizer
materials. The computer controls how
the materials are mixed as well as the
application rates. It also senses the
location of boundaries on the
digitized map relative to the precise
location in the field.
Dry fertilizer alone is not the only
aspect of site specific management.
The first variable rate liquid spreader
was used in the U.S. for the first time
during the 1992 season. The principle
is the same as with dry fertilizer. This
unit has only one tank so the rate of
only one liquid mix can be varied
through sets of triple nozzles across
the length of the spray boom. How-
ever, the unit has been modified by
adding an additional tank so that two
different fertilizer mixes can be varied.
The true test of the benefit of such
a. management system is crop yield.
Thus, the most recent step in this site
specific management system is the
development of monitors mounted on
harvesting equipment that record yield
using the same digitized maps. A
number of different types of monitors
are being used for the first time.
Controllers and monitors for variable
rate anhydrous ammonia, herbicides,
seed planters, liquid and dry fertilizer,
and yield are now available and
operational on a limited basis.
Obviously, the ideal system would be
the use of all these in the same field
and on the same farm.
By using both computer mapping
and satellite navigation tools, the
farmer will be able to apply inputs to
only those soils and areas which can
make the best use of the inputs. The
concept of "farming soils, not fields"
allows for precise farm management
practices by correlating soil data and
equipment positions. Future models
from continued research of this new
technology •will make use of more
detailed information about climates
and soil types. It is difficult to
correlate farmers' inherent under-
standing of their fields and specific
crop needs. Even though farmers
know that there are areas which
consistently do not produce good
yields in a field, they usually cannot
accurately define the boundaries of
these areas.
This site specific technology can
help farmers match the genetic
potential of specific crop varieties
with soil potential. The growers'
production challenge is, therefore,
threefold:
1. Agronomically sound
management.
2. Profitable production systems.
3. Environmentally responsible soil
stewardship.
In.the final analysis, science-based
technology, advanced mechanization
and crop management techniques,
together, are tools—powerful tools—
with remarkable potential for change
in our global food production
systems. Q
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 45
-------
Nitrogen testing
for optimum
management
D. H. Sander, D. T. Walters, andK.
D. Frank
Nitrogen testing for optimum
production requires a means to
predict or monitor crop N
needs both to maximize profitability
and to prevent environmental dam-
age. The complexity of the nitrogen
cycle and the uncertainty of climatic
effects on crop performance and N
availability make N testing a formi-
dable task. We address the current
technology for N testing and the
problems as well as future promises of
this technology.
Developing an ability to predict
nitrogen (N) requirement of crops has
been an important issue ever since N
fertilizers became widely available
after World War II (.15).
Prior to the development and avail-
ability of synthetic N fertilizers, the N
requirement for cereal grains was met
through crop rotation with legumes
and the judicious use of manures and
other organic wastes. In these crop-
ping systems, N was seldom in excess
supply for two primary reasons. It is
well known that N2 fixation assoc-
iated with legumes decreases as soil N
supply increases and since large
livestock confinements were rare,
manures were generally lacking for
individual farmers compared to crop
N needs. Therefore, excessive N appli-
cation causing environmental prob-
lems was limited to a few point sources.
With the advent of synthetic N
fertilizers, farmers soon began to
overestimate crop N requirements,
D.H. Sander is a professor of soil fertility
management, D,T. Walters is an associate
professor of soil management, andK.D.
Frank is an associate professor and director
of Soil Plant Analytical Laboratory,
Department of Agronomy, University of
Nebraska, Lincoln 68583-0910.
Published as Journal Series No. 10430,
Agricultural Research Division, University of
Nebraska.
and because of low N costs, tended to
apply excessive N rates in the hope of
producing additional yield and profit.
This resulted in nitrate-N contam-
ination of ground waters especially in
areas of high water tables or on sandy
soils •where nitrate-N can be easily
leached below the root zone. There is
some doubt that even economic
optimum yields can be produced
without some contamination of
groundwater ((?, 9, IS).
Methods of predicting crop N needs
through soil and plant analysis have
been widely published in research
and technical journals for well over 40
years. Much has been learned about
the chemistry and biology of N
transformations in the soil and crop N
needs. While early research objectives
were to develop N tests to predict
optimum application rates and
profitability, adoption of this tech-
nology was hampered by the very low
cost of N fertilizers. Increased interest
in N fertilizer efficiency in recent years
has been driven by public concern
about pollution of ground and surface
waters. This has made it mandatory to
justify the N recommendation system
in both economic and environmental
terms. In addition, with recent
increased emphasis on nutrient man-
agement plans, it has become
essential that those making these
plans have an understanding of
nitrogen testing. The objective of this
paper is not to do a comprehensive
literature review, but to provide an
overview of the basis for fertilizer N
recommendations and to discuss their
limitations. A number of reviews of
soil N testing have been previously
published (5, 7, 14).
Nitrogen testing systems
There are basically two N testing
systems available to predict crop N
requirements. One is based on an
estimate of the amount of N present in
the soil that will be available to the
crop. The other is to analyze the crop
for N needs. Neither is easy because
of the many factors that affect N
availability and plant performance.
Nitrogen is quite unstable in soil. Its
availability is also a function of soil
temperature, water content and micro-
bial activity, which determines the
amount and rate of available N
mineralized from organic matter and
crop residues.
Soil testing
Early research in soil testing con-
centrated on determining the potential
ability of the soil to mineralize avail-
able N from organic matter. However,
correlations between crop response to
applied N with total N and/or organic
matter content have been generally
poor (16). While mineralization rate
tests correlated well in the 1950s,
increased carryover of residual N from
fertilizer N use decreased the value of
these tests. It was soon discovered
that a measure of residual nitrate-N
carryover from fertilizer N was a quick
and practical means of predicting
fertilizer N needs. By 1970, many lab-
oratories changed to using residual
nitrate-N in the root zone or some
prescribed soil depth as a standard
soil test for available soil N.
A primary problem with using
residual nitrate-N in the root zone as a
measure of N availability is that
nitrate-N is highly mobile and moves
with water. Soil type and the amount
of water percolating through the root
zone determines the amount of
nitrate-N that will be leached from the
root zone. The nitrate-N content of the
soil is only a measure of N availability
at the time the sample is taken. It
does not indicate or measure the
ability of the soil to mineralize avail-
able N, which can be very important
on soils that receive organic residues
or manures (13)- In addition to
leaching losses, there are also gaseous
losses of N from the soil. Nitrate-N is
lost as various N oxides when the soil
has a low oxygen content such as
when soils are water-logged. Nitrogen
is also lost through volatilization
where ammonium N is changed to
ammonia. These gaseous losses can
be substantial (.10). Volatilization
losses of fertilizer ammonium and
urea N can be well over 50 percent of
that applied. Leaching can also be a
major loss pathway, especially on
sandy soils.
46 JOURNAL OF SOIL AND WATER CONSERVATION
-------
Because of the many factors
affecting soil N availability, N recom-
mendations may vary from state to
state and from one laboratory to
another. Users of N recommendations
need to recognize that because of all
the factors affecting both soil N
availability and fertilizer N perfor-
mance, predictability of actual fertil-
izer N crop requirements is highly var-
iable. While techniques for using soil
residual N testing are difficult
nationwide, the N recommendations
based on these soil tests are being
researched and improved in a number
of states.
Actually the most widely used
method of recommending N is to
simply use a factor times the expected
yield. This method of determining N
requirement completely ignores any
variability of available. N in the soil.
The factor 1.2 is often used since it
reflects an average amount of applied
N needed to produce a bushel of corn.
While this gross method is still widely
used, it is gradually being replaced or
modified by soil nitrate-N tests.
Soil tests to estimate residual nitrate-
N in the root zone have been in use
for the past 20 years, primarily in
states west of the Missouri River where
precipitation and . leaching are
relatively low (7, 22). The probability
of high leaching load in regions east of
the Mississippi River is believed to
limit the use of fall and sp'ring soil
nitrate-N as. a measure of N avail-
ability. However, root zone nitrate-N
has correlated well with yield response
to applied N in Wisconsin (3). Recent
research in Vermont and Iowa has
shown that a soil test for soil nitrate
sampled prior to sidedressing on corn
(pre-sidedress nitrate test-PSNT) has
shown good correlation with yield
response to applied N (.2, 12).
A major problem with the practical
acceptance of soil nitrate-N soil
sampling has been the sample depth
required to represent the available N
in the root zone. Most states in the
semi-arid areas have recommended
sampling depths from 0.6 to 2 m (2-6
ft). This depth recommendation has
generally limited acceptance of root
zone soil nitrate-N analysis, because
of the difficulty in obtaining a sample.
The recent PSNT test has been
Table 1. Effect of different mathematical models relating corn
grain yield to applied N on the average optimum N rate, R2, and
yield at recommended N. Average across 25 N rate experiments in
Nebraska, 1988-1992.
Model
Optimum
Ave R2 Yield at recommended N rate
QUAD
QUAD PL
LIN PL
MITS
kg N ha'1
162
177
127
194
0.51
0.52
0.49
0.50
Mg ha'1
10.85
10.79
10.79
11.29
correlated to 0.3-m (1 ft) samples,
which allows hand sampling. Samples
deeper than 0.3 m normally require
hydraulic sampling equipment which
limits sampling to soils where crops
are not actively growing. While PSNT
soil sampling deeper than 0.3 m
results in improved correlations, the
advantage has : been small and
probably is not worth the effort (J?).
Plant analysis and sensing
It is obvious that nutrients absorbed
by the plant are available. Therefore,
direct evaluation of the plant as an
, indicator of nutrient availability has
always been attractive. Much research
on plant analysis over the years has,
however, failed to provide a better
system of recommending N needed
for optimum yields than has soil
analysis. The primary problem with
plant analysis has been that plants
may,absorb much more N than is
actually required for optimum yields.
This luxury consumption makes it
difficult to determine true critical
levels. Another major problem is that
by the time the need is apparent, it
may be too late to apply N.
Recently, research has shown that
corn leaf chlorophyll content increases
in relation to applied N similar to
grain yield (If). This' has led to the
use of chlorophyll or "greenness"
sensing as a means of determining
when corn will respond to or needs
additional N fertilizer (21). This
technology is especially suitable for
sprinkler irrigated corn where N can
be applied as needed through irri-
gation water. While still in the
research phase, chlorophyll sensing
promises a system of increasing N
fertilizer efficiency beyond what can
currently be done with soil nitrate-N
sampling alone. By using this tech-
nique, N deficiencies can be detected
early enough to allow correction of
the problem with fertilization. How-
ever, the technology has limitations
for dryland crops because of the need
for precipitation soon after N appli-
cation in order to obtain N uptake.
The need to apply N in tall crops such
as corn also may limit the use of leaf
sensing under dryland conditions.
Making a fertilizer N
recommendation
While N recommendations are not
made uniformly across state lines and
vary from crop to crop, the Nebraska
algorithm for corn may be used as an
example of how a N recommendation
is made. This algorithm is based on a
total of 81 N rate experiments on
irrigated and dryland corn located
across the state of Nebraska (5).
Nitrogen recommendations for other
crops in other states as well as in
Nebraska may be based on more or
less data. Recommendations may be
based on relatively little actual field
correlation and calibration data. The
Nebraska algorithm for a fall or spring
soil nitrate-N sample is as follows:
N REC, kg ha'1 = 39.2 + 21.4(Y) -
8.96 (mg kg'1 NO3-N) -2.5 (OM)(Y)
minus other N credits
where
Y = grain yield, Mg ha"1 (5 year
average + 5 percent)
NO^-N = soil NOj-N concen-
tration averaged over at least 60
cm, mg kg-1
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 47
-------
cd
.c
O)
O
O
12.5
11.3
10.0
8.8
7.5
6.3
10.1
8.8
7.5
6.3
LIN PLATEAU
OPT N MAX YIELD
ha"' Mg ha'1
LIN PLAT 124 11.5
QUAD PLAT 180 11.5
QUAD 164 11.6
MITS 216 11.8
(b)
QUAD PLATEAU
OPTN MAX YIELD
kg ha'1 Mg ha'1
LIN PLAT 76 10.1
QUAD PLAT 114 10.1
QUAD 140 10.3
MITS 119 10.1
0 56 112 168 224 56 112 168 224
APPLIED N (kg ha"1)
Figure 1. Effect of model selection in determining the optimum
(OPT) and maximum (MAX) corn grain yields on two locations (a)
and (b) in Nebraska.
OM - soil organic matter content
in percent
Other credits include subtracting N
for previous legumes; N in irrigation
water; and N in manure.
The algorithm is easily used to
calculate a N recommendation, either
by computer or calculator or by hand.
For example, a soil with a 11.0 Mg
ha"-1- (175 bu acre"1) average yield; an
average soil nitrate level of 8 mg kg"1
(8 Rpm); and a soil organic matter of
3 percent with no N credits would
have a N recommendation of 120 kg
N ha"1 (107 Ibs N/acre).
It is apparent that the algorithm has
simplified a very complex and
dynamic soil N supplying system. It is
also apparent that the N recom-
mendation will be the same regardless
of future weather or other manage-,
ment variables such as hybrid selec-
tion, tillage, seeding rates, time of N
application, and a host of other factors
that influence the final yield obtained.
The N recommendation is made only
on the basis of expected yield, soil
nitrate-N, and organic matter content.
It is normally made before the corn is
even planted. Actual yield may be
zero because of drought, hail, insect
or disease attack, or a combination of
all of these. The major factor, weather,
is nearly impossible to predict very far
in the future. The N recommendation
has to be based on what has hap-
pened on average in the past. Since
yield is a major factor determining the
N requirement of a crop, irrigation
removes a major yield limitation
affecting N recommendations. How-
ever, because dryland yields are
highly variable, the accuracy of the
recommendation may vary, reducing
recommendation accuracy consider-
ably from year to year. This variation
actually increases the need for soil
nitrate-N testing for dryland in order
to evaluate N carryover for the
following crop.
Other N credits such as N in
irrigation water, cereals following
legumes and manure application can
greatly affect the recommendation.
Irrigation water N has been found to
substitute essentially equal to fertilizer
N. While irrigation water application
rate is unknown at N application time,
irrigation water N content in 22.5 cm
(9 in) of water is subtracted directly
from the N recommendation in
Nebraska. Legume credits usually
involve corn following soybeans or
alfalfa. Most recommendations credit
45 to 56 kg N ha'1 (40-50 Ib N acre'1)
for soybeans and 112 kg ha'1 (100 Ibs
N acre"1) for alfalfa.. Credits for
manure normally require a N analysis
with credits based on expected
mineralization rates, which varies
according to kind of manure and
method of handling.
How good is the N
recommendation?
Effect of model selection. From 1988-
92, 25 N rate experiments were
completed in Nebraska on irrigated
corn to study the value of PSNT under
Nebraska conditions. These experi-
ments were used to determine how
well we can predict the fertilizer N
requirement with our present algo-
rithm. The first step in this process is
to determine how much N is needed
at each site for optimum profit. Figure
1 shows the response curve for two
48 JOURNAL OF SOIL AND WATER CONSERVATION
-------
sites (a and b). It is apparent from
looking at the yield response to
applied N, that some curve smoothing
is required to determine the optimum
N rate. There are generally four
models that are used to fit yield
response curves: linear-plateau,
quadratic-plateau, quadratic, or
Mitscherlich. The selection of the best
model to use is not an easy decision
(.4.
Figure 1 shows the variation in the
optimum N that one would conclude
was required for each of two sites
using the four different models
discussed above. Optimum N rates
were determined for the Mitscherlich
and quadratic functions by deter-
mining the N rate which maximized
profit at a given cost/income ratio
($98.42 per Mg of corn and $0.33 per
kg N). For the linear and quadratic-
plateau, optimum N was determined
statistically. For example, in Figure Ib
the optimum N rate was 76 (68), 114
(102), 140 (125), and 119 kg N ha'1
(106 Ib N acre"1) for the linear-
plateau, quadratic-plateau, quadratic
and the Mitscherlich model, respec-
tively. In Figure la and, on the
average, for the 25 sites (Table 1), the
linear-plateau consistently had the
lowest optimum N, followed by the
quadratic, quadratic-plateau, and the
Mitscherlich. Similar to the findings of
Cerrato and Blackmer (4), the R^
(coefficient of determination) and
maximum yields determined by each
model are very similar, except the
Mitscherlich was somewhat higher.
Even though the N optimum for the
linear-plateau averaged 36 kg N ha"1
(32 Ibs N acre"1) less than the
quadratic, 50 kg N ha"1 (45 Ibs N
acre"1) less than the quadratic-plateau,
and 67 kg N ha"1 (60 Ibs N acre"1)
less than the Mitscherlich, all models
had very similar R^ values—a
common statistical measure of how
well the model fits the data. Our
purpose in showing these discrep-
ancies between the commonly accept-
ed models is not to provide a solution
to the problem, but to show how
difficult it is to determine the optimum
N application rate even with repli-
cated N rate experiments. Fortunately,
since the response curve is relatively
flat on top, this error does not
HAMILTON CO. ME 1989
50 100 150 200
APPLIED N (kg ha~1)
250
Figure 2. Corn grain yield in relation to applied N showing linear
yield response from N rate experiment in Nebraska, 1989.
generally result in large yield losses or
grossly excessive N recommendations.
However, Cerrato and Blackmer (4)
determined from their data analysis
that if the optimum was based on the
linear-plateau model and the quad-
ratic-plateau was the correct model,
the producer would have lost $47.00
ha"1 ($18.95/acre"1) by under-
fertilization of N. If the optimum was
based on the quadratic model in their
data, and the quadratic-plateau model
was correct, the producer would have
lost $16.00 ha"1 ($6.45/acre"1) from
over-fertilization. This is without any
consideration for any environmental
damage that might result from the
excessive N application.
As more research data is collected
to improve present N recommen-
dations, it is clear that response model
evaluation is an important factor in N
recommendation development, be-
cause the N rates calculated from
these models are used to derive the N
recommendation algorithm.
Effect of soil available N supply.
Some of these factors have already
been discussed, such as leaching of
nitrate-N and mineralization of N after
soil sampling, which is especially
important following cover crop incor-
poration or manure application. The
reasoning behind PSNT is to evaluate
available N status after spring leaching
and mineralization have occurred with
time remaining to apply any needed N.
Additional factors include spatial
variability of soil nitrate, which is
generally increased with fertilizer N
application and by poor irrigation
water distribution. Even nitrate-N
distribution in the root zone may
influence soil nitrate effectiveness
since nitrate enters the root primarily
. by mass flow in water. Nitrate deeper
in the root zone may have low
availability if root development is
maintained in surface soil when
frequently wetted by precipitation or
irrigation water. Methods of tillage or
degree of residue incorporation can
also greatly affect mineralization.
Effect of fertilizer efficiency. All
nitrogen recommendations must
assume a certain average effectiveness
of the fertilizer N being applied.
Nitrogen recommendations based on
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 49
-------
CD
O
O
Z
UJ
O
UJ
o:
LU
N
_]
a:
LLJ
LJ_
40 50
60
80
90 100
PERCENT OF OPTIMUM N RATE
Figure 3. Corn grain fertilizer N efficiency as affected by percent of
optimum N rate averaged across 10 locations in Nebraska, 1988-
199O. Optimum based on $98.42 Mg'1 of corn ($2.5O bu"1) and
$0.33 kg'1 N ($O.25 Ib'1 N).
field calibration experiments neces-
sarily reflect the average N fertilizer
effectiveness of all experiments in the
database. Calibration experiments
often utilize ammonium nitrate as a
preplant application to standardize the
N source and method of application.
However, there is a mass of data to
show that N fertilizer effectiveness can
vary widely depending on many
factors. Varying amounts of fertilizer N
may be lost by leaching, denitrifi-
cation, and volatilization, depending
on the temperature and precipitation
that occur after application. Sources of
N also vary in their susceptibility to be
lost by leaching or by gaseous
mechanisms.
Fertilizer N may also be effectively
removed from the available N pool by
immobilization in crop residues
depending on residue kind and
degree of incorporation.
A well-known means of increasing
N fertilizer effectiveness is to delay
application time until the crop is
approaching maximum N uptake.
Maximum N fertilizer effectiveness
usually occurs with sidedressing row
crops, topdressing small grains, and
applying through irrigation water.
Fertilizer N efficiency' is also
influenced by such factors as insects,
disease, plant genetics, and environ-
mental factors affecting plant health,
and therefore, potential yield. All of
these factors affect yield response to
applied N and one or more of the
factors is probably the reason for
linear response to applied N such as
shown in Figure 2. The various factors
that affect N fertilizer efficiency result
in above ground N uptake efficiencies
for corn of only 50 to 60 percent.
Because of the law of diminishing
returns, N use efficiency declines
rapidly as the optimum N rate is
approached (6). In Nebraska, average
irrigated corn grain N efficiency
averaged only 30 percent at the
optimum N rate (Figure 3). This data
also showed that even decreasing the
optimum N rate to only 50 percent of
optimum increased corn grain efficien-
cy to only 40 percent. This indicates
that since most N recom-mendations
attempt to recommend at the optimum
economic rate, about 60 percent of
the fertilizer N for irrigated corn is
either lost in gaseous forms, leached,
or remains in the soil as root and
stover residues, immobilized as organ-
ic forms or as available inorganic N.
Effect of soil sample variability. Any
discussion of the factors affecting soil
test N recommendations is incomplete
without some recognition of soil
sample variability (IP). Soil sample
nitrate-N variability can greatly affect
the N recommendation. Variation can
be several hundred percent, depend-
ing on soil property variation, i.e.,
texture, organic matter content, past
fertilizer history and distribution,
precipitation, and past crop yields.
Poor recommendations because of soil
sample variability can only be
controlled by obtaining adequate
sample numbers that represent the
area to be fertilized. One needs to
always recognize that soil nitrate-N
analysis will vary vertically and
horizontally as well as in time. Soil
nitrate-N content is not static, but
dynamic and constantly changing.
This change is affected by all factors
that influence nitrate-N loss and
accumulation in the soil.
Taking soil samples as suggested by
the various soil testing laboratories
and state extension services normally
provides soil nitrate-N analyses that
have errors in recommendations at a
level commensurate with errors from
other factors that effect N recom-
mendations.
How good are N recommendations?
It is probable that most N recommen-
dations based on present soil testing
procedures are no better than ± 20-30
percent of the actual N need due to
the many unpredictable factors that
affect N availability to the plant.
However, N recommendations based
on soil nitrate-N is the best tool we
currently have for recommending N
fertilizer under most conditions. It is
certainly both economically and
environmentally superior to using a
factor times yield goal to predict N
needs, a method that is still widely
used. The value of the soil nitrate-N
test increases greatly as residual soil N
increases to levels where no yield
responses occur. At these high levels,
soil nitrate-N based recommendations
go to zero, while the factor method
50 JOURNAL OF SOIL AND WATER CONSERVATION
-------
continues to recommend excessive
rates of N. Soil nitrate-N testing is
especially important for dryland
cropping where yield expectations are
often unpredictable. Soil nitrate-N
testing in these situations can
substantially reduce the following
crops' N fertilizer recommendation
and improve profitability as well as
reduce nitrate-N contamination of
ground and surface water.
The ability to establish a realistic
yield expectation is certainly a major
factor affecting the N recommen-
dation. Even under irrigation, climatic
conditions may increase or decrease
the yield by 30 percent which means
a yield goal of 11 Mg ha"1 (175 bu
acre"1) may actually range from 8 to
14 Mg ha"1 (127 to 223 bu acre"1). A
3.1 Mg ha"1 (50 bu acre"1) variability
translates into about a ± 67 kg ha"1
(60 Ib N acre"1) variation in N
requirement.
New technology
In many respects, it appears
possible that relatively little improve-
ment can be made in N recommen-
dations using current soil testing
practices for available N where
adequate databases exist. However,
research can fine-tune the soil test
system, which certainly can be made
more site specific. It is difficult to
know what impact better knowledge
can have on recommendation accu-
racy—for example, how N is immo-
bilized and released from residues and
how nitrate-N at various depths in the
root zone affects N availability. In
addition, little is known quantitatively
of how N affects cereal yields
depending on time of N uptake.
Expanded research programs can
certainly provide better N recom-
mendations when the -existing data-
base is small or non-existent, but it
must be recognized that the problem
is a difficult one and large improve-
ments are limited by factors that either
cannot be controlled, are difficult to
measure quantitatively, or are
unpredictable.
The PSNT soil test is an example of
refining the soil nitrate test to account
for changes in soil nitrate-N status
after the crop is established. By
waiting until June to take soil samples,
most mineralization and leaching has
probably occurred and time remains
for sidedressing or applying N in
irrigation water. The test appears to
do well in differentiating whether corn
will respond in yield to applied N or
not. A soil test of 21 to 26 ppm in a
0.3-m (1 ft) sample is currently the
critical level for determining whether
to apply N. How much N to apply
when the test is below 21 ppm is still
being researched.
The newest technology and prob-
ably the one with the greatest promise
for irrigated corn is chlorophyll
sensing (17, 20, 2f). Chlorophyll
content can now be sensed by a small
portable meter that senses leaf color,
which is closely related to chlorophyll
content. This method potentially
allows one to directly determine the
relative N sufficiency of a crop in time
to apply corrective action. Research
has shown that corn chlorophyll
readings as early as the sixth leaf
stage are as accurate as soil nitrate-N
tests in separating responsive from
non-responsive sites (17). This
method has promise, especially for
irrigated corn where N can be applied
in later stages of growth, providing a
method of "spoon feeding" N accord-
ing to need (.21). Plant sensing with
variable rate technology coupled to
pivot irrigation systems promises to
provide a N management system that
has the potential to improve N
fertilizer efficiency over current best N
management practices.
Summary
Predicting the N requirements of a
crop is quite difficult because of the
many factors affecting availability of N
already present in the soil and N that
may be added as fertilizer. It is
difficult for one mathematic function
to predict N need for even one crop
grown under widely varying condi-
tions of climate and soil. However,
soil nitrate tests of either the root zone
to at least a 0.6-m (2 ft) depth prior to
planting, or in early June (PSNT) to a
depth of 0.3 m (1 ft) offer much
improvement over using a factor times
the expected yield. Certainly model
fitting limitations, weather, pests, and
variable fertilizer N effectiveness limits
predictive ability of soil tests.
However, there is little doubt that
such tests can help prevent over-
fertilization, which has been a major
factor in elevated nitrate-N levels in
our groundwater. New plant sensing
techniques promise to increase N
fertilizer efficiency greatly, especially
under irrigation where N can be easily
applied late in the growing season.
Plant sensing coupled with fertilizer
variable rate technology could result
in significant improvement in fertilizer
N use efficiency, and thereby, reduce
environmental contamination and
increase profitability for producers.
REFERENCES CITED
1. Binford, G., 'A.M. Blackmer, and C.E.
Cerrato. 1992. Relationships between com
yield and soil nitrate in later spring.
Agron. J. 84:53-59.
2. Blackmer, A.M., D. Pottker, M.E. Cerrato,
and J. Webb. 1989. Correlations between
soil nitrate concentrations in late spring
and com yields in Iowa. J. Prod. Agric.
2:103-109.
3. Bundy, L.G., and E.S. Malone. 1988.
Effect of residual profile nitrate on corn
response to applied nitrogen. Soil Sci.
Soc. Amer. J. 52:1377-1383.
4. Cerrato, M.E., and A.M. Blackmer. 1990.
Comparison of models for describing
com yield response to nitrogen fertilizer.
Agron. J. 82:138-143.
5. Dahnke, W.C., and E.H. Vasey. 1973.
Testing soils for nitrogen, p. 97-114. In:
L.M. Walsh and J.D. Beaton (eds.)' Soil
testing plant analysis. Soil Science
Society of America, Madison, Wise.
6. Fox, R.H., and W.P. Piekielek. 1983.
Response of corn to nitrogen fertilizer
and the prediction of soil nitrogen
availability with chemical tests in
Pennsylvania, Bull. 843, Agric. Exp. Sta.,
The Pennsylvania State University,
University Park.
7. Hergert, G.W. 1987. Status of residual
nitrate-nitrogen soil tests in the United
States of America. In: J.R. Brown (ed.)
Soil Testing, Sampling, Correlation,
Calibration and Interpretation. Soil Sci.
Soc. Amer., Special Publ., No. 21, 144
pp., Madison, Wise.
8. Hergert, G.W. 1993. Developing a new
nitrogen recommendation for corn. Soil
Sci. News. Vol. 15, No. 3. Institute of
Agriculture and Natural Resources,
University of Nebraska-Lincoln.
9. Johnson, S.L., R.M. Adams, and G.M.
Perry. 1991. The on-farm costs of
reducing groundwater pollution. Amer. J.
Agric. Econ. 73:1063-1073.
10. Legg, J.O., and J.J. Meisinger. 1982. Soil
nitrogen budgets. In: FJ. Stevenson (ed.)
Nitrogen in Agricultural Soils. Agronomy
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Monograph No. 22., pp. 503-566. Am.
Soc. Agron., Madison, Wise.
11. Lohry, R-D. 1989. Effect of N fertilizer
rate and nitrapyrin on leaf chlorophyll,
leaf N concentration and yield of three
Irrigated maize hybrids in Nebraska.
Ph.D. Thesis.
12. Magdoff, F.R., D. Ross, and J. Amadon.
1984. A soil test for nitrogen availability
to corn. Soil Sci. Soc. Am. J. 48:1301-
1304.
13. Magdoff, F. 1991. Understanding the
magdoff pre-sidedress nitrate test for
com.]. Prod. Agric. 4:297-305.
14. Meisinger, J.J. 1984. Evaluating plant-
available nitrogen in soil-crop system. In:
R.D. Hauck (ed.) Nitrogen in crop
production. Am. Soc. Agron., Crop Sci.
Soc. Am., Soil Sci. Soc. Am., Madison,
Wise. p. 391-417.
15. Nelson, L.B. 1990. History of U.S.
fertilizer industry. Tennessee Valley
Authority, Muscle Shoals, Ala.
16, Olson, R.A., and H.F. Rhoades. 1953.
Commercial fertilizers for winter wheat
in relation to the properties of Nebraska
soils. Nebr. Agr. Expt. Sta., Bull. 172.
17. Piekielek, W.P., and R.H. Fox. 1992. Use
of a chlorophyll meter to predict sidedress
nitrogen requirements for maize. Agron.
J. 84:59-65.
18. Roth, G., and R.H. Fox. 1990. Soil nitrate
accumulation following nitrogen-
fertilized corn in Pennsylvania. J.
Environ. Qual. 19:243-248.
19. Sabbe, W.E., and D.B. Marx. 1987. Soil
sampling: Spatial and temporal
variability. In: J.R. Brown (ed.) Soil
testing, sampling, correlation, calibration
and interpretation. Soil Sci. Soc. Amer.,
Special Publ., No. 21, 144 pp., Madison,
Wise.
20. Schepers, J.S., D.D. Francis, and C.
Clausen. 1990. Techniques to evaluate N
status of com. Agronomy Abstracts. Am.
Soc. Agron., Madison, Wise. p. 280.
21. Schepers, J.S. 1993. Chlorophyll meter
-measures midseason nitrogen uptake.
Pert. Solutions, 3:44-45.
22. Stewart, B.A., D.A. Woolhiser, W.H.
Wischmeier, J.H. Caro, and M.H. Freere.
1975. Control of water pollution from
cropland. Vol. I., USDA Rep. ARS-H-5-1.
U.S. Government Printing Office,
Washington, D.C. Q
52 JOURNAL OF SOIL AND WATER CONSERVATION
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Managing Animal
Wastes
Agricultural waste
management
planning
William H.Boyd P.E.
An agricultural waste manage-
ment system (AWMS) is a
planned system in which all
necessary components are installed
and managed to control and use by
products of agricultural production in
a manner that sustains or enhances
the quality of air, water, soil, plant,
and animal resources.
In the U.S. Soil Conservation Service
(SCS), AWMSs are planned under the
umbrella of a Resource Management
System (RMS) (Figure 1). A RMS is a
unique combination of practices and
management systems that, when
applied, will protect the resource base
and environment. It provides solutions
to all identified resource problems and
meets both the decision maker's and
public's resource use, conservation,
and maintenance objectives. There-
William H. Boyd is an environmental
engineer at the Midwest National Technical
Center, USDA Soil Conservation Service,
Lincoln, Nebraska 68508.
fore, an AWMS is a subsystem of a
RMS that deals with an agricultural
waste problem. In solving an agri-
cultural waste problem, an AWMS will
interface or relate to other sub-systems
in an RMS, such as a cropping system
or a water management system.
The major objective in planning an
AWMS is to help the producer achieve
wise use of natural resources. Because
of the number of alternatives to be
considered, the planning process is
often complex; however, the AWMS
selected should be as simple and
easily managed as possible. The key
to doing this is to involve the decision
maker in the planning process.
Resource considerations
SCS soil conservationists work with
decision makers to help them recog-
nize the nature, extent, and impor-
tance of the five resources—soil,
water, air, plants, and animals (Figure
2).
Soil. The soil is often the medium
used in the final assimilation of many
of the agricultural waste products. The
application of organic agricultural
wastes benefits soil condition by
improving tilth, decreasing crusting,
increasing organic matter, and increas-
ing infiltration. Waste must be applied
to the soil so that the waste con-
stituents do not exceed the soil's
capacity to absorb and store them.
Application of wastes at a rate that
exceeds the soil's infiltration rate can
result in unwanted runoff and erosion.
When this occurs, plant nutrients in
solution and those attached to the soil
particles along with bacteria, organic
matter, and other agricultural, material
may be transported to the receiving
water.
Water. Maintaining or improving
the quality of surface and ground-
water is an important consideration in
planning an AWMS. Potential ground-
water contaminants from agricultural
operations include nitrate, salts, waste
pesticides, and bacteria. Potential
surface water contaminants from
agricultural operations are nutrients,
organic matter, and bacteria. The
usual objective in planning an AWMS
is to exclude clean water and capture
polluted water for treatment or storage
for subsequent use when conditions
are appropriate.
Air. An AWMS often has an adverse
impact on the air resource, so
planning must consider ways to
minimize degradation of air quality.
Objectionable odors from confined
livestock, waste storage areas,
lagoons, and field application of
wastes must be considered in plan-
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 53
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Other
Management
Other
Managemen
Other
Management
System
Figure 1. Relationship of an agricultural waste management
system other management systems, and the resource
management system.
ning an AWMS. Emissions of ammonia
and gases from livestock operations
are associated with acid rain. These
types of emissions are also coming
under scrutiny for their contribution to
other environmental concerns, such as
die greenhouse effect/global warming.
Air movement, humidity, and the
odors air may carry from the AWMS
must be considered. Windbreaks,
screens, or structure modification may
be required to create conditions that
minimize the movement of air.
Plants. Plants are used to recycle
nutrients, screen undesirable views,
channel or funnel wind, reduce noise,
modify temperature, or prevent ero-
sion. Plants selected for an AWMS
must be adapted to the site con-
ditions. If wastes are applied to
agricultural fields, the application
must be planned so that the available
nutrients do not exceed the plants'
need or contain other constituents in
amounts that would be toxic to plant
growth.
Animals. Obviously, an AWMS for a
livestock enterprise must be planned
to be compatible with the animals
involved. A healthy, safe environment
is essential for domesticated farm
animals. Structures are planned both
to protect the AWMS components
from the animals and the animals from
the components. Planning should also
consider hazards from disease, para-
sites, and insects. The impact on
wildlife also must be considered.
Pollution of receiving water can have
a significant effect on animals.
Organic matter can drastically reduce
dissolved oxygen levels in a stream,
and high ammonia concentrations can
kill fish. In addition, water with excess
nutrients, or contaminated by agri-
cultural chemicals, or polluted by
bacteria can result in an environment
that has a very negative effect on
animals.
Human considerations. In addition
to the resources, the social, cultural,
and economic effects of alternative
AWMSs on the human environment
are considered. SCS provides assis-
tance to help the producer comply
with federal, state, and local laws,
rules, and regulations, and to take into
account such factors as financial status
and management capabilities.
The planning process
Planning an Agricultural Waste
Management System (AWMS) involves
the same process used for any type of
natural resource management system.
The steps in this planning process are
(1) identify the problem; (2)
determine the objective; (3) inventory
the resources; (4) analyze the resource
data; (5) formulate alternative solu-
tions; (6) evaluate alternative solu-
tions; (7) determine a course of
action; (8) implement the plan; and
(9) evaluate the results of the plan.
Following is a discussion of the plan-
ner's activities and responsibilities in
each planning step as it relates to an
AWMS.
Identify the problem. Decision
makers must know what problems,
potential problems, and federal, state,
and local laws and regulations affect
their operation. This information can
help them recognize the need to
develop an AWMS that will protect the
resource base.
Determine the objectives. To plan an
AWMS that is acceptable and will be
implemented, the planner must deter-
mine the decision makers' objectives
early in the planning process. The
objectives greatly influence the type of
AWMS planned. For example, the type
of AWMS planned would be signifi-
cantly affected if the decision maker's
primary objective is to use the waste
for power generation rather than for
land application. A decision maker's
objective to bring the operation into
54 JOURNAL OF SOIL AND WATER CONSERVATION
-------
compliance with laws and regulations
may result in an AWMS that is not as
extensive as one where the objective is
to minimize the effect on the envi-
ronment and enhance public accep-
tance of the system. A decision maker's
objective to minimize management
efforts would result in an AWMS
significantly different from one that
would emphasize the role of man-
agement.
Inventory the resources. After the
objectives are determined and docu-
mented, it is time to inventory the
resources. The planner must assure
that the resource inventory data are
complete to the extent that they can
be used to develop alternatives for a
proposed AWMS. This requires an
inventory based on compilation of
data from many different sources.
Some of the required data can be
physically measured. For example, the
number of acres available for land
application of waste often can be
determined from a map. Other needed
data, such as the level of man-
agement, are less tangible and must
be determined based on observation,
discussions with the decision maker,
and judgement of the planner.
Analyze the resource data. This can
be best accomplished by viewing an
AWMS as having six functions. The
inventory data are categorized into
one of the six functions and then
interpreted, analyzed, and evaluated
in preparation for developing alter-
natives.
Formulate alternative solutions.
Alternative AWMSs are formed based
on the analysis of the inventory data
as cataloged into one of the six
functions of an AWMS. A more
complete discussion of these six
functions is presented in the next
section.
Evaluate alternative solutions.
Alternative solutions need to be eval-
uated to determine if they meet the
objectives, solve the problem, and are
socially, culturally, and economically
acceptable.
Determine a course of action. If the
preceding planning elements are
properly carried out, the decision
maker will have all of the information
available, including the private and
public objectives, on which to make
\ Erosion
\
\ Condition >
Figure 2. Resource considerations.
the needed decision. The decision
should be based on whether the alter-
native is cost effective, environmen-
tally sound, and socially acceptable.
Implement the plan. Well planned,
economically sound, and acceptable
plans have a much greater likelihood
of being implemented. Decision
makers ultimately have almost total
control over implementation. The
planner can help decision makers by
providing approved detailed construc-
tion drawings and specifications for
facilities, specific operation and
maintenance plans for each compo-
nent, and information on cost sharing
programs, low interest loans, and
other opportunities or conditions,
such as pending laws, that may affect
the decision to implement the AWMS
installation.
Evaluate the results of the plan.
Changing demands, growth, and
technological advances create a need
to evaluate an AWMS to update
objectives and modify plans. Plans
developed but not implemented
within a few years must be re-
evaluated. This requires repeating
some or all of the planning elements
to maintain a viable plan. The
implemented AWMS may need to be
fine-tuned not only because of
technical advances, but because of
what the decision maker has learned
about the system. This planning
element gives the planner an excellent
opportunity to gain experience and
knowledge that will be useful when
providing planning assistance to other
decision makers.
The total systems approach
Agricultural 'waste management
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 55
-------
Production
Collection I
Storage
Transfer
Utilization I
>^. _^f
Figure 3. Waste management system functions.
system alternatives are developed
using the total systems approach. A
total system accounts for all the waste
associated with an agricultural enter-
prise throughout the year from
production to utilization. In short, it is
the management of all the waste, all
the time, all the way. A total system
for the management of agricultural
waste consists of the following six
basic functions: (1) production, (2)
collection, (3) storage, (4) treatment,
(5) transfer, and (6) utilization (Figure
3). For a specific system these
functions may be combined, repeated,
eliminated, or arranged as necessary.
Production refers to the amount
and nature of agricultural waste
generated by an agricultural enter-
prise. Waste requires management
when enough is produced to become
a resource concern. A complete
analysis of production includes the
kind, consistency, volume, location,
and timing of the waste produced.
The production of waste should
always be kept to a minimum. For
example, a large part of the waste
associated with many livestock oper-
ations includes contaminated runoff
from open holding areas. The runoff
is reduced by restricting the size of
open holding areas, roofing part of
the holding area, and installing gutters
and diversions to direct uncontam-
inated water away from the waste. A
proverb to remember is, "Keep the
clean water clean." Leaking watering
facilities and spilled feed also
contribute to waste production. These
problems are reduced by careful
management and maintenance of
feeders, watering facilities, and
associated equipment. The waste
management system also accom-
modates seasonal variations in the rate
of production, and considers fixed
expansion of the operation. A record
should be kept of the data, assump-
tions, and calculations used to deter-
mine the kind, consistency, volume,
location, and timing of the waste
produced.
Collection refers to the initial
capture and gathering of the waste
from the point of origin or deposition
to the collection point. The AWMS
plan identifies the method of collec-
tion, location of the collection points,
scheduling of the collection, labor
requirements, necessary equip-ment
or structural facilities, manage-ment
and installation costs of the compo-
nents, and the impact that collection
has on the consistency of the waste.
Storage is the temporary contain-
ment of the waste. The storage facility
of a waste management system is the
tool that gives the manager control
over the scheduling and timing of the
system functions. With adequate
storage the manager has the flexibility
to schedule the land application of the
waste when the spreading operations
do not interfere with other necessary
tasks, when weather and field con-
ditions are suitable, and when the
nutrients in the waste can best be
used by the crop. The storage period
is determined by the utilization
schedule. The waste management
system plans identify the storage
period, the required storage volume,
the type of storage facility, the
estimated size of the facility, the
location of the facility, the installation
cost of the storage facility and the cost
of management, and the impact of the
storage on the consistency of the
waste.
Treatment is any function designed
to reduce the pollution potential of
the waste, including physical, bio-
logical, and chemical treatment. It
includes activities that are sometimes
considered pretreatment, such as the
separation of solids. Plans include an
analysis of the characteristics of the
waste before treatment and a
determination of the desired charac-
teristics of the waste following
treatment; the selection of the type,
estimated size, location, and the
installation costs of the treatment
facility; and the management cost of
56 JOURNAL OF SOIL AND WATER CONSERVATION
-------
the treatment process.
Transfer refers to the movement
and transportation of the waste
throughout the system. It includes the
transfer of the waste from the collec-
tion point to the storage facility, to the
treatment facility, and to the utilization
site. The waste may require transfer as
a solid, liquid, or slurry, depending on
the total solids concentration. The
system plans include an analysis of
the consistency of the waste to be
moved, method of transportation,
distance between points, frequency
and scheduling, necessary equipment,
and the installation and management
costs of the transfer system.
Utilization is the recycling of
reusable waste products and the
reintroduction of nonreusable waste
products into the environment. Agri-
cultural wastes may be used as a
source of energy, bedding, animal
feed, mulch, organic matter, or plant
nutrients. Properly treated, it can be
marketable. The most common prac-
tice is to recycle the nutrients in the
waste through land application. A
complete analysis of utilization
through land application includes
selecting the fields, scheduling appli-
cations, designing the distribution
system, selecting necessary equip-
ment, and determining application
rates and volumes, the value of the
recycled products, and the installation
and management costs associated with
the utilization process.
The functions are accomplished by
implementing and managing individ-
ual components. The components
may be an interrelated group of
conservation practices, such as a
waste storage pond, roof runoff water
management, diversion, and waste
utilization. Push-off ramps, manure
pumps, transport equipment, grade
control structures, and vegetative
treatments are examples of compo-
nents that support the function.
The -waste management plan
The best waste management system
is of little value and has the potential
for much harm if it is not properly
managed and maintained. Also, the
owner of the waste management
system is often subject to fines and
litigation if unable to provide ..docu-
mentation for the rationale of the plan
and the procedures followed in
operation and maintenance. For this
reason it is recommended that the
owner be provided with the following
set of documents which constitute the
waste management plan.
« A narrative description of the
management of the -waste from
production to utilization.
• A set of "as build" plans and
construction specifications for the
components installed to imple-
ment the plan.
« A copy of pertinent correspon-
dence including agreements and
permits.
• A written operation and mainten-
ance plan describing the upkeep
and management of the system
and the individual components in
a safe manner so that it functions
as intended throughout its design
life.
Properly done, the AWMS plan
guides the actions of the producer in
a way that enables the producer to
utilize the waste while protecting the
natural resources. Q
Best management
practices for
livestock
production
L. M. So/ley, Jr. P.E.
Livestock production is a major
component of agriculture in the
U.S. However, the livestock
industry faces significant environ-
mental challenges, which have risen
from increased public awareness and
desire by the public for aesthetic and
environmental protection. On one
L.M. Safley, Jr. is a professor in the
Department of Biological and Agricultural
Engineering, North Carolina State University,
Raleigh 27695-7625.
hand, fewer people in the U.S. are
directly involved with livestock
production and there is less sensitivity
to the problems that livestock
producers face. On the other hand,
there is a trend to develop larger,
more sophisticated livestock produc-
tion facilities which can be more
visible. Livestock producers must
develop strategies for managing waste
materials in a manner that will
minimize the potential for offensive-
ness and environmental degradation.
This paper will identify several
management practices that livestock
producers should consider carefully.
Because each livestock enterprise is
unique, there is no one specific waste
handling system that will meet all
needs. Rather, a specific set of
management practices must be
adopted by each producer.
Primary environmental concerns
There are two primary environ-
mental concerns facing livestock
producers, nutrients and odor.
Many livestock producers import
the majority of feed materials con-
sumed on a given site. Only a portion
of these nutrients are retained by the
animal. The remaining nutrients pass
to the waste treatment/storage system
where additional loss can occur. The
nutrients left after waste treatment
should not exceed the assimilative
capacity of the receiver site.
Some odor can result from livestock
production. When odor causes neigh-
bors to initiate litigation and/or
production restrictions, livestock
producers face real problems. Live-
stock producers will have to locate
future facilities in low population
density areas or develop technology
for superior odor control.
Developing a waste management
system
During the planning of any
livestock enterprise considerable
thought should be given to devel-
oping an appropriate waste manage-
ment system. The system must accom-
plish the following:
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 57
-------
• timely waste collection
• adequate waste treatment and/or
storage
• efficient land application
• utilization/management of
nutrients
It is important for the producer to
realize the capabilities and flexibility
of a waste management system prior
to committing the resources to
develop it. All system components
should be designed with the pro-
ducer's objectives in mind. The pro-
ducer must also be aware of the
operating costs associated with the
waste management system:
• Processing waste
• Land application of waste
• Equipment maintenance
• Planting and harvesting crops
• Waste analyses
• Record keeping
Site selection
A waste management system must
be developed around a given tract of
land. Each tract of land has its own set
of attributes. Site selection is probably
the most critical element in devel-
oping a livestock enterprise. A
number of factors that should be
considered when evaluating a site
relative to waste management are
discussed below.
Geology
• Are there any limitations to
constructing lagoons or earthen
storage basins (e.g. depth to
bedrock, Karst areas, excessive
sand)?
• What is the clay content of the
soil?
• How deep is the water table? Does
it vary throughout the year?
Land
• How much land is available for
applying waste materials?
• What types of crops can be
grown?
• Is the land adequate to
accommodate all of the nutrients
to be applied?
• What is die background level of
soil nutrients?
Location
• What is the proximity to wells,
streams, ponds, churches,
businesses, schools, and
residences?
• What type of agriculture is
practiced adjacent to the site
(livestock, row crop, etc.)?
• Are the neighbors sympathetic to
livestock production?
• How visible will be the livestock
production facilities, the lagoons
or waste storage units, and the
land that will receive the waste?
• What is the likelihood of future
development within two miles of
the site's boundaries?
Climate
• What is the mean ambient
temperature by month? What is the
mean monthly rainfall?
• What is the prevailing wind
direction?
• What is the natural air drainage
pattern (especially for conditions
of calm wind and high humidity)?
Prior to purchasing a tract of land a
careful appraisal should be made of
the site considering the factors
identified above.
Livestock nutrient production
The quantity of nutrients excreted
by livestock is directly influenced by
diet. This is a very important obser-
vation for two reasons. First, reduced
nutrient excretion implies increased
nutrient utilization for a given level of
performance and this translates into
reduced production cost. Second, a
reduction in the amount of nutrients
produced reduces the amount of land
required for application of manure.
Probably the simplest example of
the impact of managing feed nutrients
relative to manure nutrients can be
seen in a model of nitrogen utilization
by a mature lactating cow. Equation 1
predicts the nitrogen in manure as a
function of nitrogen intake and milk
production:
Nmanure = Nfeed - Nmilk
[1]
This model was first suggested and
validated by Boussingault (2) for
maturing lactating dairy cattle being
fed a ration to maintain body weight.
The model is now accepted as the
basis for nutrient balance research in
all mammals (.12, 16). Using the
model, Safley, Westerman, and Barker
(.13) determined that approximately 75
percent of the ingested feed nitrogen
was excreted for mature, lactating
dairy cattle.
Schatzchen and Kuhl (14) have
estimated that 76 percent of the feed
nitrogen in a large swine facility was
excreted.
The simplest way of reducing
manurial nutrients is to improve feed
efficiency. This can be accomplished
by reducing feed loss or altering the
ingredient blend in feeds. For exam-
ple, a 5 percent feed loss in swine
production translates into an increase
in excreted volatile solids of approx-
imately 46 percent (Earth, 1985).
European research (7, 9*) has
suggested several possibilities for
reducing nitrogen in swine manure.
The first option is to improve effi-
ciency. A reduction in feed conversion
of 0.5 units translates into a 10-15
percent reduction in nitrogen excre-
tion. Another option is that of phase
feeding. In phase feeding, finishing
swine are fed a reduced protein diet
as they approach market weight.
Another option is to balance a ration
using synthetic amino acids. This has
the impact of reducing the protein in
the ration. Using soybeans as the
principal protein source will lead to
"over feeding" of certain amino acids
(lysine, tryptophan, threonine, etc). It
may be possible to reduce nitrogen
excretion in urine by more than 25
percent if synthetic amino acids are
used. However, economics will dictate
the feasibility of this option. Hall et al.
(3) have found nitrogen excretion
reductions in the range of 40 to 50
percent with the use of feed grade
amino acids with no apparent reduc-
tion in animal performance.
Nitrogen is not the only nutrient of
concern to the environment. Phos-
phorus is also coming under increased
scrutiny. The state of Ohio now
suggests that manure applications
should be made on the basis of
meeting crop phosphorus needs. This
typically increases the amount of land
required by 50 to 100 percent as
compared to nitrogen. Only 14-15
percent of the phosphorus in a corn-
soybean ration is available to finish
58 JOURNAL OF SOIL AND WATER CONSERVATION
-------
swine (3). The remainder is excreted
in the feces. Research has indicated
that the addition of microbial phytase
has increased phosphorus utilization
(4, 6, 8). This could lead to reduced
amounts of excreted phosphorus and
other nutrients (calcium, etc.).
Lindemann (Iff) has conducted
research in Virginia on reducing nitro-
gen and phosphorus excretions from
swine. Large differences have been
found in feed efficiency within a given
herd of swine that exhibit similar
growth rates. This would suggest the
need for evaluating the genetic
potential of livestock for nutrient
utilization efficiency. Other ideas
being considered include split-sex
feeding and changes in diet to match
environmental conditions. Lindemann
et al. (.11*) has suggested that the
addition of chromium to swine diets
can improve feed efficiency by
approximately 6 percent and at the
same time accomplish improvement in
carcass measurements.
Research on reducing nutrient
excretion has been conducted with
caged layers (.15). It was determined
that the use of methionine along with
reduced protein inputs could reduce
nitrogen excretions by 16 percent.
Reduction in phosphorus levels in the
diet also lead to significant reductions
in excreted phosphorus.
There has even been discussion of
developing "designer" grains that
would be more digestible (Charles
Murphy, University of Maryland, 301-
504-5560) and, therefore, reduce
nutrient excretion when fed to
livestock.
Nutrient losses during collection,
treatment, storage, and land
application
A critical element required in the
evaluation of a given site is an
estimate of the quantity of nutrients
that will be produced by the waste
system. An appreGiable amount of the
nitrogen in manure can be lost
(become unavailable) in certain waste
management components (anaerobic
lagoons, irrigation, etc.). Considerable
quantities of phosphorus can be
concentrated in the sludge in lagoons
that is only periodically removed. It is
a good idea to seek the advice of
professionals that routinely work in
livestock waste management when
developing an estimate of the effective
amounts of nutrients that must be
managed from a given livestock
enterprise.
Waste management plan
Every livestock enterprise should
develop a comprehensive waste
management plan. This may be a
requirement of the permitting process.
Development of a waste management
plan typically identifies most potential
problems associated with a given
enterprise. Such knowledge is
essential. A well-developed, well-
executed waste management plan is
one of the livestock producer's most
valuable tools.
The following should be included
in waste management plans:
Livestock population. Identify the
type, number, and mean live weight
of the livestock. This information is
essential to any planning process.
Schematic of production facilities.
• All production facilities should be
identified on a site sketch. All waste
management system components
(pipes, storages, etc.) should be
identified.
Facility map. A map should be
prepared that identifies the boundaries
of the enterprise and the surrounding
land. Often a USGS topographical
map can be used. An ASCS aerial map
may also be useful.
System design. A file should be
initiated that will contain information
on any professional design work (SCS,
Cooperative Extension Service, private
practice engineers, equipment manu-
facturers, etc.) that has been done on
the waste management system. This
may include the design work done on
lagoons or other components. In
addition, literature, specifications, and
other information on any manure
management system equipment
(pumps, spreaders, etc.) should be
retained for ready reference.
Permit file. A copy of any permit
materials and related correspondence
should be maintained in a separate
file. The producer should be thor-
oughly familiar with all requirements
(especially reporting) of the permit.
Waste management calendar. Every
livestock enterprise should have some
type of calendar that identifies
pertinent waste management activities:
permit renewal, reports due, analyses
schedules, estimated dates of waste
application, etc. Someone should be
responsible for making sure that the
calendar activities are appropriately
managed.
Land receiving waste. A map should
be prepared that identifies each field
that will receive waste. Each field
should be uniquely identified to
facilitate communication. The crop-
able acreage, soil type, and any
agronomic limitations (seasonal high
water, excessive slope, etc.) should be
identified. A table should be prepared
that identifies all of the fields.
Cropping plan. A cropping plan
should be developed that identifies.
the acreages of crops that will be
produced for a given year. It is a good
idea to have at least a preliminary
plan for the crops to be produced for
one to two subsequent years. This will
aid in managing crop rotations. The
potential nutrient uptake (N, P, and K)
of each crop should be identified.
This information should be available
from the Cooperative Extension
Service. A simple computation should
be made to determine the probable
amount of each nutrient that should
be assimilated for all of the crops that
will receive waste during the year.
These figures can be compared with
the estimates of nutrients that will be
applied routinely during the same
time period. The goal is to have
sufficient land to utilize the nutrients
produced.
Field records. An annual record
should be maintained for each field
that includes the following infor-
mation:
• crop grown
• yield
• important crop dates—planting,
harvesting, waste application, etc.
• amount of waste applied
• application of any commercial
fertilizers
Waste production and charac-
teristics records. A file should be
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 59
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established that records the amounts
of waste materials that are removed
from storage/treatment. This can be
compared to the records being main-
tained for land application. Periodic,
representative waste samples should
be collected and analyzed. Copies of
the lab reports should be retained and
used to determine the quantities of
nutrients removed/land applied.
Typical analysis parameters include
• TKN—total Kjeldahl nitrogen;
includes organic nitrogen and
ammonia nitrogen
• Ammonia-N—ammonia nitrogen;
can be readily used by plants
• Nitrate-N—nitrate nitrogen; can
also be used by plants; an analysis
for nitrate-N is needed only if the
waste has been treated aerobically
• P—phosphorus
• K—potassium
• TS—total solids
Soil and crop samples. Represen-
tative samples of crops from each field
should be collected and analyzed.
This information, along with the yield,
can be used to estimate crop nutrient
uptake. At the end of the growing
season, soil samples should be
collected from each field that received
waste during the year. The analytical
results should be compared to those
from previous years for a given field.
The above information can be used to
evaluate the effectiveness of the waste
management scheme and changes can
be made as needed.
Monitoring well records. If mon-
itoring wells are required by a permit,
the sampling schedule should be
closely followed. It is a good policy to
collect water samples periodically
from existing wells in the vicinity of
the livestock production facilities and
the fields that receive waste. Well
water samples typically are analyzed
for nitrate nitrogen and pathogenic
bacteria.
Permits for waste management
systems
Several states now require livestock
producers to obtain permits for waste
management. Much of the information
identified above typically will be
required. The permitting process
(collecting the information needed
and evaluation by regulatory agency)
can be time-consuming. In many
cases the permit has to be issued prior
to construction. Therefore, producers
should investigate the requirements of
the permitting agency in a given state
and plan accordingly.
Once the permit has been received,
the producer should read it thor-
oughly. Most states allow a period of
review and discussion before the
permit is final. In some cases it may
be in the best interest of the producer
to challenge certain assumptions
(nutrient uptake, etc.) used in
developing the permit. However, the
producer typically will have to
support his/her position thoroughly.
Nutrient management
For planning purposes the phos-
phorus and potassium in livestock
waste can be considered equivalent to
that found in commercial fertilizers.
However, not all of the nitrogen that
is applied can be considered plant
available. Frequently a decision has to
be made with regard as to how the
nutrients in livestock will be managed
since the concentrations of the
individual nutrients are rarely in the
required proportions. Therefore, some
nutrients may be applied in excess.
Phosphorus and potassium are
frequently applied in excess of
immediate crop needs when using
livestock waste as the sole source of
nutrients. This is not necessarily bad.
However, annual soil samples should
be taken from all fields receiving
livestock waste to see if nutrient
imbalances are developing.
The following equation can be used
to estimate the plant available portion
of the nitrogen in livestock waste:
PAN = (MR X (TFN-NH3-N)) + ((1-
VR) X NH3-N) + N03-N
where
PAN—plant available nitrogen
MR—mineralization rate (organic
nitrogen converted to inorganic
nitrogen)
TKN—total Kjeldahl nitrogen
concentration
NH3-N—ammonia nitrogen
concentration
VR—volatilization rate; amount of
ammonia nitrogen lost during
application
NOg-N—nitrate nitrogen concen-
tration
Laboratories can differ in the
reporting units used, which can be
confusing. The producer should
request that the analytical reports be
prepared using units that are most
useful to the producer. Frequently
laboratories use the concentration
units of ppm (parts per million) or
mg/1 (milligrams per liter). These
terms are the same for liquid samples
(as received basis).
There is some debate with regard to
what value for MR should be used. In
general, the fresher the waste material
the higher the MR. The MR for freshly
excreted waste typically ranges from
0.35 to 0.5. Waste that has been
through some type of treatment
(aerobic or anaerobic) will have a
lower MR—typically 0.2 to 0.35. The
IF can also vary. For injection of waste
the IF is in the range of 0.05 to 0.10.
For irrigated lagoon liquid the IF, is
typically assumed to be 0.5. It is
suggested that the Cooperative Exten-
sion Service be consulted with regard
to appropriate MR and VR values for a
given system and climate.
Estimates of nutrient application
should be taken from published
sources during the initial planning
process. As soon as waste material is
removed from a facility, representative
samples should be collected and the
information used to determine actual
application rates. Apparently similar
waste systems have been found to
have significantly different waste
characteristics. This difference is a
function of variation in management
and feeding programs. A database of
waste characteristics should be
developed for a given enterprise. This
information is essential to proper
waste management.
Odor management
Some odor is a natural part of
livestock production. Given this fact, it
would be best to locate livestock
production facilities away from
potentially complaining neighbors.
60 JOURNAL OF SOIL AND WATER CONSERVATION
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Odor should always be a primary
siting consideration. However, there is
almost always the potential for
someone being offended. Odors can
come from production facilities as
well as waste treatment/storage units.
Sometimes it is difficult to determine
the exact source of odor.
Odor management as a part of
waste treatment begins with design.
Underdesigned lagoons will generate
more odor than properly designed
lagoons. The additional cost asso-
ciated with larger lagoons can be
offset by the reduction in odor
potential.
There are numerous products on
the market that make claims regarding
odor control/reduction. However, few,
if any, of the manufacturers of these
products can support their claims with
scientific evidence.
Floating covers have been placed
over a few lagoons to help reduce
odor. However, this alternative should
only be considered as a last resort due
to the expense of the covers. How-
ever, if an anaerobic lagoon must be
covered, the cover design should
allow for harvesting of the biogas.
There is some potential for utilizing
biogas as a fuel. However, the eco-
nomics of covering anaerobic lagoons
for biogas collection and utilization
have not been fully developed.
Other important best management
practices
Visual buffers. Visual buffers can
reduce complaints from neighbors and
passersby. Such buffers should be
established prior to or during con-
struction. If possible, locate waste
management systems using natural
visual buffers (trees, topography, etc.).
Vegetative buffers. Vegetative
buffers should be implemented
around all fields receiving waste.
Vegetative buffers will reduce the
potential unanticipated runoff leaving
the field. All waste application systems
should be planned to promote rapid
incorporation of the waste into the
soil. Vegetative buffers serve mainly as
a second line of defense. They can
help strip nutrients from the runoff.
Appropriately designed treatment/
storage units. Some producers want to
determine the size of treatment and
storage components using the smallest
possible recommendation. This typi-
cally can lead to problems with odor,
excessive nutrient and sludge buildup,
and application scheduling.
Runoff control. Absolutely no mnoff
that has passed through feedlots or
otherwise made contact with livestock
manure should flow into any water-
way or drainageway. Collection ponds
and vegetative buffers should be used
to help manage runoff.
Soil Conservation Service BMPs
The USDA Soil Conservation Service
Best Management Practices (BMPS)
typically associated with livestock
production are identified as follows:
SCS Practice Name Code
Compost facility 317
Conservation cropping
sequence 328
Conservation tillage 329
Contour farming 330
Controlled drainage 335
Critical area planting 342
Dike 356
Diversion 362
Fencing 382
Field border 386
Filter strip 393
Grassed waterway 412
Heavy use area protection 56l
Irrigation water management 449
Lined waterway or outlet 468
Mulching 484
Nutrient management 590
Pasture and hayland
management 510
Pond , 378
Pond sealing or lining 521
Roof runoff management , 558
Sediment basin 350
Structure for water control 587
Subsurface drain 606
Field ditch 607
Main or lateral 608
Terrace 600
Underground outlet 620
Waste management system 312
Waste storage pond 425
Waste storage structure 313
Waste treatment lagoon' 359
Waste utilization 633
Water and sediment control
basin 638
Water table control 641
Summary
Livestock waste management
systems must be developed for
individual enterprises. Adequate
planning, development, and imple-
mentation of a waste management
plan will allow producers to operate
in ways that minimize the potential for
environmental degradation and pro-
tect the investment made in the entire
production'facility. Producers must
exercise the initiative and be willing
to commit the needed resources to
manage livestock waste.
Reducing the quantity of nutrients
excreted by livestock will positively
impact profitability and reduce the
potential for environmental problems.
REFERENCES CITED
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2. Boussingault, J.B. 1839. Analyses
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d'examiner si les animaux herbivores
enpruntent de I'azote a I'atmosphere.
Ann. Chem. et Phys. 71(2), 113-127.
3. Cromwell, G.L. 1991. Feeding phytase to
increase the availability of phosphorus in
feeds for swine. Proc. 52nd Minnesota
Nutrition Conference, pp. 189-200.
4. Cromwell, G.L., T.S. Stahly, and J.H.
Randolph. 1991. Effects of phytase on the
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Anim. Sci. 69 Suppl. 1) :385 (Abstr.).
5. Hall, D.D., A. Madsen, and H.P.
Mortenson. 1988. Protein og aminosyrer
til slagtesvin. 3- Balancefors0g med
forskellige forhold mellem treonin og
lysin. Beretning fra Statens
Husdyrbrugsforsog #639. Cited in
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6. Jongbloed, A.W., Z. Mroz, and P.A.
Kemme. 1992. The effect of supple-
mentary Aspergillus nigerphytase in diets
for pigs on concentration and apparent
digestibility of dry matter, total
phosphorus and phytic acid in different
sections of the alimentary tract. J. Anim.
Sci. 70:1179.
7. Koch, F. 1990. Amino acid formulation
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to Improve carcass quality and limit
nitrogen load on ivaste. Proc. of the
North Carolina Swine Nutrition
Conference, pp. 76-95.
8. Lei, X.G., P.K. Ku, E.R. Miller, D.E.
Ullrey, and M.T. Yokoyama. 1992.
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phytase phosphorus in corn-soybean
meal diet for weanling pigs. ]. Anim. Sci.
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excretion in pig husbandry by feeding:
current and future possibilities. Neth. J.
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10. Lindemann, M.D. 1993. A feeding
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phosphorus in ivaste. Proc. of 37th North
Carolina Pork Producers Conference, pp.
69-76.
11. Lindemann, M.D., C,M. Wood, A.F.
Harper, and E.T. Kornegay. 1993.
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J.C. Barker. 1986. Fresh manure
characteristics and barnlot nutrient
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88-98. Q
Methane
production from
animal wastes
Andrew G. Hashimoto, Thorn G.
Edgar, and Hiroshi Nakano
The anaerobic digestion process
has been used since the early
1900s primarily to treat sewage.
Methane was a by-product that was
occasionally used to heat buildings or
generate electricity. The renewed in-
terest in anaerobic digestion has been
directed toward evaluating its feasi-
bility for converting biomass feedstock
into energy. In the U.S., initial efforts
to commercialize anaerobic digestion
technology for converting biomass to
energy and other products have been
primarily focused on livestock
enterprises. This paper describes
general considerations for commer-
cializing this technology and describes
our efforts to design and construct a
centralized anaerobic digestion facility
to convert dairy manure into electrical
energy and fertilizer.
General considerations
Most commercial anaerobic diges-
tion systems are operated at meso-
philic temperatures (90° to 95°F) with
retention times ranging from 0.25 to
0.45 lb (0.11-0.2 kg) volatile solids
(VS) per ft^ per day. Methane pro-
duction rates from these systems
range from 0.8 to 1.2 ft3 (0.02-0.03
mg) CHyft^ day digester.
Both upright steel tanks and trench-
type, plug-flow digesters have been
used. The type of digester has no
apparent effect on the design reten-
tion time or loading rate.
Typical capital cost for major com-
Andrew G. Hashimoto is a professor and
department head, and Thorn G. Edgar is a
former research assistant in the Department
ofBioresource Engineering, Oregon State
University, Coruallis 97331- Hiroshi Nakano
is an international business specialist at
Unisyn Biowaste Technology, Seattle,
Washington 98109.
ponents of a manure digestion system
are: manure preparation and storage,
16 percent; digester, 42 percent;
engine-generator, 30 percent; and mis-
cellaneous, 12 percent. These are gen-
eral guidelines and the relative per-
centages can vary considerably. For
example, the engine-generator can be
up to 50 percent of the total cost for
small plants, and the manure prepa-
ration and storage component may be
much higher if sludge thickeners or
size reduction equipment are needed.
Products. Biogas is being used in
various ways. The majority of plants
convert biogas to electricity. However,
several plants use the biogas as boiler
fuel for a steam flaker, dehydrators,
meat packing plant, or alcohol still.-
The ultimate use of the biogas
should be based on local energy
demands and relative values of the
different forms of energy. If there is a
large local demand for thermal ener-
gy, then this alternative is generally
the most economical since the capital
and operating costs for engine-gener-
ator sets can be avoided. However,
for the majority of plants and most on-
farm applications, biogas production
generally exceeds the farm's thermal
energy demand during most of the
year, and it is not economical to store
biogas for seasonal use. Thus, many
farmers have decided to convert
biogas into electricity.
Electricity generation is attractive
because the biogas can be converted
as it is produced. This alleviates the
need to store the biogas for long
periods, and any excess electricity can
be sold to an electrical utility. The
price received from the sale of
electricity varies considerably between
states and utilities. In most cases, the
utility pays only a fraction of the rate
they charge farmers for the use of
electricity. Thus, it is important to use
as much of the generated electricity
on the farm as possible and minimize
the amount sold to the utility. To
accomplish this, farmers may elect to
manage their energy demands to
match their energy production (load
leveling) and/or produce energy to
meet periods of high energy demand
(peak shaving).
Digester effluent is being used in
several different ways. The predom-
62 JOURNAL OF SOIL AND WATER CONSERVATION
-------
inant uses are as fertilizer, livestock
feedstuff, and livestock bedding. The
digestion process does not affect the
concentration of the major nutrients
(nitrogen, phosphorous, and potas-
sium). Thus, the digester effluent .has
the same fertilizer value as the influent
manure, although some farmers feel
that the effluent is a better fertilizer
because a higher portion of the total
nitrogen is in the more readily avail-
able ammonia form.
Digested solids are being separated
by centrifuging, screening, and/or
pressing. In some cases, mildly cation-
ic polyelectrolytes are being used to
increase solids capture efficiency. The
solids are being used as livestock
feedstuff or bedding.
The value of the digester effluent as
a livestock feedstuff ranges from $20
to $100 per ton. These values were
generally estimated by the value of
the feedstuff that the digested solids
replaced in the ration, with some
discount for the lower digestibility of
the effluent solids. Using digested
solids for bedding is gaining popu-
larity in dairy operations because of
the increasing cost of traditional
livestock bedding.
Incentives. Several state and federal
incentives are available for using
anaerobic digestion systems. The
Oregon Department of Energy offers a
35 percent Business Energy Tax Credit
for equipment and installation costs,
and a Small Scale Energy Loan Pro-
gram that will finance projects like
these at interest rates below commer-
cial rates. An additional 10 percent
federal pollution tax credit is avail-
able. The proposed federal investment
tax credit would also be an incentive
to construct these systems. In add-
ition, accelerated depreciation sched-
ules may be available. The Public
Utilities Regulatory Policies Act of 1978
states that all utility companies must
purchase electric power from private
facilities at an avoided-cost rate.
Barriers to commercialization. Most
of the firms that build digesters feel
that the major barrier to commer-
cialization is financial rather than
technical. The economic conditions in
the U.S. during the 1980s (low energy
prices and high interest rates) have
caused some enterprises to delay
installing anaerobic digestion systems.
Other enterprises wishing to install
digestion systems have not been able
to secure financing because of the
perceived high risk of these systems.
With the recent improvement in the
economy and examples of successful
anaerobic digester operations, more
interest has been generated for instal-
ling these systems. Also, recent projec-
tions about energy shortages by the
end of this century has renewed inter-
est in alternate energy sources.
Even if an anaerobic digestion
system is economically feasible for a
livestock enterprise, other factors must
be considered before installing a
system. The additional labor and man-
agement needed to operate and main-
tain the system must be considered in
relation to other labor demands of the
enterprise. For a fairly well automated
plant, one or two hours per day
would be sufficient to monitor the
operation of the plant. However,
when more sophisticated management
strategies are imposed, such as gener-
ating electricity, only at high demand
periods, more time must be devoted
to the operation of the plant.
Effluent from the digester must be
handled and ultimately disposed of in
an. environmentally sound manner.
Although the digestion process
removes most of the organic matter in
the manure, the effluent from the
digester still contains many of the
other nutrients and oxygen demand-
ing substances that must be disposed
of properly.
In summary, it is clear that methane
can be recovered from livestock
manure. The majo'r questions are
whether the process is economically
feasible for a particular farm and if the
process fits in with the overall oper-
ational objectives of the farm. The
process appears to be feasible for only
relatively large farms. However, the
need for alternative sources of energy
will become more acute in the next
decade and this may improve the
economic feasibility of the process for
smaller farms.
Tillamook feasibility study
Background. Tillamook County is
located on the northwest coast of
Oregon and is the largest producer of
milk and shellfish in the state.
Approximately 30 percent of all
Oregon dairies are located in the
county. The dairy industry contributes
about $62 million from milk pro-
duction alone to the local economy.
All but two of the dairy farms in the
county are members of a dairy coop-
erative, the Tillamook County
Creamery Association (TCCA).
With the expansion of the Tilla-
mook Creamery in 1990 to double (or
more) its previous cheese production
capacity, the opportunity exists for the
members of the TCCA to increase the
county's milk production. However,
before the 191 area dairies can
. increase their dairy herd size, the
problem of manure management must
be addressed. With the current cow
population already producing about
195 tons of total manure solids daily,
there is a history of water quality
problems in the county watersheds.
There are concerns about pathogens
attributable to livestock and other
sources. Intermittent elevated coliform
counts in the oyster harvesting areas
of Tillamook Bay have resulted in
fishing closures of the bay and fines
to the TCCA.
Nitrogen is also perceived to be a
potential threat to public health.
Estimates indicate that the nitrogen
loading rate to the agricultural pasture
lands of the county is approaching
agronomic limits. The region's high
rainfall (more than 90 inches [229 cm]
annually), poor draining soils, and
high water table pose environmental
limits on agricultural practices that
cannot be easily improved by conven-
tional methods. Any plan to increase
animal numbers significantly must
include alternatives of managing
manure. Waste management alterna-
tives must responsibly account for
pathogens and nitrogen in excess of
the crop uptake rate. The stream
bacteria standard is 200 fecal coliforms
(FQ/10.0 nil and the bay standard is
14 FC/100 ml. Even after dilution from
rainwater, fecal coliform counts from
1,000 FC/100 ml to over 6,000 FC/100
ml have been measured during the fall
months in Tillamook area waterways
(.2). Progress has been made in recent
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 63
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years with improving manure manage-
ment in area dairies, but the fecal
coliform problem is not yet fully
resolved.
Because of these concerns, a
feasibility study (1) was conducted by
Oregon State University (OSU) and
supported by the Tillamook Methane
Energy and Agricultural Development
Committee (MEAD). We estimated the
total county cow population to be
26,000 head of 1,400 Ib (635 kg) cow
units. Sixty-four percent of the cows
(118 dairies) are located within 10.5
miles (17 km) of the Port of Tillamook
Industrial Park, the preferred site for
the proposed facility. Within 10 miles
Cl6 km) of the town of Cloverdale,
but as far as 26 miles (42 km) from
the port site, are 58 dairies with 28
percent of the county's herd. Finally,
14 producers with 8 percent of the
cow population are within 5 miles (8
km) of the village of Nehalem but
more than 28 miles (45 km) from
Tillamook.
A number of scenarios were evalu-
ated to assess the economic feasibility
of constructing one or more central-
ized anaerobic digestion facilities. The
scenarios included: constructing one
plant (Port of Tillamook) up to three
plants (Port of Tillamook, Cloverdale,
Nehalem); cost of transporting the
dairy manure to the plant(s); plant
size to handle maximum projected
manure production or only a portion
of the current manure production;
effluent handling alternatives; and
conversion of effluent solids into a
slow-release fertilizer.
Summary. Remedying the manure
management problems of Tillamook
County dairies with a centralized,
county-wide waste-treatment system
will necessitate undertaking a rather
complex and comprehensive activity,
requiring participation and cooper-
ation among many area dairy farmers,
governmental agencies, and residents.
Economies of scale could allow area
dairies to benefit from sharing in a
common, management-intensive
waste-treatment system, as opposed to
multiple, individual dairy systems.
Installation of one or two methane
production plants, including lagoon
storage and solids recovery facilities
central to Tillamook and Cloverdale,
to serve all the dairies in the county is
technically feasible for treating and
reducing pathogen and nitrogen levels
in county watersheds. This, in turn,
would permit area .dairies to expand
their milking herds to meet the
Tillamook Creamery's production
capacity while realizing increased
income per dairy.
Unlsyn pre-construction study
Because the feasibility study showed
promising results, the MEAD
committee contracted with Unisyn
Biowaste Technology (a subsidiary of
Washington Energy Company, Seattle)
to examine and report on issues
critical to the implementation of the
project. The subsequent Preconstruc-
tion Report (3) showed that the
patented biowaste technology devel-
oped by Unisyn would effectively
address the environmental issues
facing the Tillamook dairy industry at
a cost within the range determined by
the OSU feasibility study. By partici-
pating in the project, farmers could ex-
pect to increase milk production and
overall farm revenue, while easing the
environmental pressures inherent in
increased land application of manure.
Summary highlights. The analysis
showed that the facility would relieve
the pressure to land-apply manure
during periods of high manure accu-
mulation and rainfalls (during the
winter months'). After digestion and
effluent processing, the liquid effluent
would contain only 25 percent of the
nitrogen in the fresh raw manure and
almost none of the fecal bacteria
normally present in untreated manure.
Financial analysis showed that the
projected operating cost to the farmer
for hauling manure to be less than $2
per ton of untreated manure. Total
cost for a design capacity of 121,000
gallons (458,033 1) per day including
site preparation, equipment, buildings,
construction management, financing,
design and technical fees, permits,
bonding, start-up and commissioning
costs) would be between $12 and 15
million.
The field survey of 30 farmers indi-
cated high receptivity to the project
and the perceived need to address the
problems of excess manure for the
long-term health of the Tillamook
dairy industry.
Market research demonstrated a
high receptivity to the concept of a
slow-release, recycled fertilizer
product associated with the Tillamook
name. This receptivity should create a
high first-purchase demand. Perfor-
mance and price of the product will
dictate long-term success.
Capital requirements were estimated
to be $3.8 million in equity and $10.5
million in debt. A significant portion
of the equity would need to be in the
form of public grants. Unit price for
by-product sales are projected at 6
-------
gation. If necessary, the nitrogen value
will be decreased further by lagoon
storage. Pathogens and weed seeds
will be monitored and controlled to
assure a clean effluent to area farmers.
Digester operations, including trans-
portation and waste contracts with
farmers will be the responsibility of
the Soil and Water Conservation
District. The fertilizer facility and its
products are proposed to be the
responsibility of the TCCA and Unisyn
as 50-50 private venture partners. The
energy facility would convert biogas
from the treatment facility into sale-
able electricity and would be solely
owned by the PUD. An advisory
board would be composed of a voting
member from each entity to direct and
inform the operator coordinating the
three facilities. The operating partner
is proposed to be Unisyn, to oversee
and manage the day-to-day activities
at the combined facilities.
Herd size. The initial survey of
farmers interested in sending their
manure to the plant resulted in a total
herd size of 10,000 dairy animals. On
average, most of the farmers would
like to increase their herd size by 43
percent over the next five years. A
major constraint to such expansion is
the current limit on available land for
manure application.
Financial. The financial prospective
for the initial plant is as follows:
• Plant capacity-121,000 to 145,000
gallons (458,033-548,883 1) of
manure input per day
• Plant production-13,700 to 16,400
tons (12,435-14,886 metric tons) of
blended fertilizer annually; 4.8 to
5.8 million kWh of net electrical
production; 11,350 to 13,600 tons
(10,302-12,345 metric tons) of soil
amendments annually; 330 to 400
tons (300-363 metric tons) of grit
annually; 29.4 to 35.4 million
gallons (111-134 million 1) of
liquid nutrient annually
• Capital cost-$l4.0 to 17.8 million
• Operating revenue at year 3 - $4.4
to 5.2 million
• Operating expense at year 3 - $3.0
to 3.5 million
• Direct payroll (excludes contract
hauling)-$0.5 to 0.6 million
• Annual farmer's service charge-
Less than $2.00 per ton of manure
Current project status
After acceptance of the Unisyn Pre-
Construction Study by the MEAD
Committee, development of the
project focused on two issues, organ-
ization development and financing.
Organizational development. The
recommended organizational structure
was developed to meet a number of
objectives. These objectives include
matching ownership with individual
organizational mission; matching
ownership with financing capabilities;
recognizing community-wide environ-
mental benefits; and linking public
and private entities.
The Tillamook County Soil and
Water Conservation District (TCSWCD)
and the PUD are currently negotiating
an Inter-Governmental Agreement that
will allow the PUD to operate the
TCSWCD portion of the project. The
TCSWCD will retain final authority
over decisions affecting digester
operations. The TCSWCD has the
mission of protecting the soil and
water resources of the county, as
directed by the local dairy farmei-s and
has state-granted authority to raise
funds to meet its mission. The PUD
has organizational depth, staffing, and
administrative support services. By
combining the two public entities for
the development of the facility, the
project has the capability of devel-
oping faster, involving the right
segments of the community, and
simplifying the public-private contract.
Unisyn and the TCCA are also
discussing the potential for the joint
venture fertilizer facility that will take
the solid by-products from, the
digesters and form, package, and
market fertilizers and soil amendment
products. The joint venture entity
would contract with the TCSWCD/
PUD. The advantage of the joint
venture would be to combine a
number of organizational assets that
add value to the marketing of the
fertilizer products.
Financing. The Pre-Construction
Study outlined a combination of
financing sources, including public
revenue bonds, private equity, and
government grants.
A number of state agencies have
been approached by the MEAD
Committee. Preliminary indications are
that the agencies are interested in the
project and have the capability to
provide revenue bonds for the project.
Private equity contributions to the
project are being discussed between
the private parties.
Grants are currently being proposed
to a number of federal agencies for
specific portions of the project. In
October, the U.S. Congress funded
$750,000 to initiate the project in 1993.
REFERENCES CITED
1. Edgar, T.G., and A.G. Hashimoto. 1991.
Feasibility Study for a Tillamook County
Dairy Waste Treatment and Methane
Generation Facility. Department of
Bioresource Engineering, Oregon State
University, Corvallis.
2. TBRCWP. 1984. Tillamook Bay Rural
Clean Water Project, Annual Report.
3. Unisyn Biowaste Technology. 1992.
Tillamook Anaerobic Digestion Facility
Pre-Construction Study. Seattle, Wash. Q
Proper animal
manure utilization
Alan L. Button
Livestock and poultry producers
are considering the manure man-
agement system in their opera-
tions seriously today for two reasons:.
the need for efficiency of operation to
increase profitability and the need for
environmental responsibility. Several
alternatives for manure collection,
transport, storage, treatment, and
utilization are available which are
environmentally sound and can
reduce the cost of production. In
addition, proper management and
Alan L. Sutlon is a professor of animal
sciences in the Department of Animal
Sciences, Purdue University, West Lafayette,
Indiana 47907-1026.
Journal Paper No. 13953, Purdue
Agricultural Research Programs, Purdue
University, West Lafayette, Indiana 47907.
Mention of product trade names does not
mean endorsement or exclusion of other
similar products by Purdue University.
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 65
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Table 1. Comparative cost between swine lagoons and pit
systems when all costs and benefits are compared. (1)
System
Cost - $/head capacity
600-head 1,000-head
capacity capacity
Pit storage
Concrete pit
Concrete slats
Tanker system w/injectors
Tractor
Labor
Total cost
Nutrient returns
Net costs
$3
5
5
2
1
$16/hd
$9
$7/hd
$3
5
3
2
1
$14/hd
$9
$5/hd
Lagoon
Concrete floor
Recycle system
Lagoon
Irrigation
Labor
Tractor
Total cost
Nutrient returns
Net costs
$2
1
3
3
1
1
$11/hd
$2
$9/hd
$2
0
3
2
1
1
$9/hd
$2
$7/hd
planning of a manure system is imper-
ative for it to be used successfully.
Following is a brief discussion of
some problems facing the livestock
industry' related to manure manage-
ment, solutions with proper manage-
ment techniques, and research needs.
Pollution concerns
The potential contribution of animal
agriculture to environmental pollution
has been under scrutiny recently.
Reports indicate that agriculture is the
one of the biggest contributors to
water pollution and animal production
is a major component. Animal agri-
culture can contribute to pollution in
three ways. First, water pollution can
be caused by direct runoff after field
application of manure or by contam-
inated water from open feedlots; by
leaching caused by excessive nutrient
applications or leaking earthen
manure storages; and by direct runoff
into poorly sealed wellheads. Second,
air pollution can be caused within the
buildings and during land application
from odors and gasses created by
manure decomposition, microbial
agents, and dust from feed systems
and the animals. Third, soil pollution
can be caused by applying extremely
high rates of nutrients to the land
(through manure) and creating an
imbalance of nutrients that can cause
poor plant growth.
Proper land application of manure
with efficient crop utilization offers
the most environmentally safe use of
manure. However, there has been
concern about lack of uniformity in
nutrient application and reported soil
compaction problems with heavy
application equipment. Some livestock
operations do not have sufficient
manure storage capacities or enough
land to apply manure for maximum
nutrient utilization. Excessive nutrients
in livestock and poultry diets, and
poorly operated feed delivery systems
can result in excessive nutrients being
excreted in manure that must be
applied to the land.
Because of isolated cases of pollu-
tion and the perceived threat of
animal agriculture's contribution to
nonpoint source pollution, the possi-
bility of stricter environmental regu-
lations is evident. The major focus of
regulations, at the federal, state, and
local level, is to control runoff, control
odors, have sufficient storage and land
available for timely application of
manure, and apply manure at agro-
nomic rates. The goal must be a com-
plete environmentally-sound manure
management plan which is unique for
each and every livestock and poultry
producer.
Solutions
The goals of a manure management
plan are to control and utilize the
available manure nutrients from a
livestock operation, reduce the costs
and enhance the beneficial returns
from the system to the enterprise, and
maintain an optimum environment.
Table 1 shows an example of the
comparative costs (based on 1992
prices) between slurry pit and lagoon
systems for two pork production
operations of different sizes. Credit for
fertilizer use of manure nutrients can
reduce the manure system costs,
especially with larger operations. In
addition, due to a greater nutrient
value of slurry manure, the system
cost per head-capacity was reduced as
compared to the earthen lagoon
system. "With earthen systems, proper
management practices and design of
facilities to control, store, and apply
manure also are necessary.
Available nutrients from manure
produced on the operation can be
effectively utilized in a productive
cropping program or processed and
utilized in a non-polluting manner. In
cases where there is not sufficient
land available for crop utilization,
agreements with neighboring land
owners should be arranged. Infor-
mation needed to develop a manure
nutrient management plan includes
crop nutrient needs; manure nutrient
content to be applied; previous crop
grown on the land site; soil charac-
teristics and test results (cation
exchange capacity [CEC], pH, phos-
phorus [P], potassium [K], and other
minor elements); amount of manure
applied on the field previously; and
method and time of application of the
manure.
Manure nutrient content
Nutrient levels in manure can vary
considerably depending upon compo-
sition of the diet fed to the animals,
system and length of time of storage,
66 JOURNAL OF SOIL AND WATER CONSERVATION
-------
and the amount of •water, bedding, or
feed spillage in the manure. Producers
have had little confidence in maxi-
mizing the nutrients in manure
because there has not been an easy
method for analyzing nutrient con-
tents. Mixing liquid manure through
mechanical agitation is the best means
of obtaining a uniform sample of
manure for laboratory analysis and
being assured of a uniform application
of manure nutrients applied to the
soil. Manure analyses (dry matter, pH,
total N, ammonium N, P, and K)
should be conducted on manure from
different storages over time until the
nutrient content and variability of the
manure on the farm has been firmly
established. Analyses should be done
routinely as a check or when a
significant change in management of
the operation takes place, i.e.,
changing the composition of the diet
or addition of waterers.
A quick on-the-farm nitrogen test
can be used to estimate available
nitrogen in manure. This test, avail-
able in a kit, N-Meter (Agros, Kallby,
Sweden), takes only five minutes and
results can be used to adjust appli-
cation rates when there is consid-
erable variation in manure nitrogen
content due to incomplete agitation or
when changing manure storage loca-
tions, i.e. farrowing, nursery, growing-
finishing. N-Meter values with esti-
mated available N values were com-
pared from various manures incubated
in soil and the results •were very
similar (Sutton, 1993, unpublished
data). Table 2 shows a comparison of
available N in selected duck and
swine manures. Westerman et al. (.13)
showed similar results comparing
various types of manure for available
N values with these methods.
The system and length of storage
primarily affect the nitrogen content of
manure. Long-term storages such as
lagoon systems result in less organic
nitrogen and more ammonium nitro-
gen. However, with increased length
of storage, more ammonium nitrogen
is volatilized into the atmosphere. The
least amount of nitrogen loss is found
in slurry storages for liquid manure
systems and manure pack or litter
systems for solid manure systems. P
and K are not lost prior to land
Table 2. Comparison of nitrogen meter values with laboratory
available nitrogen estimates*
Manure type
Liquid duck pit
Liquid swine pit
Number
(n)
8
21
Nitrogen
meter
23.3
21.8
Available
nitrogen
(IbAIOOOgal)
25.8
26.4
*100% ammonium N plus 30% organic N.
Table 3. Nutrient losses from animal manure as affected by
method of handling and storage. *
Losses
Manure handling and
storage method
Solid systems
Daily scrap and haul
Manure pack
Open lot
Deep pit (poultry)
Liquid systems
Anaerobic deep pit
Above ground storage
Earthen storage pit
Lagoon
15-35
20-40
40-60
15-45
15-30
5-25
20-40
70-80
10-20
5-10
20-40
5-10
5-10
5-10
10-20
50-80
20-30
5-10
30-50
5-10
0-5
0-5
10-20
50-80
*Based on composition of manure applied to the land vs. composition of freshly excreted
manure, adjusted for dilution effects of the various systems.
application unless there is runoff from
an uncovered feedlot. Collection and
storage of feedlot runoff is necessary
and this dilute waste has some N, P,
and K content that is generally irri-
gated onto cropland. In a lagoon
system, most of the P (50-80 percent)
and 50 to 75 percent of the K settles
in the bottom of the lagoon. This is
recoverable only when the sludge in
the lagoon is removed. Table 5
summarizes the range of N, P, and K
losses as affected by manure storage
systems.
Due to the organic nature of animal
manures, specific management prac-
tices must be used to maximize the
value of manures as a nutrient
resource. Nitrogen in manures can be
lost by volatilization, denitrification,
and leaching when applied to the soil.
Early work in our laboratory deter-
mined that considerable nitrogen can
be lost very rapidly by volatilization
when surface-applying manure with a
tanker wagon or irrigation system
(Table 4). Most of the ammonia
nitrogen loss takes place within 48
hours after application (2). Higher pH
manure such as lagoon effluent,
poultry manures, and veal calf
manures volatilize more rapidly than
manures with a pH below 7.0.
Incorporation of manure is impor-
tant to conserve and utilize its full
fertilizer value. This is especially
important if the manure is applied in
the spring or summer when temper-
atures are warm. Ammonia loss from
surface-applied manure is greater
during warm temperatures, and days
with lower humidity and more air
movement. In contrast, incorporating
manure in the soil, whether by direct
injection or by a tillage practice, will
reduce ammonia loss significantly.
Other advantages to incorporation
include reduced runoff potential and
NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT 67
-------
odors. Comparing injection versus
surface applications on corn yields
showed an average advantage in corn
yields of 23.5 percent (range 9.8-43.6
percent) for injection. (If).
Crop nutrient needs
Application rates of manure must be
based upon the nutrients available in
the manure and the nutrient require-
ments of the crop using realistic yield
goals based on experience from farm
history. Recommended nutrient needs
should be adjusted based on P and K
soil tests and whether a legume was
grown on the land the previous year.
The carryover of nitrogen from
previous years of manure application
should be estimated and manure
application rates adjusted. The range
of N carry over from legumes can be
20 to 30 Ib N per acre (22-34 kg/ha)
for soybean up to above 80 Ib N per
acre (90 kg/ha) for a good stand of
alfalfa forage. With this information,
the nutrient needs of the crop can be
calculated precisely and over-
application of N can be avoided.
Due to the organic nature of
manure, considerable biological trans-
formation takes place in the soil.
Nitrogen mineralization and immobil-
ization and the relative amount of N
available for plant use depends upon
the carbon to nitrogen ratio in the soil
along with the contribution from the
manure source. Nitrogen can be tied
up in the organic matrix to a great
extent and increased soil microbial
activity results when manures are
incorporated in the soil. With the
increased microbial activity, there is a
potential for increased release of N in
the inorganic form. Unless the N is
retained in the ammonium form,
which is firmly attached to the soil
particle, the N is converted to the
nitrate form and potentially leached. If
the soil is saturated with water, the
nitrate form can be converted to
nitrous N gas and volatilized (denitri-
fied). In either case, nitrogen is lost
from the soil and is unavailable for
plant use. It has been estimated that
only 3 to 35 percent of manure
nitrogen and about 50 percent of
fertilizer nitrogen is used for plant
growth (3, 6).
The challenge of nutrient appli-
cation, whether from manure or
commercial fertilizer sources, is to
have nutrients available at the stage of
growth when the plant needs them
most. In the case of corn, P is
required just after germination and for
early growth. But in the case of nitro-
gen, little nitrogen is needed by the
young plant. Considerable nitrogen is
needed during the reproductive stage,
i.e., silking, tasseling, etc. Manure is
usually applied in the spring or fall,
prior to the growing season or after
harvest. Thus, considerable N can be
lost before the plant can utilize it
Table 4. Nitrogen losses from animal manure to the air as affected
by method of application.
Method of application
Broadcast without incorporation
Broadcast with incorporationt
Injection (knifing)
Irrigation
Type of manure
Solid
Liquid
Solid
Liquid
Liquid
Liquid
Nitrogen loss*
(%)
15-30
10-25
1-5
1-5
0-2
30-40
* Percent of total N in manure applied which was lost within three days after application; wind
and temperature effects may increase losses.
t Incorporation within a few hours of application.
unless the N is stabilized in the soil.
Field and laboratory research
studies have shown that nitrification
inhibitors can stabilize the nitrogen in
manures by keeping the N in the
ammonium form through suppression
of the soil-borne Nitrosomonas
bacteria (§). Retained nitrogen in the
soil, increased grain yields, tissue
nitrogen levels, grain protein levels,
and less incidence of disease have
been recorded by using nitrification
inhibitors with commercial fertilizers
(.4) or manures (7, 9, 10, 11, 12). As a
result, the nitrogen in the manure can
be fully utilized for greater efficiency
and there can be greater confidence
that the nitrogen placed in the soil is
there to be used by crops. The water
pollution potential of the manure
nutrients applied is greatly reduced.
This positive effect has been most
significant for summer or fall appli-
cations prior to the next year's crop
season, or if the soil is saturated with
water in the spring. Increased corn
yields from the use of nitrification
inhibitors have ranged from 5 to 53
percent for fall applications, 5 to 15
percent for spring applications, and 3
to 15 percent for summer applications
(If). In addition, the greatest benefit
of the nitrification inhibitors is realized
when the nitrogen rate applied is near
the nitrogen requirements of the crop.
This also allows the producer to
enhance the nutrient potential of the
manure, realize reduced fertilizer
costs, and,apply manure at a lower
rate which will reduce the build-up of
other nutrients in the soil. Using
nitrification inhibitors increases man-
agement flexibility for land application
since manure can be applied in the
fall, when the soil is in better condi-
tion to handle heavy equipment and
when labor and equipment may be
more readily available.
When manure is applied to meet
the nitrogen requirement of the plant,
there will be an over-application of P
and K which will build up in the soil.
The producer must decide either to
apply this higher rate and rotate the
fields to receive manure about every
three or four years, or reduce the rate
of application and supplement with
additional nitrogen. Enriching the
manure with anhydrous ammonia and
68 JOURNAL OF SOIL AND WATER CONSERVATION
-------
applying the manure at a lower rate
has been done successfully {.W, IT).
This practice can be accomplished by
;using an asparger tube in the tanker
wagon or within a manure discharge
pipe during loading of the manure
into the tanker wagon (35. The major
benefits of enriching manure with
nitrogen are balancing the manure
nutrients to meet crop nutrient needs
while lessening the buildup of nutri-
ents in the soil, fewer trips required
across the field, and greater efficien-
cies of nutrient utilization from the
manure sources.
The use of rapid transport trucks
with wide or flotation-type tires for
manure application results in less soil
compaction under a variety of soil
conditions. Some custom haulers
apply 24 hours a day to remove
manure from livestock pits. The trucks
have powerful vacuum pump systems
which allow for greater solids removal
from pits. Agitation pumps are avail-
able to agitate manure in the pits for
three to four hours before application
to provide a more uniform application
of nutrients to the field. Reliable
custom applicators calibrate their
equipment, thus application rates for
specific crop needs can be imple-
mented. This bulk hauling system
allows for application on fields a
greater distance from the building in a
reasonable amount of time. In most
cases, custom applicators should be
considered as a viable option because
of the efficiencies and services
provided.
Another application alternative is
the large self-propelled semi-truck
tanker units used to haul large vol-
umes of manure to distant fields
where the liquid manure is loaded
into smaller machines for field
application. Some producers use two
semi-tanker units to reduce the
amount of down time with loading
and unloading in the field. Another
method is to locate a portable fire-
man's tank in the application field. A
semi-truck fills the portable canvas
storage unit. The application machine
then loads manure directly from the
canvas fireman's tank. This system can
be temporarily located at any field
site.
Calibration of equipment is neces-
sary to ensure the desired manure
application rate. Calibration can be
accomplished simply by determining
the weight, in the case of solid
manures, or volume, in the case of
liquid manures, applied to a certain
area. The width of the application
swath and distance and speed traveled
during application are required for the
calculation. By determining the
amount of manure applied to a given
area at a certain speed, one can
calculate the speed required to apply
a desired amount of manure, assum-
ing that the rpm of the tractor and
pressure in the tanker wagons are
similar.
In Denmark, an N-Dos Meter
(Samson Co., Bjerringbr0, Denmark),
has been developed for control of
nitrogen application to the land by
adjusting the flow rate of manure from
a tanker wagon during land appli-
cation. Possibly this type of equip-
ment and technology will be devel-
oped and expanded to deliver accu-
rate amounts of nutrients to the land
during manure applications.
Other management techniques to
evaluate nutrient needs in the soil
include the use of the pre-sidedress
nitrate test. This on-the-farrn test
measures soil nitrate levels when the
corn is about 8 to 12 inches (20-30
cm) tall to determine the need for
additional sidedress nitrogen. This
technique is important if manure has
been applied in the fall or summer
previous to planting and if a nitri-
fication inhibitor was not used to
stabilize the nitrogen.
Research needs
There are several areas in manure
management requiring additional
research and implementation. These
include efforts in developing genet-
ically engineered microbes to decom-
pose manure solids and control odors
and development of odor control
additives more efficiently, either for
addition into animal diets or through
direct addition to manure storage.
There is a need for more precisely
controlled manure application systems
to assure uniform application of
manures to the land. There is a need
for continued work on the control of
nitrogen in the manure storage sys-
tems and after application to the soil
so that it will be available for plant
uptake. Research is needed to
improve the efficiency with which
animals digest and utilize feed,
thereby reducing nutrient output in
manure. Considerable research is
being conducted to determine the
efficiency of feeding phytase enzymes
to reduce P output in manure and
balancing the amino acid require-
ments of monogastries to reduce N
output in manure. Investigations of
methane production efficiencies and
recovery of nutrients for other uses,
such as refeeding, bedding, or soil
amendments are needed. Develop-
ment of computer systems to assist
producers in manure management
planning are now available and will
need to be refined as more research
information is generated.
Maximum benefits/reduced costs
Maximum benefits of the manure
management plan are realized when
manure is applied to low test soils,
applied under optimal soil conditions,
applied to well drained soils, applied
to productive crops, and when nutri-
ent application levels are balanced
with the needs of the crop. Reduced
costs are realized when producers
develop a manure management plan,
reduce fertilizer usage, implement the
best management practices, and keep
good records. Proper design and man-
agement of manure systems are the
keys to enhancing potential nutrient
benefits, reducing costs, and making a
positive environmental impact.
Through future technological develop-
ments and implementation, producers
will be able to utilize animal manures
more precisely on a "prescription"
basis.
REFERENCES CITED
1. Foster, K.A. 1992. Purdue University,
West Lafayette, Ind. Personal com-
munication.
2. Hoff, J.D., D.W. Nelson, and A.L. Sutton.
1981. Ammonia volatilization from swine
applied to cropland, J. Environ. Quality
10:90-95.
3. Huber, D.M., H.L. Warren, And C.Y. Tsai.
JOURNAL OF SOIL AND WATER CONSERVATION 69
-------
1977. Nitrification inhibitors—new tools
for food production. BioScience 27:523-
529.
4. Huber, D.M., H.L. Warren, D.W. Nelson,
C.Y. Tsai, and G.E. Shaner. 1980.
Response of winter wheat to inhibiting
nitrification of fall-applied fertilizer
nitrogen. Agron. J. 72-632-637.
5. Huber, D.M., P.D. Karamesines, and
D.W. Nelson. 1983. The "Ammoniator":
A device to enrich waste solutions with
nitrogen. Agron. J. 75-710-712.
6. McCormick, R.A. 1979. Carbon and
nitrogen transformations in animal
wastes affected by nitrapyrin. M.S.
Thesis. Purdue University, West
Lafayette, Ind.
7. McCormick, R.A. 1981. Nitrification
inhibitors: effects on nitrogen loss from
soils and corn yields. Ph.D. Thesis,
Purdue University, West Lafayette, Ind.
8. McCormick, R.A., D.W. Nelson, A.L.
Sutton, and D.M. Huber. 1983. Effect of
nitrapyrin on nitrogen transformations
in soil treated with liquid swine manure.
Agron. J. 75:947-950.
9. McCormick, R.A., D.W. Nelson, A.L.
Sutton, and D.M. Huber. 1984. Increased
N efficiency from nitrapyrin added to
liquid swine manure used as a fertilizer
for com. Agron. J. 76:1,010-1,014.
10. Sutton, A.L., D.M. Huber, D.D. Jones,
D.T. Kelly, and D.H. Bache. 1986. Use of
nitrification inhibitors and ammonia
enrichment with swine manure appli-
cations. J. Appl. Engr. Agric. 2:179-185.
11. Sutton, A.L., D.M. Huber, and D.D.
Jones. 1990. Strategies for maximizing
the nutrient utilization of animal wastes
as a fertilizer resource. In: Proc. 6th Intl.
Symp. Agr. Food Proc. Wastes, pp. 139-
147. Chicago, 111. Amer. Soc. Agr. Engr.
ASAE Pub. 05-90.
12. Sutton, A.L., D.M. Huber, D.D. Jones,
and D.T. Kelly. 1990. Use of nitrification
inhibitors with summer application of
swine manure. ]. Appl. Engr. Agric.
6:296-300.
13. Westerman, P.W., L.M. Safley, Jr., J.C.
Barker, and G.M. Chescheir III. 1985.
Available nutrients in livestock waste. In:
Proc. 5th Intl. Symp. Agric. Wastes, pp.
295-307. Chicago, 111. Amer. Soc. Agr.
Engr. ASAE Pub. 13-85. Q
70 NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT
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Coastal Zone Act
Reauthorization Amendments
of 1990 (CZARA)
Nutrient
management
measure to be
implemented in
the coastal zone
Anne C. Weinberg
Several of the articles in this
special issue refer to the nutrient
management measure which is
one of the management measures to
be implemented under section 6217 of
the Coastal Zone Act Reauthorization
Amendments of 1990 (CZARA).
CZARA requires states and territories
(hereinafter referred to as States) with
approved coastal zone management
programs to submit "Coastal Nonpoint
Pollution Control Programs" to the
U.S. Environmental Protection Agency
(EPA) and the National Oceanic and
Atmospheric Administration (NOAA)
for approval. These state programs are
to employ initial, technology-based
Anne C. Weinberg is an environmental
protection specialist with the Nonpoint Source
Control Branch, U.S. EPA, Washington, D.C.
20460.
"management measures" throughout
the coastal management area, to be
followed by additional measures,
where necessary, to address remain-
ing, known water quality problems.
CZARA required EPA to publish
(and periodically revise thereafter), in
consultation •with NOAA, the U.S. Fish
and Wildlife Service, and other federal
agencies, management measures guid-
ance for sources of nonpoint pol-
lution in coastal waters. In January
1993 EPA published "Guidance Speci-
fying Management Measures for
Sources of Nonpoint Pollution in
Coastal Waters" (.1). Coastal states and
territories will need to develop Coastal
Nonpoint Pollution Control Programs
to implement the approximately 55
management measures in this guidance.
Following is a copy of the nutrient
management measure in the "Guid-
ance Specifying Management Mea-
sures for Sources of Nonpoint Pollu-
tion in Coastal Waters" (1):
Develop, implement, and period-
ically update a nutrient management
plan to (a) apply nutrients at rates
necessary to achieve realistic crop
yields, (b) improve the timing of
nutrient application, and (c) use
agronomic crop production technology
to increase nutrient use efficiency.
When the source of the nutrients is
other than commercial fertilizer,
determine the nutrient value and the
rate of availability of the nutrients.
Determine and credit the nitrogen
contribution of any legume crop. Soil
and plant tissue testing should be used
routinely. Nutrient management plans
contain the following core components:
• Farm and field maps showing acre-
age, crops, soils and water bodies.
• Realistic yield expectations for the
crop(s) to be grown, based
primarily on the producer's actual
yield history, State Land Grant
University yield expectations for
the soil series, or SCS Soils-5
information for the soil series.
• A summary of the nutrient resources
available to producer, which at a
minimum include
- Soil test results for pH, phos-
phorus, nitrogen, and potassium;
- Nutrient analysis of manure,
sludge, mortality compost (birds,
pigs, etc.), or effluent (if applic-
able);
- Nitrogen contribution to the soil
from legumes grown in the
rotation (if applicable); and
- Other significant nutrient sources
(e.g., irrigation water).
• An evaluation of field limitations
based on environmental hazards
or concerns, such as
- Sinkholes, shallow soils over
fractured bedrock, and soils with
high leaching potential,
- Lands near surface water,
- Highly erodible soils, and
- Shallow aquifers.
• Use of the limiting nutrient concept
JOURNAL OF SOIL AND WATER CONSERVATION 71
-------
to establish the mix of nutrient
sources and requirements for the
crop based on a realistic yield
expectation.
• Identification of timing and appli-
cation methods for nutrients to
provide nutrients at rates neces-
sary to achieve realistic crop
yields; reduce losses to the envi-
ronment; and avoid applications as
much as possible to frozen soil
and during periods of leaching or
runoff.
• Provisions for the proper calibration
and operation of nutrient appli-
cation equipment.
REFERENCES CITED
1. U.S. Environmental Protection Agency,
Office of Water. 1993- Guidance
specifying management measures for
sources of nonpoint pollution in coastal
ivators. 840-B-92-002, Washington, D.C. Q
A new approach
to runoff—state
coastal nonpoint
pollution control
programs
Ann Beier, Steven Dressing, and
Lynn Shuyler
States, local governments, farmers,
foresters, developers, and others
will soon be faced with new
requirements to control nonpoint
source pollution—that is, the pollution
that results when rain or snow moves
pollutants like nutrients and sedi-
ments, heavy metals, bacteria, and
pesticides from sources such as farms,
urban areas, and marinas into surface
water and groundwater. In November
Ann Beier is a program analyst and Steven
Dressing is the acting chief of the rural
sources section of the Nonpoint Central
Branch, U.S. EPA, Washington, D.C. 20360.
Lynn Shuyler is the nonpoint source control
coordinator at the U.S. EPA Chesapeake Bay
Program Office, Annapolis, Maryland 21403.
1990, Congress, recognizing that non-
point pollution is a key factor in the
continuing degradation of many
coastal waters, enacted section 6217
of the Coastal Zone Act Reauthori-
zation Amendments of 1990 (CZARA)
(codified as 16 USC s. I455b).
CZARA requires that states and
territories with approved coastal zone
management programs (see Figure 1)
submit Coastal Nonpoint Pollution
Control Programs (coastal nonpoint
programs) to the U.S. Environmental
Protection Agency (EPA) and the
National Oceanic and Atmospheric
Administration (NOAA) for approval.
States that do not submit approvable
programs will lose a portion of federal
funding provided by section 319 of
the Clean Water Act and section 306
of the Coastal Zone Management Act.
The coastal nonpoint programs
required by CZARA, although building
on existing programs, are not
intended to represent "business as
usual" for addressing nonpoint pol-
lution. Rather, CZARA provides an
innovative approach to controlling
nonpoint pollution. First, the pro-
grams are truly joint programs—state
section 319 lead agencies (generally
water quality agencies) and coastal
zone management agencies are to
work together to develop and imple-
ment the programs. EPA and NOAA
are jointly responsible for providing
assistance to the states and for
approving the programs.
Second, the programs will employ
initial, technology-based "management
measures" throughout the coastal
management area, to be followed by
additional measures, where necessary,
to address remaining known water
quality problems. Unlike existing
nonpoint programs, a baseline level of
pollution prevention or control will be
required. Finally, CZARA requires
insurance, in the form of state
enforceable policies and mechanisms,
that both the technology-based and
additional nonpoint source controls
are fully implemented.
EPA and NOAA have published two
documents to assist states and others
in meeting the new program require-
ments (58 Fed. Reg. 5182, January 19,
1993). The first document, "Guidance
Specifying Management Measures for
Sources of Nonpoint Pollution in
Coastal Waters," is EPA's guidance on
the best available and affordable
technologies to restore and protect
coastal waters from nonpoint source
pollution. The second document,
"Coastal Nonpoint Pollution Control
Program—Program Development and
Approval Guidance" was developed
by EPA and NOAA as a road map for
states to develop the coastal nonpoint
programs required by CZARA in a
timely and resource-efficient manner.
Management measures guidance
Under section 6217(g), Congress
required EPA, in consultation with
other federal agencies, to develop
guidance specifying "management
measures" to control coastal nonpoint
pollution. Management measures, or
"g" measures, are defined in the law
as "economically achievable" (afford-
able) measures to control nonpoint
pollution in coastal waters which
reflect the greatest degree of pollutant
reduction achievable through the
application of best available tech-
nology, siting criteria, operating
methods, or other alternatives. EPA
developed this guidance with assis-
tance from NOAA, other federal
agencies including the U.S. Depart-
ment of Agriculture (USDA) and the
U.S. Army Corp of Engineers (COE),
and a number of state experts.
Although this article focuses only
on the agricultural management mea-
sures, the guidance document speci-
fies measures for each of five major
categories of nonpoint pollution:
agriculture, forestry, urban (including
new development, septic tanks, roads,
bridges, and highways), marinas and
recreational boating, and hydromod-
ification. A chapter describ-ing the
ways that wetlands and riparian areas
can be used to prevent nonpoint
pollution is also included.
Each chapter (corresponding to the
major nonpoint source categories) sets
forth the management measures that
must be incorporated into state pro-
grams. The chapters also describe
some of the management practices
that may be used to achieve each
measure; activities and locations for
72 NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT
-------
which each measure may be suitable;
and information on the cost and
effectiveness of the measures and
practices. Descriptions of proper oper-
ation and maintenance of measures
are included.
The management measures are
described in terms of integrated
systems of practices rather than
discrete best management practices
(BMPs). Many of these systems
include activities to reduce the genera-
tion of pollutants—a pollution preven-
tion approach—as well as actions to
keep the pollutant from reaching
surface water or groundwater. Mea-
sures range from more traditional
activities, such as erosion and sedi-
ment control, to more comprehensive
strategies, such as watershed planning
to help minimize urban runoff.
Management measures for
agricultural activities
The management measures apply to
the primary agricultural nonpoint
pollutants: nutrients (particularly
nitrogen and phosphorus), sediments,
animal wastes, salts, and pesticides.
The guidance specifies the following
management measures for agricultural
activities:
Sediment and erosion control. The
goal of this measure is to minimize
the delivery of sediment from agricul-
tural lands to receiving waters. Land-
owners may choose either to apply
the erosion component of the U.S.
Department of Agriculture's Conser-
vation Management System through
such practices as conservation tillage,
strip cropping, contour farming, and
terracing, or design and install a com-
bination of management and physical
practices to remove settleable solids
and associated pollutants in runoff
delivered from the contributing area
for storms up to and including a 10-
year, 24-hour frequency. In the first
case, erosion control on the land is
combined with sediment delivery
control to reduce both erosion and
sediment delivery; in the second case
only sediment delivery control is
explicitly addressed, although erosion
control methods can help achieve this
measure as well.
States are to apply this measure to
activities that cause erosion on., agri-
cultural lands including cropland,
irrigated cropland, range and pasture,
orchards, permanent hayland, and
land used for specialty crop and
nursery crop production.
Confined animal facility Control.
Two different management measures
apply to confined animal facilities
(feedlots) depending on the number
of animals at a particular facility.
Neither of these measures applies to
facilities that are currently required by
federal regulation (40 CFR 122.23) to
apply for and receive discharge
permits. A confined animal facility is
defined as a lot or facility (other than
a facility for aquatic animal produc-
tion) where animals have been, are,
or will be stabled or confined and fed
or maintained for a total of 45 days or
more in any 12-month period, and
crops, vegetation forage growth, or
post-harvest residues are not sustained
in the normal growing season over
any portion of the lot or facility.
The management measure that
applies to all new confined animal
facilities and to larger existing facilities
(see EPA's "Guidance Specifying; Man-
agement Measures..." for size cutoffs)
is to limit discharges from confined
animal facilities to surface water by
storing both the facility wastewater
and runoff caused by all storms up to
and including the 25-year, 24-hour
frequency storm. To protect ground-
water, it is recommended that storage
structures have either an earthen
lining or plastic membrane lining, be
constructed with concrete, or be a
storage tank.
For smaller, existing facilities, the
management measure is to design and
implement systems that collect solids,
reduce contaminant concentrations,
and reduce runoff to minimize the
discharge of contaminants in both
facility wastewater and runoff caused
by all storms up to and including a
25-year, 24-hour frequency storm.
Storage is not required. Systems must
be implemented that substantially
reduce significant increases in pollu-
tant loadings to groundwater.
Both confined animal facility mea-
sures require management of stored
runoff and accumulated solids through
Figure 1. No-till cropping
practices are recomended to
meet the erosion and sediment
control management measure.
an appropriate waste utilization
system. Neither measure, however,
specifies required methods for animal
waste management.
Nutrient management. This mea-
sure calls for development, implemen-
tation, and periodic update of a
nutrient management plan to apply
nutrients at rates necessary to achieve
realistic crop yields, improve the
timing of nutrient application, and
use agronomic crop production tech-
nology to increase nutrient use effi-
ciency. Nutrient management is
designed to prevent pollution by
developing a nutrient budget for the
crop, applying 'only the types and
amounts of nutrients necessary to
produce a crop based on realistic crop
yield expectations, and to identify and
address environmental hazards and
concerns on the site (e.g. land near
surface water, highly credible land,
and shallow aquifers).
Pesticide management. This mea-
sure is designed to minimize ground-
JOURNAL OF SOIL AND WATER CONSERVATION 73
-------
Figure 2. Subsurface injection of manure prevents runoff of
manure and may be used to achieve the goals of a nutrient
management plan.
water and surface water contam-
ination from pesticides. The measure
is to be achieved by evaluating pest
problems, previous pest control
measures, and cropping patterns;
evaluating the soil and physical
characteristics of the site (including
pesticide mixing and storage areas);
using integrated pest management
strategies (IPM) such as improving the
timing and efficiency of application;
improving calibration of pesticide
spray equipment; and using anti-
backflow devices on hoses used for
filling tank mixtures.
Livestock grazing. The focus of the
grazing management measure is on
the riparian zone, although the control
of erosion from range and pasture
land above the riparian zone is also
encouraged. Sensitive areas such as
streambanks, wetlands, estuaries,
ponds, lake shores, and riparian zones
are to be protected by reducing the
physical disturbance and direct
loadings of animal waste and sedi-
ment caused by livestock through a
variety of livestock management
practices ranging from excluding
livestock from sensitive areas to using
improved grazing management sys-
tems, such as herding. Erosion is to be
controlled on upland areas by either
implementing the range and pasture
components of a USDA Conservation
Management System or by maintaining
range, pasture, and other grazing
lands in accordance with activity plans
established by either the U.S. Depart-
ment of Interior's Bureau of Land
Management or USDA's Forest Service.
Irrigation. This measure promotes
an effective irrigation system that
delivers necessary quantities of water
yet reduces nonpoint pollution to
surface water and groundwater. The
measure calls for operation of existing
irrigation systems so that the timing
and amount of irrigation water applied
match crop water needs. This requires,
at a minimum, the accurate measure-
ment of soil-water depletion volume
and the volume of irrigation water
applied, and uniform application of
waters. The measure specifies that
backflow preventers for wells are
necessary when chemigation is used.
The measure recognizes that state
water laws may conflict with the
measure and will take precedence
over it.
State program guidance
As described above, the manage-
ment measures guidance will be
implemented through new state
coastal nonpoint pollution control
programs. EPA's and NOAA's recently
released "Program Development and
Approval Guidance" describes what
needs to be contained in each state
program for approval by EPA and
NOAA. States will have to address
issues such as where the program will
operate geographically, how manage-
ment measures will be selected and
implemented, and how the program
will be coordinated with other existing
federal, state, and local programs.
State programs must include man-
agement measures "in conformity"
with those specified in EPA's manage-
ment measures guidance. In general,
the presumption is that states will
implement all the management mea-
sures for each of the source categories
(e.g., agriculture, forestry), and
subcategories (e.g. grazing, harvest-
ing) described in the management
measures guidance. However, states
have the opportunity to exclude
nonpoint source categories and sub-
categories in certain situations. States
may exclude certain sources if they
can demonstrate either that the cate-
gory, subcategory, or specific source
is (a) neither present nor reasonably
anticipated in an area, or (b) does not,
individually or cumulatively, present
significant adverse effects to living
resources or human health. Exclusions
will most likely apply on a watershed
or local basis.
States must also provide information
on how they will ensure the imple-
mentation, operation, and mainte-
nance of the measures. States will
need to ensure the implementation of
management measures through the
use of enforceable policies and
mechanisms. These can range from
traditional regulatory activities (such
as permits) to incentive programs
(such as state or local cost-share, tax
credits) provided that the state has
74 NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT
-------
back-up authority to ensure that
measures are implemented within the
timeframe specified by EPA and
NOAA.
In addition to implementing the
technology-based management mea-
sures, states must also describe their
process for implementing "additional
measures" those measures necessary
to achieve and maintain water quality
standards, where the "g" measures
alone are inadequate. These additional
measures will be determined by the
state.
Schedule
States have until July 1995 to submit
programs to EPA and NOAA for
review. The federal agencies have
until January 1996 to review the
programs. Once approval is granted,
states have three years (until January
1999) to implement the "g" measures
and an additional two years (through
January 2001) to assess the effec-
tiveness of the "g" measures in
achieving water quality standards.
States then have three more years
(until January 2004) to implement
additional measures, where necessary
to attain or maintain water quality
standards.
Funding
Congress has authorized $12 million
a year for states' development and
implementation of the CZARA require-
ments. However, to date, actual
Congressional appropriations for this
purpose have totaled less than $2
million annually for the 29 coastal
states; $4 million is available for FY
1994. Funding for program implemen-
tation is available under section 319 of
the Clean Water Act. In addition, cost-
share funds under USDA's Agricultural
Conservation Program can be used by
farmers to implement the management
measures, unless installation is done
on an involuntary basis. The USDA-
ASCS has established a policy that
governs such situations (NOTICE ACP-
239).
If a state does not submit an
approvable coastal nonpoint pollution
Figure 3. Providing alternative water sources is a practice to
achieve the grazing management measure.
control program, EPA and NOAA are
required to withhold a percentage of
state grant funds under section 319 of
the Clean Water Act and section 306
of the Coastal Zone Management Act.
Conclusion
What will the new coastal nonpoint
programs mean for state governments
and agricultural producers? First, the
management measures are to be
implemented through new state
coastal nonpoint programs and. thus
the states will bear a major responsi-
bility for both developing the program
and implementing it. State water
quality and coastal zone management
agencies have until July 1995 to
develop these programs. Coordination
with existing programs will be a key
to successful program development
and implementation. States are now
beginning to evaluate existing pro-
grams and, where necessary, create
new programs and authorities to meet
the CZARA requirements. State offi-
cials are required to involve the public
throughout the program development
process, and there will be oppor-
tunities for the public to discuss
potential new state requirements.
Although all coastal states will be
responsible for ensuring that the
management measures are imple-
mented, there is flexibility in how
states may develop and implement
particular program components. States
may adopt a variety of approaches to
meet CZARA requirements, and of
course, much depends on the non-
point source control activities already
underway. Thus, it is difficult to
anticipate and predict exactly how
individuals or businesses in any
particular coastal state will be
impacted. In some areas the require-
ments for confined animal facilities
may far exceed existing levels of
control. However, in general, for
agricultural producers, state coastal
nonpoint programs will most likely
require an acceleration of implemen-
tation of practices that are already
widely employed throughout the
agricultural community. Practices such
as conservation tillage for erosion
control and nutrient management
plans are likely to become the norm
in coastal areas. Q
JOURNAL OF SOIL AND WATER CONSERVATION 75
-------
State/Regional
Experiences
?-*ftP-'--.i»i-«^St^to5^^^~
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» L ,i, ,1 ,» ' .," . Bli" »:ill J^U'I "..Uii'1"".
i ijiii"*"-.! • i (•'!•' 1 :',i, S"*:iiiS«*; Jw©
i-«{8*p i .« - is; ;; ,iB5fr« TWJ"
A*i-afe«f* >' ^' iS!S= i, :'*Eat:i;
California's
experience with a
voluntary
approach to
reducing nitrate
contamination of
groundwater: The
Fertilizer
Research and
Education
Program (FREP)
Jacques Franco, Stephan Schad, and
Casey Walsh Cady
D
ensely populated California
supports the fifth largest agri-
cultural economy in the world.
Jacques Franco is a program coordinator,
and Stephan Schad and Casey Walsh Cady
are research assistants at the Fertilizer
Research and Education Program, California
Department of Food and Agriculture,
Sacramento, 94271-0001.
It produces billions of dollars of
agricultural produce annually while its
population grows rapidly. California's
cities and rural areas are competing
for land, water, and other natural
resources.
Growers are being increasingly
viewed as contributors to environ-
mental degradation. One particular
concern is agriculture's impact on
groundwater quality. Many of Cali-
fornia's farmers apply fertilizers,
specifically nitrogen, to their high
value crops. Nitrogen not taken up by
plants or trees can convert to nitrate
and end up in the groundwater.
According to the California Depart-
ment of Health Services, more public
supply wells in California have been
closed due to violation of the nitrate
drinking water standards than from
any other contaminant (£>• The cur-
rent public health standard for
acceptable drinking water in California
is 45 mg/1 (45 parts per million) of
nitrate. The Environmental Protection
Agency reports that hundreds of wells
in various areas of California exceed
this level (see Map 1). In total, 10 per-
cent of the water samples taken from
38,144 California supply wells showed
nitrate concentrations exceeding the
state's maximum contaminant level of
45 ppm, according to a 1975 to 1987
survey (2). In one specific area, the
Metropolitan Water District of South-
ern California estimates that about 4
percent of its annual production has
been lost to nitrate contamination,
while only 0.5 percent has been lost
to organic contamination to date (3).
Although nitrate is a natural compo-
nent of living systems, too much
nitrate can cause health problems.
One well-known potential threat is the
relationship between high nitrate
levels in drinking water and a rare
infant disease called methemo-
globinemia (blue-baby syndrome). In
the stomachs of very young babies,
nitrate can convert to a related com-
pound (nitrite) that interferes with the
blood's oxygen-carrying capacity.
Cancer and birth defects are other
concerns, although no firm link has
been established.
There is also an economic dimen-
sion to the problem. When nitrate in a
public water supply reaches or ex-
ceeds the 45 mg/1 standard, costly
measures are necessary. The well may
have to be deepened or closed down,
a different water source may have to
be acquired for blending, or expen-
sive water treatment may be required.
For example, one southern California
water district has estimated that well-
head nitrate treatment costs about
$375 per million gallons (4). In 1986,
public water systems in California
applied to the State Department of
Health Services for more than $48
76 NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT
-------
million to correct nitrate violations (.4).
The total cost was undoubtedly larger
since many water agencies used other
sources of funds to address the
problem.
The Fertilizer Research and
Education Program (FREP)
California's state government has
only recently begun to address nitrate
contamination from agriculture. In
1988, the Director of the California
Department of Food and Agriculture
(CDFA) appointed a Nitrate Working
Group to study the nitrate problem
relating to agriculture in California (see
Map 2). After analyzing 12 years of
well data, the Working Group devel-
oped recommendations which still
form the basis of FREP's mission (3).
The Nitrate Working Group recom-
mended that CDFA identify and priori-
tize nitrate-sensitive areas throughout
California and develop research and
demonstration projects to reduce agri-
culture's contribution to ground-water
contamination from fertilizer use.
The first step in implementing these
recommendations was to decide
which locations in the state should be
given highest priority. Two conditions
indicate an urgent problem: (1) a high
level of nitrate contamination in
groundwater and (2) a population that
depends on that "water for drinking.
Those two conditions depend on
various factors. To determine nitrate
sensitivity of an area, FREP expanded
on a list of criteria originally prepared
by University of California soil
scientists (5, 8).
1. In terms of groundwater use,
nitrate concentration is critical if
groundwater is used for domestic
or animal consumption.
2. Sandy or other coarse-textured soil
types transmit water downward
more rapidly, and nitrate along
with it.
3. Inefficient irrigation practices may
lead to deep percolation which
increases the leaching of nitrate.
4. Types of crops most likely to
increase nitrate leaching are those
that need heavy nitrogen fertili-
zation, have high economic value,
are not harmed by excess nitro-
SAN FRANCISCO
LOS ANGELES
*Note: Each symbol may represent more
than 1 analysis at same well
Map 1. Well locations where nitrate levels have been recorded at
45 mg/l or greater during the period 1975-1987. (EPA STORET
SYSTEM, 1988)
gen, and tend to take up a smaller
fraction of the nitrogen applied.
5. A climate with high total rainfall,
concentrated heavy rains, and mild
temperatures lead to more nitrate
leaching.
6. Distance between root zone and
groundwater: The closer plant
roots are to the groundwater table,
the more readily nitrate enters
drinking water.
7. Potential impact: Nitrate contam-
ination of drinking water becomes
more immediate the more people
depend on it as their sole drinking
water supply.
Early activities. Using the nitrate
sensitivity criteria listed above, FREP
chose three areas to begin initial field
activities in 1990: the Salinas Valley in
Monterey County, eastern Stanislaus
and Merced Counties, and the Fall
River Valley in Shasta County. The
goal of all these projects is to develop
and extend information to growers on
improved farming practices. These
improved ways of fertilizing, irrigating,
and managing crops are designed to
fit local resource and farming condi-
tions, reduce nitrate leaching, and
improve growers' profits.
Salinas Valley. The Salinas Valley in
coastal central California produces
more than a quarter of the nation's
fresh vegetable crops, while depend-
ing almost entirely on groundwater,
not only for irrigation but for domestic
and industrial water use as well.
About 150,000 people use Salinas
Valley groundwater as a drinking
water source. According to a 1987
report by the Monterey County Water
Management Agency, almost half of
the wells sampled in unconfined
JOURNAL OF SOIL AND WATER CONSERVATION 77
-------
SAN FRANCISCO
Map 2. Generalized map of nitrate sensitive areas in California.
aquifers of the Valley had nitrate
levels above the 45 rng/1 standard (.6).
Irrigated farms are a major source of
that nitrate.
FREP was invited by the Salinas
Valley Nitrate Advisory Committee
(NAG) to help address the pressing
local nitrate problem. Pooling re-
sources with the State Water Resources
Control Board, the Monterey County
Water Resources Agency, the lettuce
industry, and University of California
Cooperative Extension, FREP funds a
number of projects which research and
demonstrate improved farming
practices.
In one Salinas project, a team of
growers and researchers are improv-
ing nitrogen uptake efficiency in veg-
etable crops. The project also demon-
strates winter cover cropping practices
compatible with vegetable production
methods.
Stanislaus and Merced Counties
(San Joaquin Valley). On the eastern
side of the San Joaquin Valley,
particularly in Stanislaus and Merced
Counties, many farming areas are
sensitive to nitrate groundwater
contamination. Local soils tend to be
sandy or coarse, with little or no
layering to restrict downward water
flow. Tree crops grown in this area
require high inputs of nitrogen but
their nitrogen uptake efficiency is
relatively low. Water delivery systems
tend to be less efficient, which
increases deep percolation. Through-
out the San Joaquin Valley, dairying,
with its associated problems of
manure disposal, is a large and
important industry.
FREP is supporting research to
develop strategies to reduce potential
nitrate leaching in almonds and
peaches, and to improve plant nitro-
gen monitoring techniques in or-
chards. One research project is devel-
oping diagnostic tools and sampling
procedures to assess nitrogen status in
tree crops.
Fall River Valley. Although this
small farming region in northeastern
California is not high in statewide
agricultural importance, it was selec-
ted for a pilot project because of its
small, confined aquifer and its unique
combination of rural residences in
close proximity to agricultural produc-
tion. The Fall River Valley produces
livestock, alfalfa, potatoes, grain, and
specialty crops such as strawberry
plants. A recent survey of local wells
showed that about 40 percent had
nitrate levels in excess of 45 mg/1.
Here, FREP works with the Fall
River Resource Conservation District,
the Regional Water Control Board,
and other agencies. In the first phase
of this project, roughly 20 wells
throughout the region are being
monitored. Information is collected
not only on nitrate levels but on
patterns of land use, population,
agriculture, and geology. Nitrate data
is being correlated with proximity of
leach fields, type of agriculture, soil
type, and depth of wells. The second
part of the project is developing best v|
management practices, primarily for
potatoes and strawberries.
The Competitive Grants Program. In
1990, the California state legislature
authorized an increased tax assess-
ment on fertilizer sales to support
research and education projects to
advance the environmentally safe and
agronomically sound use and hand-
ling of fertilizer materials. This legis-
lation was proposed and supported by
California's fertilizer industry and the
California Department of Food and
Agriculture. FREP has managed these
funds through a competitive grants
program.
. A review committee, which includes
growers, fertilizer industry represen-
tatives, state government represen-
tatives, and University of California
scientists, selects and recommends
funding for projects. At the same time,
since people from different areas of
expertise participate in the review,
FREP uses this process as an oppor-
tunity to identify new areas of
research and outreach.
The purpose of the competitive
78 NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT
-------
grants program is to generate specific
information and practices. that can be
used on farms to reduce the down-
ward flow of nitrate while maintaining
productivity and the economic viability
of the farms. Our current research
portfolio includes projects on almonds,
citrus, stone fruits, lettuce, cotton, and
grapes. Many of these projects are be-
ing carried out on growers' fields,
thereby incorporating .their views and
practices into the proje'ct management.
Educational projects include fertilizer
management training for small and
ethnic minority farmers, videotapes on
best management practices, and
agricultural curricula for secondary
school teachers (7, 8) (see Map 3).
Public service and outreach. FREP
also has a mission of outreach. It
serves as a clearinghouse to improve
information exchange among individ-
uals working on California's nitrate
groundwater problem related to
fertilizer use. It facilitates access of
local agencies, growers, and agri-
cultural service suppliers to federal,
state, and other resources. Both
technical assistance and funding are
provided (see Chart 1).
The program is currently devel-
oping a computerized information
system (FREPIS) which includes a
computerized system to store, process,
and produce resource, materials and
publications; baseline information on
fertilizer use statistics and farming
practices for target crops, and a
collection of technical articles, poten-
tial sources of funding, directories of
technical expertise, and regulatory
and legislative analysis and infor-
mation. With this structure, growers,
industry, and extension experts will
be able to easily access current infor-
mation and locate support services.
The FREP staff also helps organize
field days, workshops, and grower
meetings; works with media; and
helps develop and distribute infor-
mation on specific best management
practices for a variety of California's
crops.
Reflection on our experience
Relative to California's large agri-
cultural industry and the extent and
PROJECTS DEVELOPED WITH ,*
FREP ASSISTANCE IN 1990 12P
VEGETABLE CROPS 40
FRUIT AND NUT CROPS Q
FIELD CROPS
EDUCATION-LOCAL
EDUCATION-STATEWIDE
SAN FRANCISCO
^jr'.K
;rei£i:suLShasta Co-:
«.-B*»».4i'tei!fTi-«
Map 3. FREP project sites 1990-1992
complexity of the fertilizer and
groundwater situation we are address-
ing, FREP is a small program. Four
years of this voluntary nitrate man-
agement program have not fundamen-
tally changed fertilizer management
practices. However, FREP offers an
approach that actively involves all key
parties who have a stake in address-
ing the nitrate problem. Nevertheless,
it is too early for a formal evaluation
of the program. In the following, we
would like to look at the distance we
have covered so far, as well as at the
road still lying ahead.
Progress to date. We believe that
FREP has done a few things well. For
example, FREP brought together
growers, industry, the university, and
government, as partners who can
constructively address the nitrate
situation. Since these parties have an
opportunity to participate actively in
FREP's work and governance, we
have developed realistic and practical
approaches to deal with the nitrate
problem. Out of the same partnership,
our non-regulatory approach is more
palatable to growers than regulation
imposed by outsiders.
Another clear benefit from FREP
activities is that the value of the
adaptive research and information
gained through our activities will
increase, if fertilizer use becomes
regulated. In the worst of cases, this
information would help guide legis-
lation toward an effective and prac-
tical control of fertilizer use that hope-
fully will minimize costs to growers.
We feel that our work grows in value
as the debate around groundwater
quality heats up.
Early results from some FREP-
sponsored projects show great
promise. These projects have the
potential to increase the efficiency of
fertilizer application, and reduce
JOURNAL OF SOIL AND WATER CONSERVATION 79
-------
FERTILIZER RESEARCH AND EDUCATION INFORMATION SYSTEM (FREPIS)
MASTER MOLING
LIST AND OFFICE
AUTOMATION
COMMUNICATIONS
AND DATA
EXCHANGE
Chart 1.
Factors Affecting Groundwater Contamination
(A simplified model)
Human Aspects Technical Aspects
Awareness
Attitudes
Willingness to Change
Freedom from S other constraints
Water Management
Fertility Management
Soil & Crop Management
Outreach & Extension
Economic, Policy & Regulatory Environment
Chart 2.
nitrate contribution to groundwater. by citrus growers. If this practice is
For example, one project that shows widely adopted, it clearly will increase
how growers may replace regular soil grower returns and may prevent up to
fertilizer applications with foliar 10,000 tons of elemental nitrogen
applications is being quickly adopted from ending up in groundwater every
year. In addition this practice may also
reduce the use of insecticides; a clear
example of a "win-win" situation.
Finally, FREP's mere presence has
helped increase key players' aware-
ness of the nitrate in groundwater
situation. We have observed increas-
ing activity by various grower groups
and public entities in this area. This
increased activity probably can be
related in part to FREP's presence and
activities.
Continuing challenges. After four
years of work, what are some issues
which continue to challenge us?
California's multitude of crops and
climates has certainly posed a big
challenge to our program. With
hundreds of crops planted between
the coast and the mountains, it is
impossible to develop adaptive
research and outreach projects to
address all situations effectively;
therefore our approach to this basic
constraint has been to concentrate on
those farming systems that pose the
highest potential threat (3, 7) and
where payoffs appear most promising.
Working at a meeting-point between
California's state government and the
fertilizer industry sometimes reveals
differences in perspectives. On one
hand, we have seen both parties
successfully working alongside each
other in areas where goals and per-
spectives are clearly complementary.
On the other hand, our program's
goals, which have been embraced by
a majority of the fertilizer industry's
leadership, have yet to be translated
into clear incentives to their work-
force, particularly to the sales people.
Our other major cooperator, the
University of California Cooperative
Extension Service (UCCE), poses a
similar "institutional" challenge to
FREP's objectives. Priorities of UCCE
and the University rest on plant
improvement and protection, not as
much on plant nutrition. Faced with
budget cuts, the University dedicates
fewer resources to fertility issues and
is losing expertise that is not being
replaced. Also, extensionists work in a
research-biased environment. Educa-
tion and outreach activities often fall
victim to the infamous "publish-or-
perish" situation.
New social values placed on agri-
80 NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT
-------
culture challenge FREP and farmers
alike. Society used to expect high pro-
ductivity and efficiency from farmers.
Now, farmers are asked to balance
productivity against environmental
quality. Society and its institutions
have yet to define where that balance
lies. From a grower's point of view,
this new set of social values is less
clear and allows more room for
interpretation than the old goal of
maximum production. At this time,
neither institutional nor market incen-
tives seem to delineate "optimal"
agricultural practices.
From some growers' perspective,
these new demands are incompatible
with the high agricultural productivity
from which we all benefit. Fertilizer is
inexpensive relative to other produc-
tion inputs, for many of California's
high value crops. The potential savings
from reduced fertilizer use may be
perceived as not worth the increased
risk of potential yield or quality loss.
Given the uncertainties of crop pro-
duction, applying more fertilizer than
may be needed is a rational manage-
ment strategy {9). Over-applying
fertilizer probably is seen by many
growers as an inexpensive insurance
program. This situation could be
changed only if food prices were to
reflect the environmental costs asso-
ciated with crop production. For that
reason, farmers probably hesitate to
venture into risky or unproven prac-
tices when their foreign competitors
may not be held to the same envi-
ronmental performance standards.
Finally, we recognize that an effec-
tive interface with growers is a critical
and ongoing challenge. Practitioners
should have a major role in shaping
our program. However, it requires a
sustained effort to maintain active
grower participation. This is not
surprising in light of our previous
discussions regarding the relatively
low priority of fertilizer management
in relation to the many other issues
confronting growers. Although FREP
has encouraged growers to propose
and actively participate in the projects
we support, so far, growers play an
indirect role in formulating the
questions some FREP projects are
addressing. So, while farmers still
participate in most of the projects,
their participation has not been as
active as we would like it to be. -
The outlook. We are committed to
improving our "close to the customer"
position, and use as much input as we
can from our clientele. Growers
participate in reviewing project pro-
posals we receive and help evaluate
research results. Commodity Research
Boards cooperate with us in various
projects. By involving practitioners,
we can keep our work practical and
relevant to our clientele. We will
continue to strengthen grower partici-
pation at all levels of our program's
activities.
At the same time, we are turning
our attention to fertilizer salespeople
and production advisors. We realize
that their advice strongly influences
growers' decisions on fertilizer man-
agement. An important step in that
direction is the Certified Crop Advisor
program currently being developed by
the California Fertilizer Association,
the American Society of Agronomy,
and state agencies, and supported by
FREP. This important program is
increasing the technical proficiency of
individuals that help growers make
fertility related decisions.
As part of our effort to better under-
stand and serve our clientele, FREP is
attempting to address the human
aspects of adoption of agricultural
practices (see Chart 2). We realize that
before growers modify their farming
practices, they first need to become
aware of the effect of their practices
on groundwater quality. A good
understanding of grower attitudes,
their willingness to change, and the
constraints they face is required to
develop effective programs. By inte-
grating these social and behavioral
components of decision making, our
projects will yield information which
has a better chance of widespread
adoption.
Looking to the future, we hope that
our approach will prove effective. We
will continue to nurture the partner-
ship between industry, government,
and growers-—a partnership that
focuses on prevention and active
grower participation. We will continue
to support a partnership for adaptive
research and demonstration of
practices that are good for the envi-
ronment as well as the pocket book.
In the long run, the true test of FREP's
effectiveness will be whether we can
sustain a targeted effort which brings
tangible results and is regarded as
credible by our clientele and the
general public.
REFERENCES CITED
1. Spath, D.P. 1990. The nitrate threat. In:
Coping With Water Scarcity: The Role of
Ground Water. University of California,
Water Resources Center. Riverside.
2. Mackay, D., and L. Smith. 1990.
Agricultural chemicals in groundwater
monitoring and management in
California. Journal of Soil and Water
Conservation 45(2): 253-255.
3. California Department of Food and
Agriculture. 1989. Nitrate and Agriculture
in California. Nitrate Working Group,
Sacramento.
4. California State Water Resources Control
Board. 1988. Nitrate in drinking water.
. Report to the legislature. Rpt.No.88-
HWQ.Div. Water Quality, Sacramento.
5. Pratt, P.p. et al. 1979. Nitrate in Effluents
from Irrigated Lands. Final report to the
National Science Foundation, University of
California at Davis.
6. Monterey County Flood Control and
Water Conservation District. 1988. Nitrate
in Ground Water, Salinas Valley,
California.
7. Franco, J. 1992. Nitrate Management
Program—Fertilizer Research and Edu-
cation Program: Progress Report 2991, in
Communications in Soil Science and Plant
Analysis. 23(17-20):2111-2134.
8. Franco, J., and C.W. Cady. 1993. Fertilizer
Research and Education: A progress report
1990-92. California Department of Food
and Agriculture.
9. Weinbaum, S., S. Johnson, and T.M.
Dejong. 1992. Causes and Consequences
of Overfertilization in Orchards.
HortTechnology, January-February. Q
JOURNAL OF SOIL AND WATER CONSERVATION 81
-------
A local agency's
approach to
solving the
difficult problem
of nitrate in the
groundwater
Ron Bishop
Central Platte Natural Resources
District (NRD), located in south-
central Nebraska, is one of 23
NRDs across the state. Natural
Resources Districts are local units of
government charged with the respon-
sibility of conservation, wise develop-
ment, and proper utilization of the
natural resources. They are respon-
sible for a host of activities dealing
with soil, water, and other natural
resources.
This paper is about the manage-
ment of groundwater quality within
the Central Platte NRD. Of the 13
different NRD purposes outlined in
Nebraska Statutes, two deal directly
with groundwater quality: purpose
No. 6, "the development, manage-
ment, utilization and conservation of
groundwater and surface water," and
purpose No. 7, "pollution control."
Groundwater quality problems are
not new to the Central Platte valley.
As early as 1961, 11 years before
NRDs were created, the University of
Nebraska Extension Service docu-
mented cases of groundwater nitrate
above 10 ppm in Merrick County in
the eastern part of the Central Platte
area.
The NRDs across Nebraska were
formed July 1, 1972, and, partly
because of those earlier indications of
groundwater nitrate in Merrick
County, one of die first actions of the
Central Platte NRD was to form a
water quality committee. The efforts
of that committee resulted in a
Ron Bishop is the general manager of the
Central Platte Natural Resources District,
Grand Island, Nebraska 68803.
contract with the Conservation and
Survey Division of the University of
Nebraska at Lincoln to conduct a
baseline study of groundwater quality
across the Central Platte region.
The results of the study, published in
1974, indicated that the groundwater
nitrate problem was not unique to
Merrick County. About half the district
had nitrate levels at less than 2.5 ppm
but the other half had significant
amounts of nitrate in the groundwater.
Approximately 20 percent of the NRD,
extending from Kearney in the central
part to Columbus in the northeast
corner, had groundwater nitrate that
exceeded 10 ppm.
The 10 ppm is significant because
the U.S. Public Health Service as well
as EPA has established 10 ppm
nitrate/nitrogen as the maximum
allowable concentration in drinking
water for humans and animals. Levels
above 10 ppm can lead to methemo-
globinemia, or "blue baby" syndrome
as it is commonly called. Infants,
especially infants under six months of
age, are particularly susceptible to
methemoglobinemia. The ingested
nitrate reduces the oxygen carrying
capacity of the blood (thus causing
the blue tinge to the skin) and can
lead to brain damage or death in
severe cases.
The NRD and the Cooperative
Extension Service in 1974 started a
project in Merrick County to study
methods of extracting nitrate from
groundwater through irrigated corn
production. That same year, the NRD,
in cooperation with the Department of
Agricultural Engineering at the
University also conducted a study to
determine what contribution septic
tanks made to groundwater nitrate.
The septic tank studies, completed
in 1975, indicated that while septic
systems can be a contributing factor,
especially in development areas that
have a concentration of septic systems
for sanitary disposal, septic tank
leaching could not be a primary
source of groundwater nitrate in the
Central Platte valley. The NRD also
continued the studies with the Exten-
sion Service, looking at methods of
extracting nitrate from the ground-
water through corn production in
1975 as well as 1976 and 1977.
In 1977 the NRD entered into a
second contract with the Conservation
and Survey Division of the University
of Nebraska to carry out a study to
determine the original source of the
nitrate in the groundwater. The study
was completed in 1978 and identified
commercial fertilizers applied to
irrigated croplands as not the only,
but the major, source of groundwater
nitrate in the Central Platte valley.
Commercial fertilizers applied to
the fields were leached below the
root zone and into the groundwater
aquifer by rainfall and over-appli-
cation of irrigation water. In 1978 the
Conservation and Survey Division
conducted a third study concerning
carbon content of groundwater and a
fourth study looking at atrazine in
groundwater within the NRD. Then in
1979 the NRD entered into still
another contract with the Conser-
vation and Survey Division to study
chemical seepage, primarily nitrate
seepage from irrigation tailwater
recovery pits. The study was to
determine what contribution the pits
made to groundwater nitrate prob-
lems. Also in 1979 the NRD, working
in cooperation with the Extension
Service, Agricultural Stabilization and
Conservation Service (ASCS), and the
Soil Conservation Service of Hall
County applied for and received a
grant through the State Department of
Environmental Control with cost-share
monies through ASCS, that enabled
the NRD to establish the Hall County
Water Quality Special Project. This
was a major research and demon-
stration project covering 65 square
miles (168 km2) in an area of Hall
County that had high nitrate and
varying soil types.
The program got under way in 1980
and was carried out for the next four
cropping seasons. The objectives of
the project were to study ways to
impede the leaching of nitrate into the
aquifer from fertilizer applications, to
improve the water quality by mining
groundwater with high nitrate content,
and to demonstrate that nitrate may
be managed efficiently and effectively
while maintaining crop yields.
In 1984, 10 years after the first
baseline study, the NRD did another
inventory of groundwater nitrate. The
82 NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT
-------
inventory indicated that the areas of
high nitrate had grown in size, and it
showed that the average concentra-
tions continued to increase over time.
The average nitrate concentrations
of groundwater in Buffalo County had
increased from 2.4 ppm in 1961 to an
average of 7.3 ppm by 1984 and in
Hall County it increased from 1.5 ppm
in 1961 to 10 ppm by 1984. In Merrick
County, where the levels had aver-
aged 7.7 ppm in 1961, they had
increased to the point where the
average nitrate concentration in
groundwater was 16 ppm, 60 percent
greater than the U.S. Public Health
Service recognizes as the maximum
safe level for human or animal
consumption.
All of the investigations, demon-
strations, and research that were
conducted between 1973 and 1983
showed that the quality of the ground-
water in the Central Platte region is
impacted by three things: residual
nitrate, irrigation water, and fertilizer
applications.
Residual nitrate can impact upon
groundwater because it is the nitrogen
in the root zone left over after the
crop is harvested that is available to
leach into the groundwater supply.
Irrigation water also has an impact
on groundwater quality. First of all,
the nitrogen content of the irrigation
water and then the rate at which we
apply the irrigation water affect
groundwater. Over-application of
irrigation water leads to leaching the
nitrogen down below the root zone
and eventually into the groundwater
aquifer.
Finally, fertilizer applications have
an impact on groundwater quality.
The rate at which commercial fertilizer
is applied can have an impact. Putting
on more fertilizer than is needed or
can be utilized by the crop means
more nitrogen available to be leached
down below the root zone. The form
of the nitrogen fertilizer, whether it is
in a leachable form or not, can have
an impact, and the time of year that
the fertilizer is applied can have an
impact. Fall applications of nitrogen
fertilizer means that the "opportunity
time" for it to be leached below the
root zone and into the aquifer is
extended.
The Hall County Water Quality
Special Project 'was completed in
1983. In 1984 the Central Platte NRD,
the Soil Conservation Service, and the
Cooperative Extension Service entered
into an agreement to continue and
expand the program of utilizing "best
management practices" that were
found to be most effective in the Hall
County project. A full-time employee
was hired to work with farmers,
fertilizer dealers, soil testing labs, and
the public to promote sound nitrogen
management. Six demonstration fields
were set up on farms in Buffalo,
Merrick, and Hall Counties the first
year. The employee working on the
program took deep soil samples for
analysis on each of the demonstration
fields.
Historically only a small percentage
of the cropland fields were tested
each year for residual nitrate and most
of those that were tested only had
samples taken of the top seven or
eight inches. The demonstrations and
the soil sampling that have been done
since 1984 as well as the soil sampling
from the Hall County Special Water
Quality Project indicated that a large
volume of residual nitrate available to
the crop is missed in those shallow
samples. As an example, an 8-inch
(20-cm) sampling in Buffalo County of
the fields involved in the demon-
stration plots would have indicated an
average of 17.5 pounds (8 kg) of
nitrogen available per acre. However,
a sampling of the root depth to 4 feet
(1.2 m) indicates that in fact an
average of 125 pounds (57 kg) .of
nitrogen per acre was available on
those same fields.
The employee also took water
samples each year from each well that
was involved in the demonstration
fields.
Additional nitrogen for the crop is
also available in the irrigation water
from those high nitrate areas. Irri-
gation water from a well testing 25
ppm nitrate/nitrogen is making 50
pounds (23 kg) of nitrogen available
to the crop for every 9 inches (23 cm)
of water applied.
Looking at the averages over the
four counties in which demonstrations
were held during the 1984, 1985, and
1986 cropping years, we find that the
three-year average for each county
ranged from a low of 90 pounds of
nitrogen available per acre (101
kg/ha) in the soil and water to a high
of 166 pounds per acre (186 kg/ha) in
Buffalo County.
In addition to taking and analyzing
the soil samples and analyzing nitrate
in water that is available for the crop,
the project employee also scheduled
the irrigation applications, then
checked yields on each of the demon-
stration fields at harvest time. The
results of the yield checks indicated
that applying additional nitrogen does
not result in higher yields. Typical of
the findings is a 1984 demonstration
field study in Buffalo County in which
the recommended commercial fertil-
izer (N) amount, after taking into
account the nitrogen available in the
soil and in the water, was a nitrogen
application of 150 pounds per acre
(168 kg/ha). The field was stripped
out into test plots with some of the
plots having applications of the 150
pounds that was recommended, and
some strips 40 pounds per acre (45
kg/ha) less at 110 pounds per acre
(123 kg/ha), and other strips 40
pounds more than the recommended
at 190 pounds per acre (213 kg/ha). A
yield check at the end of the year
indicated that the 150 pound recom-
mended rate maximized yields at 187
bushels per acre, but the application
of 110 pounds, 40 less than recom-
mended, yielded within one bushel of
the recommended amount and in fact
out-yielded the plots with 190 pounds
of nitrogen by two bushels per acre.
. Another field study in Merrick
County conducted in 1984 showed
basically the same results with 56
pounds of nitrogen per acre (63
kg/ha) yielding within one bushel of
those plots on which 225 pounds per
acre (252 kg/ha) of nitrogen had been
applied.
In 1986 the Nebraska legislature
expanded the authority and respon-
sibility of natural resources districts by
adding to the management area
authority the ability to require "best
management practices" and "educa-
tion programs designed to protect
water quality."
The Central Platte Natural Resources
District Board of Directors felt that the
JOURNAL OF SOIL AND WATER CONSERVATION 83
-------
NRD was in an excellent position to
develop a reasonable and effective
program for groundwater quality
management, so they adopted a
program that establishes management
areas based on the seriousness of the
groundwater nitrate problem. Phase I
areas are those areas where the
average groundwater nitrate level is
between 0 and 12.5 ppm.
Originally in a Phase I area the only
regulation was the requirement that
fall applications of commercial nitro-
gen fertilizer be banned on the sandy
soils. The rest of the Phase I program
was a combination of voluntary
cooperation, research and demon-
stration, and information and educa-
tion. Effective January 1, 1992, two
new requirements were added. First,
all operators using nitrogen fertilizer
on corn or sorghum must become
certified by attending a two and a half
hour educational class on fertilizer
and water management with re-
certification required every four years.
Second, the NRD now bans fall
nitrogen applications on the heavier
soils until after November 1 each year.
Phase II areas are areas where the
average nitrate concentration in
groundwater is from 12.6 to 20 ppm.
In a Phase II area the programs and
regulations established in Phase I
continue and there are additional
requirements or regulations imposed
upon operators. Irrigation wells are
required to be sampled and analyzed
for nitrate each year, deep soil
analysis for nitrate is required on
every field every year, and in addition
to the ban of fall applications of
fertilizers on sandy soils, the fall
applications are permitted on heavier
soils only after November 1, and
require the use of an approved
inhibitor. Each operator is also
required to submit an annual report to
the NRD, Additional regulations
effective January 1, 1992 include
furnishing a certification from the
dealer that an inhibitor was used
when required and a requirement that
all irrigation water applications be
metered. The reason for the metering
can be seen by looking at the results
and records of some of the demon-
stration fields. Irrigation water
applications on two different fields of
corn in the same county during the
same year can range from 9.6 inches
(24 cm) to 38.5 inches (98 cm).
Phase III areas have been
established recently in the NRD. Phase
III areas have an average nitrate
concentration of greater than 20 ppm.
In a Phase III area the programs and
regulations that were started in the
Phase I and Phase II areas are
continued and in addition, two more
regulations are imposed dealing with
fertilizer applications. First, the com-
mercial nitrogen fertilizer applications
are banned on all land in the fall and
winter and second, when those com-
mercial nitrogen fertilizer applications
are made in the spring, the NRD
requires either a split application or
the use of an approved inhibitor.
Phase I areas cover about 80
percent of the NRD and about 50
percent of the irrigated cropland.
Phase II areas cover some 225,000
acres (91,058 ha) extending from
approximately Kearney on the west,
eastward across the valley to the
eastern end of the NRD near
Columbus. The four Phase III areas
scattered across the eastern half of the
NRD cover' some 250,000 acres
(101,175 ha) of land.
The purpose of the groundwater
quality management program that the
Central Platte Natural Resources
District has adopted is really two-fold.
The first purpose is to clean up our
groundwater supplies since each of
the 115,000 residents of the NRD rely
upon that groundwater as a source of
drinking water. The second purpose is
to accomplish groundwater cleanup in
such a way that we do not have a
detrimental impact upon the irrigated
agriculture economy that is so
important to the Central Platte Valley
of Nebraska.
The results from the first four years
of the program are very encouraging.
Nitrate levels, that averaged 19.0 ppm
over an area of 500,000 acres (202,350
ha) and were increasing at the rate of
0.5 ppm per year up through 1987,
have not only stopped the increase,
but have declined at an average
annual rate of 0.25 ppm per year. Q
Nutrient
management
legislation in
Pennsylvania
Douglas B. Beegle and Les E. Lanyon
In the spring of 1993, the
Pennsylvania state legislature
passed and the governor signed
the Nutrient Management Act into law.
Before this legislation was passed,
problems with nutrient pollution were
handled primarily under the Clean
Streams Law. This law basically states
that if a farmer is following practices
in the Department of Environmental
Resources (DER) publication Manure
Management for Environmental Prote-
ction, no special permits or approvals
are required for manure utilization on
farms. The Nutrient Management Act
is the first law in Pennsylvania to
directly affect nutrient application on
farm fields. This article summarizes
the main provisions of the Act.
Purposes
The purposes of this legislation as
stated in the Act are as follows:
• Establish criteria, planning require-
ments, and an implementation
schedule for nutrient management
control on certain agricultural
operations that generate or use
manure.
• Provide for development of an
educational program on nutrient
management.
• Provide for development of
technical and financial assistance
for nutrient management and
alternative uses of animal manure.
• Require DER to assess the extent
of other nonpoint sources of
pollution.
Douglas B. Beegle is an associate professor of
agronomy and Les E. Lanyon is an associate
professor of soil fertility in the Department of
Agronomy, The Pennsylvania State University,
University Park 16802
84 NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT
-------
Who will be affected?
The Act states that "concentrated
animal operations" will be required to
develop and maintain a nutrient
management plan. Concentrated
animal operations are defined as oper-
ations where the animal density
exceeds two animal units per acre on
ah annual basis. An animal unit is
1,000 pounds of live weight. Thus, for
example, a 1,300-pound dairy cow is
1.3 animal units; 333 chickens
weighing 3 pounds each is 1.0 animal
unit; and 5 hogs weighing 200 pounds
each is 1.0 animal unit. Which acres
will be counted in calculating the
animal density is unclear, but presum-
ably acres available for manure appli-
cation will be counted. The worksheet
contained in Table 1 can be used to
estimate the animal density on your
farm (See Table 1).
To calculate the animal density on
your farm, insert the total animal units
(AU) calculated in Table 1 into Table
2 along with the number of acres
available for manure (See Table 2).
The actual calculations used in the
regulations may be different from
those used in these tables, but these
figures will give farmers an idea of
where they stand.
The criterion of two animal units
per acre is a fairly high animal
density. Farms with a higher density
are likely to have more nutrients than
can be utilized safely by crops on the
farm. Thus nutrient management plans
often will not only include detailed
plans for on-farm manure utilization
but also may require plans for moving
some manure off the farm.
Plan development, approval, and
implementation
A certification program will be
developed by the Pennsylvania
Department of Agriculture and all
plans will have to be written by
certified nutrient management special-
ists. Farmers may become certified to
write their own nutrient management
plans. Details on what will be
required for certification have not yet
been developed.
Plans required under this legislation
must be submitted to the local conser-
vation district of other designated
authority for review. Existing opera-
tions which have more than two
animal units per acre will have one
year from the time the regulations are
adopted to submit their plans for
approval. New operations or opera-
tions that expand and then have more
than two animal units per acre must
submit a plan within three months of
the time when regulations are adopted
or prior to the start of operations,
whichever is later.
Conservation districts will have 90
days to act on the plan. If the plan is
not approved, the operator has 90
days to submit a revised plan. Plans
must be implemented within three
years. This implementation deadline
can be extended by two years if
substantial capital improvements are
required for implementation.
The animal density criterion is not
to be construed as prohibiting devel-
opment or expansion of agricultural
operations that exceed the criterion. It
just means that these operations will
be required to have a nutrient man-
agement plan.
Any farm that violates the Clean
Streams Law also must have a nutrient
management plan. Farms with fewer
than two animal units per acre will be
encouraged to have voluntary nutrient
management plans. Plans can be
transferred to subsequent owners of
an operation.
Authority under the Act
The State Conservation Commission
—the authority for this Act—is
charged with the following:
• Develop regulations, within two
years of the legislation being
passed, that establish minimum
criteria for nutrient management
plans. The following criteria were
specified in the Act:
— identify the nutrient of concern,
which is nitrogen for at least the
next five years
- establish procedures to deter-
mine acceptable application
rates for manure
— establish record-keeping require-
ments for land application and
nutrient distribution
- identify recommended best
management practices (BMPs)
— establish minimum standards for
storages
- establish conditions under which
plans must be amended
- establish criteria for emergency
situations
Continually evaluate emerging
technologies for use as BMPs.
After five years, reevaluate the
criterion for "concentrated animal
operations."
Develop and implement an
educational program on nutrient
management.
To the extent that funds are avail-
able, provide financial assistance
for implementation of nutrient
management plans.
Administer this Act. Administration
and enforcement can be delegated
to local conservation districts with
adequate programs and resources
for implementation.
Nutrient Management Advisory
Board
The Act establishes a Nutrient Man-
agement Advisory Board to review
and comment on all regulations,
criteria, and policies of the Conser-
vation Commission related to the
Nutrient Management Act. The board
members will include
• farmers (5)
• nutrition specialist
• feed industry representative
• fertilizer industry representative
• commercial lenders representative
« local government representative
• university agronomist
• hydrologist
• citizen representatives (2)
• environmental representative
Financial assistance
To the extent that funds are avail-
able, the Conservation Commission
will provide financial assistance in the
form of loans, loan guarantees, or
grants for implementation of nutrient
management plans for existing opera-
tions. A special nutrient management
JOURNAL OF SOIL AND WATER CONSERVATION 85
-------
Table 1.
Animal
operation(s)
Example:
Cows
No.
animals
(annual
average)
100
X
X
X
X
X
X
Animal
weight
1300
-=-1000=
-1000=
-r1000=
-=-1000=
-=-1000=
-1000=
Total
Animal
units
130
Table 2.
Total AU
*
Acres available
for manure
=
AU per acre
fund will be established for this pur-
pose. To receive financial assistance
under this Act, a farm must have an
approved nutrient management plan.
Enforcement
An authorized agent of the Conser-
vation Commission or conservation
district will be able to conduct investi-
gations of agricultural operations and
take action necessary to enforce the
Act. Civil penalties of not more than
$500 for die first day of each offense
and $100 for every additional day of
continuing violation can be assessed
by the Conservation Commission. The
amount of the penalty will be deter-
mined by the gravity of the violation,
potential harm to the public, potential
effect on the environment, willfulness
of the violation, previous violations,
and economic benefit to the violator
for failing to comply. In the case of a
violation which causes no harm, a
warning may be issued in lieu of a
penalty.
If a violation occurs in an operation
where a valid nutrient management
plan is being fully and properly imple-
mented, the farmer will be exempt
from penalty, and the liability for any
damages will be limited.
Preemption of local ordinances
No ordinance or regulation of any
political subdivision may prohibit or
in any way regulate practices related
to the storage, handling, or land
application of animal manure or
nutrients if the local ordinance or
regulation is in conflict with this Act
or its regulations. This includes
ordinances related to construction,
location or operation of facilities used
for storage of animal wastes or
nutrients. Local nutrient management
ordinances can be adopted, but they
must be consistent with this Act, and
their requirements can be no more
stringent than the requirements under
this Act. Finally, no local penalty can
be assessed for a violation where a
penalty has already been assessed
under this Act.
Other nonpoint sources of
potential nutrient pollution
While this Act deals only with
regulation of nutrient management on
concentrated animal operations, the
Pennsylvania Department of Environ-
mental Resources is charged with
assessing the extent of the impact of
other potential nonpoint sources of
nutrient pollution on the environment,
including
• assess the impact of on-lot septic
systems on nutrient pollution
problems and make recommen-
dations within one year.
• assess the impact of improper
water well construction on nutri-
ent pollution problems and make
recommendations within one year.
« assess the impact of nonagricul-
tural use of nutrients on nutrient
pollution and make recommen-
dations within two years.
• assess the impact of storm water
runoff on nutrient pollution
problems and make recommen-
dations within one year.
• assess the impact of atmospheric
deposition on nutrient pollution
problems and make recommen-
dations within two years.
Perspective
This Act is expected to have an
impact on a small but significant
number of farms in Pennsylvania.
However, all farmers and agricultural
industries have a stake in protecting
the environment from potential agri-
cultural nutrient pollution. Even
though a formal, approved nutrient
management plan is not required of
most farmers under this law, all
farmers already have a nutrient man-
agement plan that guides their nutri-
ent management activities. Most of
these plans are based on optimizing
the economics of their production
systems. An effort should be made to
review each plan regularly, not only
from an economic and agronomic
perspective but also from an environ-
mental perspective, and to make
modifications to reduce potential envi-
ronmental damage. Q
86 NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT
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Evolution of
nutrient
management in
the Chesapeake
Bay region
Rtiss Perkinson
The Chesapeake Bay is the
largest and most productive
estuary in North America. The
bay produces half of the blue crabs
and one quarter of the oysters har-
vested in the U.S. The main stem of
the bay is about 200 miles (322 km)
long and varies in width from 3 to 30
miles (5-48 km), with a surface area of
2,200 square miles (5,698 km2). Nine
major rivers draining 64,000 square
miles (165,760 km2) empty into the
bay.
There has been a heavy emphasis
placed on agricultural nutrient man-
agement as a method of reducing
nitrogen and phosphorus loadings in
the bay. In 1982 the results of a six-
year study were published by EPA.
The study was authorized by Congress
at a cost of $27 million to identify the
causes of declining water quality in
the Chesapeake Bay. In the bay,
acreage of submerged bottom grasses,
a vital habitat for many forms of bay
life, had declined sharply over the last
two decades. Previously, vast acreages
of submerged grasses had been docu-
mented back to colonial times. The
study concluded that three primary
factors were contributing to the bay's
decline: excessive sediment loads;
excessive levels of nitrogen and phos-
phorus; and toxic contaminants. It is
interesting to note that of the toxic
compounds found in the study, agri-
cultural pesticides were not found to
be a significant factor in the decline of
the bay.
High nutrient levels in the bay
Russ Perkinson is the nutrient management
program manager at the Virginia Department
of Conservation and Recreation, Division of
Soil and Water Conservation, Richmond
23219.
result in excessive growth of phyto-
plankton, tiny plants which grow
suspended in water. At low to mod-
erate populations, the phytoplankton
benefit bay life by providing a food
source to animal forms. At high pop-
ulations, the phytoplankton growth
clouds the water, reducing light
transmission to the bottom grasses
which reduces their vigor or results in
death of the grass beds. As the phyto-
plankton die, the decomposition
process decreases dissolved oxygen in
the water, which directly stresses
higher forms of marine life.
Nutrient reduction strategies must
focus on both nitrogen and phos-
phorus levels in the Chesapeake Bay
region. In the fresh water tributaries,
phosphorus is generally the limiting
factor to phytoplankton growth.
However, in the salt water areas of
the bay, nitrogen is the limiting factor
in the summer months when most
phytoplankton growth occurs, while
phosphorus may be the limiting factor
in other seasons.
Agriculture's contribution to the
nutrient enrichment of the bay is
significant. As long as a significant
agricultural industry has existed in the
bay watershed, it has contributed
nutrients to the bay's waters. How-
ever, as the agricultural industry
became increasingly specialized and
the population base in the area grew,
nutrient inputs to the bay increased.
In evaluating the evolution of
agricultural practices over the past few
decades, it is interesting to observe
that nitrogen deficient corn is rare in
most years. Thirty or more years ago,
corn plants exhibiting mild nitrogen
deficiency symptoms were likely the
rule rather than the exception.
Following the six-year EPA study,
models were used to assist in the
determination that a 40 percent
reduction in controllable nutrient
loads in the bay would be necessary
to return it to an acceptable condition.
In 1987, the Governors of Maryland,
Pennsylvania, and Virginia, and the
Mayor of Washington, D.C. signed the
second Chesapeake Bay Agreement
which committed the jurisdictions to
meet a 40 percent reduction in
controllable nutrient loads.
During the mid-1980s, the Bay states
developed or expanded agricultural
BMP cost-share programs as a means
of reducing agricultural impacts on the
bay. In each state, the lead agency
which operates agricultural BMP
programs also plays a major role in
nutrient management. In Pennsylvania
and Virginia, overall direction and
field delivery of nutrient management
programs are the responsibility of the
natural resources agencies which rely
partially on conservation districts,
while Maryland's program is led by
the agricultural agency with field
delivery through Cooperative Exten-
sion. Many similarities exist in the
nutrient management programs of
each state, yet each has initiated
innovative approaches.
Pennsylvania
Nutrient management on a state-
wide scale in the Bay region first
began in Pennsylvania in 1985 when
an innovative, fully integrated farm
planning program was established for
animal waste management. Land-
owner/district agreements are formed
which require the installation and
maintenance of all practices in the
contract and the implementation and
maintenance of a nutrient manage-
ment plan. In return, practices are
cost-shared at 80 percent, up to
$30,000 per farm. Agreements have
been established on 616 farms in the
Bay watershed. Approximately $2
million annually is budgeted for these
agreements. Pennsylvania State
University staff provides training to
the 38 conservation district technicians
who develop the nutrient manage-
ment plans. The Pennsylvania Depart-
ment of Environmental Resources
funds the district positions and the
cost-share programs and maintains a
staff of six engineers who design
animal waste structures and other
BMPs.
Proposed legislation in Pennsyl-
vania would require nutrient manage-
ment planning on high density live-
stock farms if enacted. Nutrient man-
agement ordinances currently exist in
two counties and numerous townships
across the state.
Pennsylvania has been a leader in
JOURNAL OF SOIL AND WATER CONSERVATION 87
-------
die water quality research pertaining
to nutrient management. For example,
some of the early work on the pre-
sidedress nitrate test for corn was
initiated in Pennsylvania.
Maryland
Maryland initiated the nutrient
management program in 1989.
Currently, 20 nutrient management
"consultants" are housed in Coop-
erative Extension offices in the state.
The consultants develop nutrient
management plans for farmers and
conduct educational activities includ-
ing field days and demonstrations.
The supervision of day-to-day activ-
ities is by county Cooperative
Extension unit directors and the
program technical direction originates
from the University of Maryland. The
positions are funded through the
Maryland Department of Environment
(MDE) and the Maryland Department
of Agriculture (MDA), with the MDA
Office of Resource Conservation
formulating strategic program direc-
tion. To date, nutrient management
plans have been developed on
175,671 acres (71,094 ha) by the
consultants.
Innovative programs in Maryland
include a Nutrient Management Con-
sultant Certification Program offered
by the MDA Office of Resource
Conservation. The program is aimed
at private and public sector personnel
who may develop nutrient manage-
ment plans. Groups targeted for certi-
fication include employees of the
retail fertilizer industry, sludge con-
tractors, private consultants, and
government employees. The first test
was held in January. Of the 121
people who applied for certification,
83 (68 percent) passed the exam.
Nutrient management agencies in
Pennsylvania, Maryland, and Virginia
cooperated in the development of a
bank of test questions to be used in
nutrient management certification
programs. New sewage sludge regu-
lations being developed in Maryland
will require nutrient management
plans developed by sludge contractors
for sites to receive sludge applications.
Virginia
Virginia's statewide nutrient man-
agement program also was established
in 1989. The Division of Soil and
Water Conservation, in the Depart-
ment of Conservation and Recreation,
is the lead non-point source pollution
management agency and operates the
nutrient management program. Ten
nutrient management specialists
develop nutrient management plans
and conduct educational programs
across the state. These specialists have
developed more than 800 nutrient
management plans on 180,000 acres
(72,846 ha) of cropland. Nitrogen and
phosphate use reductions are esti-
mated at 4.4 million pounds (2 million
kg) and 3.9 million pounds (1.8
million kg) respectively from the
planning activities.
Innovative programs in Virginia
include several incentive and regu-
latory programs. A state tax credit on
nutrient management-related farm
equipment was enacted in 1990. The
state tax credit is 25 percent of the
purchase price or $3,750, whichever is
lower, on manure spreaders, fertilizer
applicators, and tramline equipment
that meet established criteria. To claim
the credit the farmer must have a
nutrient management plan approved
by the local conservation district in
place. A plan must also be developed
for farmers receiving state animal
waste storage cost-share assistance.
Regulatory programs requiring
nutrient management include Virginia
Pollution Abatement (VPA) permits
and the Chesapeake Bay Preservation
Act. VPA permits, issued by the State
Water Control Board, which include a
nutrient management plan are
required on farms with 1,000 animal
units that have liquid or semi-solid
manures. The Chesapeake Bay Preser-
vation Act requires soil and water
quality conservation plans in 31
coastal zone counties if farmers want
to reduce required 100 foot (30 m)
buffers around surface waters to 25
feet (8 m). These plans include nutri-
ent management, soil erosion, and
IPM components. In addition, several
counties in the state also have poultry
ordinances which require nutrient
management plans.
Summary
Although each state is using various
methods to deliver nutrient manage-
ment programs, many program com-
ponents are the same and the states
have cooperated extensively. The
nutrient management coordina-tors
from each state meet quarterly to
exchange ideas and work on common
projects. As a result, content and
format of nutrient management plans
are similar across the jurisdictions. The
group has developed uniform criteria
and standards for nutrient manage-
ment plans and the framework for a
nutrient management certification
program for each state. In addition,
the states cooperated in the develop-
ment of a pool of 600 test questions
for use in nutrient management
certification programs in the Bay area.
Regional training materials are being
developed for use in nutrient manage-
ment certification programs. In order
to realize the goal of nutrient reduc-
tion in the bay, the states must contin-
ue to invest in research, cooperate
extensively, and develop creative
program strategies.
REFERENCES CITED
1. Environmental Protection Agency. 1982.
Chesapeake Bay Program Studies: A
Synopsis. Annapolis, Md.
2. Environmental Protection Agency. 1987.
Chesapeake Bay, Introduction to an
Ecosystem. Washington, D.C. Q
88 NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT
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Nutrient
management in
Idaho
R. L. Mahler and F. G. Bailey
As Idaho's major industry,
agriculture accounts for 36
percent of the states' total gross
product. Farm sales directly account
for 21 percent of the gross product
with an additional 15 percent attrib-
uted to food processing. More than
12,000,000 acres (4,856,400 ha) of
cropland and hayland are found in the
state. About 4,000,000 acres (1,618,800
ha) are irrigated (2).
The irrigated lands are the most
intensively managed and most
productive, resulting in the wide-
spread axiom that water is the
lifeblood of Idaho. On an average day
23,000,000,000 gallons (87,064,000,000
1) of water are used in the state (5).
Dividing this by Idaho's current
population of 1,060,000, per capita
water use is 22,000 gallons/
person/day (83,279 I/person/day), the
highest per capita water use rate in
the U.S. More than 97 percent of the
state's water use is attributed to
agriculture. Most of the irrigation
water comes from rivers, but Idaho is
also the country's fourth largest user
of groundwater. Groundwater com-
prises only 22 percent of Idaho's total
water use, but it accounts for nearly
95 percent of the state's drinking
water.
Many Idaho crops are intensively
fertilized with nitrogen (N), phos-
phorus (P), and sulfur (S). Nitrogen
application rates range from 100 to
480 Ibs/acre (112-538 kg/ha) on
irrigated land and from 25 to 140
Ibs/acre (28-157 kg/ha) on rainfed
cropland. Phosphorus is applied to
roughly 30 percent of Idaho's crop-
land each year at rates ranging from
R.L. Mahler is a professor of soil science, Soil
Science Division, University of Idaho, Moscow
83844. F.G. Bailey is the state agronomist,
USDA Soil Conservation Service, Boise, Idaho
83705. Paper No. 93-7-67 of the Idaho
Agricultural Experiment Station.
20 to 70 Ibs/acre (22-78 kg/ha). Sulfur
is applied to about 35 percent of
Idaho's rainfed cropland each year at
rates between 10 and 25 Ibs/acre (11-
28 kg/ha). Potassium is annually
applied to less than 5 percent of the
cropland in the state. More than 85
different crops are grown in Idaho.
Major crops include potatoes, barley,
wheat, sugarbeets, dry beans, alfalfa,
sweet corn, arid onions (Table 1).
Based on regional and national
information, poor N management can
impair both groundwater and surface
water. Conversely, poor P manage-
ment primarily impairs surface water.
Since soil erosion is the major mech-
anism by which P enters surface
water, its control will provide environ-
mental protection from P-containing
fertilizers. Best management practices
to control erosion in Idaho have been
encouraged for years. However, few
practices to discourage N leaching
through soils and into groundwater
have been utilized to date.
Nitrogen leaching is a concern in
Idaho, particularly in irrigated areas of
the state, as locations of prime
aquifers and intensively managed
farmland often coincide. In many
areas water tables are within a few
feet of the soil surface. The Idaho
Division of Environmental Quality and
U.S. Environmental Protection Agency
are concerned that agriculture may
contaminate aquifers with nutrients,
particularly N. Of particular concern
are dairy operations and irrigated
fields receiving large amounts of
commercial N fertilizers.
Nitrogen use efficiency (NUE) is
often used as a measure of the effi-
ciency of nutrient management. NUE
can be defined as the percent of N
applied to the land that actually ends
up in the plant. In Idaho, NUE ranges
from 10 to 80 percent depending on
both the crop grown and the level of
management. NUE averages about 50
percent in Idaho. The lower the NUE
value, the greater the likelihood that a
significant portion of the applied N
may end up in the groundwater.
The relatively low NUE values
observed across Idaho can be attri-
buted to one or more of the following
factors: poor irrigation water manage-
ment, incorrect rates of N applied to
fields (usually too much N), poor
environmental conditions (weather),
improper agronomic practices, and/or
an inadequate research database
resulting in incorrect fertilizer appli-
cation rates.
In Idaho, nutrient recommendations
are research-based for major crops.
The University of Idaho has published
fertilizer guidelines for 34 of the state's
40 most important crops. These fertili-
zer guidelines are based on soil test
correlation research and depend on
soil sampling. In addition, tissue
analysis for nutrient management can
be used throughout the season for
some of the most intensively managed
crops like potatoes and sugarbeets.
Best management practices (BMPs)
for N management in Idaho should
include one or more of the following
practices: soil sampling, fertilizer
recommendations based on the soil
sample and research data, split appli-
cations of N fertilizer, nutrient credits
for plow-down residues, of legumes
and applied manures, use of nitrifi-
cation inhibitors, manure manage-
ment, irrigation water management,
use of slow release N fertilizers, crop
rotation selection to maximize NUE,
and variable fertilizer management
within a single field (.4).
Nitrogen management in Idaho
crops
Three crops are introduced to
examine the current status of N
management in Idaho. These crops
are onions, potatoes, and winter
wheat.
Onions. Onions are a high value,
intensively managed, irrigated crop
grown primarily in southwestern
Idaho. Under current management
conditions NUE ranges between 15
and 40 percent. Current N manage-
ment is far from optimum as N
application rates are based primarily
on tradition even though a research-
based onion fertilizer guide is avail-
able for grower use (£). Nitrogen is
applied in split applications; however,
total amounts of N applied over the
growing season often exceed 300
Ibs/acre (336 kg/ha). The high market
value of onions results in farmers
JOURNAL OF SOIL AND WATER CONSERVATION 89
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Table 1. Acreage, production, and ranking statistics for major
Idaho crops in 1992.
Crop
Acreage
Production
Ranking of states
Potatoes
Sugarbeets
Peas
Lentils
Barley
Hops
Mint
Onions
Spring wheat
Dry beans
Sweet com
Alfalfa hay
All wheat
All hay
405,000
207,500
80,000
47,000
1,370,000
4,200
16,000
8,000
971,000
246,000
130,000
1,110,000
1,852,000
1,420,000
122,1 75,000 Cwt
5,070,000 Ton
1,501 ,000 Cwt
621 ,000 Cwt
59,250,000 Bu
5,431, 000 Lb
1, 375,000 Lb
4,880,000 Cwt
32,660,000 Bu
2,932,000 Cwt
180,000 Ton
3,91 4,000 Ton
81, 660,000 Bu
4,294,000 Ton
1
2
2
2
3
3
3
3
6
6
6
8
8
15
Table 2. Nitrogen use efficiency values in winter wheat production
as affected by annual precipitation when all nitrogen is applied at
planting.
Precipitation zone (inches) Nitrogen use efficiency (percent)
16 to 18
181020
20 to 22
22 to 24
24 to 26
>26
65
58 ,
50
42
34
21
ensuring that adequate N has been
applied to their crop, even at the
expense of the environment.
A survey conducted in 1992 found
virtually all onion fields were subject-
ed to soil and/or tissue sampling (.7).
Average N application rates to onion
fields in this survey was 297 Ibs/acre
(333 kg/ha). The N was applied in
three to four split applications over
the growing season.
Nitrogen use efficiency in onions is
low for several reasons. The major
problem with N management in
onions is related to over-irrigation and
the fact that the effective rooting
depth is only 12 to 16 inches (30-41
cm). Combined with the fact that
onions do not tolerate dry soils,
excess irrigation water often leaches N
below the root zone. Consequently, a
"catch 22" situation occurs where N is
repeatedly applied to onions after
irrigations to replenish the previously
leached nutrient. The net effect is low
NUE and nitrate contamination of
groundwater.
Nitrogen use efficiency in onions
can be improved using a three-
pronged approach. First, soil samples
should be collected from each field
prior to planting. The applied N
should be based on the onion yield
potential and the University of Idaho
fertilizer guide for onions. The N
fertilizer should be applied as a slow
release material or in several multiple
(6 to 10) small increment applications
over the course of the growing
season. Second, irrigation water man-
agement should be improved to
reduce leaching potential. And third,
the N status of the onion plants
should be monitored throughout the
growing season using tissue sampling
and analysis. The N applied during
the growing season should be based
on needs determined from the plant
nitrogen status.
Potatoes. Potatoes are Idaho's
largest cash crop. Potatoes are grown
under irrigated conditions throughout
the southern part of the state. This
high value crop currently receives
intensive N management with help
from private consultants. Under super-
ior management NUE can approach
75 percent (S, 9). Nitrogen manage-
ment is intense in potatoes because
either a lack of or an excess of N will
reduce crop yields and impair crop
quality. Excess N results in vegetative
plant growth at the expense of tuber
growth.
Nutrient management for potatoes
is well refined. Excellent soil and
plant tissue test correlation databases
exist for the Russet Burbank potato
(6). Growers routinely apply a portion
of their N requirement prior to
planting. Virtually all the potato
cropland in Idaho is sampled for a soil
analysis prior to planting. The N
applied is based on a soil sample and
the research database in the University
of Idaho Fertilizer Guide for potatoes.
Additional N is applied in the irri-
gation water in small increments
throughout the growing season as
needs are determined by weekly plant
tissue analysis. This spoon-feeding of
N throughout the growing season
based on need results in relatively
high NUE values.
Nutrient management can be further
enhanced in potatoes with better
irrigation water management. Since
potato roots are concentrated in the
upper two feet of the soil profile it is
easy to leach nitrates below the root
zone.
Growers currently use superior
nutrient management in potatoes
because the economics of potatoes
make it pay. Potatoes are probably the
most efficiently managed crop for N in
Idaho. Realistically, N management
cannot be further enhanced without a
better irrigation water management
program.
Winter wheat. Dryland winter wheat
is grown extensively in northern
Idaho. The crop is grown where
annual precipitation ranges from 18 to
35 inches (46-89 cm). Winter wheat
yields exceeding 100 bushels/acre are
quite common. Nitrogen applications
range from 75 to 150 Ibs/acre (84-168
kg/ha). Even though wheat is a low
90 NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT
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value crop when compared to irri-
gated potatoes or onions, the high
yield potentials attainable in northern
Idaho encourage moderate to inten-
sive nutrient management. Currently,
NUE in winter wheat ranges from 35
to 60 percent, with an average value
of 45 percent in northern Idaho.
Nitrogen use efficiency values are
higher in the lower precipitation
regions (Table 2).
Ideal nutrient management BMPs
for winter wheat in northern Idaho
include all of the following: soil
sampling prior to seeding; basing N
application rates on soil analysis,
realistic yield goals; and University of
Idaho fertilizer guides, and split N
application between the spring and
the fall in areas that receive more than
22 inches (56 cm) of annual precipi-
tation.
Approximately 40 percent of the
wheat fields currently have soil
samples taken prior to seeding wheat.
The recommended soil sampling
depth is 5 feet (1.5 m); however, less
than 25 percent of the fields are
sampled to a depth greater than 2 feet
(0.6 m). In fields which are not
sampled, N application rates are often
based on historical application rates.
Fertilizer recommendations are based
on the University of Idaho Fertilizer
Guide for winter wheat (3). Split
applications of N improve NUE in the
higher precipitation areas.
As a rule plant tissue analysis on
dryland wheat is not performed
during the growing season. Thus an
initial soil sample is the only measure
of nutrition. Recent studies of drain
tiles have shown that a significant
amount of N is leaching during the
winter and spring periods, particularly
in areas where fall N is applied
(Mahler, unpublished data).
Idaho nutrient management
specification
In 1990 the U.S. Department of
Agriculture's Soil Conservation Service
(USDA-SCS) in Idaho began the devel-
opment of a nutrient manage-ment
specification for the SCS field office
technical guides. The intent was to
establish technical quality criteria for
protecting water quality. The practice
was written to be .voluntary; however,
the management guidelines were to
be designed so that all environmental
concerns were adequately addressed.
An initial committee consisting of
representatives from SCS, University of
Idaho, USDA-Agricultural Research
Service, Idaho Soil Improvement
Committee, private consultants, indus-
try agronomists, fertilizer dealers, and
producers was put together in the
spring of 1990. The committee devel-
oped Idaho's nutrient management
specification. More than 90 percent of
the document was put together with
unanimous consensus. However,
when an issue or a numerical value
could not be resolved by consensus,
SCS made the ultimate decision. The
specification requires use of the latest
research and technology and uses the
University of Idaho crop fertilizer
guides as the basis for fertilizer recom-
mendations. This document has
received wide-spread exposure in
Idaho and has generated much con-
troversy. The document is not perfect,
but it is an excellent starting point for
nutrient management programs in
Idaho. The goal of the committee was
to develop guidelines whereby pro-
ducers, the fertilizer industry, and
conservationists could position them-
selves to meet water quality needs
without having to be regulated. The
nutrient management specification has
five parts: (1) a general specification
section, (2) N, (3) P, (4) organic
wastes and manure, and (5) operation
and management. The general portion
of the Idaho' nutrient management
specification contains the following:
• Soil sampling will follow the guide-
lines in the University of Idaho Co-
operative Extension System Bul-
letin No. 704 titled "Soil Sampling."
• The soil sampling depth for each
crop will follow the guidelines
contained in the current crop
fertilizer guides developed by the
University of Idaho and coop-
erating agencies.
• Plant tissue sampling methods and
analysis procedures will follow
current University of Idaho or
industry guidelines for individual
crops.
• Soil laboratory analysis will be
according to accepted industry
methods and standards.
• Growers will establish realistic
yield goals for each crop and each
field. Yield goals will be based on
crop yield history and the planned
management level.
• Nutrient recommendations will be
based on the crop fertilizer guides
or locally supported databases.
• The grower will maintain a record
for each field showing the crop
sequence, crop variety, soil test
data, kind and amount of nutrients
applied, special application
practices, and crop yields. These
records begin with the practice
and will be maintained for at least
a five-year period or until the
grower no longer manages the
field.
• Irrigation water management is
required on irrigated cropland.
Irrigation water management will
be applied to meet the Irrigation
Water Management No. 449 Prac-
tice Standard and Specification.
• Periods with high leaching poten-
tial will be identified for each
field.
In addition to the general part of
the nutrient management specification
both N and P are further addressed.
The N section is of particular interest
and contains the following:
• Nitrogen applications will be
based upon a current soil test or
plant tissue analysis. The minimum
will be one soil test per year prior
to planting.
• A yearly nitrogen management
plan will be developed for each
field and crop. The plan will
include as a minimum:
- previous crop variety
— current crop variety
- current yield goal
- current soil test data including
the amount of available nitrogen
in the soil
- an estimate of the amount of
nitrogen in organic matter to be
available during the crop growth
period
- amount of supplemental
nitrogen to be applied to the
crop in order to meet produc-
tion goals and residue decom-
position needs (This includes
JOURNAL OF SOIL AND WATER CONSERVATION 91
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nitrogen from chemical fertil-
izers, manures, organic wastes,
or other sources.)
- special application practices or
materials needed on the field to
meet water quality objectives
including timing of application,
multiple applications, side-
dressing, banding, foliar feeding,
fertigation, stable forms of
nitrogen, nitrogen inhibitors, or
needed changes in crops or
crop sequence
• The maximum amount of nitrogen
applied to each crop in a given
year will not exceed 1.2 times the
amount recommended in individ-
ual University of Idaho Fertilizer
Guides unless additional soil tests
or plant tissue analyses show a
need. Additional nitrogen applica-
tions will follow recommendations
based on the new soil test and/or
tissue analysis data.
• The following limitations apply to
cropland fields where the water
budget shows more than 8 inches
of water leaching below the root
zone:
- Crops following alfalfa or clover
will be limited to high nitrogen
use crops such as small grains,
corn, or potatoes that efficiently
utilize nitrogen fixed by the
legume.
- Fall nitrogen applications will be
planned to avoid high concen-
trations of mobile nitrogen in
the soil during the normal
winter-spring high leaching
periods.
The most controversial portion of
die entire N management specification
is the N limitation which states that N
application cannot exceed 1.2 times
the amount of N as recommended by
University of Idaho fertilizer guides.
The phosphorus portion of the
specification states
• Phosphorus applications will be
based on current soil test or plant
tissue analysis and the University
of Idaho fertilizer guides or locally
developed databases. A minimum
of one soil test per field is required
before applying phosphorus.
• Phosphorus may be applied so
that one application will meet
phosphorus requirements for
several years.
• Phosphorus will be soil incorpor-
ated where a potential exists for
surface runoff and soil erosion
before the next tillage operation.
Phosphorus may be applied
during active crop growth with
sprinkler irrigation systems if plant
tissue analysis indicates a need
and if no surface water runoff
occurs from the target area.
Although somewhat controversial,
this voluntary nutrient management
specification has several positive
aspects. Perhaps most important is
that the plan is research-based. Nitro-
gen management relies on University
of Idaho fertilizer guides. In addition,
there is adequate flexibility for grow-
ers to supplement original nutrient
applications with justification based
on additional soil and/or plant tissue
tests during the growing season. And
last, this plan is based on a combina-
tion of proven N management BMPs.
The down side of the nutrient man-
agement plan is that under conditions
of poor management a grower must
spend more money for diagnostic
purposes to justify additional fertilizer
applications to fields. The plan also
assumes that the University of Idaho
fertilizer guidelines are up-to-date.
This requires a university commitment
to a continuous soil test correlation
research and extension program. This
may be difficult in light of the fact that
the University of Idaho soil fertility
program has been reduced by 50
percent over the last 15 years.
The fact that this plan is a voluntary
effort will allow refinement with time.
Some states have already enacted laws
limiting fertilizer use in especially
vulnerable areas. The authors of this
paper predict, however, that sometime
in the not-too-distant future nutrient
management planning will no longer
be voluntary unless producers and the
fertilizer industry are willing to apply
fertilizer according to research-based
technical criteria such as the Idaho
Nutrient Management Specification.
REFERENCES CITED
1. Brown, B.D., W.R. Simpson, and R.E.
McDole. 1982. Idaho fertilizer guide for
onions. University of Idaho Cooperative
Extension System Current Information
Series No. 315. Moscow.
2. Idaho Agricultural Statistics Service. 1992.
1992 Idaho agricultural statistics. Idaho
Department of Agriculture. Boise.
3. Mahler, R.L. 1991. Northern Idaho
fertilizer guide for winter wheat.
University of Idaho Cooperative Extension
System Current Information Series No.
453. Moscow.
4. Mahler, R.L., T.A. Tindall, and K.A.
Mahler. 1992. Best management practices
for nitrogen management to protect
groundwater. University of Idaho
Cooperative Extension System Current
Information Series No. 962. Moscow.
5. Mahler, R.L., and M. Van Steeter. 1991.
Idaho's water resource. University of
Idaho Cooperative Extension System
Current Information Series No. 887.
Moscow.
6. 'McDole, R.E., D.T. Westermann, G.D.
Kleinschmidt, G.E. Kleinkopf, and J.C.
Ojala. 1987. Idaho fertilizer guide for
potatoes. University of Idaho Cooperative
Extension System Current Information
Series No. 261. Moscow.
6. Stieber, T.D., and R.L. Mahler. 1993.
Cropping practices survey: fertilizer results.
University of Idaho Cooperative Extension
System Brochure WQ-17. Moscow.
8. Westermann, D.T., and G.E. Kleinkopf.
1985. Nitrogen requirements of potatoes.
Agron. J. 77:616-621.
9. Westermann, D.T., G.E. Kleinkopf, and
L.K. Porter. 1988. Nitrogen fertilizer
efficiencies on potatoes. Am. Potato J.
65:377-385. Q
Innovative local
dealer nutrient
management
programs—How
they work
John E. Gulp
Tennessee Valley Authority (TVA)
and the National Fertilizer and
Environmental Research Center
(NFERC) in Muscle Shoals, Alabama,
have a unique position in the agri-
business community. TVA/NFERC
John E. Gulp is the manager, Technology
Introduction, National Fertilizer and
Environmental Research Center, Tennessee
Valley Authority, Muscle Shoals, Alabama
35661.
92 NUTRIENT MANAGEMENT SPECIAL SUPPLEMENT
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interacts with fertilizer dealerships,
providing them with information
about new products and processes
and ways to increase the efficiency of
growing crops, and environmental
information about their businesses
and operations. Therefore, NFERC can
have a significant impact on how the
dealer manages the nutrients he/she
markets to the farm community. Here
we discuss innovative local dealer
nutrient management programs.
The NFERC programs that deal with
nutrient management involve contain-
ment of the nutrients at the dealer site
to prevent contamination of the air
and of surface and groundwater,
development and evaluation of more
efficient and environmentally friendly
fertilizer processes and products, and
development and evaluation of agri-
cultural practices and soil testing
procedures to make more efficient use
of the nutrients applied.
A major objective of NFERC is to
promote more efficient and environ-
mentally acceptable use of plant
nutrients to benefit U.S. farmers and
consumers. Our efforts in the environ-
mental area are to help maintain a
competitive, sustainable, and environ-
mentally acceptable U.S. agriculture.
We are doing this through three
program activities: containment,
research and development, and tech-
nology transfer.
The idea behind the containment
program is to show fertilizer dealers
how to prevent point source pollution
from contaminating surface water,
groundwater, and the air. In our
containment and compliance program,
we are establishing 20 model site
demonstrations (MSDs) across the
country to introduce technologies to
help dealers contain potential pollu-
tants onsite. The idea is to develop
containment systems at retail dealer
sites that get raw materials in and
send finished products out. Everything
else stays onsite.
The model demonstrations are
located in areas of high fertilizer use.
They are established to provide other
dealers from the surrounding areas
with an actual operating facility where
they can see how to install secondary
containment and prevent point source
pollution. This is information they can
take home and use.
Fertilizer and agribusiness associates
and regulatory officials also are
encouraged to cooperate in this
program. These sites are real-life solu-
tions to dealers' problems of how to
install containment at either an
existing or new site.
The dealer pays all construction
costs, keeps records, and divulges
how much is spent on containment.
TVA/NFERC provides engineers and
drawings and conducts educational
programs at the site. Cost of contain-
ment structures run from $75,000 to
more than $350,000.
After the construction is completed,
an open house is held to help the
dealer show customers, business
associates, legislators, and regulators
how he/she is being a good steward
of the environment. Following are
highlights from model site demon-
stration facilities in Oregon, Maryland,
and Florida. Each uses different
construction materials and a different
approach to solve similar problems.
Manager Dennis Reich started from
the ground up, building a state-of-the-
art fluid fertilizer plant in a rural area
of Oregon. The plant was fully
contained to protect the environment.
The entire tank farm was lined with a
hypalon liner and covered with
gravel. This was less expensive than
concrete, but concrete was used in the
load pads and under the fluid mixing
system. Proper attention was given to
sloping the "load-out" and transfer
areas so any major spills could drain
into the tank farm dike and could be
recovered. Proper management of
piping also was made to detect leaks
and to move any fluids from leaks or
spills into a sump and holding area
for reuse in formulations, land appli-
cations, or other disposal methods.
Another model demonstration site is
Willard Ag Service in Frederick,
Maryland. This business is located in
downtown Frederick and was espe-
cially sensitive to potential pollution
that could result from accidents or
rinsing operations. They primarily mix
and distribute fluid fertilizers. Con-
crete dikes were installed around the
tank farms, leak detection systems
were installed, and materials transfer
points were contained using a com-
bination of concrete and asphalt. The
transport areas in and around the
plant were covered with asphalt and
sloped into a containment area.
Congressional members and staff from
Washington and state regulatory
officials visited during the open house
to learn how the industry is respond-
ing to environmental issues and
protection.
About 150 fertilizer dealers, cus-
tomers, business associates, and regu-
latory officials attended the model site
open house in January at Ranch
Fertilizer in Okeechokee, Florida.
Ranch Fertilizer is a large operation—
last year it moved about 100,000 tons
(90,720 metric tons) of fertilizer, about
80 percent solid and 20 percent fluids.
The company is situated adjacent to a
creek that flows into Lake Okee-
chobee. Fertilizer has been sold from
this site for many years. Recently, the
Florida Department of Environmental
Regulation had cited them for increas-
ing the N and P levels in the creek
which flows directly into Lake
Okeechobee. Management at Ranch
immediately began to install additional
secondary containment and to cap the
site and prevent any further nutrients
from entering the ground. TVA
personnel provided technical input
into the design of containment and
storm water management. Monitoring
of the site and the creek will continue
for years to provide data on the time
required to lower the nutrient content
leaving this facility. Results have
already been and will be useful in
determining how to handle other sites
in Florida.
The model site demonstration
program is proving to be an excellent
educational tool in helping the indus-
try and environmental officials con-
duct scientific-based environmental
protection programs. Several dealers
have said what they learned at the
model sites has saved them money by
causing them to change or modify
their containment design to one that
was more efficient and less costly.
The other part of the containment
program involves environmental site
assessments. The idea is to provide
dealers with information on changes
that should be made to enable them
to keep their raw materials and
JOURNAL OF SOIL AND WATER CONSERVATION 93
-------
products onsite.
In addition to the containment work
just described, TVA/NFERC also assists
in research to develop technologies to
help prevent and solve environmental
problems. Major emphasis is in three
areas: agricultural, chemical and bio-
chemical, and chemical engineering.
One approach to increasing nitro-
gen efficiency is being able to deter-
mine how much residual nitrogen
remains in the soil and is available for
the growing plant. TVA over the years
has cooperated with various land-
grant universities to develop such a
test. A test has been available and is
in use now in the relatively dry (0-8
inches [0-20 cm] rainfall per year)
areas of the country. Results have not
been as consistent in the wetter areas
of the country which are generally
areas east of the Mississippi River.
This then gives you a brief sketch
of the cooperative work going on
between TVA, the dealers, and others
to improve nutrient management tech-
niques. Cooperative research tech-
nologies, development, and finally
technology transfer are all keys in this
effort. Q
JOURNAL OF SOIL AND WATER CONSERVATION 94
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