Submitted to: Journal of Soil and Water Conservation Society
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/21/2002
Publication Date: N/A
Citation: Interpretive Summary: Pollution entering a water body can significantly affect the ecological balance needed in maintaining healthy recreational and municipal river or reservoir systems. Producers have to balance the effects of their farming practices on pollution with their economic benefit from those practices. A study was conducted to evaluate typical farming practices used to control erosion on Mississippi Delta farms as part of the Mississippi Delta MSEA Project. BMPs considered included: no-tillage, reduced-tillage, cover crops, filter strips, grade control pipes, and impoundments. Application of the USDA AnnAGNPS watershed model demonstrated that no-tillage or permanent impoundment practices were the best options in reducing up to one-half the erosion compared to conventional practices. The cost of savings of each ton per hectare per year of sediment was approximately $60/ ha for up to a 60% reduction and was $100/ha for further improvement. By successfully applying this model to agricultural watersheds, alternative farming practices can be evaluated before their actual implementation, thus reducing the time and costs needed to determine the best practices that provide the most economic benefit and pollution control.
Technical Abstract: Sediment has been identified as the pollutant most limiting to fishery health in oxbow lakes in the Mississippi Delta. The Mississippi Delta Management System Evaluation Area (MDMSEA) project seeks to reduce the adverse agricultural impacts on water resources and ecological processes through the development and adoption of alternative Best Management Practices (BMPs). However, resource limitations dictate that only a few combinations of BMPs can actually be tested over a few years at a limited number of locations. Therefore, the Annualized Agricultural Nonpoint Source Pollutant Loading model (AnnAGNPS 2.0) was used to generalize and extend findings in order to better evaluate the effectiveness of alternative BMP combinations on sediment reduction. BMPs considered included: no-till, reduced-till, cover crops, filter strips, grade control pipes, and impoundments. Costs of BMPs were estimated from state average prices and published literature using a 25-year planning horizon. Initial and future costs were combined into a single current cost using annuity calculations. For the Mississippi Delta, no-till or a permanent impoundment reduced sediment yield by at least 50%. Use of volunteer winter weeds as cover crops and installation of edge-of-field grade control pipes were among the most cost-effective supplemental BMPs. The cost of each ton/ha/y reduction in sediment yield was approximately $60/ha for up to a 60% reduction and was $100/ha for further improvement. However, if conservation tillage systems can be made more profitable than conventional tillage systems, producers and the environment can achieve a win-win outcome of cleaner water and increased profits.