Basalt powder potential for carbon sequestration in Brazilian sandy soils

Brazil has an extensive area of sandy soils, correspoding to 1.6 million squared kilometers, almost 19% of the country’s territory, many of them under cultivation but presenting limited soil organic carbon (SOC) stabilization. The production of basalt from the aggregate industry and its true potential to be used as rock powder remain underexplored for climate-smart soil management. These subproducts can enhance SOC both through the formation of new organomineral interactions aided by calcium release when weathered, and by stimulating the soil’s microbiome and improving its structure. This study aimed to evaluate the spatial feasibility and potential relevance of basalt powder application for carbon sequestration in Brazilian sandy agricultural soils. Spatial analysis revealed overlaps between sandy soils and basalt extraction sites that could possibly supply rock-powder across Brazil over an area of approximately 69,000 km², 4.3% of all sandy soils in Brazil. This number might seem small, but 47% of these sandy soils (32,644 km²) were under cultivation in 2024. Thus, identifying priority regions where basalt application is logistically feasible is a key component to rock-powder practice. These areas represent strategic targets where mineral-mediated mechanisms of soil organic matter stabilization reported in the literature may be effectively deployed, and, when held by literature-reported meta-analysis response ranges for enhanced rock weathering in a 4-year scenario, could yield an additional ~5.6–5.9 Tg C increase in SOC stocks at the national scale.