SORPTION OF BENTAZON AND DEGRADATION PRODUCTS IN 2 MISSISSIPPI SOILS

Bentazon degradation in soil typically proceeds with development of bo und residue, Low sorption of bentazon suggests that this residue consi sts of degradation products; however, there is little data on the sorp tion behavior of these products, This study was undertaken to determin e the sorption of bentazon and the degradation products 2-amino-N-isop ropyl benzamide, 2-aminobenzoic acid, and N-methyl bentazon in Dundee silt loam and Sharkey clay, two common agricultural soils of the Missi ssippi Delta, Greater sorption of bentazon and degradation products in the Sharkey soil was related to finer texture and higher organic C co ntent, Isotherms were nonlinear, with sorption increasing in the order bentazon << 2-amino-N-isopropyl benzamide < N-methyl bentazon, In gen eral, methanol extraction indicated reversible sorption of these compo unds, Therefore, it is unlikely that sorption of either 2-amino-N-isop ropyl benzamide or N-methyl bentazon contributes to bound residue. In contrast, essentially all of the C-14 sorbed from radiolabeled 2-amino benzoic acid solution remained bound after methanol extraction, Howeve r, due to degradation of 2-aminobenzoic acid, it was not possible to c onclude the extent to which this compound contributed to bound C-14, S orption of C-14 from 2-aminobenzoic acid exceeded that of N-methyl ben tazon, and at low initial concentrations (less than or equal to 20 mu M) was nearly 1000-fold greater than bentazon sorption.