Effect of biochar on soil properties and lead (Pb) availability in a military camp in South West Ethiopia

Application of biochar to soil can improve numerous physicochemical and biological properties of the soil. The method for lead metal (Pb) remediation in soil is a challenge worldwide. The excessive Pb accumulation in the soil can radically reduce the soil quality and fertility. This study was conducted to find out the efficiency of biochar in improving the physicochemical properties of soil and to evaluate its effect on Pb availability in a military camp soil. Soil sample was collected from military camp of Jimma town, southwestern Ethiopia and was incubated for 90 days with different application rates (0, 2.5, 5, 7.5, 10, 12.5 and 15 t/ha) of biochar. The results showed that the addition of biochar improved, pH, electric conductivity (EC), cation exchange capacity (CEC), organic carbon (OC), organic matter (OM), total nitrogen (TN), exchangeable cations and available phosphorous of the soil and had no significant effect on soil texture. Sequential extraction of Pb showed that at 15 t/ha (4.2 g/kg) application of biochar, the exchangeable form of Pb significantly transformed the carbonate bound, Fe/Mn oxide bound, organic bound and residual fractions to 66.79, 100.5, 112.7 and 112.1 mg/kg, which is reduced by 88.6, 88.9, 88.5 and 88.3%, respectively as compared to the control. It is concluded that the application of biochar could not only improve physicochemical properties of the soil but also stabilize Pb in a military camp soil.