Submitted to: Soil and Water Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 10, 2012
Publication Date: February 1, 2012
Repository URL: http://handle.nal.usda.gov/10113/58942
Citation: Knight, S.S., Rebich, R.A., Locke, M.A., Smith, Jr., S. 2012. Effects of agricultural conservation practices on oxbow lake watersheds in the Mississippi River alluvial plain. Soil and Water Research. 8(3):113-123. Interpretive Summary: Agricultural lands can be a major source of source pollutants such as sediment, pesticides and nutrients in the United States. Conservation practices that slow down the flow of water should allow time for water to soak into the ground, for the biodegradation of pesticides and nutrients to occur and to trap soil that has eroded from fields. The effects of conservation practices on lake water quality were measured in three oxbow lake watersheds in the Mississippi River Delta. This study showed that conservation practices reduced sediments, fertilizers, and pesticides in oxbow lakes, resulting in improved water clarity, plankton growth, and fish stocks.
Technical Abstract: Globally, agricultural lands are considered to major sources of nonpoint source pollutants such as sediment, pesticides and nutrients in the United States. While conservation practices have been tested for their effectiveness in reducing agricultural related pollutants on test plot scales, they typically have not been evaluated on a farm watershed scale nor have they been evaluated in terms of their impact on down stream ecology. Several projects focused on oxbow lake watersheds in the Mississippi River alluvial plain have been designed to utilize working farms to evaluate primary pollutants in water resources and to identify conservation practices that are most effective in reducing the transport of those pollutants in surface and ground water on a watershed scale. Major findings of theses studies include: (1) BMPs reduced sediment in oxbow lakes, resulting in improved water clarity, plankton growth, and fish stocks; (2) Total phosphorus in lakes decreased between 39 to 50% following BMP implementation; (3) Conservation tillage and cover crops reduced NO3-N losses by 73%, sediment losses by 70% and fluometuron herbicide loss in runoff by 50%; and (4) Riparian areas mitigated the transport of sediment in runoff and enhanced the degradation of pesticides.