Soils with slow infiltration rate may be more prone to runoff, as more water will remain on the surface. Pesticides sorbed to soil will not be lost to runoff. However, if runoff results in soil erosion, pesticides sorbed to surface soil will also move with runoff. To understand the potential for pesticide movement toward groundwater or in runoff, pesticide properties, application factors, soil and site conditions must be evaluated. Rainfall, irrigation practices, and evapotranspiration will also significantly influence the potential for pesticide movement in water.
Plant uptake can be important to pesticide movement.
Pesticides that are taken up by plants are not available for movement into the atmosphere, or movement into ground or surface water. However, if the plants are harvested some pesticide may move from the site with the crop. Pesticides applied to soil, water, vegetation, or other surfaces indoors usually breakdown at a slower rate than pesticides applied outdoors. This is due primarily to the lack of sunlight indoors. This includes glass greenhouses, as the UV light necessary for pesticide breakdown is filtered out by glass.