Towards a soil health diagnostic tool to preserve and improve ecosystem services of Belgian soils

Van de Casteele, Clélia [UCL] Pereira, Benoît [UCL] Vandeuren, Aubry [UCL] Bielders, Charles [UCL] Agnan, Yannick [UCL]

A healthy soil is able to perform many ecosystem services, such as plant production, water cycle regulation, biodiversity support, or climate regulation. An accurate assessment of soil health is an important step in implementing soil conservation and improvement practices for policy makers, soil professionals, and citizens. Many soil health indices have been developed for this purpose. They consist of a soil health score resulting from the aggregation of different types of soil parameters (chemical, physical, or biological). Most soil health indices, however, are tailored to a particular land use and pedoclimatic region that are not relevant to the Belgian context. Moreover, these indices often depend on complex and expensive measurements, making them poorly operational. Here, we propose a methodology that aims to develop a soil health diagnostic tool tailored for Belgian soils by capitalizing on the strengths of existing soil health indices. The proposed approach consists in a review of existing indices to select some to be applied and tested in the field. Based on the critical analysis of the application results, we will be able to develop a tool that would estimate ecosystem services provided by soils of various land uses in Belgium. This tool will be based, as far as possible, on inexpensive, rapid, and accessible measurement protocols. First, the literature review will identify the parameters, protocols, and ecosystem services assessed by existing approaches. To date, few land uses are covered, most existing indices having been developed for agricultural soils. Despite that some indices include only one type of parameter, recent indices (11 out of 23 indices considered) target a more comprehensive understanding by combining chemical, physical, and biological parameters. Indeed, soil health indices tend to encompass the soil in all its complexity, sometimes including indicators of soil functioning highlighting the proper functioning of soil processes, such as organic matter degradation or root development. This review will result in the selection of a limited number of relevant existing indices that will then be applied to various Belgian study sites, including contrasting land uses, in collaboration with the project partners (Aries Consultants and the Walloon Agricultural Research Centre). The application of these selected indices will allow to compare their outcome by considering error propagation, parameter sensitivity, and possible collinearity between parameters. The results obtained after index application will be confronted to an expert panel evaluation. This step will allow us to identify the strengths of existing approaches, on which we will capitalise to build the diagnostic tool. The development of a simplified tool both in terms of use and interpretation is intended to lead to sustainable land management that maintains and improves soil ecosystem services.