CHEMICAL OR MICROBIAL-DEGRADATION OF SULFONYLUREAS IN THE SOIL .2. METSULFURON METHYL

The rate of metsulfuron methyl degradation in a sandy loam soil was studied in relation to herbicide concentration, temperature and different soil treatments, i.e. sterilization and reinoculation by soil. This rate is not dependent on the initial concentration of herbicide; it is reduced by sterilization, and greatly increased by an increase in temperature. In soil and sterilized soil, C-14 metsulfuron methyl gives different degradation products. These results demonstrate that chemical hydrolysis and microbial breakdown play a role in soil degradation, although attempts to extract degrading micro-organisms from the soil were unsuccessful.