In an extensive review published in the journal Biochar, authors Bhaskar Jyoti Parasar and Niraj Agarwala explore the complex biological interplays that occur when biochar is added to soil. As global agriculture faces the twin challenges of feeding a growing population and mitigating climate change, biochar has emerged as a promising tool. The researchers detail how biochar interacts with soil microorganisms and the chemical environment to regulate the soil’s carbon and nitrogen budget. By acting as a pyrogenic solid with high carbon content and a porous structure, biochar fundamentally modifies the physical and chemical characteristics of the soil, leading to enhanced fertility and more resilient ecosystems.

The integration of biochar into the soil leads to a remarkable increase in both the quantity and stability of organic carbon. The study highlights that long-term application can boost total soil carbon stocks by nearly half, with an even more pronounced increase in the resistant forms of carbon that stay in the ground for long periods. This sequestration is largely driven by a shift in the microbial community. Biochar provides a specialized habitat that protects beneficial microbes from predators and environmental stress. These microorganisms then work to stabilize carbon through organo-mineral interactions. The porous nature of biochar also helps reduce the rate at which organic matter decomposes, effectively turning agricultural land into a permanent carbon sink.

Nitrogen regulation is another critical benefit discussed by the researchers. Traditional chemical fertilizers often lead to nutrient leaching and the emission of nitrous oxide, a potent greenhouse gas. Biochar mitigates these issues by enhancing the soil’s cation exchange capacity, which allows it to hold onto nitrogen more effectively. The study found that biochar promotes the growth of nitrogen-fixing bacteria and increases the activity of specific enzymes like urease and nitrate reductase. This accelerated nitrogen cycling ensures that more nutrients are available for plant uptake rather than being lost to the atmosphere or groundwater. In some cases, the combination of biochar and traditional fertilizers has been shown to boost crop productivity by an additional ten percent beyond the effects of fertilizer alone.

Furthermore, biochar serves as a powerful inhibitor of greenhouse gas emissions. By raising the soil’s pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More and improving aeration, biochar creates an environment that discourages the production of methane and carbon dioxide. It specifically recruits nitrous oxide-reducing bacteria, which can significantly lower the emissions associated with intensive farming. The researchers note that biochar prepared at lower temperatures for longer durations is particularly effective at carbon sequestration and gas reduction. This suggests that the specific properties of the biochar, such as its porosityPorosity of biochar is a key factor in its effectiveness as a soil amendment and its ability to retain water and nutrients. Biochar’s porosity is influenced by feedstock type and pyrolysis temperature, and it plays a crucial role in microbial activity and overall soil health. Biochar More and surface chemistry, play a decisive role in its environmental performance.

While the benefits are substantial, the review emphasizes that the application of biochar must be carefully tailored to specific soil types. In some nutrient-rich or salt-stressed soils, excessive use could potentially lead to micronutrient shortages or localized salinity issues. However, when applied appropriately, biochar functions as an essential soil conditioner that restores ecological functions and promotes sustainable nutrient management. Developing guidelines for crop-specific doses and long-term monitoring will be vital for maximizing these benefits. Ultimately, the study positions the tripartite interaction between biochar, microbes, and soil as a cornerstone for achieving global carbon neutrality and securing a healthy, productive future for the world’s soil ecosystems.

Source: Parasar, B. J., & Agarwala, N. (2025). Unravelling the role of biochar-microbe-soil tripartite interaction in regulating soil carbon and nitrogen budget: a panacea to soil sustainability. Biochar, 7, 37.