Soil organic carbon storage and land management strategies in South African central grasslands

Grasslands cover 40 % of the earth's surface and store 10 % of the global soil carbon stock. Their degradation weakens its capacity to support biodiversity, ecosystem services and human well-being, as well as soil carbon storage. Research on how different strategies affect soil carbon accumulation in South Africa's semi-arid regions, particularly the Free State, is scarce. This study aimed to establish land management strategies suitable for enhancing soil organic carbon (SOC) storage in South African grasslands. DAYCENT carbon model was used to simulate SOC under various management scenarios; soil samples were collected to parameterize the model and further analyse carbon amount in each soil type. Results indicate that Lixisols can store more carbon compared to other soil types, with higher carbon concentrations linked to soils with higher silt content, while less carbon was found in soils with high sand content such as Arenosols. Carbon was stored differently based on soil depth, with new carbon in shallow depths and old carbon in deeper layers. Simulation results suggest that grasslands with moderate grazing could enhance shallow carbon storage over time. The work suggests that native grassland has the potential to act as a significant carbon sink with improved management practices.