A global synthesis on organic carbon accrual caused by soil pH amelioration with nature-based solution

Soil pH amelioration is fundamental to carbon sequestration and food security across global croplands. Nonetheless, illuminating the pH amelioration-shared effect on soil organic carbon (SOC) and crop yields remains challenging under organic substitution (partial replacement of synthetic fertilizers with organic amendments), as soil pH remediation typically co-occur with other confounding factors. This study quantitatively partitioned soil pH amelioration-shared effect on SOC and crop yields under organic substitution practices and elucidated the underlying mechanisms, leveraging global field observations from 251 experimental sites. Organic substitution consistently remediated soil pH across all initial pH conditions, increasing pH by 6.2% in acidic soils and decreasing it by 0.6% in alkaline soils. Soil pH amelioration remarkably enhanced SOC accrual predominantly through increased microbial biomass, resulting in SOC accrual of 15.0% in acidic soils, 9.4% in neutral soils, and 4.1% in alkaline soils. SOC accrual caused by pH amelioration contributed substantially to yield gains, accounting for 8.6% in acidic soils, 5.1% in neutral soils, and 8.1% in alkaline soils. Yield gains are remarkable across five continents, with Africa exhibiting the most pronounced gain at 9.9%. Our findings underscore that integrating precision pH management into agricultural policy and practice offers a transformative pathway toward climate-smart food security.