ATRAZINE DISSIPATION IN CONVENTIONAL-TILL AND NO-TILL SORGHUM

Dissipation was similar in both tillage treatments and the half-life of atrazine in the surface 10 cm of soil was estimated by linear regression to be approximately 42 and 50 d in conventional-till and no-till plots, respectively. Movement of the herbicide below the upper 10 cm of soil was not significant during the 105-d sampling period and only traces of atrazine were found at the 40-cm depth. Rectangular hyperbola equations were fit to quantitative data and could be used to estimate atrazine levels in the soil profile. Laboratory incubation suggested nonbiological hydrolysis to be the primary means of degradation.