Contrasting Soil Organic Carbon Concentrations and Mass Storage Between Conventional Farming and Organic Farming: A Meta-Analysis

This meta-analysis studied the impact of conventional versus organic farming practices on soil organic carbon (SOC) concentrations and mass storage. We aimed to understand the carbon dynamics associated with adopting organic agricultural practices by reviewing and synthesizing data from 1950 to 2023. We analyzed data from 64 experimental field comparisons that involved SOC concentration and mass storage measurements, covering a wide range of studies selected for soil depth analyses, carbon concentration measurements, and comparative methods between conventional and organic systems. Our results indicated a significant increase in SOC under organic agriculture. An analysis of the response ratios (LnRR) for SOC concentration showed variability, with a 95% confidence interval of 0.089–0.149. Similarly, the analysis of carbon storage data indicated a 95% confidence interval of LnRR of 0.053–0.205. These increases in SOC concentration and mass storage reflect the variable but statistically positive impact of organic farming on SOC. Fine soil textures demonstrated the highest mean LnRR for both SOC concentration (0.163) and mass storage (0.173), suggesting the role of soil texture in mediating the effects of organic agriculture on SOC dynamics. Furthermore, there was a significant negative correlation between soil pH and SOC mass storage, with a regression coefficient of −0.174 ( p < 0.039). Although a slight positive correlation was observed between temperature and SOC mass storage as LnRR, other environmental factors likely play a critical role in SOC dynamics. These findings emphasize the complexity of SOC dynamics and the significant impact of organic agriculture on increasing SOC concentrations and mass storage. This study broadly contributes to the debate in sustainable agriculture by providing quantitative evidence of the role and benefits of organic agriculture on climate change mitigation. The results also emphasize the importance of adopting organic farming practices for broadly enhancing ecosystems’ resilience and long-term food security.