Pesticides: Measurement and Mitigation

Authored by: George F. Antonįous

Encyclopedia of Environmental Management

Print publication date:  December  2012
Online publication date:  December  2012

Print ISBN: 9781439829271
eBook ISBN: 9781351235860
Adobe ISBN:

10.1081/E-EEM-120046251

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Abstract

In intensively cultivated areas, agriculture is a significant source of pesticides associated with runoff. Environmental pollution by pesticides is a matter of growing concern. Movement of pesticides in runoff is influenced by the pesticide chemical properties, application methods, soil type, crop management, and environmental conditions. Water solubility is one of the pesticide characteristics that control mobility. Runoff water and sediment are frequent in sloping areas where most of the arable lands are highly erodible. Utilization of vegetative filter strips contiguous to agricultural fields revealed a reduction of the transport of pesticides (clomazone, bensulide, trifluralin, and napropamide) into runoff water, allowing for their water infiltration into the vadose zone (the unsaturated water zone below the plant root). Planting living fescue strips against the contour of the land slope reduced runoff but has the disadvantage of increasing the potential of soil infiltration by pesticides. Unfortunately, plastic mulch, which could cover between 50% and 70% of a field, increased surface water runoff from both rainfall and irrigation. This means that much of the pesticides applied in living fescue or in plastic-mulched fields might seep into groundwater or leave the field into surface runoff. Although many factors are responsible for decomposition of pesticides in soils, two are considered the most important: 1) adsorption increases the availability of the pesticide for soil degradation processes; and 2) microbiological activity increases pesticide metabolism and degradation. Agriculture makes relatively little use of soil microorganisms as producers of several detoxifying enzymes capable of breaking down pesticides and other contaminants. Contaminated surface water has become a critical environmental problem. Runoff from agricultural watersheds carries enormous amounts of pesticides. Rainfall intensity and flow rate are critical factors in determining pesticide movement from application site into surface runoff, rivers, and streams. Accordingly, there is an urgent need to develop long-term, low-energy, biological, self-sustainable systems of farming. Methods of application of these systems must be simple, inexpensive, energy conserving, safe, and effective for pesticide mitigation, nutrient recycling, and erosion control. Addition of soil amendments to increase soil organic matter, enhancing the activity of soil microorganisms, and installation of biofilters against the contour of agricultural fields are potential solutions to mitigate environmental pollution by pesticides. Addition of municipal sewage sludge (MSS) to native soil has reduced the concentration of the insecticide dimethoate in surface runoff water by 47% and increased soil retention of the two herbicides trifluralin and napropamide, lowering their concentration in runoff, and reducing their transport into streams and rivers. Little information, however, exists on the economic aspects of sludge application to agronomic crops. The following were the main objectives of this entry: 1) to provide an overview of pesticide quantification and field mitigation techniques (soil amendments, living fescue strips, biobed systems, constructed wetlands, natural products for pest control); 2) to provide information on the use of MSS for land farming, which could decrease dependence on synthetic fertilizers; and 3) to present Kentucky State University (KSU) research and field studies on reducing environmental impact of pesticides.

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