Biochar application stabilized the heavy metals in coal mined soil

Abstract

The waste of cool mining activities causes accumulation of hazardous elements in soil for plants. Biochar is considered an important soil remediation strategy to stabilize the heavy metals. The aim of this study is to quantify the effect of biochar sources and rate on the heavy metal stabilization in coal contaminated soil. Biochar of three feedstocks (maize straw-MBC, rice straw-RBC and sugarcane bagasse-SBC) with four levels (0, 0.5, 1 and 2% i.e. 0, 10, 20, 40 tons ha-1) were applied to two types of soils (naturally (NCS) vs. artificially (ACS) spiked with Cd, Cu, Cr and Pb). Plastic pots were incubated at 30% field capacity for 90 days at 25 °C, and soil pH, EC and heavy metals concentration were measured after 1-, 4-, 8- and 12-weeks. Among the biochars, RBC showed maximum immobilization of Cd, Pb, Cu and Cr as compared to MBC and SBC. Similarly, biochar application increased heavy immobilization being maximum at 2% (40 tons ha-1) rate than control. The pH of both soils with biochar addition increased as compared to control. The remediation effect of biochar on heavy metal stabilization was positive over time. The higher rate (40 tons ha-1) of RBC for artificially and MBC for naturally contaminated soil could be used effectively for heavy metal stabilization.