Wednesday, November 15, 2006
285-25
Reducing Soil Erosion and Nitrogen Leaching Through Sustainable Cropping Systems.
P.H. Davis, W.E. Thomason, and S.B. Phillips. Virginia Tech, 422 Smyth Hall, Blacksburg, VA 24061
Winter annual cover crops are an important tool for improving water quality in the Chesapeake Bay region because they can scavenge and utilize soil nutrients, especially nitrogen (N), which could otherwise be lost from the soil/plant system through leaching and runoff during winter months. The objective of this study was to determine the winter cover crop species and planting date that provides the most vigorous winter soil cover, the greatest biomass return to the soil system, and the highest level of N uptake. One on-farm experimental site was established as a split plot design with three replications. Main plots were crop species or mix (Rye, Oats, Barley, Crimson Clover, Vetch, and Rye+Vetch) and planting date (Oct. 10, Oct. 25, and Nov 10), sub plots were spring N rate (0 or 34 kg N/ha). In early winter, percent ground cover was estimated and aboveground biomass was harvested from a 0.5-m2 area in each to determine dry matter yield. Nitrogen uptake was determined as the product of dry matter yield and tissue N concentration. Each plot was soil sampled to a depth of 90 cm in increments of 0-15, 15-30, 30-60, and 60-90 cm. Soil samples were analyzed for NH4-N and NO3-N. Biomass, N uptake, and soil N data will be presented.