For the advancement of climate-smart sustainable management of agricultural soils, we have to know more about three major topics of soil research, namely 1. Soil carbon stocks, 2. Soil degradation and fertility, and 3. Strategies for improved soil management. This report addresses state-of-the-art knowledge on these topics by bringing together the expertise of 254 members of the EJP SOIL consortium and by reviewing more than 1,800 documents. Based on this aggregation of available knowledge we identify major knowledge gaps raised by several authors. Regarding the first topic, ‘Carbon stocks’, the analysis of European literature and national inputs identified the following main knowledge needs: Assessment and mapping of SOC under various management practices as well as life cycle assessment of management options beyond farm scale; the effect of C-enhancing management measures on GHG emissions; standardised approaches for SOC assessment across nations; the influence of management and environmental factors on deep soil carbon; SOC spatial and temporal dynamics; more information on SOC sequestration potentials of different soils across Europe; monitoring of SOC changes in long-term field experiments; the impacts of policies on C sequestration and means of transfer of information to relevant stakeholders; mapping peatlands and estimating their SOC stocks. Regarding ‘Soil degradation and fertility’ the following knowledge needs were revealed by the review of national inputs as well as by EU projects and literature: Modelling and monitoring changes in SOC at different scales and climates; soil mineral SOC interaction in relation to soil structure, productivity and soil nutrients; impact of field traffic and livestock trampling on soil structure; soil functions and plant growth in different pedo-climatic zones; development of engineering solutions to limit risk of compaction; assessment of soil compaction impact in a changing climate and regulation measures to prevent soil structure degradation; improved monitoring programmes for wind, water and tillage erosion; development of site-specific soil erosion models and improved validation of the models; monitoring programmes and harmonised monitoring systems for pollutants; optimizing the use of plants for remediation of contaminated soils and the need for long-term soil remediation experiments; monitoring programmes of soil salinization and the impact of climate change on salinization risk; quantification of soil sealing; and, finally, systematic monitoring of soil acidification on non-forest soil. For the topic ‘Strategies for improved soil management’, numerous knowledge needs have been mentioned, such as: Monitoring programmes for different soil parameters to be used for soil sustainable management decisions; monitoring and modelling sustainable soil management practices at a site-specific level under different climate change scenarios; need for a common conceptual understanding of crop/cover crop rotations and the effects of diversification – to be created at cultivar and genetic level; spatial and temporal dynamics of C and nutrients in the soil-plant-atmosphere system; multidisciplinary/comprehensive studies of cover cropping, intercropping and perennial cropping under different pedo-climatic conditions and with consideration for climate change; assessment of the effect of different organic amendments on soil C storage, GHG emissions, productivity, nutrient losses, water availability and soil quality; assessment of management practices to mitigate subsoil compaction and practices for efficient water management (site-specific) in a changing climate. For all of the three addressed topics, more specific knowledge gaps were identified either from the European projects and literature or from the national inputs. In a general analysis of the three topics, peatlands, models and monitoring, and soil compaction were overarching issues, which demand assessment and improved management. The need for harmonised soil data and aligned monitoring programmes were also identified as key issues. This report provides a list of important general and specific aspects within the three addressed topics, which are fundamental for setting the targets for the EJP SOIL research roadmap.
