Assessment of soil multi-functionality to support the sustainable use of soil resources on the Swiss Plateau

Spatial information on soils and their abilities to fulfil their functions is key to sustainable soil resource use. Maps indicating how soils fulfil their functions, e.g., regulating nutrient and water flows, providing appropriate habitats, and supporting biomass production, have allowed soil information to be embedded in spatial planning programmes. We adapted 10 static soil function assessment (SFA) methods and applied them to agricultural soils in a study area on the Swiss Plateau. Soil function maps were created by applying the SFA methods to maps of eight basic soil properties generated previously using digital soil mapping techniques. The soil function maps were compared with results obtained by applying the SFA methods to data for >7000 soil profiles to determine how reasonable the maps were. Soil in the study area had distinctive spatial patterns for most of the regulation, habitat, and production functions, clearly indicating the multiple roles played by soil in supporting ecosystem services. The fulfilment of individual soil functions is linked to the inherent soil properties, the terrain, and climatic conditions. The soil function maps agreed well with the SFA results for the profiles in terms of land use, soil type, and drainage class. Four aggregation rules were tested to give total assessment values (soil indices). Aggregating the 10 soil functions into an overall soil functionality value gave quite diverse spatial patterns, indicating that merging might average out the spatial characteristics of certain soil functions. We conclude that a quite comprehensive set of soil functions can be assessed using spatial information for eight basic soil properties to a soil depth of at least 1 m and approved pedotransfer functions for secondary soil properties. SFA methods for the production function are well established, but methods for assessing habitat and regulation functions need to be developed further. This is also true for forest soils, for which SFA methods are yet to be established.