Boron adsorption and desorption in some acid soils of West Bengal, India

Laboratory and greenhouse experiments were conducted to determine the influ ence of soil properties on adsorption and desorption of boron (B) as well a s to estimate the degree of reversibility of adsorption reactions. The util ity of Freundlich and Langmuir equations for characterizing the plant avail ability of applied B in soils was established using soybean [Glycine max (L .) Merr.] as a test crop. The adsorption-desorption study revealed that Fe2O3 and clay were primarily responsible for retaining added B in all the 25 different soils under inve stigation. Organic carbon, pH and cation exchange capacity (CEC) positively influenced the adsorption of B while free Fe2O3, organic carbon and clay r etarded release of B from these soils. The degree of irreversibility (hyste resis) of B adsorption/desorption increased with increase in organic carbon and CEC of these soils. Freundlich isotherm proved more effective in descr ibing B adsorption in soils as compared to Langmuir equation. The split Lan gmuir isotherm demonstrated that any of the adsorption maxima, calculated f rom lower, upper or entire isotherm, could be of practical use. Contrary, b onding energy coefficient, calculated either at lower or higher equilibrium concentration failed to show any practical benefit. Regression models as a function of B application rate and adsorption equation parameters to predi ct B uptake from applied B, demonstrated the utility of Langmuir and Freund lich equation parameters.