Adsorption-desorption of Boron in Major Soils of India

Studies on adsorption of boron (B) undertaken in 12 soils representing different agro-ecological regions of India revealed that the adsorption of added B was in the order: Vertisols > Inceptisols > Alfisols. Higher the concentration of added B solution, greater was the variability in B adsorption. Soil within each order also differed in B adsorption. Of the three adsorption equations namely, Freundlich, Langmuir and Temkin fitted to the data, Freundlich and Langmuir equations explained the adsorption behaviour of the soils, yet based on prediction coefficients (R²) Freundlich appeared the best fit for Vertisols and Inceptisols, and Langmuir for Alfisols which showed lowest B adsorption. Freundlich constant ‘a’ and Langmuir constant ‘b’ were positively correlated with free CaCO₃, CEC and clay content. Desorption of added B was in the order: Inceptisols > Vertisols > Alfisols. Desorption of B increased with an increase in soil pH, whereas it decreased with an increase in organic C, clay and CEC.