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2007 Soil and Water Conservation Society - Soil Quality Workshop

"Soil Quality: the Foundation for Natural Resource Quality"


Miguel Cabrera
Crop & Soil Sciences
University of Georgia, Athens, GA

Management techniques to improve water quality can be divided into those that impact groundwater and those that impact surface water. Among management techniques that protect groundwater, the use of winter cover crops is one of the most important ones. Many studies have shown that non-leguminous cover crops, such as rye, can remove considerable amounts of residual N from the soil profile, thereby preventing its leaching into groundwater. Among management techniques that protect surface water are the use of conservation tillage and buffers. The effect of these two techniques will be discussed in relation to phosphorus (P) losses because P is usually the nutrient limiting eutrophication in fresh waters. Phosphorus lost to surface water can be divided into dissolved P (=<0.45 micron) and particulate P (>0.45 micron). When compared to conventional tillage, conservation tillage leads to overall smaller losses of P in surface runoff, mainly because of smaller losses of particulate P. Although total P losses are smaller with conservation tillage, dissolved P losses may be larger than in conventional tillage because of solubilization of P from surface residues and fertilizers. One of the most important types of buffers used to improve surface water quality is vegetated filter strips (VFS). It has been shown that VFS are more effective at removing particulate P than soluble P, and that their effectiveness is reduced in fields with concentrated flow. Additional research is needed to improve the capacity of VFS to filter particulate and dissolved P from surface runoff.

Miguel Cabrera - Miguel L. Cabrera has research interests in nutrient cycling and water quality in grasslands and croplands fertilized with animal manures. He received a MS and PhD in agronomy from Kansas State University in 1982 and 1986, respectively. His post-doctoral work at Kansas State spanned 1986 to 1990. Miguel is currently Professor, Crop & Soil Sciences/Institute of Ecology, at the University of Georgia.