Harnessing biochar innovations to combat heavy metal contamination and sustain crop resilience amid climate challenges.

Abstract

Asian and European regions are characterized by huge inequalities, with the levels of cadmium, lead, and zinc tending to rise above safe concentrations by 1.26-6.01 times, disrupting nutrient cycling and microbial communities due to more than 37% of arable land at risk of high levels of metal mobilization. This literature review summarizes the patterns of spatial pollution, pyrolysis-based biochar engineering, adsorption mechanisms, soil property transformation, remediation performance, nutrient synergies in enhancing agricultural productivity, and emergent soil-plant-microbe interactions to create a biochar development model (BDM) as a multifunctional biochar usage tool in sustainable agriculture. Under controlled experimental conditions, engineered biochars have demonstrated sorption capacities ranging from 22 to 303 mg g - 1 , reduced heavy metal bioavailability by 25%-62%, increased crop yields by 10%-32%, and enhanced soil organic carbon stocks by up to 595% in specialized degraded karst grassland restoration systems. However, these quantitative benefits are highly context-dependent, and long-term field evidence remains considerably more limited than that obtained from controlled laboratory and pot-scale studies. This review integrates these findings into a BDM, a practical decision-support framework that links spatial contamination patterns and climate-driven redox dynamics with speciation-informed pyrolysis engineering to optimize biochar design and guide field-scale implementation for sustainable agricultural systems.