Environmental drivers regulate particulate and mineral-associated organic carbon storage in the Cerrado region of Brazil

Understanding the controls on soil organic carbon (SOC) pools is essential for designing land use strategies that support soil recovery and carbon storage in the Cerrado region of Brazil. In this study, we combined a systematic meta-analysis with structural equation modeling to evaluate how different land uses (e.g., croplands, pastures, integrated systems, and native vegetation) affect particulate organic carbon (POC) and mineral-associated organic carbon (MAOC), as well as their underlying drivers. Changes in POC (∆POC) and MAOC (∆MAOC) were also quantified following the conversion of native vegetation to agricultural systems. Native vegetation showed higher stocks of both SOC fractions compared to croplands. Variations in POC were mainly associated with microbial decomposition processes, whereas MAOC dynamics were largely governed by mineral stabilization, with limited influence from carbon inputs or climatic factors. Responses of ∆POC and ∆MAOC to land use change varied widely among sites, with net primary production and soil pH emerging as key drivers for ∆POC, and soil moisture for ∆MAOC, independently of land uses. MAOC accumulation was not limited by MAOC saturation deficit, remaining below its theoretical mineralogical saturation capacity, likely due to climatic limitations characteristic of the Cerrado. Overall, our findings demonstrate that environmental controls play a central role in regulating SOC fractions and emphasize the importance of site-specific management strategies to enhance carbon inputs and reduce losses in agricultural systems of the Cerrado