Adsorption and desorption characteristics of monosulfuron in Chinese soils.

Through batch equilibration experiments, the adsorption-desorption characteristics of monosulfuron, a new sulfonylurea herbicide widely used, were investigated in eight agricultural soil samples collected from China. The isotherms for monosulfuron adsorption were nonlinear (n ranged from 0.748 to 0.943) and well described by the revised Freundlich equation. Data obtained from adsorption experiments showed that monosulfuron had weak to moderate adsorption capability in different soils and might readily result in leaching problems, which was correlated significantly with soil properties. The content and chemical characteristic of the soil organic matter (SOM) was considered to be one of the important factors leading to differences in sorption capacity. Meanwhile, the extent of monosulfuron adsorption on soil was at rather high level under low pH value conditions and decreased with increasing pH value. Besides, desorption hysteresis of monosulfuron were observed in most of tested soils, and was demonstrated to be improved with increased concentration in initial solution and depended significantly on SOM.