ID-590 - 1
NATURAL RESOURCES CONSERVATION SERVICE
CONSERVATION PRACTICE STANDARD
DEFINITION pasture or rangeland where there are no
additional nutrients applied as commercial
Managing the amount, source, placement, form
fertilizer or soil amendments is not considered
and timing of the application of nutrients and soil
General Criteria Applicable to All Purposes
It is intended that nutrient management plans,
developed from this standard, be used to help A Nutrient Management Plan (NMP) for
producers improve or maintain their level of nitrogen (N), phosphorus (P) and potassium (K)
management and expertise as it relates to the shall be developed when nutrients are applied.
application of nutrients on the lands they own
NMPs shall be developed in accordance with
policy requirements of the Natural Resources
• To budget and supply adequate nutrients for Conservation Service (NRCS) General Manual
plant production. Title 450, Part 401.03 (Technical Guides, Policy
and Responsibilities) and Title 190, Part 402
• To properly utilize manure or organic by-
(Ecological Sciences, Nutrient Management,
products as a plant nutrient source.
Policy); technical requirements of the Idaho
• To minimize or prevent agricultural nonpoint NRCS Field Office Technical Guide (FOTG);
source pollution of surface and ground water procedures contained in the National Planning
resources. Procedures Handbook (NPPH) and the NRCS
National Agronomy Manual (NAM), Section
• To protect air quality by reducing nitrogen
emissions (ammonia and NOx compounds)
and the formation of atmospheric Persons who approve plans for nutrient
particulates. management shall be certified through the joint
certification program of the Idaho State
• To maintain or improve the physical, Department of Agriculture, Idaho NRCS and the
chemical and biological condition of soil. University of Idaho, or other acceptable program
as designated by the State Conservationist.
CONDITIONS WHERE PRACTICE
APPLIES The NMP shall consider all potential sources of
nutrients. These sources include, but are not
This practice applies to all lands where plant
limited to, animal waste, composted animal
nutrients and soil amendments are applied. Soil
waste, other composted by-products, organic by-
amendments include composted animal waste.
products, waste water, commercial fertilizer,
Animal waste deposited by grazing animals on crop residues, legumes and irrigation water.
Conservation practice standards are reviewed periodically, and updated if needed. To obtain the NRCS, IDAHO
current version of this standard, contact your Natural Resources Conservation Service State Office or
download it from the electronic Field Office Technical Guide for your state. June 2007
The NMP shall specify the source, amount, requirements are contained in the standards
timing and method of application of nutrients on Riparian Forest Buffer (391) and Filter Strip
each field to achieve realistic production goals, (393). Rock outcrops may also pose a potential
while minimizing movement of nutrients and for off-site transport. Direct application of
other potential contaminants to surface and/or nutrients on rock outcrops should be avoided
ground waters. wherever feasible.
Soil Sampling and Laboratory Analyses
The NMP shall contain all the required elements
(Testing). Soil samples shall be collected and
outlined in the “Plans and Specifications” section
prepared such that they are representative of the
of this document. The NMP will include the
entire Conservation Management Unit (CMU),
nutrient budget for each field based on a current
field or portion of the field to be managed
soil test, and will provide a risk assessment to
separately. Requirements for soil sampling shall
determine if additional conservation practices
follow the specifications outlined in the UI
will be required to prevent off-site movement of
publication “Soil Sampling” (CES Number 704
N and P. Off-site movement is defined as
movement of N or P off the field or management
pdf) or crop-specific soil sampling requirements
unit, downward through the soil profile beyond
outlined in the UI Fertilizer Recommendations
the rooting zone, or above the canopy, of the crop
to be planted.
For development of the risk assessment,
Soil analyses shall be performed by a laboratory
acceptable soil tests are those no older than five
that meets the requirements and performance
years. If the field has a history of manure
standards of the North American Proficiency
application or the management has changed
Testing Program (NAPT) under the auspices of
significantly, then the requirement is no older
the Soil Science Society of America.
than one year.
Laboratory analysis shall include the components
Soil samples taken for purposes of developing the
shown in Table 1. Soil samples will be analyzed
annual nutrient budget shall be taken as
for P using the test methods specified in the
described in Table 1, or as specified in the
applicable UI Fertilizer Guides or other UI
appropriate Fertilizer Guides (FG) or University
production publications containing nutrient
of Idaho (UI) “Soil Sampling” publication.
The potential for loss of nutrients via erosion,
runoff, irrigation and drainage shall be
addressed. Individual risk factors that rate “high” Table 1. Soil sampling requirements for
or “very high,” as determined by the approved annual budget development.
risk assessment tools, will require application of Sample Date
mitigating practices. Constituent
Depth No Older
Realistic yield goals shall be established based on Than:
soil productivity information, historical yield Northern Idaho
data, climatic conditions, level of management
and/or local research on similar soils, cropping NO3-N, NH4-N
0 - 12 P, K
systems and soil moisture conditions (dryland). 9 months
inches pH, % SOM2,
Setbacks and buffers shall be established around EC3
sensitive areas (e.g. sinkholes, wells, gullies, 12 – 24 9 months
ditches, surface inlets or rapidly permeable soil NO3-N
areas). These setbacks shall not receive direct
application of nutrients from any source Southern Idaho
including sprinkler irrigation. Minimum setback
ID-590 - 3
NO3-N, NH4-N 3 months other conditions so as to maximize
availability to the plant and minimize the risk
0 - 12 of runoff, leaching and volatilization losses.
inches P, K
9 months • Calibrate waste and fertilizer application
pH, % SOM2
% free lime, EC3 equipment to ensure recommended rates are
12 – 24 applied.
NO3-N, NH4-N 3 months
inches Additional Criteria Applicable to Manure and
Organic By-Products or Biosolids Applied as
In northern Idaho, P is usually analyzed using a Plant Nutrient Source
the Morgan (Sodium Acetate) method or Bray1
(Ammonium Fluoride-Hydrochloric Acid), and Manure and Organic By-Products Nutrient
in southern Idaho, P is analyzed using the Olsen Application Methods. In addition to previously
(Sodium Bicarbonate) method. detailed criteria, manure and organic by-product
application methods shall be selected to minimize
SOM is soil organic matter. the risk of nutrient transport to surface and
EC is electrical conductivity, salt concentration, ground water, into the atmosphere and to reduce
soluble salts, etc. negative impacts on plant health. NMPs that
address land application of animal waste shall
Nutrient Application Rates. The planned rates comply with the Idaho Waste Management
of nutrient application, as documented in the Guidelines for Confined Animal Feeding
nutrient budget, shall be applied to meet the crop Operations (CAFOs), 1993, amended 1997
needs except when manure or organic by- (http://www.idahoag.us/Categories/Animals/Dair
products are a source of nutrients. When manure y/Documents/Idaho%20Waste%20Management
or organic-matter by-products are applied, refer %20Guidelines%20For%20Confined%20Feeding
to “Additional Criteria Applicable to Manure and %20Operations,%20Amended%20in%201997.pd
Organic By-Products or Biosolids Applied as a f) and other applicable Federal, State and local
Plant Nutrient Source.” rules and regulations.
Nutrient Application Timing. Timing and Manure Testing. Nutrient values of manure and
method of nutrient application (particularly organic by-products shall be determined prior to
nitrogen) shall correspond as closely as possible land application. Samples will be taken and
with plant nutrient uptake characteristics while analyzed with each hauling/emptying cycle for a
considering cropping system limitations, weather particular storage/treatment facility. Manure
and climatic conditions, risk analysis and field sampling frequency may vary based on the
accessibility. operation’s manure handling strategy and
spreading schedule. If there is no prior sampling
Nutrient Application Methods. Application history, the manure shall be analyzed at least
methods to reduce the risk of nutrient transport to annually for a minimum of three consecutive
surface and ground water or into the atmosphere years. A cumulative record shall be developed
shall be employed. and maintained until a consistent (i.e.,
To minimize nutrient losses: maintaining a certain nutrient concentration with
minimal variation) level of nutrient values is
• Apply nutrient materials uniformly to realized. Significant changes in feed P ration or
application area(s). manure storage and handling procedures will
Nutrients shall not be applied to frozen, require additional manure sampling. Samples
snow-covered or saturated soil if the shall be collected and prepared according to UI
potential risk for runoff exists. “Manure and Wastewater Sampling” guidance
• Nutrients shall be applied considering the (http://info.ag.uidaho.edu/pdf/CIS/CIS1139.pdf)
plant growth habits, irrigation practices and
At a minimum, manure analyses shall identify
total N, P2O5 and K2O in pounds per ton for Application of liquid wastes through surface or
solids and pounds per 1,000 gallons for liquids. sprinkler irrigation systems will be timed to
Percent moisture for solids and percent solids for prevent deep percolation or runoff. The
liquids will also be identified. application rate (in/hr) of liquids shall not exceed
the soil intake/infiltration rate and shall be
In planning for new operations, acceptable “book
adjusted to minimize ponding and to avoid
values” recognized by the Idaho NRCS and/or
runoff. The total application volume shall not
the University of Idaho may be used (e.g., NRCS
exceed the soil water holding capacity of the soil
Agricultural Waste Management Field
and shall be adjusted, as needed, to minimize
nutrient loss below the root zone.
Application of Solid Wastes. Solid waste shall
Manure and Organic By-Product Nutrient
be incorporated into the soil unless applications
Application Rates. Nutrient budgets which
are made on frozen ground, perennial crops or
include application of animal waste shall be
cropland under no-till. In these cases, emergency
based upon the NRCS Idaho Phosphorus
tillage (i.e., chiseling and disking cross slope),
construction of berms or other containment
practices will be applied as necessary to prevent Idaho Phosphorus Threshold (IDPTH)
The IDPTH is based on a soil test P
• Winter application of solids on 0 – 2% slope concentration. It is used:
fields can be considered if there is no
• To determine the method for developing the
potential for runoff.
nutrient budget. This could be either crop
• Fall and winter application of solid wastes on uptake or recommended application rate cited
shallow and/or sandy soils should be made in the UI Crop Specific Fertilizer Guide.
when soil temperatures are <50 o F to
• To track trends in soil P concentrations over
minimize loss of nitrogen.
time and to assess environmental risk.
• Solid waste applications used as part of a Soil samples taken soon after manure, bio-solid
management system on croplands that have or other organic by-product application may
soils erodible by wind should utilize delayed produce erroneous soil test results for
incorporation or incorporation with chisel phosphorus. Soil samples taken for the IDPTH
plow, provided there is low potential for should be delayed for 9-12 months after organic
runoff. amendment applications. The on-site surface or
Biosolids (sewage sludge) shall be applied in ground water resource concern will determine the
accordance with the Idaho Department of appropriate depth of the soil sample taken (Table
Environmental Quality (DEQ) 2) for comparison to the IDPTH:
• Surface water concerns exist when surface
117.pdf) and US Environmental Protection
runoff leaves the field(s) from average
Agency (EPA) regulations. (40 CFR Parts 403
annual precipitation, rain on snow or frozen
(Pretreatment) and 503 (Biosolids).
ground or irrigation.
Application of Liquid Wastes. For purposes of
• Ground water concerns exist when surface
this standard, animal waste containing less than
water (from any source) does not leave the
10% solids will be classified as a liquid.
field. A high water table, fractured bedrock,
Application of liquid waste shall not be made
poor irrigation water management, cobbles,
outside the active crop growing period unless a
gravel or coarse-textured soils can contribute
site-specific water budget shows that deep
to downward movement of water and
percolation of wastewater or runoff will not
occur prior to the next crop-growing season.
ID-590 - 5
When both a surface and ground water concern Table 3. IDPTH concentration by resource
exists, the surface water concern governs NMP concern.
development. If neither concern exists, then the Primary Idaho P Threshold
NMP is developed based on the IDPTH for the Resource (IDPTH)
ground water concern to maintain soil quality and Concern Concentration
long-term sustainability. Olsen Bray-1 Morgan
Table 2. Required soil sample depth for the Surface Water 40 ppm 60 ppm 6 ppm
IDPTH Ground Water
Idaho P Threshold Water < 5 feet 20 ppm 25 ppm 2.5 ppm
Primary Resource Water > 5 feet 30 ppm 45 ppm 4.5 ppm
Soil Sample Depth
Phosphorus-based applications are allowed on
Surface Water 0” – 12”1 sites where soil phosphorus levels equal or
Ground Water 18” – 24”2 exceed threshold values.
Soil samples taken for development of the Table 4. Phosphorus application rates
IDPTH can be utilized to develop the annual based on the IDPTH.
nutrient budget if they meet the criteria in Table Soil Test P P Application Rate1
If environmental considerations have been < IDPTH Fertilizer Guide or Crop
identified (high water tables, leaching (ppm) Rotational P uptake
vulnerability, tile drains, fractured bedrock,
deep or shallow soils), sampling greater than or > IDPTH Crop Rotational P uptake
less than the prescribed depths may be (ppm)
Phosphorus application rate is based on crop P
IDPTH concentrations by resource concern are uptake and not on crop P removal.
listed in Table 3. Use the primary resource
concern identified and site characteristics to
determine the appropriate IDPTH for the site. Where phosphorus-based applications are made,
the application rate shall:
Nitrogen-based manure applications are
allowed on sites where the soil test phosphorus • Not exceed the recommended nitrogen
levels are below the IDPTH (Tables 3 and 4). application rate for the current crop during
The nitrogen availability of the planned the year of application, and
application shall match plant uptake • Not be made on sites considered vulnerable
characteristics as closely as possible, taking into to off-site phosphorus transport unless
consideration the timing of nutrient application(s) appropriate conservation practices, best
in order to minimize leaching and atmospheric management practices or management
losses. activities are used to reduce the vulnerability.
Management activities and technologies shall be Heavy Metal Monitoring. When sewage sludge
used that effectively utilize mineralized nitrogen (biosolids) is applied, the accumulation of
and minimize nitrogen losses through potential pollutants (including arsenic, cadmium,
denitrification and ammonia volatilization. copper, lead, mercury, selenium and zinc) in the
soil shall be monitored in accordance with US
Code, Reference 40 CFR, Parts 403 and 503
and/or any applicable state and local laws or
regulations. Animal waste may also contain
heavy metals (e.g., copper or zinc in liquid
wastes originating from hoof care products). The standard.
landowner should test for heavy metals if they
Additional Criteria to Improve the Physical,
are concerned or observe problems that may be
Chemical and Biological Condition of the Soil
associated with heavy metal contamination.
Nutrients shall be applied and managed in a
Additional Criteria to Protect Air Quality by
manner that maintains or improves the physical,
Reducing Nitrogen and/or Particulate
chemical and biological condition of the soil.
Emissions to the Atmosphere
All nutrient sources should be used with the total
In areas with an identified or designated nutrient
salt load in mind for the existing soil conditions
management-related air quality concern, any
and crop to be grown.
component(s) of nutrient management (i.e.,
amount, source, placement, form, timing of To the extent practicable, nutrients shall not be
application) identified by risk assessment tools as applied when the potential for soil compaction
a potential source of atmospheric pollutants shall and rutting is high.
be adjusted, as necessary, to minimize the
When tillage can be performed, surface Individual conservation practices should be
applications of manure and fertilizer nitrogen planned as part of a comprehensive conservation
formulations that are subject to volatilization on plan which addresses all resource concerns on the
the soil surface (e.g., urea) shall be incorporated unit and reaches a Resource Management System
into the soil within 24 hours after application. (RMS) level of treatment.
When manure or organic by-products are applied When soil test P concentrations approach 75% of
to grassland, hayland, pasture or minimum-till the IDPTH, consider developing the nutrient
areas, the rate, form and timing of application(s) management plan using application rates at crop
shall be managed to minimize volatilization P uptake or less or consider growing crops that
losses. have a greater potential to remove P from the
system. When soil test P concentrations are
When liquid forms of manure are applied with above the IDPTH, P application rates less than
irrigation equipment, operators will schedule crop P uptake should be utilized to reduce the
application during weather conditions that will soil phosphorus level.
minimize volatilization losses.
When monitoring indicates soil test P
Following incorporation, manure N goes through concentrations are increasing over time, consider
rapid nitrification with the production of Nitrate- reviewing the nutrient management plan and
N. If the soil becomes saturated following this implementation for appropriate changes to reduce
period of rapid conversion, significant N loss can the P applied, especially when soil test P is near
occur through denitrification. Application of or above the IDPTH.
manure shall be done when the probability of soil
saturation is low to minimize this N loss. Consider varying the amount of fertilizer in
Operators will handle and apply poultry litter or different parts of the field to account for differing
other dry types of animal manures when the soil types and conditions, yield potential,
potential for wind-driven loss is low and there is fertilizer needs and the potential for leaching and
less potential for transport of particulates into the runoff.
atmosphere. Consider applying liquid wastes mixed with
Weather and climatic conditions during manure irrigation water during the last 1/4 to 1/3 of the
or organic by-product application(s) shall be irrigation set when using in-place or non-mobile
systems to minimize runoff of nutrients.
recorded and maintained in accordance with the
operation and maintenance section of this Consider split applications to provide N at the
ID-590 - 7
time of maximum crop utilization, especially on Reference the UI Fertilizer Guides (FG) section
fall-seeded crops. “Water Quality Considerations” or sections
which address N movement in soils. Specific
Consider routine mineral and nutrient status
guidance is provided in the FGs for application
testing of forages produced from land with long
of N in high precipitation areas or on irrigated
term and/or heavy waste application rates to
crops. Follow the FGs when addressing
protect livestock health and productivity.
movement of N in the soil profile.
Consider cover crops whenever possible to utilize
Utilize nutrient form and nutrient application
and recycle excessive residual N.
timing and placement to reduce N and P pollution
Consider delaying field application of animal of ground and surface waters. Special
wastes or other organic by-products if consideration will be given to application of
precipitation capable of producing runoff and nutrients on sensitive areas: Highly Erodible
erosion is forecast within 24 hours of the time of Lands (HEL), within flood plains, near sensitive
the planned application. water bodies, in areas of ground water
Consider the potential problems from odors and contamination within sole source aquifers,
insects associated with the land application of wellhead protection areas or within other areas of
animal wastes especially when applied near or water quality concern.
upwind of residences. Proper nutrient application in combination with
Consider sampling the surface layer (0-4 inches) other mitigating practices will help reduce
for elevated soil phosphorus or soil acidity when potential of transport to gullies, ditches, surface
there is permanent vegetation, non-inversion inlets, sinkhole areas, fractured bedrock or
tillage or when animal manure or other organic wellhead areas. There should be no application of
by-products are broadcast or surface applied and animal waste on sites where runoff is delivered
not incorporated. directly to a conveyance channel or receiving
water body unless runoff is treated with a
Consider plant tissue testing. Tissue sampling conservation buffer or other mitigating practice
and testing is encouraged during the growing prior to delivery.
season to monitor crop nutrient concentrations.
Tissue sampling shall be done in accordance with Recommended mitigating practices include:
the University of Idaho guidelines. • Split fall/spring applications utilizing soil
When planning nutrient applications and tillage temperatures (<50 o F), nitrification
operations, encourage soil carbon build-up and inhibitors, time release fertilizers or split
minimize the volatilization of nitrogen and the spring applications of N to provide nutrients
emission of greenhouse gases. at the times of maximum crop uptake.
Additional Consideration to Protect Water • Band P near the seed row.
Quality on Vulnerable Sites • Incorporate broadcasted nutrients.
Vulnerable sites are: • Farm on the contour or cross slope on all
• Areas of average annual precipitation greater non-irrigated fields adjacent to wetlands if
than 24 inches. nutrient runoff appears to pose a more
significant hazard than leaching.
• Coarse textured soils and/or areas with high
water tables (perched water less than 24 • Utilize fall cover crops whenever possible to
inches) with average annual precipitation immobilize excess residual N and retain for
greater than 21 inches or under irrigation. spring crops.
• Idaho Nitrate Priority Areas and subbasins • Use Conservation Cover (327), Residue
with impacted surface water (as identified in Management (329, 344, 345 or 346),
the Idaho DEQ’s “Integrated Report”). Conservation Crop Rotation (328), Grassed
Waterway (412), Irrigation Water
Management (449), Riparian Forest Buffers
• Increase or decrease in livestock by 10%
(391), Filter Strips (393), Fencing (382),
Watering Facility (614), etc., as needed to • Major changes to waste handling and
protect or improve water quality. storage system
PLANS AND SPECIFICATIONS • Increase or decrease in application area
Plans and specifications shall be in keeping with
this standard, and shall describe the requirements • Change in crop or crop rotation
for applying the practice to achieve its intended • Change in irrigation system
• New designation as a sensitive area
The following components shall be included in a
nutrient management plan. • Changes in livestock type
• Aerial site photograph or map and a soil map • Changes in feed rations
• Quantification of all nutrient sources Significant changes in animal numbers and/or
feed management will necessitate additional
• Current and/or planned plant production manure sampling and analyses to establish a
sequence or crop rotation revised average nutrient content.
• An IWM plan for fields under irrigation Field Records. The producer will maintain field
• Annual soil tests level records for a minimum of five years; for a
period longer than five years if required by other
• Realistic yield goals for the crops in the Federal, State or local ordinances; or program or
rotation contract requirements.
• Recommended nutrient rates, timing and As applicable, records should include:
method of application and incorporation
• Soil, plant tissue, organic and water test
• Location of designated sensitive areas or results as collected and recommendations for
resources and the associated practices or nutrient application
methods planned to protect the area
• Quantities, analyses and sources of nutrients
• Complete nutrient budget for N, P and K for applied
the rotation, and the annual nutrient budget
• Approximate dates and methods by which
for the current crop
nutrients were applied
OPERATION AND MAINTENANCE • Weather conditions and soil moisture at the
Nutrient Management Plan Review and time of application; lapsed time to manure
Revision. The owner/client is responsible for the incorporation, rainfall or irrigation event
safe operation and maintenance of this practice
• Crops planted, planting and harvest dates,
including all equipment.
yields and crop residues removed
Nutrient management plans shall be reviewed
• Dates of annual review and person
annually by the producer or his/her representative
performing the review, and recommendations
to determine if significant changes in the
that resulted from the review
operation have occurred that will affect the
overall nutrient management plan or upon change • Any additional information as required by
in landowner or tenant. this standard (e.g., site vulnerability, risk
assessment, biosolids application records and
Significant changes may include:
other appropriate cautions and discussions).
ID-590 - 9
• Irrigation water management evaluations as when working with plant nutrients. Extra caution
applicable must be taken when handling ammonia sources of
nutrients, or when dealing with organic wastes
• Documentation of the actual rate at which
stored in unventilated enclosures.
nutrients were applied. When the actual
rates used differ from the recommended and Protect fertilizer and organic by-product storage
planned rates, records will indicate the facilities from weather and accidental leakage or
rationale. spillage. Storage of manure, fertilizers and
cleaning of application equipment should be done
Annual Nutrient Budget. Soil samples used to
away from a wellhead.
develop the annual nutrient budget shall meet the
criteria in Table 1. Calibrate application equipment to ensure
uniform distribution of material at planned rates.
The planned rates of nutrient application, as
documented in the nutrient budget, shall be Backflow protection devices shall be installed
determined based on the following guidance: according to Idaho chemigation requirements
when using irrigation systems for application or
• Nitrogen (N), Phosphorus (P) and Potassium distribution of liquid waste or commercial
(K) application rates shall match the FG fertilizer.
recommended rates as closely as possible, or
within reasonable limits, except when The disposal of material generated from cleaning
manure or organic by-products are a source nutrient application equipment should be stored
of nutrients. Reasonable limits are defined as and disposed of properly. Excess material should
40 lbs-N, 20 lbs-P2O5 and 40 lbs-K2O per be collected and stored, or field applied, in an
acre. appropriate manner. Excess material should not
be applied on areas of high potential risk for
• When the applied fertilizer rate exceeds the runoff and leaching.
reasonable limits defined above, the
application must be justified by either a pre- The disposal or recycling of nutrient containers
application soil test or an approved tissue should be done according to state and local
test or feed analysis. For over-application of guidelines or regulations.
N without justification, a post-harvest
rooting depth soil test will be required. REFERENCES
• Potassium shall not be applied in situations Follett, RF, DR Keeney, and RM Cruse (eds.)
in which excess K2O causes unacceptable 1991. Managing nitrogen for groundwater
nutrient imbalances in crops or forages. quality and farm profitability. SSSA,
• The planned rates of application of other
plant nutrients shall be consistent with the Idaho ONEPLAN.
University of Idaho Nutrient http://www.oneplan.org/index.shtml
• A starter band of up to 30 lbs of P2O5 per Idaho Water Quality Technical Note 4. 2005.
acre is allowed under special localized Nitrogen Transport Risk Assessment.
conditions (wet-cold or high P fixing soils)
regardless of soil test. When starter fertilizers Idaho Water Quality Technical Note 5. 2005.
are used, they shall be applied in accordance Phosphorus Transport Risk Assessment: A
with UI recommendations. Phosphorus Assessment Tool.
Safety. Workers should be protected from and Sharpley, AN, T Daniel, T Sims, J Lemunyon, R
avoid unnecessary contact with chemical Stevens, and R Parry. 2003. Agricultural
fertilizers and organic by-products. Protection phosphorus and eutrophication (second
should include the use of protective clothing edition). USDA-Agricultural Research