Biochar in sustainable agriculture and Climate Mitigation: Mechanisms, challenges, and applications in the circular bioeconomy

Biochar, a carbon-rich material produced through the pyrolysis of biomass, has gained significant attention for its potential in sustainable agriculture, environmental management, and climate change mitigation. This review provides a comprehensive synthesis of the latest research on biochar production, characterization, and its roles in enhancing soil health and agricultural productivity, focusing on novel insights and emerging applications. Biochar improves soil structure, nutrient retention, water-holding capacity, and microbial activity, benefiting degraded soils such as acidic, sandy, and nutrient-poor soils, which are prone to poor water retention and nutrient leaching. Studies have shown that biochars produced from wood and agricultural residues are particularly effective for long-term carbon sequestration and improving soil fertility. Furthermore, biochar has demonstrated significant impacts on boosting crop yields, with some studies reporting up to a 30 % increase in yields for crops grown in nutrient-poor soils. Biochar sequesters carbon for centuries, reduces greenhouse gas emissions (e.g., nitrous oxide by up to 50 %), and mitigates water contamination by adsorbing excess nutrients and heavy metals. Despite these benefits, large-scale biochar application faces challenges, including variable effectiveness across soil types and climates, high production and transport costs, and the need for standardized production methods. This review emphasizes the integration of biochar into waste management and bioenergy systems, aligning it with the principles of a circular bioeconomy. It also underscores the importance of further research to optimize production processes, assess long-term impacts on soil health and crop productivity, and explore biochar's role in enhancing resource efficiency and addressing critical agricultural and environmental challenges.