Behaviour of metazachlor applied with additives in soil: laboratory and field studies.

Abstract

The aim of the present study was to determine the influence of an addition of adjuvants on behavior of metazachlor in soil - residues, degradation rate and leaching into the soil profile. Experiments were carried out in field and laboratory conditions. Metazachlor was applied alone and in mixture with three different adjuvants: oil, surfactant and multicomponent (dedicated to preemergence application). Metazachlor residue was analyzed using GC/ ECD. At harvest time, in soil samples taken from plots where metazachlor was applied alone, the residue amounted to 0.0072 mg kg -1 . The addition of adjuvants caused an increase of metazachlor residues (0.0082–0.0108 mg kg -1 ). The adjuvant addition caused a slowdown of leaching of herbicide into soil profile. Moreover the addition of oil and surfactant adjuvants slowed down the degradation of metazachlor in soils. The DT 50 values for mixture metazachlor + oil and surfactant adjuvants were about 8-16 days higher in comparison with the DT 50 for metazachlor applied alone (26 days). No significant differences were observed between degradation rates and the DT 50 for metazachlor applied alone and with multicomponent adjuvant.