The management of soil organic carbon is essential for maintaining agricultural productivity and addressing global climate concerns, as detailed in a recent study published in Agronomy by Boying Wang and a team of researchers from Shenyang Agricultural University. While many previous studies have focused on the effects of massive amounts of biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More, this research highlights how continuous, low-dose applications of biochar and biochar-based fertilizers can fundamentally reshape soil health. The study found that these amendments significantly increase several types of carbon within the soil, ranging from active components that feed microorganisms to stable forms that resist decomposition. By tracking these changes over a long period, the researchers demonstrated that biochar does not just add carbon to the soil but actually improves the structural integrity and longevity of the existing carbon pool.

A major finding of this research involves the shift in the chemical structure of soil organic carbon. The application of biochar and biochar-based fertilizers increased the abundance of aromatic functional groups, which are naturally more resistant to being broken down by microbes. This change was reflected in a significant rise in the anti-degradation ability of the soil. Specifically, the biochar-based fertilizer treatment improved this stability index by more than twenty-one percent in the topsoil and twenty-five percent in deeper layers compared to standard chemical fertilizers. This suggests that biochar helps create a more permanent carbon reservoir in the ground, which is vital for long-term soil fertility.

The study also shed light on the critical role of the soil microbial carbon pump, a process where microorganisms transform organic matter into stable residues. The researchers used amino sugar biomarkers to trace how much carbon was derived from dead microbial cells, known as necromass. They discovered that biochar-based fertilizers significantly boosted the levels of these microbial residues. Interestingly, fungal-derived carbon was found to be the dominant contributor to this stable pool, accounting for over half of the organic carbon in the surface soil. This indicates that biochar provides a favorable environment for fungi to thrive and eventually contribute their cellular remains to the soil matrix.

Furthermore, the research showed that biochar-based fertilizers are more effective than biochar alone or standard chemical fertilizers at promoting this microbial carbon accumulation. Because these specialized fertilizers provide a balanced mix of available carbon and essential nutrients, they allow soil microbes to work more efficiently. This efficient processing leads to a higher rate of carbon being converted into stable microbial residues rather than being lost to the atmosphere as carbon dioxide. These findings provide a scientific basis for using low-dose biochar applications as a practical and economic strategy for sustainable farming. By focusing on the biological and chemical pathways of carbon stabilization, this work helps bridge the gap between lab-scale theories and real-world agricultural management.

Source: Wang, B., Guo, C., Xu, X., Sun, Y., Fu, S., Cui, C., Yang, C., Yang, J., & Yang, Y. (2025). Response of organic carbon components and stability to long-term application of low doses of biochar and biochar-based fertilizers. Agronomy, 16(1), 99.