Enhanced degradation in soil of tri‐allate and other carbamate pesticides following application of tri‐allate

Summary Tri‐allate degraded faster in soil from a site (T1) that had received 1·7 kg ha−1 of tri‐allate annually for 23 years than in soil from an adjacent site (TO) that had received no pesticide application. Soil from the untreated site, which had been removed to a glasshouse and treated three times per annum with tri‐allate at 1·7 kg ha−1 for 7 years (T2), also showed faster degradation. Soil previously treated with tri‐allate showed an increased degradation rate for carbofuran and EPTC but not for aldicarb. A further experiment, 2 years after the last treatment with tri‐allate, showed that the enhanced degradation effect was still present. Degradation rates were always in the order T1 > T2 > T0 for tri‐allate, EPTC and carbofuran. Half‐life for degradation was reduced for tri‐allate and carbofuran by approximately 40% in the previously treated soils and for EPTC by approximately 80% when compared with the previously untreated soil.