Soil pH Amelioration Synergizes Carbon Accrual with Yield Gains Under Organic Substitution

Soil pH management underpins sustainable agriculture globally, yet the intrinsic effects of pH change on soil organic carbon (SOC) accrual and crop yields remain obscured by concomitant shifts in other soil properties. Here, using two complementary global field datasets, we disentangle pH-specific contributions to SOC accrual and yield gains under organic substitution regimes (partial replacement of synthetic fertilizers with organic amendments). Organic substitution consistently shifted soil pH toward neutrality. Quantitative partitioning revealed that pH amelioration independently accounted for 15.0%, 9.2%, and 4.1% of SOC accrual in acidic, neutral, and alkaline soils, respectively, effects primarily mediated by enhanced microbial biomass. The pH amelioration-shared SOC accrual underpinned yield gains of 8.6%, 5.1%, and 8.1% across the three pH categories. These benefits were sustained over extended organic substitution durations, with the most pronounced effects in acidic soils. Spatially, pH-driven yield gains peaked at 9.9% in Africa. Our findings underscore that integrating proactive pH management into organic substitution strategies advances both soil carbon sequestration and global food security.