Herbicide runoff studies in an arable soil under simulated rainfall

Abstract

Runoff potential of five herbicides (acetochlor atrazine hexazinone pendimethalin and terbuthylazine) was investigated on a fallow Hamilton clay loam soil with a 10 slope Twentyfour hours after the herbicide application simulated rainfall was applied at three intensities Sediment amounts and herbicide concentrations were determined in the water phase of runoff samples Herbicide residues attached to sediment were estimated using Kdvalues determined locally for the Hamilton clay loam soil Pesticide concentrations were the highest in the first runoff samples and decreased exponentially with further rain Results show that herbicides were primarily transported in their dissolved forms in runoff and that losses are dependent on the time to runoff and runoff rates Rainfall intensity had no significant effect on herbicide losses In all cases losses were <1 of the amounts applied