Sorption and Mobility of Bentazon in Coastal Plain Soils

Sorption and mobility of14C-bentazon were evaluated using soil solution and soil-thin-layer chromatography, respectively on three Coastal Plain soils. The proportion of bentazon adsorbed, was pH and concentration dependent and ranged between 28 to 47, 31 to 61, and 17 to 68% for the Dothan loamy sand, Greenville clay, and Troup loamy sand, respectively. Bentazon sorption decreased as soil pH increased from 5.4 to 5.8 on the Troup loamy sand, regardless of bentazon concentration. Sorption of 1 and 10 ppm bentazon decreased as soil pH increased from 5.0 to 5.7 on the Greenville clay and 6.1 to 6.4 on the Dothan loamy sand. Bentazon was least mobile on the Greenville clay and mobility increased as pH increased. Mobility of bentazon was greatest on the Troup loamy sand and was not pH dependent. Bentazon mobility decreased as soil pH increased for the Dothan loamy sand.