Effect of Variability of Soil Properties as a Function of Depth on Pesticide Sorption-Desorption

Abstract

Sorption-desorption is arguably the most important process affecting the transport of pesticides through soil since it controls the amount of chemical available for transport. Sorption is usually characterized by determining surface soil sorption coefficients that are then used in solute transport models. Significant drawbacks to using surface soil sorption coefficients to predict pesticide transport are the spatial variability of 1) surface soil properties over large fields and 2) soil properties in the soil profile. Our objective is to give an overview of how pesticide sorption and desorption is influenced by changes in soil properties with depth. This will be illustrated using several classes of pesticides. Specific pesticides include atrazine, alachlor, sulfometuron methyl, tebuthiuron, and imidacloprid. Results indicate that correlations between pesticide sorption-desorption and soil properties of surface soils cannot necessarily be used to characterize pesticide sorption-desorption in subsurface soils.