Effect of Biochar on the Stability of Soil Organic Carbon in the Context of Global Warming

Since the industrial revolution, the mean global temperature has increased by more than 0.6°C, and this has led to serious ecoenvironmental problems, such as melting ice sheets, retreating glaciers, species extinction and extreme weather-climate events, which have substantially affected human social life. The issue of how to reduce global warming has become a worldwide concern. Soil is one of the primary carbon emission sources, and maintaining the stability of soil organic carbon (SOC) plays a crucial part in reducing soil carbon emission. Soil-biochar has great potential as a natural carbon sequestration solution. Biochar produces positive/negative stimulation effects on soil organic carbon when applied to soil. In this review, the direct and indirect effects of biochar on the soil environment are described, with a focus on priming effects and influencing factors of biochar. In terms of direct effects, biochar and its surface dissolved organic carbon can directly replenish the organic carbon source required by the soil carbon cycle. In terms of indirect effects, biochar can influence SOC mineralization by affecting the species, number, and activity of microorganisms in soil. Soil properties, vegetation type, biochar raw material, and pyrolysis temperature as well as their aging effects are the key factors affecting soil-biochar carbon sequestration. This review will contribute to the understanding of the contribution of biochar to the reduction of soil emissions.