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Effects of agricultural conservation practices on oxbow lake watersheds in the Mississippi River alluvial plain

Knight, Scott Stephen, Locke, Martin Anderson, Smith Jr., Sammie
Soil and Water Research 2013 v.8 no.3 pp. 113
agricultural land, agricultural runoff, agricultural watersheds, alluvial plains, best management practices, conservation practices, conservation tillage, cover crops, farms, fish, groundwater, groundwater contamination, herbicide residues, herbicides, losses from soil, nitrate nitrogen, nonpoint source pollution, oxbow lakes, phosphorus, plankton, pollutants, pollution control, riparian areas, sediment transport, sediment yield, sediments, water quality, Mississippi River, United States
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.