Degradation and mobility of metolachlor and terbuthylazine in a sandy clay loam soil

Abstract

The degradation of metolachlor and terbuthylazine, two maize herbicides, was studied in laboratory in a sandy clay loam soil under different temperature and soil moisture conditions and in drainage field lysimeters. Identification of the main degradation products of the two herbicides was attempted both in laboratory and field lysimeter soil samples. The results show that the degradation of the two herbicides in laboratory followed a first order kinetics influenced by temperature and soil moisture. Metolachlor disappeared in soil more rapidly than terbuthylazine. Metolachlor moved more rapidly than terbuthylazine through the soil profile in field lysimeters and noticeable quantities were found in drainage water. In the laboratory degradation studies, the main degradation products of both herbicides were found in soil samples as early as the first week of incubation while in the field lysimeter studies only the degradation product of terbuthylazine was found in soil samples.