*>EPA
United States
Environmental Protection
Agency
Source Water Protection
Practices Bulletin
Managing Agricultural Fertilizer Application
to Prevent Contamination of Drinking Water
If improperly managed, elements of fertilizer can move into surface water through
field runoff or leach into ground water. The two main components of fertilizer that
are of greatest concern to source water quality (ground water and surface water
used as public drinking water supplies) are nitrogen (N) and phosphorus (P). This
fact sheet focuses on the management of agricultural fertilizer applications; see the
fact sheets on managing agricultural pesticide use, animal waste, and storm water
runoff for other prevention measures that relate to agriculture.
Inside this issue:
Why is it Important to 2
Manage Fertilizer Use?
Available Prevention 3
Measures
Additional Information 6
1 - Fertilizer tractor.
Fertiliser Use in Agriculture
Fertilizer application is
required to replace crop
land nutrients that have
been consumed by
previous plant growth. It is
essential for economic
yields. However, excess
fertilizer use and poor
application methods can
cause fertilizer movement
into ground and surface
waters. While fertilizer
efficiency has increased,
Colorado State University
estimated that about 25
percent of all preplant
nitrogen applied to corn is
lost through leaching
(entering ground water as
nitrate) or denitrification
(entering the atmosphere
as nitrogen gas).
Fertilizer and Fertilizer Use Facts:
	The Nitrogen and Phosphorus in fertilizer
are the greatest concern to source water
quality.
	25% of all preplant N applied to corn is
lost through leaching or dentrification.
	60-90% of P moves with the soil.
	Consumption of nitrates can cause "blue
baby syndrome".
	Nitrate has a drinking water MCL of
10mg/l.
	Nutrient management abates nutrient
movement by minimizing the quantity of
nutrients available for loss.
	Fertilizer applied in the fall causes ground
water degradation. Partial application in
the spring can improve N uptake.
	Ammonium N fertilizers are not subject to
immediate leaching, but convert to
nitrate.

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Page 2
Source Water Protection Practices Bulletin
Why is it Important to Manage Fertiliser Use Near Sources of Drinking Water?
Improper or excessive use of fertilizer
can lead to nitrate pollution of ground
or surface water. Nitrogen fertilizer,
whether organic or inorganic, is bio-
logically transformed to nitrate that is
highly soluble in water. In this soluble
form, nitrate can readily be absorbed
and used by plants. On the other
hand, soluble nitrate is highly mobile
and can move with percolating water
out of the soil, thus making it unavail-
able for plant uptakes. Crop produc-
ers, therefore, need to match nitrogen
applications to crop uptake to mini-
mize nitrate leaching and maximize
efficiency.
Use of nitrogen-containing fertilizers
can contribute to nitrates in drinking
water. Consumption of nitrates can
cause methemoglobinemia (blue baby
syndrome) in infants, which reduces
the ability of the blood to carry oxygen.
If left untreated, methemoglobinemia
can be fatal for affected infants. Due to
this health risk, EPA set a drinking
water maximum contaminant level
(MCL) of 10 milligrams per liter (mg/l)
or parts per million (ppm) for nitrate
measured as nitrogen.
Another major component of fertilizer
is phosphorus. Under certain condi-
tions phosphorus can be readily trans-
ported with the soil. In fact, 60 to 90
percent of phosphorus moves with the
soil. Phosphorus is the major source
of water quality impairments in lakes
nationwide. Even though regulations
that affect the taste and odor of water
are not Federally enforceable under
the Safe Drinking Water Act, munici-
palities often must treat their drinking
water supplies for these aesthetic rea-
sons.
The use of organic nutrient sources,
such as manure, can supply all or part
of the nitrogen, phosphorus, and po-
tassium needs for crop production.
However, organic fertilizers can also
cause excessive nutrient
loads if improperly applied.
Blue Baby Syndrome Effects
Superior
vena Cava
Pulmonary
r'ulmonary
2 - Healthy
hearts.
Right
Atrium
'""Aortic
Pulmonary
valve
Right
Ventricle
Tricuspid "
Valve
nfertor Vena Cava
Small (hypoplastic) aorta
Patent (open)
ductus arteriosus
Atrial septal defect
opening betwee-n the atrial
SF-
Small (hypoplastic]
left veniriculum
4 - Hypoplastic left heart syndrome.
3 - dextro-Transposition of the great arteries, dTGA.
Oxygenated blood shown in dark pink (above left)
5 - Tricuspid atresia
6 - Tetralogy of Fallot,
vena cava
Pulmonary
1 artery
I Left\
satrium
Ventricle
Superior
Pulmonary
vein
Atresic
tricuspid
valve
Rudimentary
right ventricle
Inferior vena cava
Overriding aorta
Pulmonic
stenosis
ventricular
septal defect
Right ventricular
hypertrophy

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Source Water Protection Practices Bulletin
Page 3
Available Prevention Measures to Address Agricultural Applications of Fertiliser
This section discusses some of the
most often used prevention meas-
ures, but is not an exhaustive list of
all known measures. For information
on additional prevention measures,
see the documents referenced in the
last section of this fact sheet. Please
keep in mind that individual preven-
tion measures may or may not be
adequate to prevent contamination of
source waters. Most likely, individual
measures should be combined in an
overall prevention approach
that considers the nature of the po-
Comprehensive
Nutrient
Management
Plans include
soil sampling,
crediting other
sources of
nutrients and
limiting
fertilizer use.
Application Kates and Fertiliser Types
tential source of contamination, the
purpose, cost, operational, and main-
tenance requirements of the meas-
ures, the vulnerability of the source
water, the public's acceptance of the
measures, and the community's de-
sired degree of risk reduction.
The goal of these prevention meas-
ures is to minimize nutrient losses
from agricultural lands occurring by
edge-of-field runoff and by leaching
from the root zone. Effective nutrient
management abates nutrient move-
ment by minimizing the quantity of
7, 8, 9, 10 - Seasons,
One component of a comprehensive
nutrient management plan is to de-
termine proper fertilizer application
rates. The goal is to limit fertilizer to
an amount necessary to achieve a
realistic yield goal for the crop. Soil
sampling and crediting other sources
are also parts of the concept.
Yearly soil sampling is necessary for
determining plant nutrient needs and
to make accurate fertilizer recom-
mendations. Many factors must be
considered when determining sam-
pling methods and frequency.
Calculating the optimal rate of appli-
cation also includes crediting other
sources that contribute nitrogen and
phosphorous to the soil. Previous
legume crops, irrigation water,
manure, and organic matter all con-
tribute nitrogen to the soil, while or-
ganic matter and manure contribute
phosphorus.
Along with soil samples and fertilizer
credits from other sources, nitrogen
fertilizer recommendations are based
on yield goals established by the
crop producers. Yield expectations
are established for each crop and
field based on soil properties, avail-
able moisture, yield history, and
management level.
Applying the appropriate form of ni-
trogen fertilizer can reduce leaching.
Nitrate forms of nitrogen fertilizer are
readily available to crops, but are
subject to leaching losses. Nitrate
fertilizer use should be limited when
nutrients available for loss. This is
achieved by developing a compre-
hensive nutrient management plan
and using only the types and
amounts of nutrients necessary to
produce the crop, applying nutrients
at the proper times and with proper
methods, implementing additional
farming practices to reduce nutrient
losses, and following proper proce-
dures for fertilizer storage and han-
dling.
Fertiliser Application Timing
Nitrogen fertilizer applications
should be timed to coincide as
closely as possible to the period of
maximum crop uptake. Fertilizer
applied in the fall has been shown
to cause ground water degrada-
tion. Partial application of fertilizer
in the spring, followed by small
additional applications as needed,
can improve nitrogen uptake and
reduce leaching. Reasons to alter
nitrogen amounts include abnormal
weather or crop quality.
the leaching potential is moderate to
high. In these situations, ammonium
nitrogen fertilizers should be used
because they are not subject to imme-
diate leaching. However, ammonium
nitrogen transforms rapidly into nitrate
when soils are warm and moist. More
slowly available nitrogen fertilizers
should be used in these conditions.
Nitrification inhibitors can also delay
the conversion of ammonium to ni-
trate under certain conditions.
Phosphorus fertilizer is less subject to
leaching, but loss through surface
runoff is more common. To minimize
losses of phosphorus fertilizer, appli-
cations should only be made when
needed (determined through soii
testings) and at recommended rates.

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Page 4
Source Water Protection Practices Bulletin
Fertiliser Application Methods
Fertilizer application equipment,
should be inspected at least once
annually. Application equipment
must also be properly calibrated to
insure that the recommended
amount of fertilizer is spread.
Correct fertilizer placement in the
root zone can greatly enhance plant
nutrient uptake and minimize
losses. Subsurface applied or incor-
porated fertilizer should be used
instead of a surface broadcast fertil-
izer. The most efficient application
method for many crops, especially
in erosive soils, is to place dry fertil-
izer into the ground in bands. Band
or drilled row fertilizers are applied
closer to the seed and can be
recovered by the crop more effi-
ciently. All surface-applied fertilizers
should be mechanically incorporated
into the soil to reduce losses through
surface runoff and volatilization. Fer-
tilizer should never be applied to fro-
zen ground, and also should be lim-
ited on slopes and areas with high
runoff or overland flow.
Irrigation water should be managed
to maximize efficiency and minimize
runoff or leaching. Irrigated crop pro-
duction has the greatest potential for
source water contamination because
of the large amount of water applied.
Both nitrogen and phosphorus can
leach into ground water or run off
into surface water when excess
water is applied to fields. Irrigation
systems, such as sprinklers, low-
energy precision applications,
surges, and drips, allow producers to
apply water uniformly and with great
efficiency. Efficiency can also be im-
proved by using delivery systems
such as lined ditches and gated pipe,
as well as reuse systems such as
field drainage recovery ponds that
efficiently capture sediment and nu-
trients. Gravity-controlled irrigation or
furrow runs should be shortened to
prevent over-watering at the top of
the furrow before the lower end is
adequately watered.
11 - Crop bands.
A complete system is needed to reduce fertilizer loss. Components
of this system often include farming practices that are not strictly
related to fertilizer, such as conservation tillage and buffers.
Correct fertilizer
placement in the
root zone can greatly
enhance plant
nutrient uptake and
minimize losses.
Subsurface applied
or incorporated
fertilizer should be
used instead of a
surface broadcast
fertilizer.
Conservation Tillage
Conservation tillage is another field management
method used to reduce runoff. In conservation
tillage, crops are grown with minimal cultivation
of the soil. When the amount of tillage is reduced,
the plant residues are not completely incorpo-
rated and most or all remain on top of the soil.
This practice is critical to reducing phosphorus
losses because the residue provides cover and
thereby reduces nutrient runoff and erosion by
water.
12 - Conservation tillage.

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Source Water Protection Practices Bulletin
Page 5
Irrigated crop
production has
the greatest
potential for
source water
contamination
because of the
large amount of
water applied,
Creating buffer strips or filter strips can impede run-
off and help filter nitrogen and phosphorus from
runoff. Buffer strips and filter strips are created by
planting dense vegetation near surface water bod-
ies. The root systems of these plants hold soil in
place, thereby decreasing the velocity of runoff and
preventing erosion. The vegetation and soils strain
and filter sediments and chemicals. For more infor-
mation on buffer strips and filter strips see the fact
sheet on storm water runoff.
14 - Buffer strip.
13 Crop rotation.
Crop rotation can often yield crop improvement and
economic benefits by minimizing fertilizer and pesticide
needs. Planting legumes as part of a crop rotation plan
provides nitrogen for subsequent crops. Deep-rooted
crops can be used to scavenge nitrogen left in the soil by
shallow-rooted crops. Cover crops stop wind and water
erosion, and can use residual nitrogen in the soil.
Field Leveling
A high-tech way to level or grade a field
is to use laser-controlled land leveling
equipment. Field leveling helps to con-
trol water advance and improve uni-
formity of soil saturation in gravity-flow
irrigation systems. This improves irriga-
tion efficiency and reduces the potential
for nutrient pollution through runoff.	15 - Laser-controlled land leveling.
Fertiliser Storage and Handling
Follow label directions for storing and mixing fertilizer and
for disposing empty containers. Lock or secure storage
container valves when the container is not in use.
Protect permanent fertilizer storage and mixing sites from
spills, leaks, or storm water infiltration. Storage buildings
should have impermeable floors and be securely locked.
Impermeable secondary containment dikes can also be
used to contain liquid spills or leaks. Do not store fertilizer
in underground containers or pits.
To prevent accidental contamination of water supplies,
mix, handle, and store fertilizer away from wellheads and
surface water bodies. Installing anti-backflow devices on
equipment can also prevent spillage. Ideally, mix and load
fertilizers at the application spot.
Immediately recover and reuse or properly dispose of
spills. Granular absorbent material can be used at the mix-
ing site to clean up small liquid spills
Control box
Laser beam
Laser
Transmitter

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Page 6
Source Water Protection Practices Bulletin
Additional Information
These references have information on agricultural fertilizer use and best management practices. All of the following
documents are available for free on the internet. You should also contact the U.S. Department of Agriculture (USDA),
Natural Resources Conservation Service (NRCS), Conservation District, and Agricultural Extension Service representa-
tives in your area for more information on nutrient management and cost-share programs, such as the Environmental
Quality Incentives Program (EQIP), the Conservation Reserve Program (CRP), and the Conservation Reserve Enhance-
ment Program (CREP), to assist in financing source water protection measures.
Contact local government authorities in your area to see if there are ordinances in place to manage fertilizer use. Numer-
ous examples of local source water protection-related ordinances for various potential contaminant sources can be found
at: http://www. epa .gov/r5water/ord com/
h tt p: //www .epa.gov/owow/nps/ordinance/
http://www.epa.gov/owow/nps/ordinance/links.htm
The following documents provide more detailed information on prevention measures for fertilizer use on the farm
Colorado State University Cooperative Extension. Best Management Practices for Nitrogen Fertilization (XCM-172).
(1994, August). Retrieved February 9, 2001 from the World Wide Web:
http://www.ext.colostate.edU/PUBS/CROPS/pubcrop.html#soil
Colorado State University Cooperative Extension. Best Management Practices for Pesticide and Fertilizer Storage and
Handling (XCM-178). (1994, August). Retrieved February 9, 2001 from the World Wde Web:
http://www.ext.colostate.edU/PUBS/CROPS/pubcrop.html#soil
Colorado State University Cooperative Extension. Best Management Practices for Phosphorus Fertilization (XCM-175).
(1994, August). Retrieved February 9, 2001 from the World Wde Web:
http://www.ext.colostate.edU/PUBS/CROPS/pubcrop.html#soil
Farm*A*Syst - University of Wisconsin. Retrieved May 22, 2001 from the World Wide Web:
http://www.uwex.edu/farmasyst/
Kansas State University Cooperative Extension Service. Best Management Practices for Nitrogen. (1996, March). Re-
trieved February 9, 2001 from the World Wide Web: http://www.oznet.ksu.edU/library/ageng2/#WaterQuality
Kansas State University Cooperative Extension Service. Best Management Practices for Phosphorus. (1998, February).
Retrieved February 9, 2001 from the World Wde Web: http://www.oznet.ksu.edU/library/ageng2/#WaterQuality
North Carolina State University. Sustainable Practices for Vegetable Production in the South -Conservation Tillage.
(1997, July 9). Retrieved March 14, 2001 from the World Wide Web:
http://www.cals.ncsu.edu/sustainable/peet/tillage/c03tilla.html
Purdue University Extension Service. Fertilizer Storage and Handling on the Farm. (1999). Retrieved February 12, 2001
from the World Wde Web: http://pasture.ecn.purdue.edu/~epados/farmstead/fert/src/title.htm
Texas Agricultural Extension Service. Reducing the Risk of Ground Water Contamination by Improving Fertilizer Storage
and Handling (B-6026). (n.d.). Retrieved February 9, 2001 from the World Wide Web:
http://agpublications.tamu.edu/catalog/index.html
University of Maryland - Cooperative Extension. Agricultural Nutrient Management. Retrieved May 22, 2001 from the
World Wde Web: http://www.agnr.umd.edu/users/agron/nutrient/
University of Saskatchewan, Department of Agriculture. Fertilizer: The Basics, (n.d.). Retrieved February 16, 2001 from
the World Wide Web: http://www.ag.usask.ca/cofa/departments/hort/hortinfo/misc/fertiliz.html
U.S. Department of Agriculture. Irrigation Systems and Land Treatment Practices. (2001, February 6). Retrieved March
14, 2001 from the World Wde Web: http://151.121,66.126/Briefing/wateruse/Questions/glossary.htm
U.S. Department of Agriculture, Natural Resources Conservation Service. Comprehensive Nutrient Management Plan-
ning - Technical Guidance. (2000, December). Retrieved April 30, 2001 from the World Wde Web:
http://www.nhq.nrcs.usda.gov/PROGRAMS/ahcwpd/ahCNMP.html

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Source Water Protection Practices Bulletin
Page 7
U.S. Department of Agriculture, Natural Resources Conservation Service. Conservation Practices Training Guide. (1999,
August). Retrieved April 30, 2001 from the World Wide Web: http://www.ftw.nrcs.usda.gov/tech_ref.html
Virginia Cooperative Extension. Fertilizer Storage, Handling, and Management (442-906). (1996, June). Retrieved Feb-
ruary 9, 2001 from the World Wde Web: http://www.ext.vt.edu/pubs/farmasyst/442-906/442-906.html
1	- Flickr Creative Commons, attribute only search, liquid fertilizer application uploaded by "eutrophication&hypoxia" on
March 31, 2010. http://www.flickr.eom/photos/48722974@N07/4478367887/
2	- Wikipedia. Diagram of the Human Heart: http://commons.wikimedia.Org/wiki/File:Diagram_of_the_human_heart.svg
3	- Wikipedia, copyright image for any use. dextro-Transposition of the great arteries:
http://en.wikipedia.0rg/wiki/File:D-TGA.jpg
4	- Wikipedia, public domain image. Hypoplastic left heart syndrome:
http://en.wikipedia.org/wiki/Hypoplastic_left_heart_syndrome
5	- Wikipedia Tricuspid Atresia: http://en.wikipedia.Org/wiki/File:Tricuspid_atresia.svg
6	- Wikipedia, public domain image. Tetralogy of Fallot: http://en.wikipedia.org/wiki/Tetralogy_of_Fallot
7	- Flickr Creative Commons, attribute only search. Just a reminder of the long cold winter we had	, uploaded by "Per
Ola Wber~ Powi" on July 5, 2010. http://www.flickr.com/photos/powi/4762908073/
8	- Flickr Creative Commons, attribute only search. Spring Blossoms, uploaded by "Noel Zia Lee" on March 8, 2007.
http://www.flickr.com/photos/noelzialee/414585445/
9	- Flickr Creative Commons, attribute only search. Oh Summer..., uploaded by "bark" on December 5, 2009.
http://www.flickr.com/photos/barkbud/4160654917/
10	- Flickr Creative Commons, attribute only search. Autumn Stream, uploaded by "digitalART2" on December 8, 2007.
http://www.flickr.com/photos/digitalart/2095802085/
11	- Flickr Creative Commons, attribute only search. Lettuce and fertilizer tanks, uploaded by "benketaro" on September
13, 2009. http://www.flickr.com/photos/misskei/3918032323/
12	- From original bulletin, 2001.
13	- Baltic Agricultural run-off Action Programme, http://www.baap.lt/codes_gap/lithuania/chapter_2.htm
14	- Wkipedia public domain image from the USDA. Riparian buffer on Bear Creek in Story County, Iowa.
http://en.wikipedia.0rg/wiki/File:Riparian_buffer_0n_Bear_Creek_in_St0ry_C0unty,_lowa.JPG
15	- Department of Soil and Water Conservation, Punjab. Laser Leveling: Resource Conservation through Laser Level-
ing. http://dswcpunjab.gov.in/contents/data_folder/Laser_Level.htm
Back Cover - From original bulletin, 2001.

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Source Water Protection Practices Bulletin
Managing Agricultural Fertilizer Application to Prevent
Contamination of Drinking Water
The mission of EPA is to protect human health
and to safeguard the natural environment  air,
water and land  upon which life depends.
USEPA East (EPAEast) [Old ICC Building]
1201 Constitution Avenue.
Washington, DC 20004
United States
Environmental Protection
Agency
Office of Water (4606)
EPA ### ### ### ###
wwnv. epa.gov/ safewater
August 2010

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