Relationships between Soil Properties and Sorption Behavior of the Herbicide Halosulfuron-methyl in Selected Japanese Soils

The sorption of a sulfonylurea herbicide, halosulfuron-methyl was studied in seven Japanese soils with different physicochemical properties. Soils were equilibrated with four levels of concentrations of halosulfuron-methyl using batch technique. Sorption affinity for halosulfuron-methyl was approximated by the Freundlich constant (K f ), distribution coefficient (K d ), and the normalized K d based on organic carbon content (K oc ). The sorption isotherms followed the Freundlich equation. Freundlich K values indicated that organic carbon was the predominant factor for halosulfuron-methyl sorption in the soils. Sorption was highly correlated with soil organic content and inversely correlatetl with soil pH. However, there was no significant correlation with clay content and cation exchange capacity of the soils.