Editorial for the <scp>EJP SOIL</scp> Special Issue 1 on “Climate‐Smart Sustainable Agricultural Soil Management for the Future”

It all began in a dark and crammed room in the basement of an unadorned office building close to the Eiffel Tower in Paris. It was broodingly hot, and outside a strike led to a standstill of public transport. Inside some 20 scientists juggled ideas and started gluing together what was to become the Research Programme EJP SOIL. What is EJP SOIL? It is an European Joint Programme on Agricultural Soil Management addressing key societal challenges including climate change and future food supply. EJP SOIL unites a unique group of 26 partner institutions, 46 including linked third parties from 24 European countries with 1327 experts collaborating. This is made possible by 5 years of funding under Horizon Europe 2020 with 50% national co-funding (https://ejpsoil.eu/). The aim is to pool national research efforts in order to make better use of Europe's research and development resources. Why was EJP SOIL initiated? Soil provides a wide range of ecosystem services and plays a critical role in climate change adaptation and mitigation. At the same time soil is a limited resource and it is fragile. The Mission ‘A Soil Deal for Europe’ estimated that 60%–70% of all soils in the EU are unhealthy due to current management practices, pollution, urbanisation and the effects of climate change. Climate change necessitates that European agriculture adapts and becomes more resilient to extreme events (droughts, fires, heatwaves, storms, and heavy rain), which have increased significantly over the past decade. European agricultural soils contain 31% of the EU's total soil carbon stocks and have the potential to store more carbon. However, those soils are severely affected by the loss of soil organic carbon (SOC, biodiversity, nutrients and increased salinization, sealing, compaction and pollution. Improved knowledge and farming practices are fundamental to address these challenges. Actions in stopping the damages are dependent on societal, scientific, policy, economic and educational capacities. The EJP SOIL goal is to improve the understanding of agricultural soil management by finding synergies in research, strengthening research communities and contributing to public policies. EJP SOIL takes into account the need for effective policy solutions and strategic multi-actor approach allowing to initiate inter-society dialogues and the adoption of best practices. Following this narrative, the first year of this five-year programme focused on taking stock of soil problems and their possible solutions, soil knowledge and soil knowledge gaps, and on expertise and availability of data. This is reflected in this first Special Issue of EJP SOIL by 10 surveys, eight reviews and four research papers. A new article type “Survey Article” was developed and introduced within the EJSS to contribute to systematic assessments across European countries, allowing to know the soil status and development of research and state of play. All papers resulting from EJP SOIL relate to one or more of the six “Expected Impacts” (EIs, Table 1) which were defined before the start of the programme. These EIs include targeted activities in response to societal, scientific, policy and operational challenges. They are crucial in integrating the impact of project activities and how they lead to expected outputs and forecasted outcomes of EJP SOIL, not only in the short term but also in the long term. In the following we highlight some important new insights on these six topics displayed in this Special Issue. Four articles bring new insights and critical reflections on sustainable practices for European soils. These studies collectively reveal the challenges and knowledge gaps that must be addressed to secure soil health and resilience across diverse landscapes. Each article adds a perspective to the ongoing conversation. For example, Weninger et al. (2024) highlight how inconsistent soil terminology creates barriers between researchers and practitioners, underscoring the need for clear, standardised language to facilitate widespread adoption of sustainable practices. Meanwhile, Paz et al. (2024) provide a comprehensive stocktake of current soil management practices across Europe, shedding light on underexplored areas like the complex relationship between tillage and long-term carbon storage in deep soil layers. Thorsøe et al. (2023) delve into the knowledge gaps around soil organic carbon loss, peatland degradation, and compaction—issues that demand both improved models and more effective communication between scientists and farmers. Finally, Keesstra et al. (2023) bring a policy-oriented perspective, advocating for interdisciplinary research on climate-smart soils aligned with the EU ‘Green Deal’. Their work calls for a collaborative, multi-scale approach that includes both scientific and socio-economic considerations. These articles not only identify key areas for future research but also offer actionable strategies to strengthen Europe's soil management framework. Together, they foster our understanding of soil management and its influence on climate mitigation and adaptation, sustainable agricultural production and the environment. Concerning climate mitigation, improved techniques for carbon sequestration are a major research focus. Expected Impact 2 spans from fostering better understanding of carbon sequestration to estimating and projecting the sequestration potential at the local and European scale. Along with this goes the evaluation of management practices such as amendments of external organic matters (EOMs). In the last decade, a lot of attention has been put on biochar and on understanding its effects and stability under different pedo-climatic conditions. In their study, Rodrigues et al. (2023) suggest a comprehensive metric for assessing the carbon sequestration efficiency of biochar, combining pyrolysis carbon yield and biochar stability in soil. By combining data from the literature with mathematical modelling, the authors suggest a pyrolysis temperature range in which carbon sequestration efficiency is optimal. Another management practice that has been suggested as favourable for, among others, the water regulation function of European soils (Blanchy et al. 2023) is the establishment of cover crops, in order to keep the soil covered and protected from, for example, wind and water erosion. Furthermore, two review articles on the effects of cover crops on SOC accrual are included in this Special Issue: while the meta-analysis of Fohrafellner et al. (2024) focuses on the fate of the carbon that comes as input from cover crops in different carbon pools, the review of Pisarčik et al. (2024) considers primarily the role of the roots on SOC accrual. In both cases, cover crops had a positive effect on SOC by feeding into the stable but also the more labile carbon pools (Fohrafellner et al. 2024) and supporting soil structure through appropriate combination of root traits (Pisarčik et al. 2024). Nevertheless, both studies highlight limitations and knowledge gaps of cover crop effects and experimental designs that require future attention. In addition to the two reviews, in a Norwegian study (Budai et al. 2024), the use of cover crops was the one agricultural measure that scored well for different criteria related to food production, among others due to the high carbon sequestration potential. Nevertheless, more knowledge is needed specifically related to regional conditions as shown in the example of Norway with short growing seasons. The important role of soil structure in SOC accrual that is highlighted by Pisarčik et al. (2024) is the centre point of a new dynamic model developed by Jarvis et al. (2024). The new model accounts for the effects of soil structure dynamics on water and organic matter cycling and is able to represent positive feedbacks in the soil–plant system that can lead to either soil physical degradation or soil structure recovery in the longer term. The model application has so far been limited to Swedish conditions, but the study suggests that considering dynamic soil processes can be of central importance for long-term predictions under a changing climate. Well-educated soil experts are needed to further develop carbon sequestration measures and in the next section it is questioned, whether our education system is sufficient to provide these? It is well known that strengthening scientific cooperation and capacity promotes knowledge sharing and soil literacy to address global issues like biodiversity loss, land degradation and extreme climate events to find regional and local scale solutions. To this end, Walter et al. (2024) surveyed almost 300 European stakeholders to identify 60 soil-related professional profiles grouped into 10 clusters, emphasising diverse fields like communication, data science, and policy. These clusters inform about updates of existing courses and the development of new interdisciplinary programs. Enhancing educational programs supports achieving sustainable soil management through improved soil literacy. On the other hand, Veenstra et al. (2024) presented the perspectives of 669 European stakeholders who emphasised dual agronomy-soil science profiles with strong soil science skills. They advocated integrating soil biology and ecology into soil education, maintaining core fundamentals. Prioritising effective two-way knowledge exchange with farmers is crucial to foster adoption of sustainable management practices that promote soil health. As farmers are highly interested in their own land and soil, soil data have to be made available. The need for soil data has led to a range of activities from the rescue of legacy data to accelerating harmonising data collection and utilisation of soil health information. A clear overview of data availability, data types and indicators across Europe has not been provided yet. Cornu et al. (2023) identified 170 soil databases across 24 European countries, highlighting gaps in data harmonisation and underreported indicators like soil biology. They highlighted that integration of diverse data and harmonised methods is essential for effective data reuse to support decision making on soil health policies. Soil organic carbon (SOC) is vital for soil quality and ecosystem services but it has been declining across Europe due to unsustainable practices (Prăvălie et al. 2024). EU policies, such as the ‘Carbon Removal and Carbon Farming Regulation’, the ‘Soil Monitoring Law’ and the ‘Nature Restoration Law’ aim to preserve SOC. However, evaluation faces challenges from diverse national monitoring strategies. Meurer et al. (2024) recommended five potential strategies for harmonisation under the EU ‘Soil Monitoring Law’. A special challenge is the need for quick and reliable determination of SOC. In-field soil spectroscopy, particularly Vis–NIR (350–2500 nm), enables rapid and chemical-free analysis of multiple soil properties. The review of Piccini et al. (2024) identifies gaps in reliability, emphasises the need for harmonised protocols to advance practical applications and to integrate laboratory and in-field methodologies. If farmers or farm advisers are enabled to make soil properties visible in the field, adoption of sustainable practices will become more likely. One way of fostering adoption of scientific results is citizen science. Engaging the public in citizen science empowers communities, leverages open data, drives large-scale research and fosters sustainable soil management practices. Soils, crucial for ecosystems and food production, are inspiring increased citizen science projects in Europe. Mason et al. (2024) reviewed 24 citizen science projects to highlight that 66% studied soil biodiversity, while others focused on vegetation and SOC. Success criteria recommended for citizen projects are: aligning with citizen science principles, co-creation, knowledge-sharing networks, and sustained citizen engagement, offering untapped potential for advancing European soil health research. Understanding current usage, socio-technical barriers, and bio-physical limitations is crucial to foster adoption of soil health improving practices. Heller et al. (2024) identified 53 management practices addressing soil challenges and their adoption rates across 20 European countries. Key barriers identified were lack of knowledge of management practices and equipment, financial risks and traditions. In addition, evaluation of climatic constraints showed that 54% of arable land is suitable for cover cropping, emphasising a region-specific approach to increase the adoption rate. Criscuoli et al. (2024) reviewed existing carbon removal methodologies for agricultural soils from industrialised countries in temperate zones. More specifically, they compared extra-European Union removal methodologies (from USA, Canada and Australia) with the ones proposed by the European Commission. Based on their literature review, the authors recommend a list of proposed European Commission regulations on carbon removals, including expanding the list of eligible agricultural practices and setting a minimum maintenance time frame for each of the practices. This should ensure interaction and conformity with policies already in place, such as the European ‘Common Agricultural Policy’ (CAP), the ‘Soil Monitoring Law’, and the ‘Land Use/Cover Area Frame Survey’ inventory (LUCAS). A specific aim of the European policies as specified in the ‘European Green Deal’ is the reduction in nutrient losses from both organic and mineral fertilisers of at least 50% by 2030, while ensuring no deterioration in soil fertility. Jordan-Meille et al. (2023) and Higgins et al. (2023) explore whether this can be targeted by harmonisation of the very heterogeneous fertiliser regulations across Europe. Jordan-Meille's study reveals substantial variability in nitrogen (N) fertilisation methods and recommendations across 10 Western European countries, with differences of up to 100 kg N ha−1. This inconsistency is due to varying models of nitrogen availability and crop uptake, highlighting the complexity of standardising fertilisation practices. Instead, tailored, farm-scale mass balance approaches are suggested for better nitrogen use efficiency. Higgins expands this analysis with a stocktake across 23 European countries, showing that harmonisation could improve nutrient management and help meet EU targets for nutrient reduction. However, uniformity is difficult due to diverse soil types and agro-ecosystems. Both studies emphasise that fostering shared learning and collaboration, especially between neighbouring countries with similar environmental conditions, could enhance nutrient management strategies. Together, they call for adaptable fertilisation policies that respect local conditions while promoting sustainability. This first Special Issue of the European Journal of Soil Science highlights the significant contributions of the EJP SOIL programme in advancing sustainable and climate-smart soil management in Europe. Through a combination of surveys, reviews, and research articles, it provides critical insights into the six Expected Impacts (EIs) of the programme, including fostering sustainable soil management, understanding carbon sequestration, and promoting stakeholder adoption of best practices. The findings in this Special Issue also highlight the importance of harmonised soil data systems, cooperative research, and region-specific approaches to address fertilisation and soil health challenges effectively. These contributions align with European Union goals, such as the ‘Green Deal’ and the ‘Soil Monitoring Law’ as well as the ‘Carbon Removals and Carbon Farming Certification Framework’, offering actionable pathways to enhance the resilience and sustainability of Europe's agricultural soils. A key resource that supports these efforts is the EJP SOIL Knowledge Sharing Platform (https://ejpsoil.eu/knowledge-sharing-platform), which serves as a hub for collaboration among scientists, policymakers, and practitioners. As the synthesis and publication of EJP SOIL outputs continues in Special Issue 2 and other venues, the lessons and innovations presented here will serve as a foundation for future research, policymaking, and practice. Collectively, these efforts will contribute to the sustainable management of Europe’s soils, addressing the challenges of climate change and growing food demands. Sophie Zechmeister-Boltenstern: conceptualization, investigation, supervision, writing – original draft, writing – review and editing, data curation, resources. Rajasekaran Murugan: investigation, writing – original draft, writing – review and editing, data curation, resources. Rebecca Hood-Nowotny: writing – review and editing, data curation, resources. Lars Munkholm: writing – review and editing, data curation, resources. Claire Chenu: writing – review and editing, funding acquisition, project administration, data curation, resources. Katharina Meurer: writing – original draft, writing – review and editing, investigation, data curation, resources. This research was developed in the framework of the European Joint Programme for SOIL “Towards climate-smart sustainable management of agricultural soils” (EJP SOIL) co-funded by the European Union Horizon 2020 research and innovation programme (Grant Agreement No. 862695) and by 24 European countries. The data that support the findings of this study are available on request from the corresponding author.

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