UNDERSTANDING AND PREDICTING THE IMPACT OF AGRICULTURE ON THE ENVIRONMENTAL INTEGRITY OF MANAGED WATERSHEDS
Location: Water Quality and Ecology Research
Title: Effectiveness of vegetated agricultural drainage ditches in mitigating insecticide loadings
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: June 1, 2009
Publication Date: January 1, 2010
Citation: Bennett, E.R., Drouillard, K.G., Moore, M.T., Schulz, R. 2010. Effectiveness of vegetated agricultural drainage ditches in mitigating insecticide loadings. In: Moore, M. T. and Kroger, R. (Eds.), Agricultural Drainage Ditches: Mitigation Wetlands for the 21st Century. Research Signpost. Kerala, India, pp. 239-259.
Interpretive Summary: Drainage ditches are important agricultural landscape features that transport excess water from crops into receiving aquatic systems. Because they have characteristics of wetlands, these ditches are able to reduce the amount of insecticides associated with runoff water before they enter rivers, lakes, or streams. Studies were conducted in South Africa and the Mississippi Delta (USA) on both runoff and spray drift events, and the ability of ditches to remove harmful insecticides. Mathematical models were derived from field data to provide farmers and conservationists with the tools they need to implement this effective and economical landscape management practice.
Studies have shown that runoff and spray-drift are important sources of nonpoint-source insecticide pollution of surface waters. Owing to this, public concern over the presence of insecticides in surface and ground water has resulted in intensive scientific efforts to find economical, yet environmentally sound solutions to the problem. Implementation of best management practices (BMPs), such as vegetated drainage ditches, has been proposed to retain/reduce nonpoint-source pollution from entering receiving aquatic habitats. This chapter will summarize current and past research on the effectiveness of vegetated aquatic systems in providing buffering between natural aquatic ecosystems and agricultural landscape following insecticide associated runoff and spray-drift events. Studies discussed implement vegetated agricultural ditches in Mississippi, USA, under simulated runoff conditions and in the Western Cape, South Africa, under natural runoff and spray-drift conditions. Both chemical (analytical) and non-chemical (fate modeling and in situ bioassays) measures are outlined in this chapter to illustrate the effectiveness of this agricultural landscape feature in decreasing potential non-point and point source threats to downstream aquatic receiving systems.