Surface Erosion and Runoff As Influenced By Grazing Pressure

摘要

The poultry industry is an important sector of Alabama agriculture but waste disposal is a major concern. Many farmers use poultry waste as fertilizer for pasture. Cattle grazing alters vegetative cover and soil physical properties. These alterations can lead to increased runoff and erosion amounts from the grazed pastures. If these pastures happen to have been fertilized with poultry litter, the runoff may contain high concentrations of nitrogen and other nutrients and pollute adjacent water bodies. This study is taking place at two sites: the Tennessee Valley and Sand Mountain substations of the Alabama Agricultural Experiment Station. The Tennessee Valley site has instrumented plots vegetated with various perennial grasses. The Sand Mountain site receives pasture renovation tillage treatments in an effort to increase infiltration. Using a datalogger-cellular phone setup, rainfall and weather data, as well as runoff data, are downloaded to a lab in Auburn, Alabama. Two erosion prediction computer models are being applied to each site. The first model is GLEAMS, version 2.10 and the second model is WEPP, version 95.7. This paper presents some preliminary information from the Tennessee Valley site relative to the influence of grazing pressure on the amount of erosion and runoff from the instrumented plots. Proper and heavy grazing practices are compared based on observed and predicted data. A comparison is also made using the predicted values by the models for no grazing.