Introduction

The majority of land in Connecticut and portions of Massachusetts, Vermont, and New Hampshire drains to Long Island Sound. The health of the Sound is heavily impacted by activities within the landscape that, if not properly managed, can contribute pollutants to the waterway.

This fact sheet focuses on one source of nitrogen impacting Long Island Sound – lawn fertilizer.

Although the water quality of Long Island Sound has improved in recent years, pollution from nitrogen still leads to excess algae growth and low oxygen in certain parts of the Sound. Excess lawn fertilizer, carried by stormwater runoff, is a primary source of nitrogen pollution.

The following research-based recommendations are from leading turfgrass scientists across the United States, including New England (Guillard 2008). These simple management practices can help protect local waters, and the Long Island Sound, while keeping your lawn healthy:

Minimize Pollution Potential

• Mow your lawn as high as can be tolerated (at least three inches) and return clippings to the lawn. This practice can reduce nitrogen needs (and your fertilizer cost) by 50%.
• To prevent any soil loss from erosion, a healthy lawn should have a dense, contiguous turfgrass stand that completely covers the soil. Once a turfgrass stand reaches a maturity level of 10 years or older, the nitrogen needs substantially decrease.
• Soil test to determine if and what type of fertilization is needed. Visit UConn CAHNR's Plant and Soil Health Center for information on soil testing and getting fertilizer recommendations.

• If overseeding to fill in thin/bare areas or planting a new lawn (preferably late summer/early fall), choose turfgrass seed mixtures that are predominately improved turfgrass cultivars of tall fescue, chewings fescue, and/or creeping red fescue (i.e. > 60% of the mix by weight).
  • Once established, these turfgrass species generally require less nutrients and water. Cultivars of Kentucky bluegrass and perennial ryegrass can complete the mixture. Species diversity is important to improve disease, insect and drought tolerance.

• Consider aerating your lawn (hollow-tine or solid-tine) to a depth of three to four inches every two to three years, to help maintain the permeability of the soil to reduce runoff (and transport of excess fertilizer) during rain events.
• Consider lawn alternatives for portions of your yard to reduce fertilizer need. This can include garden beds, rain gardens, natural wildflower meadow areas, and low growing ground covers. This is particularly advantageous in environmentally sensitive areas like along waterways or water bodies.
• If you hire a company to care for your lawn, share your interest in protecting water quality (and these recommendations) with them.

Use the Right fertilizer for YOUR Lawn

• Before purchasing any fertilizer, conduct a soil test to determine exactly what your lawn needs. One size/type does not fit all.
  • You can get your soil tested through UConn CAHNR's Plant and Soil Health Center. Only apply the amount of fertilizer that the test indicates is needed and based on the square footage of the area you wish to consider for the fertilizer application. For example, if a soil test shows that phosphorus (P) and potassium (K) are adequate, only apply nitrogen fertilizer.
  • Applying more than what is recommended wastes money, increases pollution risk, and doesn’t make your lawn healthier.

• If fertilizing, always consider slow-release fertilizers to provide nutrients that are released slowly over a longer period of time. These slow-release fertilizers are more environmentally friendly compared to soluble, fast release formulations.
• If organic fertilizers are used, they need to be applied following the same guidance. Organic fertilizers applied in excess, or in a location where they can wash directly into surface waters cause the same water quality problems downstream as inorganic fertilizers.
• For new lawn establishments, if soil organic matter (SOM) is below three percent (you can request the SOM test when you submit your soil sample for nutrient testing), incorporate mature leaf compost or another high-quality organic matter source to raise the SOM to at least three percent (preferably five percent).
• Avoid using combination products that include both fertilizers and pesticides (i.e. Weed & Feed products). You may be inadvertently applying potentially or unnecessary pesticides when they are not needed.

Apply the Right Amount

Fertilizer should be applied at the rate recommended from the soil test results (instead of following ‘one size fits all’ directions on fertilizer bags). Be mindful that less fertilizer should be applied if you live near an environmentally sensitive area, such as next to a wetland or waterbody.

Fertilize at the Right Time

• In the spring, do not apply fertilizer before the turfgrass begins to green up. Turfgrass needs to be actively growing to be able to use any fertilizer. In the fall, do not apply fertilizer after October 15.
• Do not apply any fertilizer if major rain is expected within 48 hours. Fertilizer on the soil surface and not yet taken up by the turfgrass roots can move into the stormwater system, which leads directly to local streams.

Fertilize in the Right Place

• Do not apply ANY fertilizer or pesticide to turfgrass areas within 25 ft of a waterbody.
• Apply fertilizer responsibly so that excess fertilizer doesn’t land on hard surfaces like sidewalks, roadways, and driveways. Use a fertilizer guard on your spreader to keep fertilizer on turfgrass areas and to prevent fertilizer from landing on nearby impervious surfaces where it may easily move into the stormwater system and ultimately be discharged to the nearest waterbody.
• After any fertilizer application always sweep up any excess fertilizer visible on sidewalks, driveways or roadways.

Other Useful Tips

Trying to figure out the size of your lawn? Use UConn CLEAR's Rain Garden app/website (free) or FertAdvisor apps (Apple or Android app stores). The sizing tool on the website or in the app allows you to zoom in on your property and outline the area of your lawn. Use this tool to determine the size of your lawn, correctly calibrate your fertilizer spreader and to help determine how much fertilizer to apply.

For over 25 years, UConn turfgrass faculty have contributed to environmentally significant turfgrass research including the evaluation of improved turfgrass species and cultivars. Learn more about their work on the UConn Turf and Landscape IPM Program website.

Resources

Guillard, K. (editor). 2008. New England Regional Nitrogen and Phosphorus Fertilizer and Associated Management Practice Recommendations For Lawns Based on Water Quality Considerations. Turfgrass Nutrient Management Bulletin B-0100, University of Connecticut Department of Plant Science and Landscape Architecture.

NEIWPCC. Final Report to the New England and New York State Environmental Agency Commissioners: Regional Clean Water Guidelines for Fertilization of Urban Turf. New England Interstate Water Pollution Control Commission. 30 pp.