LAUSR

ABSTRACT In order to study the effects of FeCl2 modified corn residue biochar (Fe-MCB) on the bioavailability and chemical fractions of cadmium (Cd) in a contaminated calcareous soil, an experiment was conducted as a factorial in completely randomised design with three replications. This research investigated two factors: levels of Cd concentration (0, 15, and 30 mg kg−1) and type of biochar [control: without any biochar application, biochar (CB) and Fe-MCB]. Results indicated that the use of CB and Fe-MCB increased soil pH, the cation exchange capacity (CEC) of soil and soil organic matter content (SOM). The application of CB and Fe-MCB significantly decreased Cd bioavailability by 26.52 and 37.75%, respectively. The results of sequential extraction showed that the exchangeable and carbonate fractions of Cd decreased while organically bounded Cd and Fe/Mn-oxide-bounded Cd increased after Fe-MCB was applied. The application of Fe-MCB increased the IR values, but decreased MF values, demonstrating a decrease in the mobility of Cd in the soil. Overall, this study showed that Fe-MCB application especially at high concentrations of Cd can effectively immobilise Cd, thus decreasing its mobility in contaminated soils and improving the quality of soil environment and reducing remediation costs.