Appropriate biochar application methods can simultaneously mitigate Cd concentrations in different parts of soil and crops: A meta‐analysis

Abstract Agricultural soil contamination by cadmium (Cd) is a globally recognized concern, with biochar presenting considerable potential for remediation. However, the response of various crop components to biochar application for Cd pollution mitigation remains insufficiently understood. A literature review covering publications from 2017 to 2023 compiled 364 datasets from 60 studies to evaluate the responses of different parts of three crops to biochar treatment in Cd‐contaminated soil. Findings indicated that biochar application reduced soil Cd bioavailability by 30.5% and decreased Cd accumulation in roots, shoots, leaves and grains by 31.3%, 34.0%, 25.3% and 43.1%, respectively, with the most pronounced reduction observed in grains. The efficiency of biochar in Cd remediation is influenced by its characteristics and application rates. Composite biochar, synthesized through co‐pyrolysis of biomass with other materials, demonstrated the highest effectiveness in reducing Cd concentrations in crops. Pyrolysis conducted at 400–600°C for 2–4 h significantly enhanced biochar's remediation potential, while biochar with a pH range of 6.5–8.5 and application rates above 2% notably decreased Cd absorption in crops. These results contribute valuable insights into the applicability of biochar materials in agricultural soil–crop systems, offering guidance on their anticipated effectiveness in mitigating Cd contamination.