FATE OF PARATHION IN SOIL UNDER SUBTROPICAL FIELD CONDITIONS

Persistence, metabolism and binding of C-14-parathion in alkaline sandy loam soil under sub-tropical conditions of Delhi were studied for 545 days. After 3 days of treatment, C-14-residues declined to 41% of the amount applied. The dissipation curve was biphasic; an initial rapid phase (up to 7 days) followed by slow dissipation. The half life of dissipation was only 3.36 days for the first phase and 84 days for the slow phase. The overall half life was 64.5 days. The total residues at zero-time were 10.65 mu g/g dry soil and were almost totally extractable. The extracts consisted of parathion, 4-aminophenol, 4-nitrophenol and paraoxon. The bound residues gradually increased and accounted for the total residue at the end of one year (0.7 mu g/g).