Biochar as a green strategy in alleviating Cd mobility in soil and uptake in plants: A step towards Cd-free food

Contamination of agricultural soil with Cadmium (Cd) poses life-threatening risks to human health via the food chain. To alleviate Cd toxicity, biochar is a safe and efficient technique to reduce their availability in soil and subsequently their uptake by roots and translocation towards edible parts of plants. This study provides an in-depth understanding of the biochar underlying mechanisms for Cd-contaminated soils. Biochar improves soil's physicochemical properties and microbial community structure due to its unique properties including large surface area, porosity, aromatic hydrocarbons, diverse functional groups, nutrient potential, and variable pH. Based on its general and specific characteristics, Cd adsorption and immobilization in soil occur by the mechanisms of improving soil pH, ion exchange, electrostatic interactions, complexation, precipitation, surface adsorption, and activation of microorganisms. Simultaneously, biochar regulates several non-selective channels that are responsible for Cd uptake into the roots, distribute it, and redistribute it to the shoots/grains, thereby reducing their accumulation in edible parts of plants. Finally, the use of biochar may reduce the risk of Cd exposure to humans from food crops. Conclusively, this study gives a detailed account of biochar-induced Cd immobilization in soil, its absorption by roots, and accumulation in edible parts of plants. [Display omitted] •The presence of cadmium in agricultural soil poses a serious threat to human health.•Biochar could be a suitable strategy to reduce Cd availability in soil for plants.•Biochar improves soil physical and chemical adsorption of Cd on their surface.•It regulates channels that are responsible for Cd uptake and translocation in plants.