The fresh scent of newly cut, bright green grass wafts through the air; the buzzing motor of a lawn mower serves as the auditory backdrop to this sunny summer day. But behind this scene there is often an environmental cost for picturesque lawns. This cost comes in the form of excess phosphorus deposits in waterways.
The Connecticut Institute of Water Resources has granted two University of Connecticut researchers, Professors Karl Guillard and Thomas Morris, from the Department of Plant Science and Landscape Architecture, $50,000 to study phosphorus leaching from lawns treated with organic compost.
Phosphorus is an essential nutrient for photosynthetic plants. Plants take up phosphorus that naturally occurs in soil released from rock minerals, organic matter decomposition, or provided by synthetic and organic fertilizers. Since all plants need phosphorus to grow and thrive, many fertilizers add phosphorus to the soil in cases where the natural levels are not sufficient to support optimum plant growth and quality. But altering the natural phosphorus levels in the soil has been found to cause a cascade of negative effects.
In too high a concentration, especially in fresh waters, phosphorus can lead to the proliferation of algae which use large amounts of oxygen leaving the rest of the ecosystem deprived of this essential element; this process is known as eutrophication. Eutrophication occurs because excess phosphorus which has been added to the soil cannot be absorbed and so it leaches out of the soil and into groundwater and water systems.
“Applied in excess of the soil’s ability to retain it, phosphorus can move with water through the soil and pose a water quality threat whether it comes from synthetic or natural sources,” Guillard says.
Organic turf and lawn management is one of the fastest-growing areas of the industry. There are well-founded environmental concerns over the use of fertilizers and pesticides as well as health concerns about these chemicals leaching into human’s water supply. In response to these concerns, organic methods have been developed including using compost as fertilizer.
Connecticut even has a law regulating the application of fertilizers which contain phosphorus. But this law carves out an exception for composts and other organic amendment alternatives so long as they contain less than 0.67% phosphate.
While organic fertilizers are often perceived as being environmentally safer than traditional chemical fertilizers, they still contain phosphorus and there are little to no data about phosphorus leaching from lawns and other turf areas treated with compost in Connecticut’s climate.
This grant will enable Guillard and Morris to investigate the critical question of the relationship between soil phosphorus levels and phosphorus leaching from lawn turfs that have varying amounts of compost as a fertilizer applied to them.
“Just because an amendment is organic, doesn’t mean it’s benign to the environment and will have no deleterious environmental effects on water quality,” Guillard says “Our hope with this study is to be able to relate routine soil tests, which are available to the public from UConn’s Nutrient Analysis Laboratory, to phosphorus leaching losses, and these will be able to help guide compost or other organic amendments to lawns and other turf areas without having to guess how much compost to apply.”
By developing the knowledge base in this emerging segment of the turf management industry, this project will produce results that will help guide compost and organic fertilizer recommendations regarding phosphorus leaching so they can do what they are designed to do: promote the growth of beautiful lawns and turf while protecting the environment.
Karl Guillard received his Ph.D. from UConn in 1986 where he also earned his master’s. His current research projects include evaluation of soil nitrogen tests as a guide for turf fertilizer recommendations, determining the relationship between fall tissue nitrate concentrations and turf spring quality and predicting turf quality with reflectance meters.
Thomas Morris received his Ph.D. from Iowa State University in soil science in 1992 after receiving his master’s from UConn. He has been a professor at UConn since 1993. He served as the regional coordinator for the USDA Northeast Region Sustainable Agriculture Research and Education program from 2004 until 2016.
