Each layer of soil can have a different permeability, but the overall permeability is determined by the most restrictive layer. Soil permeability increases when there are macropores, large channels produced by plant roots, earthworms, soil cracks, and the burrowing of smaller animals. Soil organic matter. Soil organic matter helps to bind pesticides, especially those with high Koc values, and promotes degradation. Soil texture .
Texture is determined by the proportion of sand, silt, and clay.
Soil pH. The pH of the soil is a measure of its degree of acidity or alkalinity. Slope and landscape. Areas with high runoff capability will have less of an impact on water infiltration than areas which are flat or have a concave slope. A landscape which encourages runoff will minimize leaching. Landscapes which hold water may increase leaching potential or may provide organic matter which assists in holding the pesticide.