The European Mission "A Soil Deal for Europe" highlights the need for robust, scalable and operational indicators capable of supporting soil health assessment across diverse agricultural systems. While physical and chemical soil properties are routinely monitored, biological indicators remain underused despite their central role in ecosystem functioning and agricultural sustainability.
This study presents the establishment of a biological soil health baseline within the French Living Lab located in the Landes (South-West France). A total of 135 soil samples were collected across 25 farms representing a diversity of agricultural systems and pedoclimatic conditions. Three complementary biological indicators were assessed: total microbial abundance, relative microbial biodiversity and dehydrogenase activity as a proxy for overall microbial metabolic activity.
The objective was not only to characterize the current biological status of soils across the territory, but also to evaluate the potential of combining these indicators into an operational framework for long-term soil health monitoring within a Living Lab context. Attention was given to the relationships among community size, biodiversity and biological activity, as well as to the variability observed between farms and management contexts.
Results reveal substantial spatial heterogeneity across the territory, highlighting the diversity of biological soil conditions encountered under real farming situations. Preliminary analyses indicate that microbial abundance, biodiversity and enzymatic activity provide complementary rather than redundant information, suggesting that multiple biological dimensions should be considered when assessing soil health. The data further demonstrate the feasibility of deploying harmonized biological monitoring at territorial scale and provide a reference point against which future changes associated with soil health interventions can be evaluated.
Beyond the characterization of current conditions, this work contributes to ongoing efforts to identify practical biological indicators for soil health assessment and monitoring. The baseline established through this study will support the evaluation of future innovations implemented within the Living Lab and offers a framework that could be replicated in other European territories engaged in the transition towards healthy soils.