Soil Management: National Organic Program Regulations

1. Soil Management:
ATTRA National Organic Program Regulations
A Publication of ATTRA, the National Sustainable Agriculture Information Service • 1-800-346-9140 • www.attra.ncat.org
By Barbara C. Bellows The National Organic Program Rule, §205.203, Soil Fertility and Crop Nutrient Management Practice
NCAT Agriculture Standard, does not define specific land practices that producers must use. But it does identify general
Specialist soil management and environmental protection objectives. From these objectives, producers and the
© NCAT 2005 organic certifiers they work with must determine whether specific farming practices meet the NOP
criteria. This publication provides management guidelines for meeting, and measurable parameters
for monitoring, these objectives. It also discusses why these objectives are essential for maintaining
sustainable, organic production systems.
T
Contents he National Or-
ganic Program
Section 205.203(a)
(NOP) Rule,
........................................ 1
Section 205.203, out-
Section 205.203(b) lines general goals for
........................................ 5 organic production.
This publication does
Section 205.203(c)
not intend to interpret
and (d) ......................... 9
these regulations in a
Monitoring Practices legal sense. Instead,
for Section 205.203 it explores ecological
.......................................11 interactions that af-
fect organic produc-
References....................18
tion and points out
Resources .....................19 how understanding
these interactions can
help farmers, inspec-
tors, and certifiers
determine which soil
management practic-
es meet the National
Standard.
The first part of this
publication examines
the three major pro-
visions within Sec-
tion 205.203 and Conservation tillage helps improve or maintain soil health and minimize erosion.
discusses the relation- Photo by Tim McCabe, USDA ARS.
ATTRA is the national sustain- ship of each of the
able agriculture information provisions to soil ecology. This is followed Section 205.203(a)
service operated by the National
Center for Appropriate Tech- by a list of management options suggested Select and implement tillage and cul-
nology, through a grant from by each provision. The second part of the tivation practices that maintain or
the Rural Business-Cooperative
Service, U.S. Department of
publication discusses interactions among the improve the physical, chemical, and
Agriculture. These organizations three provisions and describes how certain biological condition of soil and mini-
do not recommend or endorse
products, companies, or individ-
management practices can meet multiple mize soil erosion.
uals. NCAT has offices provisions within this section. It also exam-
in Fayetteville, Arkansas,
Butte,Montana, and
ines methods for monitoring compliance This subsection provides guidelines for soil
Davis, California. ���� with the provisions of this section. preparation. It requires that producers use

2. tillage and cultivation practices that protect plants and soil organisms can move
against soil erosion, while also maintaining through the soil with relative ease.
or improving soil quality.
 Water from rainfall or irrigation
To better understand this subsection, we seeps into the soil, rather than flow-
will first examine soil characteristics associ- ing over the soil surface as runoff.
ated with improved physical, chemical, and
 Soil organisms involved in decom-
biological conditions. Then we will look at
position and mineralization of plant
how these changes in soil quality affect plant
and animal residues are able to
growth, health, and production. Finally, we
thrive and disperse throughout the
will look at management practices that can
soil.
facilitate these changes.
Improve physical condition of soil Improve chemical
properties of soil
Producers describe soil’s physical condi-
tions using terms such as “softness,” “mel- Producers describe soil chemical properties
lowness,” “workability,” or “tilth.” Soil in terms of soil fertility, salinity, and acidity
scientists measure soil physical conditions or alkalinity (soil pH). Soil fertility can be
using the terms “bulk density,” “penetrabil- subdivided into nutrient availability for plant
S
oil that has ity,” “water infiltration rate,” “water hold- uptake, the soil’s nutrient-holding capac-
good physi- ing capacity,” and “erodibility.” Soil that ity, and the balances among plant-available
has good physical condition is porous, like nutrients. You can evaluate your soils for
cal condition
a sponge, rather than tightly packed, like a good chemical conditions by monitoring the
is porous, like a following characteristics.
sponge, rather than
ball of modeling clay. Soil in good physical
condition provides several benefits for plant  Soils have a near-neutral pH (unless
tightly packed, like
growth. the soil is used to grow acid-loving
a ball of modeling
 Plant roots can grow through the soil crops, such as blueberries or cran-
clay. berries).
without restriction.
Photo by Lynn Betts,  Air, water, and nutrients needed by  Sufficient nutrients are available for
USDA NRCS. productive crop growth, but not in
excess that causes plant toxicities
or contaminates nearby streams or
aquifers.
 Soil nutrients are in forms
available for plant uptake,
but they are held suffi-
ciently enough not to be
easily leached or car-
ried away by runoff.
 The availability of plant
nutrients is sufficiently
balanced to promote
healthy plant growth and
microbial activity. This objec-
tive recognizes that a plant is only
as healthy as its most limiting nutri-
ent allows.
 Soils do not contain toxins or heavy
metals in concentrations high enough
to inhibit plant growth or the growth
of beneficial soil organisms.
Page 2 ATTRA Soil Management: National Organic Program Regulations

3.  Soils contain enough moisture to the soil are readily broken down and
facilitate nutrient movement to plant decomposed so that plant nutrients
roots. become available.
 Soils contain sufficient oxygen for  A good soil structure, provided by
plant growth and the growth of soil stable organic compounds, remains
organisms. following the decomposition of plant
and animal materials.
 Soils contain relatively high levels
of organic matter, which helps them  Soil is well-aggregated; that is, it
hold water and nutrients. is composed of soft clumps held
together with fungal threads and
Improve biological bacterial gel.
properties of soil  Legumes form healthy nodules and
Improving soil physical and chemical prop- fix abundant nitrogen, especially in
erties is important for both conventional and nitrogen-depleted soils.
organic production, but improving biologi-
 Plants have a relatively high resis-
cal properties is particularly important for
M
tance to soil-borne diseases. inimizing
organic production. Producers describe soil
biological health in terms of “earthy smell,” soil ero-
“soil crumbliness,” and “greasy feel.” Soil Minimize soil erosion sion is criti-
scientists measure soil biological health in Soil erosion is the loss of surface soil to forces cal for sustainable
terms of microbial biomass, microbial com- of wind and water. Soil erosion reduces soil
agriculture.
munities, and rate of organic matter decom- productivity and can cause water and air pol-
position. lution. Minimizing soil erosion is critical for
sustainable agricultural production, because
Organic production relies on nutrients the top layer of soil has properties—physi-
released through the decomposition of cal, chemical, and biological—that are much
plant and animal residues. Decomposition more favorable for crop production than the
is a biological process involving a variety of lower layers. The topsoil also contains more
soil organisms, including beetles and other organic matter than the lower layers. This
insects, worms, nematodes, fungi, bacteria, native soil organic matter—which represents
and algae. You can evaluate your soils for centuries of plant growth, death, and decom-
healthy biological properties by monitoring
position in the soil—can both protect soil
the following characteristics.
against erosion and be easily lost to it. Soil
 Plant and animal residues added to aggregates, held together by organic com-
pounds, facilitate water infil-
Earthworms improve soil tilth by creating aggregates and forming passage- tration and enhance water-
ways through the soil. Photo courtesy of USDA ARS. holding capacity. They also
are slow to erode because of
their size and weight. How-
ever, if soil aggregates are
broken down—by dry condi-
tions, excessive tillage, or by
raindrop impact—the result-
ing organic matter particles
are very lightweight and eas-
ily removed by erosion.
Tillage prepares land for
seeding or transplanting.
Cultivation practices—imple-
mented either before or after
crops are in the ground—
www.attra.ncat.org ATTRA Page 3

4. manage weeds and improve soil aeration  Protect soil from the erosive forces
and water infiltration. Traditional clean till- of wind and water
age disrupts soil organisms, reducing their
 Minimally disrupt the habitat of
numbers and, often, their diversity. Clean beneficial soil organisms
tillage also breaks down soil aggregates and
produces a bare soil that is vulnerable to  Return or add plant or animal resi-
erosion and more subject to temperature dues to the soil to serve as food and
changes than soils that have a mulch or energy sources for soil organisms
vegetation cover. Under direct exposure to Practices that you can use to reduce soil dis-
sun and high temperatures, soil organisms turbance, provide a residue cover, or oth-
break down soil organic matter rapidly. The erwise protect the soil surface from erosion
rate of organic matter decomposition further and organic matter loss include
increases when tillage breaks soil aggregates
into smaller pieces, increasing their surface  Minimum tillage
area and exposure to oxygen. While a rapid  Undercutter or roll-chopper tillage
breakdown of organic matter can benefit
plants by increasing nutrient availability,  Mulch tillage or otherwise mulching
U
se care in a substantial decrease in organic matter with organic materials
residue reduces aggregate stability, decreases soil  Promoting rapid growth of the crop
manage- tilth, and increases the potential for nutrient canopy
ment. While crop loss through leaching and runoff.
 Flame weeding
residues provide Conventional farmers control weeds through
organic matter and a combination of synthetic herbicides and Choosing the appropriate tillage and cultiva-
physical cultivation, including cutting, burn- tion practices and implements for your fields
protect against ero-
ing, incorporation, or plowing. Herbicides depends on the location of the farm, the soil
sion, they can also type, the crop being produced, the time of
can harm soil organisms, thereby reducing
increase the risk of year, the climate, and weather conditions in
nutrient cycling and aggregate formation.
plant diseases. Physical cultivation methods vary in their a particular year. Tillage tools that are most
impact on soil ecology and soil susceptibil- damaging to soil structure are those that
ity to erosion. For example, plowing under shear soil particles, such as moldboard and
weeds or crop residues can disrupt micro- disk plows, while sweeps and chisels cause
bial populations and produce a bare soil that less damage.
is susceptible to erosion. In contrast, prac- Environmental and management factors
tices that cut weeds and leave them on the can interact with particular tillage or cultiva-
soil surface can protect the soil against rain- tion practices to increase risks of soil-borne
drop impact, the heat of the sun, and drying plant diseases and insect infestations, delay
winds, while providing soil organisms with a seed emergence, or inhibit organic matter
source of food and energy. (Unfortunately, decomposition and nutrient mineralization.
these weeds may also be sources of plant For example, farmers in New England and
diseases.) the upper Midwest rarely use no-till prac-
As stated in §205.203(a), organic produc- tices, because a thick residue cover does not
ers must use tillage and cultivation practices allow the soil to warm up and dry out in
that “maintain or improve the physical, the spring. The resulting wet, cool soil con-
chemical, and biological properties of soil.” ditions increase the time needed for seed
Tillage and cultivation practices that meet germination, while also increasing the risk
these criteria will have the following general of seed and seedling diseases. Instead, they
characteristics. use modified minimum till practices, such as
ridge till, which leaves sufficient residues on
 Promote water infiltration the soil surface to reduce erosion but allows
 Minimize soil compaction the seedbed to warm up and dry out.
 Minimize degradation of soil To further “maintain or improve the physi-
aggregates cal, chemical, and biological properties of
Page 4 ATTRA Soil Management: National Organic Program Regulations

5. soil” you can use practices that replace ferent planting dates, rooting habits, lengths
organic matter lost to decomposition. These of production, cultivation requirements, and
practices include the use of harvesting requirements.(5) All of these fac-
tors affect the ability of plants to compete
 Cover crops
with weeds.
 Green manures
Cover crops effectively reduce weed pres-
 Compost sure by occupying the space and using the
 Mulch light, water, and nutrients that would other-
wise be available to weeds. Cover crops can
 High residue crops also be cut or lightly incorporated just prior
 Perennial crops to planting the main crop. The residues left
after this cutting provides a cover over the
More details on these practices are included soil surface that suppresses seed germina-
in the next section. tion.(2, 3) Cover crops indirectly affect
weed growth by increasing soil organic mat-
Related ATTRA Publications ter and soil tilth. Compacted or infertile soils
favor the growth of some weeds, while crop
C
For more information on tillage and cultivation
practices appropriate for organic production, see plants compete better in fertile, well aggre- over crops
the following ATTRA publications. gated soils.(3, 4, 5) can be used
Pursuing Conservation Tillage Systems for Organic to control
Crop Production
Section 205.203(b) weed growth.
Flame Weeding for Vegetable Crops
Manage crop nutrients and soil fertil-
ity through rotations, cover crops, and
the application of plant and animal
Use of crop rotations and cover materials.
cropping as cultivation practices
Cultivation is any practice used to “improve Practices suggested by the
soil aeration, water infiltration and conserva- requirement
tion, and control weeds.” In a well-managed This requirement makes implicit that fer-
cropping system, crop rotations and cover tility management in organic systems must
crops can provide the benefits of cultiva- involve, and rely on, biological processes.
tion and compensate for many of its nega- Section 205.203(b) does permit organic pro-
tive impacts.(1, 2) This is consistent with ducers to use mined substances of low solu-
§205.205 Crop Rotation Standard, which bility, such as rock phosphate and green-
states that a “producer must implement a sand.(6) However, this section stipulates
crop rotation including but not limited to sod, that at least some crop nutrients be provided
cover crops, green manure crops, and catch
crops that provide the following functions through crop management practices and the
that are applicable to the operation: application of organic residues.
(a) Maintain or improve soil organic matter This requirement also states that rotations,
content; cover crops, and plant and animal materials
(b) Provide for pest management in annual must be used to manage crop nutrients and
and perennial crops; soil fertility, not just supply or provide crop
nutrients. This provision encourages produc-
(c) Manage deficient or excess plant nutri-
ents; and ers to protect water quality by growing crops
that tie-up or immobilize excess nutrients.
(d) Provide erosion control.” This reduces the potential for nutrients to be
Rotating cold- and warm-weather crops leached beyond the root zone, into ground-
can suppress weeds by disrupting their life water, or carried away by runoff or erosion
cycles. Alternatively, some crops exude into nearby lakes or streams. For example,
chemicals that suppress weeds.(3, 4) Good rye is capable of tying up large amounts of
crop rotations involve crops that have dif- nitrates. Cover cropping to manage excess
www.attra.ncat.org ATTRA Page 5

6. nutrients is particularly important for pro- fixation, recycling the nutrients from plant
ducers who farm soil that is sandy or that and animal wastes, and stabilizing nutrients
develops cracks in its profile. The perme- in the soil profile will also help ensure that
ability of these soils allows for ready leach- production practices are environmentally
ing of excess nutrients. sustainable.
Reliance of soil fertility manage- Management of crop nutrients
ment on biological processes and soil fertility
A major difference between conventional Organic soil fertility management is based on
cropping systems and organic systems is the feeding the soil a rich, complex diet of plant
role of biological processes in organic sys- residues, animal manures, and compost. In
tems. Most synthetic fertilizers are immedi- contrast, conventional agriculture simplifies
ately available to plants. They do not require crop nutrient and soil fertility management
biological processes to make them available. by feeding the plant soluble nutrients. Thus,
And they do not enhance the biological crop nutrition in conventional agriculture
health of the soil. In fact, several synthetic can be managed with three pieces of infor-
O
rganic soil fertilizers degrade soil by drying it out or mation: 1) the amounts of nutrients used by
making it acidic or saline. the crop during the growing season, 2) the
fertility
amount of plant-available nutrients in the
manage- In contrast, a primary principle of organic soil, and 3) the amounts of fertilizer nutri-
ment relies on feed- farming is to feed the soil so that the soil can ents that need to be added to account for
ing the soil a rich, feed the plants. A healthy soil has good tilth differences between crop nutrient needs and
complex diet of and mineralizes organic matter efficiently, to available soil nutrients.
plant residues,
provide plants with their required nutrients.
It also has a diverse population of soil organ- Nutrient management in organic systems is
animal manures,
isms that enhance plant growth in various more complex. Organic inputs cannot eas-
and compost. ways, such as through symbiotic relation- ily be added to the soil to provide the exact
ships with the plant, exuding enzymes into balance of nutrients needed by the plant for
the soil, degrading toxins, and competing at least three reasons. First, many organic
with pathogenic organisms. inputs (such as cover crops, crop residues,
weeds, and compost) are added to the soil for
Practices and inputs used by organic pro- reasons other than fertility management, yet
ducers (as well as many others in sustain- they contribute to the pool of nutrients in the
able agriculture) promote biologically soil. Second, most organic materials, includ-
healthy soils that sustain fertility in ways dif- ing compost and manure, have only a small
ferent from conventional systems. Organic component of soluble nutrients; most of their
systems use legumes and algae to fix atmo- nutrients must be transformed through bio-
spheric nitrogen in the soil. They promote logical processes before they become avail-
the decomposition of plant and animal resi- able to plants. Thirdly, most manures and
dues to make nutrients from them available composts do not have a consistent nutrient
to plants. Additionally, soil organisms pro- content (such as the 10%N-10%P-10%K
duce bacterial gels and microbial threads found on bags of synthetic fertilizers). They
that bind soil into aggregates, form humates also contain a ratio of nutrients different
that hold water and nutrients, and develop from that needed for optimal plant growth.
symbiotic relationships with plant roots to For example, dairy manure has a nitrogen
help them reach and use water and nutri- to phosphorus ratio of approximately 2:1.
ents.(7) Recent research indicates that However, hybrid corn requires eight times
enzymes formed by soil microorganisms can more nitrogen than phosphorus.(10)
enhance the growth and nutritional value of
plants.(8, 9) Managing soil fertility with bio- You could try to combine plant and animal
logically-created inputs ensures that organic residues to get a nutrient ratio similar to that
production is a dynamic biological process. required by your crops. But these residues
Fertility management that relies on nitrogen may not provide nutrients in the amounts
Page 6 ATTRA Soil Management: National Organic Program Regulations

7. and at the times needed for optimal plant
performance. Nutrient availability in organic
systems is primarily the result of biological
processes. Soil organisms feed on some of
the nutrients in the added organic materials,
retain some in the soil as humus, and slowly
mineralize and release others over time. In
addition, environmental factors, such as soil
moisture and temperature, affect organic
matter decomposition and mineralization.
Consequently, mineralization is slow during
dry periods and in the spring and fall, when
the soil is cool.
While crop and animal residues do not
afford precise nutrient management, the Farmers are encouraged
integrated mineralization and humification to test their soils for
process provides soils with a buffered store- nutrient needs, and to
house of nutrients. The diverse populations apply only what nutri-
of soil organisms involved in decomposi- ents are needed.
Photo by Lynn Betts,
tion store residue nutrients in their bodies USDA NRCS.
(biomass). Biomass nutrients are available
for plant uptake, but they are protected
intent of the standards, nor will they reap
from runoff, leaching, or volatilization.(11)
the multiple benefits of integrated, soil-
Microbial processes also make humus from
based fertility management.
residues that are resistant to decomposition.
Humus is responsible for improving soil In summary, plant-available nutrients in
tilth, water-holding capacity, and nutrient- organic systems include minerals, nutrients
holding capacity. Following mineralization, that have been mineralized from plant and
soil nutrients provided by organic materials animal residues, nutrients held in microbial
are subject to the same chemical reactions biomass, and nutrients that are being min-
as soluble nutrients from conventional fer- eralized from decomposing residues. As a
tilizers, such as sorption of phosphorus by good organic producer, you should account
iron oxide or precipitation of calcium with for each of these nutrient sources to deter-
sulfate. mine current and future nutrient availability.
You should also view nutrient management
This provision of the standard does per- as but one component of an integrated crop
mit fertilizers with high levels of soluble and soil management plan. Cover cropping,
nutrients, as long as they are derived from for example, not only produces and con-
allowed crop and animal materials (such as serves nutrients but is also used for weed
fish and soybeans). These organic fertilizers and pest control and for soil conservation.
provide nutrients in standardized amounts
that are immediately available to plants.
Ideally, these products are used as a com-
Crop rotations, cover crops, and
plement to compost or other slow-release green manures as nutrient
organic inputs, in order to provide a bet- management components
ter nutrient balance or meet temporary high Crop rotations and cover crops can add,
nutrient demands of the plants. Producers deplete, or conserve soil nutrients, depend-
can use these soluble products to manage ing on how they are managed. They can also
nutrient availability in a manner that mimics affect nutrient availability through a variety
conventional fertility programs, while legally of processes. They use soil moisture, but
complying with the materials section of the they enhance water infiltration and aggre-
National Organic Standard.(12) However, gate formation. They also influence popula-
these producers do not comply with the tions of soil organisms.(13)
www.attra.ncat.org ATTRA Page 7

8.  Nutrient additions. Legumes fix occurs, the microorganisms must
atmospheric nitrogen through a take nitrogen from the soil as they
symbiotic relationship with nitro- proceed with decomposition and
gen-fixing bacteria. Although some mineralization. As a result, nitrogen
nitrogen is added to the soil while availability is temporarily depressed.
these plants are growing, the major- While this process can hinder plant
ity of fixed nitrogen becomes avail- growth, it can also conserve nutri-
able when they die and decompose. ents for later use, since those same
The amount of nitrogen added by microorganisms release nutrients as
legumes depends on the type of they die and decompose.
legume, the soil conditions, and
cropping practices. Alfalfa and clo-  Nutrient conservation and man-
ver fix around 175 pounds of nitro- agement. Nutrient management in
gen per acre, while soybeans fix only organic systems is not only the addi-
around 50 pounds. Most legumes fix tion of plant nutrients but also their
more nitrogen when available nitro- conservation. Good nutrient man-
gen in the soil is low. Thus, growing agement uses crop rotations and
C
legumes in nitrogen-depleted soil, cover crops to provide the main crop
rop rotations with nutrients when they are needed
and cover
underseeded with grasses or as com-
panion crops with non-legumes, will and to conserve nutrients in the soil
crops can between cropping seasons, when
stimulate them to fix more nitrogen.
add, deplete, or con- they otherwise might be lost through
serve soil nutrients,  Nutrient cycling. Deep-rooted leaching, erosion, or volatilization.
depending on how plants can retrieve nutrients that For example, organic matter decom-
they are managed. have leached below the root depth position and nutrient mineralization
of other plants. Other plants are can continue to release nutrients into
hyperaccumulators—they take up the soil following crop harvest. If not
higher-than-normal concentrations held in microbial biomass or taken
of specific nutrients. While these up by other plants, these mineral-
plants do not add nutrients to the ized nutrients, particularly nitrate,
soil, their ability to capture or accu- can leach through the soil profile,
mulate nutrients can help build soil beyond the root zone, or into the
fertility. Nutrients absorbed by these groundwater. In another example,
deep-rooted or hyperaccumulating you may apply manure that contains
plants are not available until they a ratio of nutrients different from
are cut or incorporated and allowed that needed by your crops. This can
to decompose. cause excess levels of nutrients, par-
ticularly phosphorus, to build up in
 Nutrient depletion and tie-up. the soil.
Crop rotations remove nutrients from
the soil if the crops are harvested Crop rotations can reduce or tie-up excess
and portions are removed from the nutrients in the soil. Cover crops take up
field. Even when they remain in the plant nutrients as they grow, then release
field, cover crops and crop residues these nutrients back to the soil when they
can deplete nutrients temporarily, if are cut or incorporated and undergo decom-
they do not decompose before the position.(7, 14) Rye and other grasses are
nutrients they contain are needed for good scavengers of excess nitrogen; legumes
crop production. If the added plant are good for taking up excess phosphorus.
materials are woody or dry, they Applying woody residues can help hold
may immobilize or tie up nutrients. excess nutrients in the soil. Organisms
Immobilization means that plant involved in the decomposition of these car-
materials do not contain enough bon-rich and nutrient-poor residues need to
nitrogen for microorganisms to effec- use nutrients from the soil to make up for
tively decompose them. When this nutrients not available from the residues.
Page 8 ATTRA Soil Management: National Organic Program Regulations

9. Planting rotations or mulches that include
legumes, succulent crops, and woody crops
favor a large and diverse population of soil
organisms. These organisms retain nutri-
ents in their biomass, which protects against
nutrient loss through leaching, runoff, or
volatilization.(11) Producers can also use
cover crops to control weeds that otherwise
would compete with crop plants for nutri-
ents.
Related ATTRA Publications
For more information on methods for using
crop rotations and cover crops to manage
soil and plant nutrients, see the following
ATTRA publications.
Organic Crop Production Overview
Intercropping Principles and Production
Practices
nutrients than the plant needs or to apply Photo by Steve Diver.
Diversifying Cropping Systems
T
them in a way that leaves them vulnerable
Rye as a Cover Crop to runoff or erosion. You also need to be he green
aware that some composts, manures, or manure
Protecting Water Quality on Organic Farms
other inputs may contain substances that Crimson
Also see the SAN handbook Managing can be harmful to human health or to the Clover provides
Cover Crops Profitably (2nd edition).The
handbook can be ordered at www.sare.
environment. robust growth and
org/publications/index.htm#books. The pdf high nitrogen
version of this publication is also available Maintain or improve soil organic fixation.
at this Web address.
matter content
Soil organic matter is a central component
of soil quality. Composed of relatively sta-
Section 205.203(c) and (d) ble, decomposed or humified material, soil
Manage plant and animal materials to organic matter enhances soil quality by
maintain or improve soil organic matter improving
content in a manner that does not con-  Water absorption and water holding
tribute to contamination of crops, soil, ability of soil
or water by plant nutrients, pathogenic
organisms, heavy metals, or residues of  The ability of soil to prevent nutrient
prohibited substances. (These sections go leaching
on to list acceptable and prohibited plant,  Soil tilth and aggregation
animal, and mineral nutrient inputs.)
 Plant roots’ ability to grow through
Practices suggested by the the soil
requirement  The ability of nutrients, water, and
This requirement specifies that nutrient air to flow through the soil
inputs—plant, animal, or mineral—not only
 Soil organisms’ habitat and access to
supply crops with necessary nutrients but
nutrients
also help build soil quality. It also requires
producers to manage nutrient inputs in a Not all plant and animal residues are equally
way that ensures food safety and protects effective in maintaining or improving soil
the environment. To meet these objectives, organic matter content. Soil organisms read-
you need to be careful not to apply more ily decompose fresh manure and very young
www.attra.ncat.org ATTRA Page 9

10. and fresh plant materials. As they decom- is not covered with growing plants or plant
pose these materials, they release plant- residues.
available nutrients into the soil. In contrast,
fewer soil organisms are able to break down Types of contaminants
and mineralize woody or dry materials, such
as corn stalks, wheat stubble, or woodchips. Contaminants include excessive levels of
As a result, decomposition of these materi- plant nutrients, introduced pathogenic
als takes longer than it does for more suc- organisms, heavy metals, and residues of
culent ones. In addition, soil organisms are prohibited substances.
not able to decompose some of this organic  Plant nutrients are most readily
material, and they transform it into soil removed and carried by water when
humus instead. Humus gives good quality their concentration in the soil is
soil a soft and somewhat greasy feel. It is well in excess of that needed by the
also responsible for building soil aggregates plants. This happens when heavy
and increasing the capacity of the soil to hold applications of manure are made
water and nutrients. Thus, if you add a com- many years in a row.
bination of succulent and woody residues
C
to a field, you will fulfill a key objective of  Pathogenic organisms are usu-
ontaminants
sustainable organic soil management—sup- ally associated with the application
include ex- of uncomposted manure. Organ-
plying crops with necessary nutrients while
cessive levels isms of particular concern include
building soil organic matter and enhancing
of plant nutrients, soil microbial health. E. coli, Salmonella, Giardia, and
introduced patho- Cryptosporidium. The compost
genic organisms, Soil and water contamination practice standard §205.203(c)(2)
heavy metals, and was incorporated in the National
Soil can become contaminated if harmful or Organic Standard—along with rules
residues of prohib- prohibited substances are limiting fresh manure application,
ited substances. §205.203(c)(1)—to reduce health
 Applied as components of otherwise
allowed materials, like compost hazards from pathogen contamina-
tion. Contaminated irrigation water
 Contained in irrigation water can also be a source of pathogens.
 Contained on seed coatings Irrigation water may be contami-
nated by manure-storage or sewage-
 Permitted to leach or flow into certi- treatment facilities. Over time, the
fied fields from conventional farms activities of beneficial soil organisms
will reduce populations of patho-
For agricultural practices to contaminate genic organisms.
either groundwater (aquifers) or surface
water (lakes, streams, rivers), there must be  Heavy metals. Arsenic is added to
a source of contamination, and the contami- broiler poultry feed to reduce dis-
nant must be transported into the groundwa- eases and stimulate growth. This
ter or the surface water. Contaminants leach heavy metal passes through the
into groundwater most readily when the soil birds and is deposited in the poul-
is very porous, when the contaminant is not try litter, thereby contaminating this
held in the soil either by organisms or by source of plant nutrients. Litter from
chemical forces, and when the water table is layer operations may contain copper
high. Runoff and erosion can transport con- or zinc that leaches from the cages.
taminated soil from fields into rivers, lakes, Composts may include residues of
or streams. Runoff dissolves and trans- plants that were treated with pesti-
ports weakly-bound contaminants from the cides containing heavy metals. Addi-
soil surface and off plant leaves. Erosion tionally, fertilizer pellets made from
detaches soil particles from the surface, car- manure or litter may have additives
rying with them any adhered contaminants. that contain heavy metals or other
Erosion occurs most readily when the soil non-allowed substances.
Page 10 ATTRA Soil Management: National Organic Program Regulations

11.  Residues of prohibited substances. that may be present at toxic levels. Organic
Organic producers must be sure that producers and inspectors should use these
inputs they use for nutrient manage- tests to
ment, pest control, or building soil
 Determine levels of nutrient inputs
quality do not contain materials
to add to achieve productive plant
listed as “prohibited substances”
growth
on the National Organic Program
National List.(15)  Identify any excess nutrients (If so,
cropping and nutrient management
Related ATTRA Publications practices should be developed to
decrease these nutrient levels and
For more information on methods for build- minimize their movement from the
ing soil organic matter, selecting organic root zone into groundwater or sur-
fertilizers, protecting water quality, and face water.)
minimizing risks of contamination, see the
 Monitor soil organic matter (Note:
following ATTRA publications.
This test often is not included in the
Sources of Organic Fertilizers and standard soil test, but it is available
Amendments at an extra charge. You will need
Farm-Scale Composting Resource List to specify that you want this test
done.)
Protecting Riparian Areas: Farmland
Management Strategies  Manage nutrient imbalances (Plant
Protecting Water Quality on Organic Farms
heath is determined by the avail-
ability of the least sufficient nutrient.
Arsenic in Poultry Litter: Organic Regulations High levels of sodium can degrade
For more information on soil conservation soil tilth and aggregate stability,
and methods for protecting against runoff while soils with high calcium to mag-
from manure or compost piles, contact your nesium ratios usually have better
local NRCS, Soil and Water Conservation water permeability.)
District, or Cooperative Extension office.
How often you conduct soil tests depends
on your cropping intensity and the nutri-
ent inputs you use. Annual or bi-annual soil
Monitoring Practices for testing is sufficient for general nutrient man-
agement. However, if you are a transitioning
Section 205.203 producer, changing your nutrient manage-
The remainder of this publication provides ment practices, or testing new management
producers, organic inspectors, and organic methods, you may want to conduct soil tests
certification agencies with a set of observ-
able or measurable indicators to monitor Most state soil testing laboratories provide nutrient management
compliance with this section of the NOP recommendations in terms of pounds of conventional fertilizers per
regulations. acre. To determine the appropriate amount of manure, compost, or
other organic nutrient input to apply, organic producers must make
calculations based on soil test results, crops being grown, and the
Monitoring soil nutrient levels nutrient content of any crop residues returned to the soil. Many
A good nutrient management plan involves organic growers prefer working with specialized private soil testing
on-going monitoring of soil nutrients. You laboratories that will help them with these calculations. Several of
can request a standard soil test through your these soil testing laboratories recognize that organic growers are in-
Cooperative Extension Service. These tests terested in more than just the chemical characteristics of their soils.
provide an assessment of plant-available Thus, they also provide microbial assessments and other analyses of
soil biological health
nutrients, as well as soil acidity or alkalin-
ity (pH), nutrient holding capacity (CEC, or For an annotated list of private soil testing laboratories, see the
cation exchange capacity), and trace sub- ) ATTRA publication Alternative Soil Testing Laboratories.
stances such as sodium (Na) and boron (B
www.attra.ncat.org ATTRA Page 11

12. more frequently to better understand how released through mineralization during the
your practices are affecting nutrient avail- growing season. Unfortunately, there is no
ability. As discussed below, sampling at easy or inexpensive test that assesses when,
different seasons can provide you with an which, or how many nutrients are released
indication of changes in nutrient availability from crop residues or mineralizing organic
throughout the year. matter. Instead, you will need to estimate
mineralization rates based on the following
Timing of soil tests is important. If plant and criteria.
animal residues are applied in the fall, con-
duct soil tests in the early spring, prior to  For compost, manure, poultry litter,
planting, to determine the plant-available or mulches
nutrients from these additions. This allows  Nutrient analyses of material
time for the organic materials to decompose.  Application rate (pounds per
To determine whether you need cover crops square foot or tons per acre)
to hold excess nutrients in the soil over win-
 Date of application
ter, conduct soil tests after harvesting the
main crop.
 Cover crops and green manures
N
itrogen is a Nitrogen is a major plant nutrient and a cen-  Crop grown as a cover crop or green
major plant tral component of organic nutrient manage- manure
nutrient and ment. However, standard soil tests do not  Whether a legume cover crop was
provide an accurate assessment of soil nitro- inoculated with nitrogen-fixing bac-
a central component
gen levels. (While most standard soil tests teria (Rhizobia species)
of organic nutrient provide an assessment of nitrate [NO3 ], the  Growth stage at which it was cut or
management. level of this soil nutrient is highly affected incorporated (Cut the cover crop
by when the sample was taken and how it when it is at 50% bloom, unless your
was handled between then and the analy- farm is in an arid area where this level
sis. As a result, this reading provides little of cover crop growth would deplete
useful information for nutrient management water needed for your primary crop.
practices.) Soil test strips provide a simple This is the prevailing recommenda-
indicator of nitrogen availability (or excess). tion for maximum nutrient availabil-
Soil testing meters and organic matter min- ity for the next annual crop.)
eralization tests (Solvita™ and others) pro-  Yield level
vide a more accurate assessment.  Nutrient value of the residues left in
the field
Tissue tests (i.e., leaf analysis) measure a  Management of the cover crop after
plant’s nutrient uptake. These tests are use- its growth was terminated (Was it left
ful indicators of available soil nutrient levels on the soil surface as a mulch or was
during the cropping season. Tissue testing it incorporated into the soil?)
is particularly useful for identifying nutrient
imbalances or toxic concentrations of nutri-  Environmental conditions following
ents in the soil. Unless it is used in conjunc- application of plant or animal mate-
tion with soil tests, it cannot provide a good rials (Mineralization occurs most
indication of the availability of nutrients for rapidly under warm, moist condi-
the following crop or cropping season. tions. It will slow down considerably
during winter or during drought.)
Monitoring nutrient  Mineralization over time (Only a por-
mineralization tion of the nutrients from organic
As mentioned above, you can use stan- matter becomes available during
dard soil and nutrient mineralization tests the first year following application.
to monitor soil nutrient availability. How- Accurate nutrient management
ever, organic nutrient management relies accounts for nutrient mineralization
not only on nutrients available at the time over several years, not just during
of soil sampling but also on the nutrients the current planting season.)
Page 12 ATTRA Soil Management: National Organic Program Regulations

13.  When a clump of soil is placed in
See References for publications and Web a clear glass of water, the clump
sites that provide detailed information on retains its shape and soft bubbles
how to estimate nutrient availability based form around it. It does not break
on these criteria. apart rapidly or explosively. The
For information on potential nutrient avail- water remains relatively clear, not
ability from various organic inputs, see the turning muddy or silty.
ATTRA publication Protecting Water Quality
on Organic Farms.  The soil is relatively easy to dig. Soil
samples to a depth of at least seven
inches have properties as described
Building and monitoring above. Plant roots grow throughout
soil organic matter the soil and do not appear to be
inhibited in either their downward
Standard soil organic-matter tests provide a or sideways growth.
general guideline for monitoring soil organic
matter levels and should be conducted at  A wire rod (like a straightened,
least once every two years. In addition, soil heavy-duty clothes hanger) can be
S
management should include practices that inserted into the soil with only minor oil manage-
add or return organic matter to the soil, as bending. Soil compaction typically ment should
well as practices that protect organic matter occurs as a crust on the soil surface include prac-
against erosion and excessive mineraliza- or as plow pans beneath the sur-
tices that add or
tion. These practices include face.
return organic
 Growing cover crops and green matter to the soil.
manures that are cut and left on the Building and maintaining
soil surface or incorporated into the soil chemical condition
soil Degradation of soil chemical condition is
usually visible only when conditions become
 Leaving crop residues in the field
severe enough to significantly harm crop
 Adding manure, compost, or mulch growth and yields. Severely degraded chem-
to the soil ical conditions include
 Maintaining residues or plant growth  Salinity or high levels of anions (neg-
on the soil surface for as many atively charged particles) (This con-
months as possible throughout the dition is usually found in arid, irri-
year gated environments. Degraded soils
have a surface layer with a whitish
 Using soil conservation practices
coat and a salty odor.)
such as contour farming
 Sodicity or high concentration of
Building and maintaining sodium relative to magnesium (This
soil physical condition condition is also found in arid, irri-
gated environments. Degraded soils
General indicators you can use to monitor
have a soil crust, poor aggregation,
soil physical conditions:
and limited soil pores.)
 The soil surface does not have any
 Inappropriate pH for crops being
visible soil crust. (Microbial crusts,
produced (Most crops grow best at
found in arid soils, are positive indi-
a pH between 6.5 and 7.5. This
cators of soil quality, not negative
is because chemical reactions at
indicators.)
this range enhance the availability
 When handled, soil feels soft and of plant nutrients. However, some
crumbles readily. It does not form plants, such as blueberries and cran-
hard blocks or break down into a berries, require a low pH. Plants
fine powder. produced on soils with inappropri-
www.attra.ncat.org ATTRA Page 13

14. ate pH grow poorly and often exhibit for their growth and reproduction, you will
symptoms of nutrient deficiencies.) also build or maintain soil biological qual-
ity.
 Low nutrient holding capacity (cat-
ion exchange capacity or CEC) Methods for monitoring and assessing soil
(The ability of soils to hold nutri- biological quality will differ according to soil
ents is affected by both the mineral types, location, and crops being produced.
and organic matter components of However, you may find the following assess-
soils. Soils with low nutrient hold- ment criteria effective.
ing capacity easily lose nutrients to
runoff or leaching, resulting in low  Soil smells sweet and “earthy.”
fertilizer-use efficiency and high  Legumes form abundant nodules
potential for surface or groundwater when nitrogen levels are relatively
contamination.) low.
 Toxic levels of nutrients or contami-  Crop residues and manure decom-
nants (Symptoms exhibited by plants pose relatively rapidly (especially
growing on these soils will depend when the temperature is warm and
S
tandard soil on the toxin or contaminant.) the soil is neither arid nor flooded).
tests provide Standard soil tests provide a general assess-  Soil organisms such as earthworms,
a general ment of soil chemical conditions. Soil salin- dung beetles, and springtails are
assessment of soil ity is measured in terms of electrical con- present.
chemical conditions. ductivity or EC. You can assess soil sodicity
by calculating the ratio of sodium (Na) to  Soil has good tilth and is well-aggre-
magnesium (Mg). Soil pH and CEC are gated.
standard assessments on soil tests. Appro-
priate pH levels for crop plants are available Controlling runoff and erosion
in agronomy, horticulture, or forage guides. Soil conservation practices that control run-
Often the seed packet or bag provides this off and erosion minimize the risks of ground-
information. Standard soil tests will identify and surface-water contamination. Manage-
whether micronutrients are present at toxic ment practices you can use to minimize the
levels. If not corrected, they may cause risk of surface water contamination include
deformities or changes in plant coloration the following.
typical of toxicity symptoms. Soil tests for
specific contaminants are available, at an  Provide a vegetative cover over the
extra cost, if necessary. soil surface that protects the soil
from direct raindrop impact and
Building and maintaining promotes water infiltration.
soil biological quality  Avoid the surface application of
Viable soil organisms are critical for effective manure or compost prior to rainfall.
organic matter decomposition and nutrient
management. Soil organisms also enhance  Cover compost or manure piles
nutrient holding capacity, build soil aggre- or establish water diversion areas
gates, and facilitate nutrient uptake. Rhizo- upslope from the piles and nutrient
bia, the bacteria that form nodules on the runoff buffer areas downslope from
roots of legumes, transform atmospheric the piles.
nitrogen into nitrogen available for plant  Do not apply fertilizers or manure in
use. Mychorrhizae are fungi that form at the a way that allows nutrient levels in
tips of plant roots and effectively extend the the soil to become excessive.
root length, giving the plant greater access to
nutrients and water. If you use soil manage-  Avoid excess traffic within fields,
ment practices that provide soil organisms especially when the soil is wet, to
with food, air, water, and other necessities minimize compaction.
Page 14 ATTRA Soil Management: National Organic Program Regulations

15. Very Very
Medium Slightly Slightly Medium
Strongly Acid Slightly Slightly Strongly Alkaline
Acid Acid Alkaline Alkaline
Acid Alkaline
Related ATTRA
Publications
For more monitor-
ing information
and tools, see the
following ATTRA
publications.
National Organic
Program Compli-
ance Checklist for
Producers
Organic Field Crops
Documentation
Forms
4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0
The availability of plant nutrients in soils is affected by the soil’s pH.
Avoiding the addition of and must not contain sewage sludge
contaminants or other sources of heavy metals or
toxins.
Use special care when using any manure,
compost, mulch, or similar substance for  The organic certifier may require
nutrient management. testing of manure or litter for anti-
biotics or heavy metals prior to
 Any equipment used in organic approval. In addition, the certifier
nutrient management that is also may require that you keep records
used to apply prohibited substances on the amount of these contaminants
to conventional fields must be ade- applied to fields over time.
quately cleaned to prevent contami-
nation with prohibited materials  Use mulches that do not contain
prior to use in organic fields. contaminating residues. The organic
certifier may require testing of the
 Compost must be produced in a material to see whether it is accept-
manner that meets NOP regulations able.
www.attra.ncat.org ATTRA Page 15

16.  Check irrigation water to ensure that vary according to location, soil type, crop
it does not contain contaminants. being produced, time of year, climate, and
The organic certifier may require weather conditions in a particular year. Con-
testing of the irrigation water to see sequently, practices that you use to comply
whether its use is acceptable. with the regulation may vary from field to
field, from crop to crop, and from year to
Tailoring to local year. Also, because organic soil nutrient
management is an on-going process that
conditions
operates over time, you should examine the
As in selecting tillage and cultivation practices you use to meet the standard over
practices, the “correct” soil fertility and the course of a rotation cycle or on some
crop nutrient management practice will other multi-year basis.
P
lanting on
the contour
and leaving
residues on the
soil helps control
erosion.
Photo by Lynn Betts,
USDA NRCS.
Table 1. Soil management practices that fulfill elements of the NOP Section 205.203 requirements.
Soil Management Practice 203a 203b 203c Comments
Examine soil test results for any nutrients that are exces-
Standard soil test X X X
sively high or toxic. Check pH, CEC, and EC.
Not part of standard soil test; must make special request,
Test for soil organic matter X X requiring an extra cost. See References for alternative
organic matter tests.
Conduct prior to calculating amount of nutrients to add
Nitrate assessments X X to the soil. Also conduct following harvest to determine
need for nutrient-conserving cover crop.
Conduct on fields prior to initiating organic practices
Special tests for contaminants or heavy to determine baseline levels of any suspected contami-
X
metals nants. Conduct on commercial broiler litter or other or-
ganic input that may contain contaminants.
Determines nutrient content of plant material that will
Plant tissue testing of cover crops X X
be returned to the soil.
(continued next page)
Page 16 ATTRA Soil Management: National Organic Program Regulations

17. Soil Management Practice 203a 203b 203c Comments
Weight of biomass x percent nutrient = weight of nutri-
Calculate cover crop biomass yield X X ent in biomass. Compare this amount to the amount of
nutrients needed for growth by crop plants.
Nutrient tests for manure or compost Determines nutrient content of organic material added
X X
added to the soil.
Weight of compost or manure x percent nutrient =
weight of nutrient in the amount of compost added.
Record amount of manure or compost Divide this number by the number of acres to which this
X X
added amount of material was applied to determine nutrients
per acre. Compare these numbers to the amount of nu-
trients needed for growth by crop plants.
These factors determine the rate of nutrient mineraliza-
Record time and method of application of
X X tion, potential availability for plant uptake, and potential
nutrient inputs
risk of loss through erosion or runoff.
Use to determine the amount of nutrients that need to
Calculate nutrient availability over time be added to meet crop requirements. Also alerts pro-
X X
from each added plant or animal residue ducer to need for conserving nutrients by planting cover
crops.
Identifies any nutrient deficiencies or toxicities. Special
Plant tissue testing of crop plants X X tests may be requested to identify uptake of potential
contaminants in the environment.
Nutrient additions should be based on the equation:
crop nutrient needs – (nutrients available from soil +
Know nutrient needs of each crop grown X X
nutrients available from prior additions of plant or ani-
mal materials)
Soil texture and mineralogy affect water infiltration and
Know soil texture and mineralogy X X water holding capacity, nutrient holding capacity, and
susceptibility of soil to compaction, erosion, and runoff.
Carefully check all inputs from off-farm sources for po-
Applications of NOP-approved nutrient
tential contaminants. Apply nutrients based on the nu-
sources based on soil nutrient availability,
X X trient needs of crops to be grown and on the amount of
crop nutrient needs, and expected miner-
nutrients expected to be mineralized from each nutrient
alization of previously added residues
source applied.
Cover crops can be grown to build soil organic matter,
Cover crops are grown during the “off
X X X conserve soil nutrients, enhance soil tilth, and manage
season”
weeds.
Compost and manure are applied as a source of nutri-
Compost or manure added to fields X X
ents and to build soil organic matter.
Crop residues left on the field X X X Crop residues and mulches cover the soil surface, en-
hance water infiltration, protect against runoff and
Mulches used to cover soil surface X X X erosion, control weed growth, and build soil tilth and
organic matter.
Contour cropping controls soil erosion. Good buffer
Soil conservation practices used, espe- management around streams and lakes protects against
X X
cially on sloping fields movement of nutrients or sediment into these water
bodies.
(continued next page)
www.attra.ncat.org ATTRA Page 17

18. Soil Management Practice 203a 203b 203c Comments
Using minimum tillage or “one-pass” tillage systems min-
Excessive traffic on fields is avoided, espe- imizes tillage traffic; using cover crops to control some
X X
cially when fields are wet weeds minimizes traffic needed for cultivation. Avoid
driving on wet fields during harvest.
Compost or manure piles should be built on concrete
pads or on soil that is compacted and sealed against
Protection measures used to minimize leaching. Diversion trenches built upslope from the pile
X X
runoff from compost and manure piles protect it from contaminating clean water. A grass buf-
fer downslope protects against movement of nutrients
into water bodies.
Use separate equipment for organic fields
or thoroughly clean any equipment used
Protect against the introduction of contaminants into
in fields with non-approved substances X
organic fields.
before the equipment is used for organic
production
Protect against the introduction of contaminants into
Check irrigation water to ensure that it
X organic fields. Protect exposed edible portions of crops
does not contain contaminants
from potential microbial contamination.
Prominently display “Organic – No Spray” Protect against the introduction of contaminants into
X
signs around farm boundary organic fields.
References 5. Peet, Mary. Weed Management. No date. Sus-
tainable Practices for Vegetable Production in
1. Liebman, Matt, and Elizabeth Dyck. 1993. Crop
the South. North Carolina State University.
rotation and intercropping strategies for weed
www.cals.ncsu.edu/sustainable/peet/IPM/weeds/
management. Ecological Applications. Vol. 3,
c07weeds.html
No. 1. p. 92–122. Abstract at: www.sarep.
ucdavis.edu/NEWSLTR/v5n4/sa-13.htm 6. National Organic Standards. Regulatory Text Only.
2. Staff. SAN. 1998. Managing Cover Crops Profit- AMS/USDA.
ably. Second Edition. Handbook Series Book 3. http://www.ams.usda.gov/nop/NOP/standards/Full
Sustainable Agriculture Network (SAN). Belts- RegTextOnly.html
ville, MD. 7. Magdoff, Fred, and Harold van Es. 2000. Build-
3. Ferguson, Charles, and Bala Rathinasabapathi. ing Soils for Better Crops. Second Edition.
2003. Allopathy: How plants suppress other Handbook Series Book 4. Sustainable Agricul-
plants. HS944. University of Florida IFAS ture Network (SAN). Beltsville, MD.
Extension. Gainesville, FL.
http://edis.ifas.ufl.edu/pdffiles/HS/HS18600.pdf 8. Lee, J.J., R.D. Park, Y.W. Kim, J.H. Shim, D.H.
Chae, Y.S. Rim, B.K. Sohn, T.H. Kim, and K.Y.
4. Merfield, Charles. 2002. Organic Weed Manage- Kim. 2004. Effect of food waste compost on
ment: A Practical Guide. 29 p. microbial population, soil enzyme activity and let-
www.merfield.com/research/organic-weed- tuce growth. Bioresource Technology. Vol. 93,
management-a-practical-guide.pdf No. 1. p. 21-28.
Page 18 ATTRA Soil Management: National Organic Program Regulations

19. 9. Ros, M., M.T. Hernandez, and C. Garcia. 2003. Hollister, Stephen. 2000. NRCS Nutrient Manage-
Soil microbial activity after restoration of a semi- ment Planning.
arid soil by organic amendments. Soil-Biology www.age.uiuc.edu/bee/Outreach/lwmc/lwm21.htm
and Biochemistry. Vol. 35, No. 3. p. 463-469.
Best Management Practices: A Manure Nutrient Man-
10. Sharpley, A. N., T. Daniel, T. Sims, J. Lemu- agement Program. Ohio State University Exten-
nyou, R. Stevens, and R. Parry. 1999. Agri- sion.
cultural phosphorus and eutrophication. USDA http://ohioline.osu.edu/agf-fact/0207.html
Agricultural Research Service. ARS-149.
USDA-ARS Pasture Systems and Watershed
Management Research Laboratory. University
Park, PA. 37 p.
11. Drinkwater, L.E., P. Wagoner, and M. Sarranto-
nio, 1998. Legume-based cropping systems have
reduced carbon and nitrogen losses. Nature.
Vol. 396, No. 6708. p. 262-265.
12. Guthman, Julie. 2004. Agrarian Dreams: The
Paradox of Organic Farming in California. Uni-
versity of California Press. Berkeley, CA. 26 p.
13. Clapperton, Jill, and Megan Ryan. 2002. Soil
Biology in the key to healthy soil and direct-seed-
ing advantage. Pacific Northwest Conservation
Tillage Systems Information Source. Direct Seed
Conference. Washington State University. Pull-
man, WA.
http://pnwsteep.wsu.edu/directseed/conf2k2/
dscclapperton.htm
14. McCracken, D.V., M.S. Smith, J.H. Grove, C.T.
MacKown, and R.L. Blevins. 1994. Nitrate
leaching as influenced by cover cropping and
nitrogen source. Soil Science Society of America
journal. Vol. 58, No. 5. p. 1476-1483.
15. National Organic Standards. National List-Regu-
latory Text. AMS/USDA.
www.ams.usda.gov/nop/NOP/standards/ListReg.
html
Acknowledgements
Resources
The following documents describe practices involved in I would like to thank NCAT colleagues George Kuepper
determining how much manure (or compost) to apply and Ann Baier for recommending that I address the criti-
cal interface between the legal language of the NOP
to fields, when to apply it, and application practices
regulations and the practical considerations of nutrient
that reduce the risk of nutrient runoff. While they are management. I would also like to thank them and NCAT
designed for use by dairy farmers or feedlot operators, colleague Nancy Matheson for their careful review of
most of the calculations provided in the workbooks can early drafts of this paper. George’s technical and working
be readily adapted for use by organic producers. knowledge of the NOP, Ann’s practical insights as a farmer
and organic inspector, and Nancy’s hands-on awareness
Wolkowski, Robert. A Step-by-Step Guide to Nutrient of organic dryland farming systems, as well as her critical
Management. Integrated Crop and Pest Manage- word-smithing, allowed me to make some very useful and
ment. University of Wisconsin. well-informed revisions.
http://ipcm.wisc.edu/pubs/pdf/stepbystep.pdf
www.attra.ncat.org ATTRA Page 19

20. Soil Management: National Organic Program
Regulations
By Barbara Bellows
NCAT Agriculture Specialist
© NCAT 2005
Paul Williams, Editor
Ashley Rieske and Robyn Metzger, Production
This publication is available on the Web at:
www.attra.ncat.org/attra-pub/organic_soil.html
www.attra.ncat.org/attra-pub/PDF/organic_soil.pdf
IP 270
Slot 272
Version 063005
Page 20 ATTRA