Organic materials return: Enhanced crop yields and soil carbon sequestration but increased risk of greenhouse gas...

Utilizing organic materials in farmland to synergistically enhance food security and mitigate climate change represents a key research frontier. However, a clear consensus is lacking regarding their overall impacts on crop yield, soil carbon sequestration, and greenhouse gas emissions, leading to considerable debate about this practice. Therefore, this study systematically quantified the effects and underlying mechanisms of incorporating four types of organic materials (straw, manure, biofertilizer, and biochar) by integrating 4624 field observations from 668 global studies using meta-analysis and random forest modeling. Results indicated that organic amendments increased crop yield by 16% and soil organic carbon by 25% on average. Biofertilizer and manure boosted yield most (+34% and +27%), while biochar performed best for carbon sequestration (+35%). Methane and carbon dioxide emissions rose by 16% and 7%, respectively, but nitrous oxide decreased by 19.67%. Importantly, biochar reduced global warming potential by 16.72%, whereas manure, biofertilizer, and straw increased it by 42%, 33%, and 36%. Climate, soil, and management practices significantly moderated these effects. Predictive models revealed continental variability: while yield and soil carbon benefits were consistent worldwide, significant greenhouse gas reductions occurred only in Europe and North America. Our findings underscore the importance of region-specific optimization-such as prioritizing biochar and adjusting nitrogen inputs-to synergistically achieve higher yields, carbon storage, and emissions reduction. The insights gained from this study provide a scientific basis for efficient resource use and sustainable agricultural development.