Soil erosion represents one of the largest, yet often overlooked, pathways for the loss of soil organic carbon (SOC), directly threatening the stability and sustainability of global carbon dioxide removal (CDR) strategies. According to According to EU soil survey data, many Mediterranean soils contain critically low carbon stocks, often below 1 %, making them extremely vulnerable to hydrological extremes and climate change-induced degradation. The latest research However, it shows that the application of biochar offers a solution that goes beyond its function as a simple carbon storage and becomes an active tool for protecting soil ecosystems.

The "soil sponge" mechanism„

Biochar is widely recognized as a durable carbon absorber, but its hydrological effects and potential to mitigate erosion have been underestimated in previous CDR frameworks. Study published in peer-reviewed journal Biomass Futures stresses that hydrological improvements – known as reinforcement functions of the soil sponge – are not just side benefits, but a core mechanism supporting the sustainability of carbon storage.

The soil sponge function represents the ability of soil to absorb, retain and release water and nutrients, while providing structural support to resist erosion and maintain SOC stocks. A global meta-analysis including 184 observations from 30 studies confirmed that biochar reduces surface water runoff by an average of 25 % and soil erosion by 16 %. These results are particularly pronounced for biochar produced at temperatures above 500 °C, which is related to its larger internal surface area, porosity and higher physical stability of the material.

Evidence from Mediterranean vineyards

Experiments conducted in European conditions, specifically in Mediterranean vineyards, have yielded even more convincing results. These areas are characterized by steep slopes and soils with low organic matter content, which make them among the most endangered agricultural landscapes in Europe.

Long-term studies have shown that adding 4 % biochar to soil:

• Reduced soil erosion rates by up to 65 %.
• Increased retained water reserves by 73 %, while in dry conditions this increase was up to 300 percent.
• Led to an increase in total soil organic carbon by 85 %.

An interesting finding is the strong synergy between biochar and vegetation cover. Studies with plant cover have shown more than a two-fold reduction in erosion compared to bare soil experiments. By improving soil pH and nutrient availability, biochar promotes biomass growth, which in turn mechanically stabilizes the soil.

A new era of certification and MRV

Current monitoring, reporting and verification (MRV) methodologies primarily quantify carbon storage based on the stability of biochar itself. However, topsoil loss through erosion poses an immediate threat to undoing these gains, as both biochar and naturally accumulated SOC are exported from the system.

The authors of the research therefore call for the formal integration of erosion mitigation measures into certification frameworks, such as the EU Carbon Removal Certification Framework (CRCF). They propose the introduction of „"SOC retention factor adjusted for erosion"“, which would take into account the physical protection of carbon in soil. Such a step would significantly reduce uncertainty about the permanence of storage and strengthen the credibility of credits in carbon markets.

Biochar represents a scalable strategy for climate-resilient land management. Its ability to increase water infiltration and reduce the physical export of carbon from soils directly supports the sustainability of existing stocks and new CO2 removals. Recognition of these hydrological mechanisms in future IPCC methodologies and regulatory frameworks can accelerate the deployment of biochar as a key and verifiable solution for global carbon neutrality. JRi&CO2AI