A nice-looking, well-maintained lawn enhances the value of your property. A lawn should be a source of homeowner pride. Your lawn is not only an attractive part of your landscape, but it also helps to tie your home and landscaping together. A healthy, good-looking lawn actually helps improve your living environment. On a hot day your lawn reduces the glare of the sun. Your lawn can also help keep surrounding areas cooler. A well-maintained lawn is much more attractive than pavement! Your lawn will attract birds and other wildlife. On windy days your lawn will trap dust particles from the air. And most importantly, your lawn protects the soil on your property from erosion. Inputs such as pesticides, fertilizers, and water when used incorrectly may adversely impact surface and/or groundwater quality. To protect the environment and water quality you should use Best Management Practices (BMPs), which are defined as implemented strategies that eliminate or minimize environmental pollution. BMPs are designed to be compatible with good, sound lawn management. BMPs can protect the environment without compromising the beauty of your lawn. Why should homeowners be concerned about fertilizer use on lawns? On a square foot basis many homeowners use large quantities of fertilizers on their lawns. Excessive or frequent fertilizer over-use can negatively impact the environment. Fertilizers can run off the soil surface and contaminate nearby rivers and lakes (especially phosphorus). Fertilizers also have the potential to contaminate groundwater when over applied (especially nitrogen). Fertilizer over-use can negatively impact the health of your lawn. The combination of large amounts of fertilizer, too much water, and watering at the wrong time of day sets up the perfect environment for many turfgrass diseases. Fertilizer over-use can result in excessive invasions by weeds. When given a nutrient-rich environment there are several weeds that become very competitive with the grasses you are trying to grow! Fertilizer management BMPs you should implement on your lawns include: 1. Base fertilizer application rates on a sound scientific strategy. Soil sampling is not recommended because it is relatively expensive for a homeowner with a lawn less than 3 acres in size. Rather it is best to base your nitrogen fertilizer application rate on a nutrient ratio strategy. This strategy includes: Base nitrogen (N) application on the lawn’s growing season. Applications of phosphorus (P), potassium (K), and sulfur (S) fertilizers are based on the ratio to nitrogen. 1,000 square feet of lawn (a typical lawn is 3,000 square feet) requires 0.5 pounds of N per month of active growth. Determine the length of lawn growing season in months, and once the N need is determined, P, K, and S applications are based on a ratio to N. Your desired N:P:K:S ratio is 3:1:2:1.

Pacific Northwest Regional Water Quality Coordination Project Partners Land Grant Universities Alaska Cooperative Extension Service Contact Fred Sorensen: 907-786-6311 http://www.uaf.edu/ces/water/ University Publications: http://www.alaska.edu/uaf/ces/publications/ Idaho University of Idaho Cooperative Extension System Contact Bob Mahler: 208-885-7025 http://www.uidaho.edu/wq/wqhome.html University Publications: http://info.ag.uidaho.edu/Catalog/catalog.html Oregon Oregon State University Extension Service Contact Mike Gamroth: 541-737-3316 http://extension.oregonstate.edu/ University Publications: http://extension.oregonstate.edu/catalog/ Washington Washington State University WSU Extension Contact Bob Simmons: 360-427-9670 ext. 690 http://wawater.wsu.edu/ University Publications: http://pubs.wsu.edu/ Northwest Indian College Contact Charlotte Clausing: 360-392-4319 cclausing@nwic.edu or http://www.nwic.edu/ Water Resource Research Institutes Water and Environmental Research Center (Alaska) http://www.uaf.edu/water/ Idaho Water Resources Research Institute http://www.boise.uidaho.edu/ Institute for Water and Watersheds (Oregon) http://water.oregonstate.edu/ State of Washington Water Research Center http://www.swwrc.wsu.edu/ Environmental Protection Agency EPA, Region 10 The Pacific Northwest http://www.epa.gov/r10earth/ Office of Research and Development, Corvallis Laboratory http://www.epa.gov/wed/ For more information contact Jan Seago at 206-553-0038 or seago.jan@epa.gov
	Example Problem: Q. How much N, P, K, and S do I need if my lawn is actively growing for 6 months per year? A. 0.5 pounds N/1,000 square feet × 6 months = 3.0 pounds N/1,000 square feet. So based on the ratio, I need 3 pounds N, 1 pound P, 2 pounds K, and 1 pound S per 1,000 square feet. Then buy a fertilizer with as close to a 3:1:2:1 ratio as possible, or mix different fertilizers together to make the desired fertilizer. 2. Correctly time your fertilizer applications Try to apply fertilizer at the time the lawn needs it. Use split applications on your lawn – divide the total nutrient application (determined in part 1 above) by 4 and apply: ¼ in early spring (Easter) ¼ in late spring (Memorial Day) ¼ in the summer (July 4th) ¼ in early fall (Labor Day) Example: If your year requirement for N is 3.0 pounds/1,000 square ft (as in the last example problem), apply as follows: 0.75 pounds N around Easter 0.75 pounds N around Memorial Day 0.75 pounds N around July 4th 0.75 pounds N around Labor Day 3. Use slow-release nitrogen fertilizers Slow release fertilizers improve nitrogen use efficiency by plants and reduce leaching. Look for fertilizers in home and garden stores with the word WIN on the bag. WIN stands for Water Insoluble Nitrogen. This means that the fertilizer is less likely to leach, resulting in better lawn nutrition and a reduced adverse environmental impact. 4. Use water wisely on lawns Nutrients (including nitrogen fertilizers) in the soil move with water. Over-watering causes nutrient leaching and possible environmental damage such as groundwater contamination with nitrates. If the nutrients leach they can not help meet your lawn’s needs.
	National Water Quality Program Areas The four land grant universities in the Pacific Northwest have aligned our water resource extension and research efforts with eight themes of the USDA's National Institute of Food and Agriculture. Animal Waste Management Drinking Water and Human Health Environmental Restoration Nutrient and Pesticide Management Pollution Assessment and Prevention Watershed Management Water Conservation and Agricultural Water Management Water Policy and Economics
	This material is based upon work supported by the National Institute of Food and Agriculture, U. S. Department of Agriculture, under Agreement No 2008-51130-4734.

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