Metolachlor persistence in laboratory and field soils under Indian tropical conditions

Metolachlor [2-chloro-N-(2-methoxy-1-methylethyl)-2'-ethyl-6'-methyl acetan ilide] dissipation under both field and laboratory conditions were studied during summer season in an Indian soil. Metolachlor was found to have moder ate persistence with a half-life of 27 days in field. The herbicide got lea ched down to 15-30 cm soil layer and residues were found up to harvest day of the sunflower crop in both 0-15 cm and 15-30 cm soil layers. Metolachlor was found to be more persistent in laboratory studies conducted for 190 da ys. The rate of degradation was faster in soil under flooded partial anaero bic conditions as compared to aerobic soil with a half-life of 44.3 days. I n aerobic soil, metolachlor was very stable with only 49% dissipation in 13 0 days. Residues remained in both the soils up to the end of the experiment al period of 190 days.