The European viticulture sector, especially in the Mediterranean region, faces a profound threat from water erosion. The combination of hilly terrain, bare-soil cultivation, and intense, short-duration rainfall events often following prolonged dry spells accelerates soil loss, threatening the long-term health and productivity of vineyards. With average erosion rates in Mediterranean vineyards estimated at 9.3 \ t ha-1 \yr-1, the need for a practical, long-lasting solution is critical. In response to this challenge, a study published in the journal Biochar by Behrouz Gholamahmadi, Carla S. S. Ferreira, Oscar Gonzalez-Pelayo, Ana Catarina Bastos, and Frank G. A. Verheijen set out to rigorously test a sustainable intervention: the application of biochar.

The researchers conducted an 18-month outdoor box lysimeter experiment on sloping sandy loam soil characteristic of Portuguese vineyards. The results were immediately compelling. Over the entire monitoring period, the biochar application significantly reduced the erosion rate in the vineyard soil compared to the untreated control soil. This translates to a massive 67% annual reduction in total soil erosion. The material’s ability to stabilize the soil was broad, reducing coarse fragment (gravel) erosion by 67%, fine-earth erosion by 43%, and splash erosion—the initial dislodging of soil particles by raindrop impact—by 34%. The pronounced reduction in coarse fragment erosion suggests that the physical presence of biochar particles may increase surface roughness, effectively slowing overland flow velocity and reducing the transport of larger sediment.

The key mechanism behind this improved performance is the enhancement of what scientists call the “soil sponge function”: the soil’s capacity for water infiltration and retention. Biochar, a porous, carbon-rich material, improves soil structure by physically enhancing soil structure. The experiment showed a marked improvement in soil hydraulics, including a 7% reduction in bulk density. This structural change allowed rainwater to enter the soil more easily, with total water infiltration increasing by 28% over the study period. Consequently, less water was left to run off the surface, leading to an average 45% reduction in the runoff coefficient.

For Mediterranean farmers contending with increasingly severe summer droughts, the impact of biochar on water retention is perhaps the most crucial finding. The improved soil structure resulted in an average increase of 73% in the available stored water in the topsoil. Furthermore, the greatest effect was observed during the driest months, with biochar-amended soil storing 171% – 303% more water than the control soil.

This significant boost in water storage acts as a natural drought buffer, providing plants with access to essential moisture long after the rain has stopped. The study confirms that biochar is an impactful, sustainable soil management tool for enhancing both long-term vineyard resilience and productivity by simultaneously curbing soil erosion and dramatically improving the soil’s critical water-holding capacity.

Source: Gholamahmadi, B., Ferreira, C. S. S., Gonzalez-Pelayo, O., Bastos, A. C., & Verheijen, F. G. A. (2025). Soil conservation benefits of biochar in Mediterranean vineyards: enhancing the soil sponge function and mitigating water erosion. Biochar, 7(106).