Areas available for potential carbon sequestration in European agricultural soils

In order to estimate a feasible carbon (C) sequestration potential in European agricultural soils, we need to know the area where additional measures that increase soil organic carbon (SOC) can be implemented and the corresponding SOC accrual rates. In this study, we focus on the former and identify areas where promising SOC increasing practices can be implemented on European agricultural soils. The practices considered include a higher share of agroforestry, cover crops replacing bare winter fallows, reduced tillage instead of ploughing and the integration of perennial legumes and leys into crop rotations. Open-access data of European Farm Structure Surveys as provided by EUROSTAT at NUTS2 level serve as a reference for the intensities at which the measures are already implemented in Europe. It was assumed that only the further spread of these measures could potentially sequester additional C in soils. We argue that the adoption of reduced tillage is the practice that covers by far the largest area relevant for potential C sequestration in soils under current food, feed, and fibre demands. The replacement of bare winter fallow with cover crops is restricted to regions with sufficient growing degree days to allow a second crop after harvest. The introduction of more woody features like hedgerows and alley cropping to agro-ecosystems, as well as the integration of more perennial legumes or leys in present crop rotations creates the need for land reallocation and likely compromises agricultural productivity. Overall, we conclude that reduced tillage may emerge as the most promising practice for atmospheric C sequestration in European agriculture despite its reported relatively low SOC accrual rate per hectare. Trade-offs between C sequestration in soils, agricultural production and agricultural demand warrant further inter-disciplinary attention.