Global meta-analysis dataset: Organic amendments and soil organic carbon in croplands

This dataset contains data used in the manuscript "Distinct mechanisms of different types of organic amendments interact with environmental conditions to control soil organic carbon accumulation in croplands: a global meta-analysis". Enhancing soil organic carbon (SOC) in croplands is critical for advancing food security and climate change mitigation. However, the global potential, regional effectiveness and underlying mechanisms of SOC sequestration through different types of organic amendments remain poorly resolved. Here, we performed a meta-analysis based on 743 paired observations from 325 published studies to resolve the issues at a global scale. By integrating a hybrid ensemble of eight machine-learning models to impute missing observational data and coupling this enhanced dataset with structural equation modeling, this study clarified how different types of organic amendments influenced the SOC sequestration, identifying where each amendment performs best and uncovering the underlying mechanisms. Results demonstrated that organic amendments significantly increase SOC in cropland by an average of 25.93% (P < 0.001), with biochar (31.07%), followed by compost (26.95%), manure (25.44%) and straw (17.97%). The effectiveness of straw and compost were strongly influenced by environmental conditions such as climate, soil texture, and initial SOC content, whereas the manure and biochar displayed a directly dose-dependent response to the amount of carbon applied. These differences originated from distinct mechanistic pathways on SOC sequestration under different organic amendments: an enzyme-mediated dissolved organic carbon (DOC) to mineral-associated organic carbon (MAOC) pathway for straw; a physicochemical, pH-driven and nutrient-driven MAOC pathway for biochar; a hybrid nutrient-enzyme MAOC pathway for manure; and a DOC-centered rapid-stabilization pathway for compost. Spatial modeling based on multi-model inference indicated: straw would be most effective in hot, arid regions with fine-textured soils; compost would suitable on low-SOC croplands; biochar should be applied in wetter, nitrogen-richer mid- to low-latitudes regions; and manure would be effective across warm regions. Our findings advocated a strategic shift from a generic “more is better” approach towards mechanism-informed, regionally tailored portfolios of organic amendments to maximize the magnitude and durability of SOC sequestration globally.