Agroforestry Buffers for Non Point Source Pollution Reductions from Agricultural Watersheds.

Despite increased attention and demand for the adoption of agroforestry practices throughout the world, rigorous long-term scientific studies confirming environmental benefits from the use of agroforestry practices are limited. The objective was to examine non point source pollution (NPSP) reduction as influenced by agroforestry buffers in watersheds under grazing and row crop management. The grazing study consists of six watersheds in Central Mississippi Valley Wooded Slopes and the row crop study site consists of three watersheds in a paired watershed design in Central Claypan Areas. Runoff water samples were analyzed for sediment, total nitrogen (TN) and total phosphorus (TP) for the 2004 to 2014 period. Results indicate that agroforestry and grass buffers on grazed and row crop management sites significantly reduce runoff, sediment, TN, and TP losses to streams. Buffers in association with grazing and row crop management reduced runoff by 52 and 22% during the study period as compared to respective control treatments. Average sediment loss for grazing and row crop management systems was 13.8 and 17.9 kg ha^-1 yr^-1. On average, grass and agroforestry buffers reduced sediment, TN, and TP losses by 48, 52, and 53% compared to the control treatments. Buffers were more effective in the grazing management than row crop management practice. These differences could in part be attributed to the differences in soils, management, and landscape features. Results from this study strongly indicate that agroforestry and grass buffers can be designed to improve water quality while minimizing the amount of land taken out of production.