Microbial transformation of pesticides in agricultural soil

Non-point source pollution of ground and surface water by pesticides has been recorded in agricultural areas in Europe and the US (Jamet and Delleu, 1993; Ritter, 1990). This phenomenon is causing concern, due to potential risks to public health and environmental quality. This non-point source pollution is characterized by unidentified specific origins and low concentrations of pesticides found in contaminated water. Detailed, laborious and expensive monitoring programmes are required to assess the nature and severity of the pollution. Once water is polluted, its quantity and distribution make it virtually impossible to eradicate the very low concentrations (measured in ppb) of pesticide involved. Efforts must therefore be made to minimize the risk of penetration by the pollutant to levels below the root zone, as a result of leaching or transport by run-off surface water. Such efforts must include the development of ‘best management practices’ (BMP), to ensure the proper use of pesticides by the grower, with minimal hazard to water quality. Among farm management practices, tillage is one that may have a significant impact on the fate of pesticides in the soil (USDA, 1989).