Regional simulation of long-term organic carbon stock changes in cropland soils using the DNDC model: 2. Scenario analysis of management options

The development of successful agricultural policies in response to the Kyoto Protocol is aided by the identification of regions where the effects of soil organic carbon (SOC) sequestration measures can be maximized. We describe a modelling approach which incorporates a spatial analysis of the results from regional simulation under different management alternatives. SOC stock changes in Flemish cropland soils, simulated with the DNDC model, were previously fitted to a large data set of SOC measurements for the period 1990-2000. Using the results of this study, simulations with DNDC of SOC stock changes during the period 2006-2012 including the Kyoto commitment period were carried out at the community level for a business-as-usual (BAU) scenario and seven alternative agricultural management options for SOC sequestration. The baseline SOC stock decreased during that period by 0.15 t OC ha(-1) year(-1) compared with 0.48 t OC ha(-1) year(-1) in the 1990s. All alternative scenarios resulted in net SOC storage compared with the BAU scenario, but none of the individual scenarios were able to increase the average absolute SOC stock. Overall, spatial variability in SOC storage for the selected management options was strongly dependent on the current distribution of crops and associated management. The modelling approach used in this study provides a case study in regional scale modelling of SOC sequestration and is applicable to other regions in Europe with comparable intensive agriculture.