Organic carbon in soils. Meeting climate change and food security challenges

Farmland and forests occupy more than 80% of the French territory and currently store 4 to 5 Gt of carbon (including 15 to 18 Gt of CO₂), with more than two-thirds of this carbon stored in top soils. Any positive or negative fluctuation of this stock influences national greenhouse gas (GHG) emissions, which are estimated at 0.5 Gt CO₂ eq/year (2011). The agricultural and forestry sectors also offer solutions for climate change mitigation through the production of renewable energies and preserving or increasing carbon stocks in soils and biomass. The management of organic matter, which is the principal carbon reservoir in soils, is a key determinant in the capacity of soils to produce food and material and to offer other environmental services such as the regulation of water cycles and air quality etc. Acting on soil carbon stocks also means acting on soil and environmental quality. This is the sense of the '4 per 1,000' initiative proposed by France at COP21. Drawing on data from the GIS Sol database, this brochure highlights the important role of soil carbon in French climate change mitigation strategies. In order to address soil and climate change challenges, the main agricultural and forestry levers for action are presented. An inventory of evaluation tools, from the field to the national scale, will help managers and advisers to better direct practices. (author)