Adsorption, desorption and mobility of fomesafen in Chinese soils

Fomesafen, 5-[2-chloro-4-(trifluoromethyl) phenoxy]-N-(methylsulfonyl)-2-nitrobenzamide, is used widely for weed control in soybeans since its introduction to China. Little information is available on its adsorption, desorption and movement in Chinese soils. The adsorption, desorption and mobility of fomesafen in six Chinese soils was studied. Adsorption isotherms agreed with the Freundlich equation very well. The results of regression analysis indicated that soil pH was more important than organic matter for fomesafen adsorption. Fomesafen was more readily desorbed from soils with 0.01 M CaSO4 solution. Soil TLC and column leaching studies showed that fomesafen and its metabolites was less mobile in Chinese soils. About 89.82% of applied fomesafen and its metabolites still remained in upper 5 cm layer 60 days after treatment under field conditions.