Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 25, 2003
Publication Date: November 2, 2003
Citation: Zablotowicz, R.M., Locke, M.A., Zimba, P.V., Lerch, R.N., Knight, S.S., Lizotte Jr, R.E., Steinriede Jr, R.W. 2003. Effects of land management practices on herbicides, sediments and planktonic populations of three mississippi delta msea oxbow lakes. [Abstract]. American Society of Agronomy. Technical Abstract: The Mississippi Delta Management Systems Evaluation Area (MSEA) project was designed to assess the effects of land management practices on water quality in three small oxbow lake watersheds [Thighman (1497 ha, 8.9 ha lake, corn, soybeans, wheat, rice and catfish), Beasley (850 ha, 25 ha lake, predominantly cotton and soybeans with some corn and sorghum) and Deep Hollow (202 ha, 8 ha lake, cotton and soybeans)]. Results from the project during 2000-2003 will be discussed. Monthly water samples were monitored for herbicides, enzymatic activity, chemical and physical analysis (suspended solids, total organic carbon content, pH, etc.), phytoplankton populations (diagnostic photosynthetic pigments and most probable number assays), bacterioplankton populations (plate counts and substrate utilization analysis). Thighman lake water maintained the highest sediment levels, algal and bacterial populations, enzyme activities and herbicide levels (atrazine and metolachlor for corn production). Introduction of reduced tillage practices and glyphosate resistant crops (cotton / soybeans) in Beasley watershed resulted in lower levels of suspended sediments and herbicide concentrations in lake water. Conversion of Deep Hollow watershed from reduced tillage to conventional tillage increased levels of fluometuron in lake water with little effect on suspended sediment. Water quality of the three watersheds was dynamic and was affected by crop and soil management practices and hydrology.