An open-access (meta)data platform for Long-Term Field Experiments to support soil monitoring and assessment

Long-Term Field Experiments (LTEs) are permanently operated agricultural research infrastructures designed to study the long-term effects of management practices under changing climate conditions. These trials are essential for assessing the impacts of practices on crop production and soil across different textures and types, and for understanding soil health trajectories. LTEs therefore represent a high-value legacy data; however, their information is typically dispersed across various institutions and difficult to access.To address this challenge, we developed an open-access (meta)data and knowledge platform centred on the LTE-Map (https://lte.bonares.de), providing a free and open access service to compile, harmonize, and reuse information on LTEs across Europe. The LTE-Map provides a spatial representation of LTEs and their key attributes by exchanging and harmonizing information from EU- and nationally funded initiatives (BonaRes, SoilWise, EJP SOIL). LTEs are clustered into categories directly relevant for soil monitoring (management operations, land use, duration, experimental status, etc.) (Grosse et al., 2020; Donmez et al., 2022; Donmez et al., 2023; Blanchy et al., 2024). Applying minimum duration thresholds of 5 years for mid-term trials and 20 years for LTEs, the (meta)database currently includes approximately 700 LTE records in a well structured and harmonized form across Europe and in a global context.Our platform indicates that fertilization experiments represent the dominant research theme, followed by crop rotation and tillage, highlighting both strengths and gaps in long-term soil research coverage. By enabling the reuse of LTE data (as published in the BonaRes Repository - https://doi.org/10.17616/R31NJMVY) through geospatial approaches, including GIS-based climate impact analysis (Donmez et al., 2023), spatial representation (Grosse et al., 2020), GeoAI, and modelling (Donmez et al., 2024), the platform supports cross-country comparability and methodological innovation. It facilitates the scaling up of soil and agricultural knowledge from field to landscape level and supports strategies for resilient agricultural production, soil management, and food security in Europe, contributing to EU soil monitoring objectives. In our contribution, we demonstrate the potential that the LTE map has as a platform for collaboration in general and identify possible scientific evaluation methods for published LTE data and metadata.ReferencesDonmez C., Sahingoz M., Paul C., Cilek A., Hoffmann C., Berberoglu S., Webber H., Helming K., (2024): Climate change causes spatial shifts in the productivity of agricultural long-term field experiments. https://doi.org/10.1016/j.eja.2024.127121. European Journal of Agronomy.Blanchy G., D’Hose T., Donmez C., Hoffmann C., Makoschitz L., Murugan R., O’Sullivan L., Sanden T., Spiegel A., Svoboda N., Boltenstern S.Z., Klummp K., (2024): An open-source database of European long-term field experiments. https://doi.org/10.1111/sum.12978 Soil Use and ManagementDonmez C., Schmidt M., Cilek A., Grosse M., Paul C., Hierold W., Helming K., (2023): Climate Change Impacts on Long-Term Field Experiments in Germany. https://doi.org/10.1016/j.agsy.2022.103578. Vol.205, 103578. Agricultural Systems.Donmez C., Blanchy G., Svoboda N., D’Hose T., Hoffmann C., Hierold W., Klummp K., (2022): Provision of the metadata of European Agricultural Long-Term Experiments through BonaRes and EJP SOIL Collaboration. https://doi.org/10.1016/j.dib.2022.108226. Data in Brief.Grosse, M. et al., (2020): Long-term field experiments in Germany: classification and spatial representation. https://doi.org/10.5194/soil-6-579-2020. Soil.