The capacity of soils to store organic carbon is increasingly recognised as an opportunity to mitigate for greenhouse gas emissions while increasing biomass production and improving drought resilience1. However, soils are heterogeneous and dynamic systems: carbon storage capacity and residence time depend on intrinsic soil properties, but also on land occupation and management choices. Gaps in knowledge also need to be addressed: in particular, the behaviour of deep soil carbon (below 30cm) plays an important role in carbon storage due to its longer residence time, but remains poorly considered and understood2. This study analyses soil carbon dynamics and storage capacity over 50 years, distinguishing between 8 soil types and 3 land covers (cropland, grassland, forest). Carbon stocks are calculated based on 190 profiles covering a depth up to 2m. We compare two methods to assess C storage potential: the soil carbon saturation within the fine fraction using the Hassink method3 and the maximum total carbon content using a data-driven approach4. We then model the carbon stocks that could be stored in each soil type within 50 years, based on annual carbon inputs estimated for different land covers and uses, and from previously defined vertical profiles of carbon mean residence time5. Finally, we map the additional carbon storage potential after 50 years within a 300 km2 region (Meuse / Haute Marne, France), and discuss the potential of different combinations of soil type and land use to store carbon: what are the optimal management strategies for carbon storage at the regional scale? 1. Basile-Doelsch, I., Balesdent, J., & Pellerin, S. (2020). Reviews and syntheses: The mechanisms underlying carbon storage in soil. Biogeosciences, 17(21), 5223–5242. https://doi.org/10.5194/bg-17-5223-2020 2. Mathieu, J. A., Hatté, C., Balesdent, J., & Parent, É. (2015). Deep soil carbon dynamics are driven more by soil type than by climate: A worldwide meta-analysis of radiocarbon profiles. Global Change Biology, 21(11), 4278–4292. https://doi.org/10.1111/gcb.13012 3. Hassink, J. (1997). The capacity of soils to preserve organic C and N by their association with clay and silt particles. Plant and Soil, 191(1), 77–87. https://doi.org/10.1023/A:1004213929699 4. Chen, S., Arrouays, D., Angers, D. A., Chenu, C., Barré, P., Martin, M. P., Saby, N. P. A., & Walter, C. (2019). National estimation of soil organic carbon storage potential for arable soils: A data-driven approach coupled with carbon-landscape zones. Science of the Total Environment, 666, 355–367. https://doi.org/10.1016/j.scitotenv.2019.02.249 5. Balesdent, J., Basile-Doelsch, I., Chadoeuf, J., Cornu, S., Derrien, D., Fekiacova, Z., & Hatté, C. (2018). Atmosphere–soil carbon transfer as a function of soil depth. Nature, 559(7715), 599–602. https://doi.org/10.1038/s41586-018-0328-3