By Carla Gavilan
As a central factor of the Carbon Farming Alliance for Research and Management (C-FARM) project, monitoring changes in soil organic carbon (SOC) stocks is crucial for identifying sustainable land use practices related to climate change mitigation, food security, and land degradation. Accurately quantifying SOC and modeling its spatial variability is vital for making informed decisions. A major challenge in many developing countries is the lack of data to establish a solid basis for connecting changes in soil carbon sequestration with changes in agricultural activities.
As part of the Living Soils of the Americas Initiative (LiSAm) led by IICA (Inter-American Institute for Cooperation on Agriculture) and the CFAES Rattan Lal Center for Carbon Management and Sequestration of Ohio State University, we have proposed and implemented a monitoring framework in a pilot area in the Brazilian Cerrado Biome. Our framework integrates the RothC model, georeferenced databases, and spatially explicit environmental covariates to map and analyze the SOC stock dynamics associated with different land uses in the Brazilian Cerrado biome.
The most important environmental covariates influencing SOC stocks distribution in the Brazilian Cerrado were the soil class, climate, topography and vegetation indices. Soil classes were key to predict the distribution of SOC stocks as they are associated with texture and structure. Most SOC stocks are stored in Ferralsols and Cambisols in the Cerrado. Climate-related covariates such as monthly mean temperature and precipitation were more critical for SOC accretion within the 30 cm profile. Terrain derivatives such as slope and elevation were crucial to define the accumulation of carbon in areas of the Central Plateau, where the combination of moderate climate and high altitude influence decomposition rates. Finally, vegetation proxies such as NDVI (Normalized Difference Vegetation Index) and NPP (Net Primary Production) largely influenced SOC stocks distribution, mainly in the topsoil.
The estimated SOC stocks (30 cm) in the Cerrado biome (Fig. 1) show a mean SOC of 35.2 Mg C ha-1. Areas with higher stocks overlap a mix of pastures and cropland. Areas covering savanna formation present lower stocks, probably due to the limited carbon input compared to managed croplands and pastures. These findings underscore the strategic importance of protecting and managing the Cerrado biome to maintain stored SOC and mitigate potential future climate and land use change scenarios.