United States
Environmental Protection
Agency
Office of Water
(4606)
EPA816-F-01-029
July 2001
Source Water Protection
Practices Bulletin
Managing Turfgrass and Garden
Fertilizer Application to Prevent
Contamination of Drinking Water
Fertilizers are made up of organic and inorganic materials that are added to soil to supply
nutrients required for plant growth. If improperly managed, fertilizer elements, specifically
phosphorus (P) and nitrogen (N), can run off into surface water or leach into ground water.
This fact sheet focuses on the management of small-scale fertilizer applications to prevent
contamination of drinking water sources (ground water and surface water used as public
drinking water supplies); see the fact sheets on pesticide application and storm water for other
preventative measures related to lawn and garden care.
FERTILIZER USE IN TURFGRASS AND GARDENS
The care of landscaped areas can
contribute to the pollution of surface
water and ground water. Heavily
landscaped areas include residential
yards, commercial lawns, golf
courses, ball fields, and parks. The
soils in many of these areas require
frequent fertilization to maintain their
turf grass. Because excess fertilizer
use and poor application methods can
cause fertilizer movement into
sources of drinking water, the
increased application of lawn and
garden fertilizers in recent years has
raised concern over the pollution of surface water and ground water.
The two main components of fertilizer that are of the greatest concern to source water quality
are nitrogen and phosphorus. Nitrogen is used to promote green, leafy, vegetative growth in
plants. Plants with nitrogen deficiency show stunted growth. Phosphorus promotes root growth,
root branching, stem growth, flowering, fruiting, seed formation, and maturation.
A recent nonpoint source loading analysis from a New Jersey study indicated that ten percent of
the nitrogen and four percent of the phosphorus applied annually in a 193-square-mile area of
landscaped residential development ended up in surface waters as a result of over-application.
Another study (South Jersey Resource Conservation and Development Council, Inc.) found that
more than 50 percent of the nitrogen in fertilizer leaches from lawns when improperly applied.
This kind of nutrient loss can be reduced by following the prevention measures given in this fact
sheet.
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WHY IS IT IMPORTANT TO MANAGE FERTILIZER USE NEAR THE SOURCES
OF YOUR 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 biologically transformed to nitrate that is
highly soluble in water.
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/1) or parts per million (ppm) has been set for nitrate
measured as nitrogen.
Phosphorus is the other element of concern in fertilizer. Under certain conditions phosphorus
can be readily transported 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, municipalities often must treat their drinking water supplies for
these aesthetic reasons.
AVAILABLE PREVENTION MEASURES TO ADDRESS TURFGRASS AND
GARDEN APPLICATIONS OF FERTILIZER
This section discusses some of the most often used prevention measures, 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 prevention 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 potential source of contamination, the purpose, cost, operational,
and maintenance requirements of the measures, the vulnerability of the source water, the
public's acceptance of the measures, and the community's desired degree of risk reduction.
Ways to Eliminate Excess Fertilizer Use
Fertilizer applications should be based on soil tests to avoid the economic and environmental
costs that can be incurred with excess fertilizer use. A soil test will show the levels of
phosphorus and potassium present in the lawn; however, soil tests for nitrogen are rare.
Nitrogen is highly mobile in the soil and tests generally provide little useful information relative to
lawns. Most newly planted areas should be tested during initial planting and every one or two
years following that. A minimum of three to four weeks after the last fertilization should pass
before sampling. For sampling, 15 to 20 cores should be taken at about three to four inches in
depth and mixed in a plastic container. Samples can be tested using readily available field kits or
submitted to a private laboratory or extension office for testing and interpretation.
Selecting the appropriate fertilizer is the next crucial step after receiving soil testing results.
Most homeowners use blended fertilizers that list percentages of nitrogen, phosphorus, and
potassium in the fertilizer. For example, a 100-pound bag of 10-5-10 would contain ten pounds
of nitrogen, five pounds of phosphorus, and ten pounds of potassium. The remainder of the bag
contains micronutrients and filler materials that allow for an even application of nutrients. If the
soil test shows phosphorus is high, then a fertilizer with a low percentage of phosphorus should
be chosen (such as 20-0-10 or 24-3-8). Most lawns contain adequate phosphorus, and
continuous use of fertilizers high in phosphorus can result in excessive buildups. These lawns
are more likely to contribute high levels of phosphorus to surface water during storm runoff
events. The use of organic nutrient sources, such as manure, can supply all or part of the
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nitrogen, phosphorus, and potassium needs for turfgrass and gardens. However, organic
fertilizers can also cause excessive nutrient loads if improperly applied.
Nitrogen should be applied as recommended for the type of grass being grown. It is often
recommended that 1,000 square feet of lawn requires 0.5 pounds of nitrogen per month of
active growth. A good rule is never to apply more
than one pound of nitrogen fertilizer per 1,000 square
feet of lawn in any one application. For vegetable and
flower gardens only 0.1 to 0.2 pounds of nitrogen per
100 square feet should be applied per year, although
corn, tomatoes, and cole crops may require more.
To help maintain a healthy lawn it is best to mow
frequently at a height of 2.5 to 3 inches. Grass
clippings should remain on the lawn to decompose
and recycle nutrients back
to the lawn. By leaving
grass clippings on the
lawn, nitrogen applications
can be reduced by 30 to
40 percent.
Mulching lawnmower
Native plants
Wherever possible, low maintenance, native plants and grasses
should be planted to minimize the use of fertilizer. Plants that are
adapted to the local soils require less fertilization and watering (for
example, xeriscaping is a landscaping method to minimize the use
of water in dry climates). In fact, these practices can reduce
required lawn maintenance up to 50 percent. Local planting
suggestions may be obtained from State and county extension
offices and Web sites.
Proper Fertilizer Application
The use of an appropriate form of nitrogen fertilizer can reduce the potential for leaching and
runoff problems. Quick-release fertilizers should be used on heavy clay or compacted soils,
because the longer a fertilizer granule remains intact, the greater the chances it will be washed
away into surface water. On sandy soils, however, nitrogen can leach through the soil quickly.
On these soils, slow-release nitrogen sources provide soluble nitrogen over a period of time so a
large concentration of nitrogen is not made available for leaching. Fertilizer bags are generally
labeled as a ratio of water-insoluble nitrogen (WIN) slow-release fraction, to water-soluble
nitrogen (WSN) quick-release fraction. A large WTN/WSN ratio indicates a high percentage of
slow-release nitrogen is contained in the product.
While the proper time of year to fertilize varies by location, applying a smaller amount of
fertilizer at a higher frequency is often best. Eliminating excess nutrients in soil reduces the
chances of polluting surface runoff and ground water. Ideally, fertilizer application should be
timed to coincide as closely as possible to the period of maximum uptake and growth. The most
active growth periods are spring and fall in cool climates and early and late summer in warm
climates. Avoid fertilizer applications before heavy rains.
Core compacted soils before applying fertilizer to insure incorporation. In all types of soil, it
is always best to incorporate organic fertilizers into the lawn. When the phosphorus in organic
fertilizer remains on top of the soil it has an increased chance of washing away during heavy
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rains. Fertilizer should never be applied to frozen ground, and also should be limited on slopes
and areas with high runoff or overland flow.
It is important to irrigate with % to 1A inch of water immediately after application of phosphorus
or water-soluble nitrogen fertilizer. Afterwards, the key is to add only enough water to
compensate for that removed by plant uptake and evaporation; this will minimize potential
pollution problems from runoff and leaching. Over-watering can increase nitrogen loss five to
11 times the amount lost when proper watering strategies are used. Soaker hoses and trickle or
drip irrigation systems are preferred
alternatives to sprinkler systems. These
systems deliver water at lower rates,
which can conserve water, increase the
volume infiltrated, and reduce surface
runoff.
To ensure the proper amount of fertilizer
is applied, spreaders should be properly
calibrated. As spreaders get older,
settings gradually change because of
wear and tear. Regular cleaning and
lubrication of the spreader will help it
perform properly. Labels on fertilizer
bags often list the proper spreader settings for different types of spreaders. In general, drop
spreaders are slower and more precise than rotary spreaders. Drop spreaders should be used
near bodies of water because rotary spreaders can easily cast granules into the water bodies.
Buffer strips or filter strips can be created to slow runoff and help filter nitrogen and
phosphorus from runoff. Buffers to runoff can be created simply by avoiding consistent mowing
near water bodies. Additionally, natural deep-rooted vegetation can be planted to enhance
nutrient filtering. Soil is held in place by the root systems of these plants. This decreases the
velocity of runoff and helps prevent erosion near sources of surface water. The vegetation and
soil strain and filter sediments, nutrients, and chemicals. For more information on buffer strips
and filter strips see the fact sheet on storm water runoff.
Fertilizer Storage and Handling
Closely follow label directions when storing and handling fertilizer and when disposing empty
containers. Stored dry fertilizer poses little threat to ground water as long as it is kept dry.
Therefore, stored fertilizer should be kept covered to keep precipitation off. Keep bags on
pallets to reduce the possibility of water damage.
Fill spreaders on hard or paved surfaces where spills can be cleaned up easily by sweeping or
scooping up the spilled granules.
Additional Prevention Measures for Golf Courses
Golf course fairways, tees, and greens should be located where the seasonal water table is not
excessively high. Fertilizer movement will be lowest on these sites.
State or local governments can produce guidelines for the design and maintenance of golf
courses. These guidelines can require golf course developers and managers to submit plans for
approval that show how they intend to lessen the impact of the site on the natural resources of
the area. Plan requirements could include ground water and surface water monitoring, and
design specifications, such as vegetative buffers or erosion controls.
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FOR ADDITIONAL INFORMATION
These documents contain information on fertilizer use and best management practices. All
sources are available for free on the Internet. See EPA's Guide to Source Water Information
at www.epa.gov/safewater/protect/sources.html for a listing of resources on management
measures. You can also contact your local Extension Service for more information.
Contact local government authorities in your area to see if there are ordinances in place to
manage fertilizer use. Numerous examples of local source water protection-related ordinances
for various potential contaminant sources can be found at:
http://www.epa.gov/r5water/ordcom/
http: //www. ep a. gov/o wow/nps/ordinance/
http://www.epa.gov/owow/nps/ordinance/links.htm
The following documents provide more detailed information on prevention measures for fertilizer
use in lawns and gardens.
Home*A*Syst - University of Wisconsin. Retrieved May 22, 2001 from the World Wide Web:
http://www.uwex.edu/homeasyst/
North Carolina Cooperative Extension Service. Water Quality and Professional Lawn Care
(WQWM-155). (1995, September). Retrieved February 9, 2001 from the World Wide Web:
http://www.ces.ncsu.edu/TurfFiles/pubs/wqwml55.html
Purdue University Extension Service. Beneficial Lawn Care and Chemical Management.
(n.d). Retrieved February 12, 2001 from the World Wide Web:
http://pasture.ecn.purdue.edu/~epados/lawn/src/title.htm
South Jersey Resource Conservation and Development Council, Inc. Non-Point Pollution
Prevention — Homeowner, (n.d.). Retrieved February 9, 2001 from the World Wide Web:
http://www.sjrcd.org/ce/erosion3.htm
University of Idaho, College of Agriculture. Fertilizer BMPs for Your Lawn. (1994, April).
Water Quality Update, volume 4, number 2. Retrieved February 9, 2001 from the World Wide
Web: http://www.uidaho.edu/wq/wqu/wqu42.html
University of Maryland - Cooperative Extension. Information Central — Greenhouse,
Nursery, Landscape, & Turf. Retrieved May 22, 2001 from the World Wide Web:
http://www.agnr.umd.edu/CES/greennursury.html
University of Minnesota Extension Service. Fertilizer - Phosphorus and Water Pollution
(282). (1992). Retrieved February 12, 2001 from the World Wide Web:
http://www.extension.umn.edu/info-u/environment/BD282.html
University of Minnesota Extension Service. Preventing Pollution Problems from Lawn and
Garden Fertilizers (FO-2923-GO). (1999). Retrieved February 12, 2001 from the World Wide
Web: http://www.extension.umn.edu/distribution/horticulture/DG2923.html
University of Minnesota Extension Service. Turfgrass Management for Protecting Surface
Water Quality (BU-5726-GO). (1997). Retrieved February 12, 2001 from the World Wide
Web: http://www.extension.umn.edu/distribution/horticulture/DG5726.html
University of Wisconsin - Extension. Lawn and Garden Fertilizers (GWQ002). (1999).
Retrieved January 23, 2001 from the World Wide Web: http://www.dean-
water.uwex.edu/pubs/stewards/index.html
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University of Wisconsin - Extension. Step in the Right Direction with Proper Lawn
Fertilizing, (n.d.). Retrieved January 23, 2001 from the World Wide Web: http://www.dean-
water.uwex.edu/pubs/stewards/index.html
University of Wisconsin - Extension. Steps for Maintaining Healthy Lawns and Quality
Waters, (n.d.). Retrieved January 23, 2001 from the World Wide Web: http://www.dean-
water.uwex.edu/pubs/stewards/index.html
The following documents are examples of local guidelines for the design and maintenance of
golf courses:
Baltimore County Environmental Protection and Resource Management. Environmental
Guidelines for the Design and Maintenance of Golf Courses, (n.d.). Retrieved May 17,
2001 from the World Wide Web: http://www.epa.gov/owow/nps/ordinance/golf.htm
Worcester County Department of Planning, Permits & Inspections. Voluntary Guidelines
Recommended for Golf Courses in Worcester County & the Delmarva Peninsula, (n.d.).
Retrieved May 18, 2001 from the World Wide Web:
http://www.dnr.state.md.us/bay/tribstrat/golf.html
The following University of Florida website details their outreach program to reduce non-point
source pollution, which includes proper nutrient management techniques:
http://hort.ufl.edu/fyn/
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