Non Point Source Pollution Reductions From Row Crop and Grazed Pasture Watersheds by Agroforestry Buffers.

Although agroforestry practices 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 practices are limited.  We examined reduction of NPSP by agroforestry buffers in watersheds under row crop and grazing managements.  The row crop study site consists of three watersheds in a paired watershed design in Central Claypan Areas and the grazing study consists of six watersheds in Central Mississippi Valley Wooded Slopes.  Water samples were collected after each runoff event and analyzed for sediment, total nitrogen (TN) and total phosphorus (TP) for the 2004 to 2008 period.  Agroforestry and grass buffers on row crop and grazed management sites significantly reduced runoff, sediment, TN, and TP losses to streams.  Grazing and row crop management reduced runoff by 49 and 19% during the study period as compared to respective control treatments.  On average, grass and agroforestry buffers reduced sediment, TN, and TP losses by 32, 42, and 46% compared to the control treatments.  This study strongly indicates that agroforestry and grass buffers can be designed to improve water quality while minimizing the amount of land taken out of production.