Groundwater Loadings by Controlled-Release Pesticides: A Gleams Simulation

ABSTRACT Controlled-release pesticide application was represented for the GLEAMS model simulation to evaluate impacts of the practice on leaching below the root zone. Pesticides with high mobility and slight to moderate persistance were simulated using a 50-year climatic record at Tifton, Georgia on two representative soils that occur in groundwater recharge areas of the Coastal Plain. A threshold level of pesticide concentration in the soil surface 7.5 cm was assumed for targeted pest control, and the annual duration of time the threshold was exceeded was analyzed for each simulated formulation. This measure of control and simulated leaching through the bottom of the root zone were analyzed to consider efficacy as well as potential impact on groundwater loadings.