Toxicity Assessment and Phytostabilization of Contaminated Soil by Using Wheat Straw-derived Biochar in Tomato Plants

Biochar is a carbon-rich, cost-effective, and multifunctional material used for the immobilization of heavy metals (HMs) in contaminated soil. This study evaluated the wheat straw-derived biochar in a pot culture experiment in a greenhouse to investigate the remediation efficiency in coal mines contaminated soils. A bulk soil sample (20 cm) was collected from the mine tailing area of Dara Adam Khel region Peshawar, Pakistan. Biochar was thoroughly mixed at a rate of 2, 4, and 6% (w/w) with 10 kg soil along with untreated pots. Ten days old seedlings of tomato plants (Rio Grande) were transferred to both treated and untreated pots. The findings of the research highlighted that the highest contents of lead (Pb), cadmium (Cd), chromium (Cr), nickle (Ni), manganese, (Mn), and copper (Cu) were recorded in untreated pots, while the lowest were recorded in the pots treated with 6% biochar. Similarly, the highest uptake of Pb, Cd, Cr, Ni, Mn, and Cu was recorded in the untreated pots, while the lowest uptake was recorded in the pots treated with 6% biochar. The highest shoot weight (40 g) was recorded with the application of 4% of biochar. The highest values of pH and EC and organic matter were recorded in the pots treated with 6% of biochar as compared to untreated soil. Overall, the application of biochar at the maximum rate of 6% significantly immobilized HMs in soil and reduced the uptake in tomato shoots. To conclude, soil organic matter and plant growth was enhanced by the integration of biochar.