Adsorption-desorption behaviour of clomazone in Planosol and Vertisol agricultural soils

Abstract

Understanding of the processes that affect soil herbicide behaviour enables the prediction of their fate in the environment. Soil-herbicide interactions are governed by adsorption-desorption processes as only the free herbicide fraction participates in all other processes occurring in or on the soil. Given the agricultural and environmental significance of clomazone, its adsorption-desorption behaviour was investigated in two widely distributed Serbian agricultural soil types, Planosol and Vertisol. Both processes were well-described by Freundlich isotherms, and the obtained sorption parameters show that clomazone sorbed to both organic matter and mineral soil components. Vertisol, characterized by higher organic matter and clay content, demonstrated greater sorption capacities (3.67-21,23 mg^(n-1)/n dm^3/n kg^-1 for 1.5-15 mg dm^-3) and lower desorption rates (the amounts desorbed of 29.49-28.48 % during 72 h for 1.5-15 mg dm^-3) compared to Planosol (3.15-18.35 mg^(n-1)/n dm^3/n kg^-1 and 33.32-29.97 % for 1.5-15 mg dm^-3). The more pronounced desorption hysteresis observed in Vertisol is likely attributable to the presence of a higher number of high-energy sorption sites compared to Planosol. These findings highlight the crucial role of soil composition in determining the environmental fate of clomazone, providing a valuable basis for developing agronomically effective and environmentally safe application recommendations.