Persistence and degradation of atrazine in soils of different Agro-climatic Zones of Karnataka under varying moisture regimes

Persistence of atrazine [2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine] in soils of different agro-climatic zones of Karnataka was studied under two moisture levels. Degradation of atrazine was more rapid under field capacity than at 60 per cent field capacity in all the soils differing in clay and organic matter content. Persistence of atrazine was considerably high in Kathalagere soil, followed by that in soils from Brahmavara, Mandya and Hebbal. Findings suggest that the persistence increased with increase in clay content in soil as well as with decrease in soil moisture content. Kinetic analysis indicated that degradation of atrazine followed the first-order reaction, irrespective of soil and moisture levels. The half-life of atrazine increased sharply with a decrease in moisture content and the observed half-life values were in the range of 13.30 to 16.94 days at field capacity, whereas at 60 per cent of field capacity, the values ranged from 28.29 to 37.36 days.