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United States Department of Agriculture

Agricultural Research Service

Research Project: MAINTAINING SOIL RESOURCES FOR EFFECTIVE CONSERVATION AND HERBICIDE MANAGEMENT IN MID-SOUTH CROP PRODUCTION

Location: Crop Production Systems Research Unit

Title: Effects of land management practices on water quality in Mississippi Delta Oxbow Lakes: biochemical and microbiological aspects

Authors
item Zablotowicz, Robert
item Zimba, Paul
item Locke, Martin
item Lizotte, Richard
item Knight, Scott
item Gordon, R Earl

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 9, 2010
Publication Date: September 6, 2010
Citation: Zablotowicz, R.M., Zimba, P.V., Locke, M.A., Lizotte Jr, R.E., Knight, S.S., Gordon, R.E. 2010. Effects of land management practices on water quality in Mississippi Delta Oxbow Lakes: biochemical and microbiological aspects. Agriculture, Ecosystems and Environment. 139(1-2):214-223.

Interpretive Summary: The Mississippi Delta Management Systems Evaluation Area (MSEA) project assessed the effects of land management practices on water quality in three small oxbow lake watersheds: Thighman; Beasley; and Deep Hollow. During 2000-2003 monthly water samples were monitored for enzymatic activity, chemical and physical analysis (suspended solids, total organic carbon content, pH, nitrate, ammonium, orthophosphate, and electrical conductivity), phytoplankton populations, and bacterioplankton populations. (Total and Gram-negative bacteria and coliforms). Introduction of reduced tillage practices and glyphosate resistant crops (cotton / soybeans) in Beasley watershed resulted in lower levels of suspended sediments, but had minimal impact on biochemical or microbiological properties. All these parameters were influenced by the intrinsic nature of the watersheds, with some parameters shifting as management changes were imposed on the surrounding agricultural fields. Dynamic changes in the water quality parameters and the microbial community suggesting that biological parameters of water quality of the lakes were affected by changes in crop and soil management practices and yearly environmental fluctuations.

Technical Abstract: The Mississippi Delta Management Systems Evaluation Area (MSEA) project assessed the effects of land management practices on water quality in three small oxbow lake watersheds; Thighman (1497 ha, 9 ha lake); Beasley (850 ha, 25 ha lake); and Deep Hollow (202 ha, 8 ha lake). During 2000-2003 monthly water samples were monitored for enzymatic activity (fluorescein diacetate hydrolysis, alkaline phosphatase, and substrate utilization [Biolog plate]) chemical and physical analysis (suspended solids, total organic carbon content, pH, nitrate, ammonium, orthophosphate, and electrical conductivity), phytoplankton populations (diagnostic photosynthetic pigments and most probable number assays), bacterioplankton populations (plate counts for total and Gram-negative bacteria and coliform MPNs). All these parameters were influenced by the intrinsic nature of the watersheds, with some parameters shifting as management changes were imposed on the surrounding agricultural fields. No change in management occurred in Thighman watershed and Thighman lake water typically contained the highest sediment levels, dissolved organic carbon content, algal and bacterial populations, enzyme activities, and heterotrophic metabolic indexes. Introduction of reduced tillage practices and glyphosate resistant crops (cotton / soybeans) in Beasley watershed resulted in lower levels of suspended sediments, but had minimal impact on biochemical or microbiological properties. Likewise, conversion of Deep Hollow watershed from reduced tillage to conventional tillage had little effect on suspended sediment, and most microbial activity parameters only changed slightly. Canonical analysis indicated dynamic changes in the water quality parameters and the microbial community suggesting that biological parameters of water quality of the lakes were affected by changes in crop and soil management practices and yearly environmental fluctuations.

Last Modified: 7/25/2014
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