Fluometuron Adsorption-Desorption Equilibria in Soil

Abstract
The adsorption-desorption equilibria of fluometuron [1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea] were studied; a slurry technique with soil at 0-bar moisture tension was used. The equilibria established with Bosket very fine sandy loam (VFSL) were evaluated by three equations. The equation best describing the adsorption isotherm was x/m = K1Ce+ K2Ce2. Successive equilibrations resulted in a shift in the equilibria toward the adsorbed state, most likeiy due to a physical change in the adsorption capacity of the soil with repeated agitation. Desorption studies with seven additional soils indicated the importance of soil organic matter content in the adsorption-desorption equilibria of fluometuron. The relationship between soil organic matter contents and the adsorption-desorption equilibrium constants was characterized by a highly significant linear correlation (r = 0.93) and the resulting regression equation: K1= 0.46 + 0.45(O.M.%). Clay content of these soils was not significantly correlated with fluometuron equilibrium constants.