Investigations on the metabolic fate of prochloraz in soil under field and laboratory conditions

The degradation of prochloraz in different soils was investigated in field and laboratory experiments. In laboratory degradation experiments in the dark, initial prochloraz concentrations decreased to 30–64% within 56 days, depending on temperature and soil pH. In neutral to basic soils, formation of up to 3.7% of the metabolite prochloraz-urea was observed. The rate of mineralization was strongly pH-dependent, not exceeding 3.2% in the acidic and 18.3% in the neutral to basic soils. Amounts of non-extractable residues ranged from 14 to 31%. Under field conditions, prochloraz disappeared much more rapidly with DT50 values of 11–43 days. The metabolites prochloraz-formylurea and prochloraz-urea were found in significant concentrations. Laboratory experiments with fresh and sterilized soils under UV irradiation confirmed the enhancing effect of light on the formation of the primary metabolite, prochloraz-formylurea. The latter is hydrolysed to prochloraz-urea predominantly by microbial degradation. © 1999 Society of Chemical Industry