Citizen Science for Soil Monitoring and Protection in Europe: Insights from the PREPSOIL Project Under the European Soil Mission

Citizen science (CS) is increasingly recognized as a complementary approach for addressing soil health challenges-including erosion, pollution, nutrient imbalances, and biodiversity loss-by harnessing public participation to broaden spatial and temporal data collection. This review synthesizes findings from the following: (i) a systematic analysis of peer-reviewed literature and grey sources, (ii) a database of 96 CS initiatives compiled by the European PREPSOIL project, and (iii) questionnaire surveys and workshops conducted in five Living Labs across Europe. Our analysis indicates that volunteer-driven monitoring can enhance the volume and granularity of soil data, providing critical insights into parameters such as organic carbon content, nutrient levels, and pollutant concentrations. However, persistent challenges remain, including inconsistencies in data validation, volunteer attrition, and concerns regarding digital literacy and data privacy. Despite these challenges, ongoing efforts to standardize protocols, integrate remote sensing and sensor-based validation methods, and employ feedback mechanisms improve data reliability and participant engagement. We conclude that sustained capacity-building, transparent data governance, and stakeholder collaboration, from local communities to governmental bodies, are essential for fully realizing the potential of citizen science in soil conservation. This work is framed within the context of the European Soil Mission, and CS is demonstrated to meaningfully support sustainable land management and evidence-based policymaking by aligning public-generated observations with established scientific frameworks.