A high resolution map of French soil organic carbon

Soil is a major carbon pool ruling the global C cycle and in climate change because soil carbon is a source and a sink of atmospheric CO2. Soil organic carbon also controls many beneficial properties such as fertility, aggregate stability and degradation of groundwater pollutants. Therefore mapping soil carbon at landscape scale is needed to define appropriate management that will favour higher soil quality. Actual soil carbon maps of France have a too coarse resolution, i.e. 8 and 12 km, to define efficient land management practices. Therefore, here, we model soil organic carbon in France at a resolution of 250 m. We study the impact of land use, soil type, climate and agro-management on soil organic carbon. We found that the total soil carbon stock in France is about 3.7 +/- 1.3 Pg. Results also show that the precipitation pattern dominates the overall spatial distribution of soil carbon. Land use is the most important factor controlling organic carbon changes at landscape scale. Our high resolution national map of soil organic C will be useful to define land management practices that will improve soil quality.