Bodenqualitätsindex

Use soil information for spatial planning

Between 1985 and 2009, Switzerland lost arable land equivalent to 2% of the surface of the entire country. The loss mainly concerns fertile soils in the Swiss Main Plateau and in the valleys. Due to new zoning according to the revised Spatial Planning Law there is lesser loss, infrastructural and other projects outside of building zones, however, still require a considerable use of ground. This is especially grave in terms of sustainable spatial planning, since there is no nationwide instrument that includes soil quality as a criterion for decision-making besides crop rotation areas, which are strictly agriculturally orientated and managed differently from canton to canton.

There is an increasing awareness in research, planning and politics that soil has so far been insufficiently considered in decision-making. The National Research Programme NRP68 “Soil as Resource” was a clear signal and among other findings resulted in the operationalisation of soil quality in the shape of two indices applicable in spatial planning. Whether or not the inclusion of soil information into spatial planning practice indeed resulted in an added value and which furthering or hindering factors were to be considered in an implementation, however, remained unanswered.

In a pilot study, PLUS and BHP Raumplan are thus developing a first set of recommendations for confederacy, cantons and municipalities to further the use of soil information in spatial planning. In a first step, based on spatial planning problems of the past years in six chosen municipalities, we will determine which role soil information and its availability played in decision-making processes. The findings will be used to develop fictitious planning scenarios which will be tested with different kinds of soil information: the nationwide available soil suitability classes, the soil quality indices developed within the framework of the NRP68 as well as a simple soil quality index based on locally available data. The question to what extent the various sets of soil information in cooperation with spatial planning instruments (e.g. a steering tax) are able to further sustainable spatial planning and land-use, is of particular interest. With view on their practical application, the results will be discussed with representatives of the spatial planning practice. Two goals are aimed for: on the one hand the identification of hindering or furthering factors regarding the consideration of soil information, on the other hand the clarification of the need for more extensive soil information based on ecosystem services.