Soil erosion, pesticide transport

Soil erosion continues to be one of the greatest threats to the sustainability of agriculture around the world. Erosion caused by water and wind reduces rich topsoil and crop yields. Soil erosion also produces a variety of adverse off-site impacts, including increased sedimentation of lakes and streams and transport of nutrients and pesticides to surface waters (Ribaudo and Johansson, 2006) (Table 1.5). 

Pesticide transport by surface runoff and soil erosion is a function of time lag between rainfall and application the chemical nature and persistence of the pesticide the hydrological, soil, and vegetative characteristics of the field and the method and target of application (43). Wauchope (44) found that unless severe rainfall occurred shortly after pesticide application, total losses for the majority of pesticides due to runoff were less than 0.5% of the amount applied in most cases, although single-event losses from small plots or watersheds can be much greater. 

Sorption to soil solids and plant cuticular material represents an important process influencing the chemodynamic behavior of insecticides, including their transport in surface runoff Sorption phenomena affect the volatilization, hydrolysis, photolysis and microbial transformation of organophosphorus insecticides. Furthermore, species sorbed to soil particles are transported by erosion processes rather than as solutes in the water phase. Sorption to foliar surfaces reduces the amount of pesticide mobilized by washoff. 

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