Enhanced weathering in China’s acidic rice fields offers potential agronomic co-benefits

China faces the converging challenges of farmland soil acidification, securing food security, and meeting carbon neutrality goals.Enhanced weathering (EW) offers a promising scalable carbon dioxide removal (CDR) pathway that can also deliver valuable agronomic benefits, but its potential for soil pH management, crop yield increases, and CDR in Chinese croplands is poorly constrained.Here, we develop a modeling framework to simulate co-benefits of basalt-based EW in acidic rice fields in China and conduct a spatially explicit national assessment.Focusing on the expected benefits from soil deacidification based on previous empirical data, EW can enhance relative rice yield by 4.61 ± 2.45% to 6.34 ± 3.98% by increasing mean soil pH by 0.68-1.02units, resulting in a preliminary economic gain of USD 3.56 billion annually.This process also has the potential to simultaneously sequester 204.39 Mt CO2 over 35 years based on strategic applications of an additional 50 t basalt ha -1 every ten years for fields where soil pH remains below 6.5.We find that the yield benefits alone would provide a gross agricultural revenue of USD 609 per tonne of gross CO2 sequestered.Jiangxi, Hunan, Guangxi, and Guangdong persistently show the greatest cobenefits and should be prioritized as areas of early deployment.Our findings identify targeted EW deployment in China's acidic rice fields as a promising strategy to improve soil quality and support rice production, while potentially contributing to national CDR targets.another long-term experiment tracking yield responses to liming, crop yields improved as soil pH rose, even though Olsen-extractable P and exchangeable K did not show sustained increases 31 .These findings suggest that the yield benefits of EW are typically mediated through the alleviation of acidity constraints.Optimizing soil pH management can thus not only reduce agricultural GHG emissions, but also enhance crop yields and soil health 32 .Acidic to weakly acidic soil accounts for 77.75% of the rice growing area in China (Supplementary Fig. 1, Supplementary Fig. 2).Given this widespread prevalence of acidic soils as well as the need for CDR, deploying EW to raise soil pH, improve rice yield, and remove CO2 appears both timely and well justified.Although several studies have modeled EW on cropland at the national scale 23 , research in this area remains at an early stage, including in China 11 .Specifically, the weathering rate and CDR fluxes of EW when optimized for crop yields remain unclear, as does the quantitative response of crop yield to pH change.We use an empirically grounded method to provide an estimate of the potential co-benefits of large-scale EW deployment in China's acidic rice fields.Specifically, we construct a spatially explicit modeling framework to evaluate soil pH elevation (ΔpH) and CDR capacity, and develop a quantitative system for rice yield that builds from a meta-analysis treating pH as a key explanatory variable.We simulate an initial basalt application of 50 t ha -1 to the upper 0-12 cm of acidic rice fields in 2026, with additional applications at the same rate in 2036, 2046, and 2056 only where modeled pre-application soil pH < 6.5.We quantify basalt dissolution, ΔpH, and gross CDR by tracking individual application cohorts, and estimate rice yield improvement (Δyield) using pH responses derived from a random-effects meta-analysis.We further integrate ΔpH, Δyield, and gross CDR into a comprehensive index of co-benefits (CIC) to identify priority deployment regions and assess robustness through sensitivity analyses of weathering kinetics, soil buffering, alkalinity export, feedstock CO2 capacity, and index weighting.By integrating agronomic and climate benefits at the national scale, this study identifies where EW could most effectively support food security, sustainable soil management, and climate mitigation in China.We also provide a preliminary economic assessment-comparing expected gains from yield increases to tonnes of carbon removed (Fig. 1).While this is only a first assessment, it further bolsters the case that enhanced weathering could be an effective component of a mitigation package in China and that large-scale field trials are needed.