Grazing Management and Buffer Strip Impacts on Sediment Delivery from Pastures Fertilized with Poultry Litter.

Increased grazing pressure may result in soil erosion of pastures due to soil compaction and higher runoff and sediment delivery to waterways. Grazing management and use of buffer strips are potential strategies to reduce erosion from pasturelands. However, little information exists on the long-term effects of grazing management associated with best management practices (BMPs), such as buffer strips, on soil erosion from pastures. Therefore, the objective of this study was to evaluate the impact of grazing management strategies and the use of buffer strips on soil erosion from pastures fertilized with poultry litter. This field research has been conducted for 12 years on 15 small watersheds and treatments consisted of hayed (H), continuously grazed (CG), rotationally grazed (R), rotationally grazed with a buffer strip (RB), and rotationally grazed with a fenced riparian buffer (RBR). Poultry litter was applied every year at a rate of 5.6 Mg ha^-1. Soil physical properties (bulk density and penetration resistance), hydrology (runoff volumes), and sediment concentrations and loads were assessed. Higher grazing pressure resulted in increased soil bulk density (up to 5 cm) and penetration resistance (up to 10 cm), with highest values found for the continuously grazed treatment. Hayfields and watersheds that were rotationally grazed with a fenced riparian buffer had less runoff as well as lower sediment concentrations and loads over the years. Annual sediment loads increased exponentially as runoff increased, and higher sediment loads were observed for continuously grazed watersheds for a given runoff volume in relation to the other grazing managements. Turning a pasture into a hayfield or using rotational grazing associated with a fenced riparian buffer strip appear to be two effective best management practices to mitigate soil erosion and runoff to waterways.