LEACHING, DISSIPATION, AND EFFICACY OF METOLACHLOR APPLIED BY CHEMIGATION OR CONVENTIONAL METHODS

Field leaching, dissipation, and efficacy of metolachlor (2-chloro-N(2-ethyl-6-methylphenyl)-N-(methoxy-1-methylethyl)acetamide) were evaluated for 8 wk when the herbicide was applied by conventional and chemigation methods to a Taloka silt loam soil (coarse-silty, mixed, nonacid, thermic Mollic Albaqualf). Laboratory studies were conducted to evaluate adsorption and mobility of the herbicide in five soil depths ranging from 0 to 38 cm. Metolachlor leaching below 30 cm was not observed in either year, regardless of application method. Dissipation rates of metolachlor were not influenced by application method either year. Efficacy of the herbicide was not affected by method of application. Metolachlor sorption was highest in the 0- to 8-cm soil depth of the Taloka silt loam with an organic matter content of 1.1%.