Relationship between soil composition and retention capacity of terbumeton onto chalky soils

Eight calcareous soils of Champagne vineyards (France) were studied to investigate the adsorption of the herbicide terbumeton (TER). A preliminary characterisation of the soil samples using X-ray diffraction (XRD), elemental and textural analyses, revealed a wide range of soil properties for the selected samples. The adsorption isotherms of TER were plotted for all samples. The determination of soil properties, which significantly correlated with the K-d distribution coefficient, allowed identification of organic matter and CaCO3 as the two main soil components that govern the retention of the herbicide. Organic matter was the predominant phase involved in the retention but its role was limited by the presence of calcite. Finally, the ratio of CaCO3 content to organic matter content was proposed as a useful parameter to predict the adsorption of terbumeton in chalky soils. The evolution of K-d as a function of this ratio was successfully described using an empirical model.