Irrigation methods and transport of imazamethabenz-methyl to ground water: Greenfields Bench, Montana

The herbicide, Assert, contains imazamethabenz-methyl as the active ingredient, and at the Greenfields Bench aquifer, MT, which serves three public water supplies and numerous private residences, the herbicide has been detected in groundwater. In this study, three commonly used irrigation methods were compared in terms of Assert residuals in soil and groundwater at Greenfields Bench to explore whether alternate irrigation practices could reduce the occurrence in groundwater. The irrigation practices were flooding, wheel line sprinkling, and center pivot sprinkling. The resulting data showed that both sprinkler irrigation methods reduced Assert metabolite flux to groundwater, with center pivot and wheel line irrigation providing about 90 and 70% less recharge, respectively, than flood irrigation.