In a recent paper, Weijie Xu from Zhejiang A&F University, China, and colleagues have investigated the effects of biochar co-pyrolysed from the mixture of peanut shells and maize straw for the immobilization of Cd in paddy soil. Previous studies show that co-pyrolysed biochar could enhance the reactions and interactions among different materials and thus enhance the favourable properties of biochar. Here, Xu and colleagues found that the addition of the co-pyrolysed biochar at a mixing ratio of 1:3 significantly improved soil biochemical properties and reduced the Cd availability in the rhizosphere soil. It improved the richness and diversity of soil bacteria, with increased metabolic activities to promote the formation of iron plaque on the rice root surface, which impeded Cd uptake by rice. The biochar application also increased the total biomass and yield and decreased the concentration of Cd in different rice tissues compared with the control.

Various approaches have been developed to ensure secure rice production in Cd-contaminated paddy soils. Biochar may prove an important tool for improving soil fertility and crop productivity, as well as mitigating soil pollution. Here, Xu and colleagues not only developed an effective co-pyrolysed biochar strategy for the remediation of Cd-contaminated paddy soils but also explored the processes and mechanisms of the bioavailability and uptake of Cd in paddy soils, which holds potential for safe and sustainable rice production.