Transport and transformation of pesticides used in agricultural situations are subject to variability from several sources that are impossible to simulate in laboratory settings. The study was conducted to characterize pesticide leaching behavior under conventional cropping conditions and to determine the impacts of related sources of variability. An agricultural field site (Ardilla fine sandy loam, Clarendon loamy sand, Tifton loamy sand, and Lucy loamy sand) located within the Dougherty Plain region of southwest Georgia was used to study pesticide movement in unsaturated and saturated soil zones from 1984 through 1988. A granular formulation of aldicarb (2-methyl-2-(methylthio) propionaldehyde O-(methylcarbamoyl) oxime), an emulsifiable concentrate of metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methyl-ethyl) acetamide, and a bromide (Br-) tracer were applied on peanut (Arachis hypogea L) crops under modified conventional tillage practices. Postapplication vertical movement was monitored for periods of up to 111 d for pesticides and 1307 d for Br-.