Effect of EU's Common Agricultural Policies on Erosion and Soil Organic Carbon Balance, Italy

Soils are the third largest global reservoir of carbon and the largest terrestrial ecosystem sink or source of atmospheric CO2 depending on land-use and management. The French authorities ahead of COP21 proposed the ‘four per mil’ initiative aimed at offsetting most global agricultural CO2 emissions by increasing global soil organic carbon (SOC). Since, the Common Agricultural Policies (CAP) reform in 2003, many efforts have already been made at the European level to promote a more environmentally friendly agriculture and increase SOC stock. In order to encourage farmers to manage their land sustainably, the GAEC (Good Agricultural and Environmental Conditions) were introduced as part of the Cross Compliance mechanism. Among the standards indicated, the protection of soils against erosion and the maintenance of soil organic matter and soil structure were two pillars to protect and enhance the soil quality and functions. However, today there is still a substantial lack of knowledge about i) the effects of this policy on erosion prevention and soil organic carbon (SOC) change and ii) the role of soil erosion in the global C cycle. To move toward filling these knowledge gaps, we coupled a high resolution erosion model based on the Revised Universal Soil Loss Equation (RUSLE; Renard et al., 1997) with the CENTURY (Parton et al., 1988) biogeochemical model, with the aim to incorporate the lateral carbon fluxes occurring with the sediment transportation (Borrelli et al., 2016). Three scenarios were simulated on the whole extent of arable land in Italy: i) a baseline without the GAEC implementation; ii) a current scenario considering a set of management related to GAEC and the corresponding area of application derived from land use and agricultural management statistics and iii) a technical potential where GAEC standards are applied to the entire surface.