Manure Application to Soybeans in the Chesapeake Bay Watershed

Corn and soybeans are major crops grown in the Chesapeake Bay watershed. The watershed has significant numbers of poultry, dairy and swine in certain areas. Land application of manure is a standard practice in the watershed. Over the years phosphorus concentrations have built up in manure applied soils because application rates have been based upon crop nitrogen requirements. In some cases research has shown manure application will increase soybean yields. One of the environmental concerns of applying manure to soybeans is the risk of increasing nitrate concentrations in the groundwater or tile drainage. Another concern is the buildup of phosphorus in the soil, which may cause phosphorus leaching on sandy soils or increase phosphorus loads in surface runoff.