Modeling the effect of precision agriculture: Pesticide losses to surface waters

In this study we evaluated the environmental impacts of spatially variable versus uniform applications of acetochlor. Spatially varying rates of acetochlor ranging from 2.0 to 2.7 kg ha(-1) were applied to a 32 ha bare field planted to corn during the spring of 1998. These rates were varied in accordance with measured soil surface organic matter contents, sorption K, values, and grassy weed populations. Surface runoff and tile drain leaching losses of acetochlor were measured using automated sampling systems. The Agricultural Drainage and Pesticide Transport (ADAPT) model was calibrated to measured water fluxes, and losses of sediment, nitrate, and acetochlor to surface waters. There was good agreement between measured and modeled water fluxes, sediment losses, nitrate losses, and acetochlor losses. Simulated acetochlor losses for the variable rate strategy were 11 - 33% lower than losses for a uniform application of 2.7 kg ha(-1).