Exploring the Synergy of Enhanced Weathering and Rhizobacteria in Sustainable Agriculture

Enhanced Weathering (EW) is a promising negative emissions technology for atmospheric CO₂ removal, particularly in agricultural setups. Spreading silicate rock powder, such as basalt, over extensive agricultural lands not only sequesters CO₂ but also provides essential nutrients like K, Mg, and Fe to crops. However, the efficiency of carbon sequestration in this system varies strongly, posing a challenge to widespread adoption, particularly among stakeholders like farmers.

Climate change intensifies weather extremes, exacerbating crop drought and heat stress, with detrimental effects on production. To address these challenges, the use of Plant Growth-Promoting Rhizobacteria (PGPR), such as Bacillus subtilis, emerges as a nature-based strategy. In addition to inducing stress resistance, B. subtilis possesses Fe and P solubilizing features, potentially enhancing EW rates. Indeed, our previous study demonstrated B. subtilis efficacy in accelerating basalt weathering by increasing Ca, Mg, and Fe dissolution in bare soil.

In a maize mesocosm experiment combining B. subtilis, basalt, and water content as variables, we observed a significant impact of B. subtilis on plant biomass in treatments, while basalt showed no major effect. In treatments with reduced irrigation, plants that were amended with basalt and B. subtilis displayed elevated leaf chlorophyll levels and improved nitrogen balance compared to plants that were not amended with B. subtilis. Across both high and low watering conditions, plants amended with basalt and B. subtilis exhibited enhanced photosynthetic activity and improved stomatal regulation. These findings suggest a promising added effect of PGPR B. subtilis to basalt-based EW for efficient crop health management under varying environmental conditions. This synergy has the potential to address the challenge of variable carbon sequestration efficiency and can provide a robust basis for improving crop health under diverse settings.