Study on Degradation Processes of 14C-Carbofuran in Soil from Northwest Morocco as Influenced by Soil Water Content, Temperature and Microbial Activity

Abstract

This study was conducted to assess the impact of soil temperature, moisture, and microbial activity on the mineralization and dissipation rate of Carbofuran on a typical sugar beet clayey soil in the Loukkos area in order to predict the fate of Carbofuran in soil and environment (Northwest Morocco). The results of incubation investigations demonstrated that both soil temperature and water content have a substantial impact on the rates of Carbofuran mineralization and dissipation, and that the autoclaving of soil greatly lengthened the half-life of the insecticide. In non-autoclaved soil, the rates of mineralization and degradation increased as soil moisture content and temperature rose. In natural soil, Carbofuran half-lives ranged from 26 to more than 90 days, and dissipation rates followed first-order kinetics. Chemical degradation and microbial breakdown are the principal pathways of Carbofuran degradation which are highly dependent on soil temperature and moisture contents. However, the half-life increased 3.6 times in the autoclaved soil, from 39 to 142 days. Autoclaving prevented mineralization, demonstrating the significance of microbes in the pesticide's breakdown process. However, since bound residues developed in large concentrations (19%) in the autoclaved soil, it appears that the insecticide was also dissolved by non-biological processes. Insecticide risk assessment studies and the validation of pesticide dissipation models for clayey soils in sugar beet-growing regions of Morocco may benefit from these findings.