Sorption and desorption of triadimefon by soils and model soil colloids

Sorption-desorption of the azole fungicide triadimefon [1-(4-chlorophenoxy) -3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)-2-butanone] on eight soils and a se ries of single, binary, and ternary model soil colloids was determined usin g the batch equilibration technique. Regression analysis between Freundlich sorption coefficients (K-f) and soil properties suggested that both clay a nd organic C (OC) were important in triadimefon sorption by soils, with inc reasing importance of clay for soils with high clay and relatively low OC c ontents. Triadimefon sorption coefficients on soil were not significantly a ffected by the concentration of electrolyte or the presence of soluble soil material in solution, but they were highly dependent on the soil:solution ratio due to the nonlinearity of triadimefon sorption on soil. Freundlich s orption isotherms slopes were very similar for all soils (0.75 +/- 0.02). D esorption did not greatly depend on the concentration at which it was deter mined and showed higher hysteresis for more sorptive soils. Results of tria dimefon sorption on model sorbents supported that both humic acid and montm orillonite-type clay constituents contribute to triadimefon retention by so il colloids.