Biochar and Phosphorous-Loaded Biochar Derived from Wood Chips or Poultry Manure Reduced Availability and Uptake of Cadmium by Plants from Cd-Contaminated Soils

This study investigated the effect of biochar (BC) and phosphorous-loaded biochar (P-BC) derived from wood chips and poultry manure on soil cadmium availability to plants in Cd-contaminated soils. The wood chips (WC) and poultry manure (PM) pyrolyzed at 400 °C to produce BCs samples. Additionally, BC samples were treated with KH2PO4 solution to produce P-BC. The effectiveness of produced BCs in removing Cd ions from aqueous solutions containing 1, 10, 25, 50, and 100 mg Cd L-1 was examined and the Cd2+ adsorption was described using Freundlich, Langmuir, and Temkin isotherm models. A pot experiment was also carried out to assess WC-BC, WCP-BC, PM-BC, and PMP-BC impacts on the growth, nutrients uptake, and availability of P and cadmium to wheat plants in soils spiked with 1, 10, 100, and 1000 mg Cd kg-1 soil. The BCs were applied to soil at a level of 3% (w:w). The results of the adsorption experiment showed that Freundlich model fitted the Cd adsorption (R2= 0.9962 – 0.9988) more than other isotherm models. The P-BCs application increased soil available P, plant growth and N, P, K uptakes. Meanwhile the soil available Cd, shoot Cd concentrations and its uptake decreased compared to BCs and control. The PM-BC was better than the WC-derived ones in improving these parameters. Applying BC and P-BC to Cd-contaminated soil introduce a promising tool to immobilize cadmium with positive impacts on soil properties and plant growth. Additionally, these biochars can be used for Cd2+ removing from aqueous solutions and waste-polluted water.