Ranjith Udawatta, The Center for Agroforestry, University of Missouri, UdawattaR@missouri.edu (Presenter)


Although buffer practices with trees and perennial grass species have been suggested as one of the possible solutions for the reduction of non point source pollution (NPSP) from agricultural watersheds throughout the world, rigorous long-term scientific studies confirming environmental benefits from the use of agroforestry and biomass integrations are limited. We examined reduction of NPSP by tree and grass buffers in row crop and grazing watersheds. Three row crop watersheds in a paired watershed design with buffers were examined for NPSP reduction in the Central Claypan region. The grazing study consists of six watersheds in Central Mississippi Valley Wooded Slopes. Water samples were analyzed for sediment, total nitrogen (TN), nitrate, total phosphorus (TP), and dissolved P from each runoff event. Tree+grass and grass buffers significantly reduced NPSP from row crop and grazed management systems. Runoff was reduced by 49 and 19 percent during the study period as compared to respective control treatments on the grazing and row crop managements. On average, grass and agroforestry buffers reduced sediment, TN, and TP losses by 32, 42, and 46 percent compared to the control treatments. This study strongly indicates that tree and perennial grass buffers can be integrated into row crop and grazing management practices to improve water quality while minimizing the amount of land taken out of production.