|Lerch, Robert - Bob|
|Steinriede, Robert - Wade|
Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/1/2004
Publication Date: 2/7/2005
Citation: Zablotowicz, R.M., Locke, M.A., Krutz, L.J., Lerch, R.N., Lizotte Jr, R.E., Knight, S.S., Steinriede Jr, R.W. 2005. Herbicide concentrations in the oxbow lakes of the mississippi delta msea project: 2000 to 2003. Weed Science Society of America Meeting Abstracts, Vol. 45, CD ROM. Interpretive Summary:
Technical Abstract: The Mississippi Delta Management Systems Evaluation Area (MSEA) project was established in 1995 in three small watersheds (Beasley, Deep Hollow and Thighman) that drain into oxbow lakes. The major objective of the project was to assess the implications of management practices on water quality. This study will report on herbicide concentrations observed in lake water sampled monthly during 2000 to 2003. Atrazine, cyanazine, metolachlor, and atrazine metabolites were concentrated by solid phase extraction and analyzed by GC-MS. Fluometuron was analyzed directly from water samples using ELISA. Herbicide concentrations observed in the lake water reflected cropping systems of the watershed, e.g., atrazine and metolachlor concentrations associated with the level of corn/sorghum production, and cyanazine and fluometuron associated with the level of conventional cotton. The dynamics of herbicide appearance and dissipation were dictated by herbicide use, lake hydrology, rainfall pattern, and land management practices. The highest maximum concentrations of atrazine (5.9 to 22.7 ppb) and metolachlor (1.1 to 9.2 ppb) were observed in Thighman lake water where significant quantities of corn were grown. Cyanazine was observed in two lakes with highest levels (1 to 4.5 ppb) in 2000 with lower detections in 2001 and 2002 (<0.3 ppb). A reduced level of fluometuron in Beasley lake water was associated with glyphosate resistant cotton use, while conversion of Deep Hollow watershed from no till to conventional tillage resulted in increased levels of fluometuron in lake water. These studies indicate that herbicide concentrations observed in these three watersheds were related to crop and soil management practices.