ETC/ULS Report 2021- Soil monitoring in Europe

Indicators and thresholds for soil quality assessments

24 Sep 2021

Rainer Baritz, Wulf Amelung, Veronique Antoni, John Boardman, Rainer Horn, Gundula Prokop, Jörg Römbke, Paul Romkens, Bastian Steinhoff-Knopp, Frank Swartjes, Marco Trombetti, Wim de Vries

This report summarizes the current state of knowledge about key soil indicators in the light of current and new policies in support of healthy soils. Healthy soils are understood to have full capacity of their functions and do not exceed the recommended thresholds. This approach is essential in order to assess soil health in the context of policy challenges and societal needs. The development and application of thresholds sensitive to the functioning of the soils, is the prerequisite to understand where soils are degraded. Once critical limits are exceeded, the soil cannot provide its multiple services, for example as a medium to filter contaminants or store and release nutrients. Indicators are sorted by soil threat, though the underlaying mechanisms is the sensitivity of parameters towards soil processes, thus its functions. Each indicator is introduced based on a short literature review, and explained based on common definitions. Quantified thresholds as targets for healthy soils are provided for soil organic carbon, nitrogen and phosphorous, acidification, soil pollution, erosion and compaction. No such limits are yet available for soil biodiversity, while for soil sealing, examples for politically set, country-specific limits are provided.