Removal of organic matter and oxides of iron and manganese from soil influences boron adsorption in soil

Abstract The influences of specific soil components such as organic matter and oxides of Fe and Mn on B adsorption characteristics are not understood well. In the present study, we compared B adsorption behavior of two acidic soils after removal of organic matter, and Fe- and Mn-oxides with that of untreated soil samples. The B adsorption capacity of the soils before and after removal of different components was low; the average values of maximum B adsorption obtained from nonlinear least square optimization of Langmuir adsorption isotherm being 20.61 mg kg− 1 for Mallerbari soil and 27.15 mg kg− 1 for Sikarpur soil. Removal of organic matter by NaOCl treatment from the soils increased B adsorption. This indicates that Fe- and Al-oxides and other available adsorption sites on the mineral surfaces are coated by organic matter and are activated only after removal of organic matter. Removal of Fe- and Mn-oxides, however, resulted considerable decrease in B adsorption in the soils. It is, therefore, suggested that B adsorbing surfaces in soil decrease on removal of Fe- and Mn-oxides, since these oxides are known to have good adsorptive capacity for B.