Soil Loss Due to Residue Removal in the Oso Creek Watershed, Texas
The SWAT model was used to quantify soil erosion losses in surface runoff caused by sorghum residue removal for bioenergy production in the Oso Creek watershed in Nueces County, Texas. The model simulated the removal of 25%, 50%, 75%, and 100% of the residue, and the results were compared to the NRCS tolerable soil loss limit of 11.21 tonnes ha-1 year-1 (5 tons acre-1 year-1) for the study area. The analysis found that maximum soil loss of 2.78 tonnes ha-1 (1.24 tons acre-1) occurred during the final year of a ten-year simulation in which 100% of the sorghum residue was removed. Therefore, grain sorghum residue can be completely removed from the Upper Oso Creek watershed without causing soil losses to exceed the tolerable limits of 11.21 tonnes ha-1 year-1 (5 tons acre-1 year-1). However, nutrient losses from residue removal will have to be replaced by fertilizer applications in order to maintain soil productivity. In addition, total residue removal is not recommended on an annual basis since this would deplete organic carbon levels in the soil and reduce soil quality and future productivity.