Sustainable alternative to biochar: Effects of oxychar on soil carbon sequestration pathway and microbial communities

The rapid development of agriculture poses significant challenges to carbon sequestration and sustainable agriculture due to frequent plowing cultivation, has resulted in a notable decline in soil quality. The application of carbon materials is regarded as a synergistic and effective approach for conserving organic carbon, increasing microbial activity, and promoting plant growth. To explore whether oxychar can serve as a substitute for traditional biochar (HBC) in enhancing soil carbon sequestration, a method combining a 680-day field experiment with a pot experiment was adopted to assess the impacts of oxychar on soil carbon sequestration, microbial communities, and rape growth. The study revealed that the addition of oxychar reduces soil pH, increases soil electrical conductivity and CO₂ emissions, and achieves carbon sequestration by increasing the content of readily oxidizable organic carbon in the soil. The soil carbon pool management index of the oxychar treatment (131.32) was significantly higher than that of the traditional biochar treatment (101.93), indicating that oxychar has higher ability to improve soil organic carbon quality. Both the oxychar and HBC treatments improved the richness and diversity of the soil bacterial community. However, oxychar indirectly influenced the soil microbial community by increasing soil electrical conductivity and promoted soil carbon sequestration through carbohydrate metabolism. And, oxychar could promote plant growth in many ways. In general, this study provides a theoretical basis for the practical application of oxychar replacing HBC in soil carbon sequestration.