Decomposition Rates of Legume Winter Cover Crops and Nutrient Release Under Three Kill Methods.

Some land in the coastal plains region of the southeastern United States has poor soil quality for the growing of agronomy crops due to intensive cultivation and improper crop residue management. Well-managed cover crop residue will increase soil organic matter content and improve overall soil quality. This study was conducted from October 2011 to October 2012 in Goldsboro, North Carolina. The objectives of the study were to evaluate the decomposition rate of  two winter cover crops under three different spring kill methods and to determine the potential availability of nutrients under each cover crop/kill method treatment. The experimental design was a split plot with two legume cover crops (hairy vetch (Vicia villosa) and Austrian winter pea (Pisum sativum)) and three cover crop kill methods (flail-mowed surface residue, flail-mowed incorporate, and roll over surface) as main-plot and sub-plot treatments, respectively. Carbon (C) and nitrogen (N) mineralization of the cover crop residue was measured at time intervals over a 16 week period after cover crop kill. Soil samples were collected at 3, 8, and 16 weeks after corn crop planting to determine basal respiration, soil microbial biomass, and inorganic N and P. The preliminary results indicate that cover crop biomass under flail-mowed incorporate kill method decomposed at a more accelerated rate. Carbon and N mineralized at a slow rate in the soil surface residue than in sub-surface. The data on nutrients and succeeding corn yield will be discussed.