Biochar induced trade-offs and synergies between ecosystem services and crop productivity

Biochar amendment offers a chance for sustainable agriculture. However, the effectiveness of biochar relies on its physical and chemical properties, which are heavily affected by biochar production conditions and management practices. Therefore, substantial uncertainties regarding the use of biochar exist in agricultural systems globally. This study provides the first quantitative evaluation of the impacts of biochar characteristics and management practices on key ecosystem services by performing a second-order meta-analysis based on 34,628 paired observations in biochar-amended and unamended systems. Overall, biochar enhances phytotoxicity alleviation, physiology regulation, soil remediation and carbon sequestration, and microbial functional gene abundance. However, some prominent trade-offs exist between crop productivity and ecosystem service deliveries including for nutrient cycling, microbial function, climate change mitigation, and the soil microbial community. The adoption of low C:N biochar produced at high pyrolysis temperatures from sewage sludge-derived feedstock, in combination with a moderate application rate and inorganic fertilizer input, shows potential for achieving synergistic promotion of crop productivity and ecosystem services. These outcomes highlight the need for judicious implementation of biochar-based solutions to site-specific soil constraints. The quantified synergy and tradeoff relationships will aid the establishment of a sustainable biochar development framework that strengthens necessary ecosystem services commensurate with food security assurance.