Influence of soil class and depth on the degradation of the insecticide-nematicide aldicarb

Abstract

The degradation of aldicarb in samples collected from the different horizons of four representative soils in Lavras, MG, Brazil, was investigated under laboratory conditions. Subsamples of each soil were incubated with the chemical during periods varying from 1 to 80 days. Aldicarb and its oxidation products, aldicarb sulphoxide and sulphone, were extracted with acetone and determined, as aldicarb sulphone, by liquidgas chromatography, with a flame photometric detector. The breakdown of aldicarb to noncarbamate products closely followed a firstorder kinetics with halflife values of 66, 155, and 236 days, respectively for A, B and C horizons of the Dark-Red Podozolic; 65, 137 and 281 days for the horizons A, B and BC of the Red-Yellow Latosol; 146 and 183 days for the horizons A and B of the Dusky-Red Latosol and, 113 and 108 days for the horizons A and C of the Low Humic Gley soil.