A conceptual framework for soil function evaluation: Towards a common base

The increasing pressure of humans on soils affects their ability to provide key functions and deliver ecosystem services. In the last decades, many methods and tools have been developed to evaluate soil functions, with the aim of providing guidance to land users and policymakers for the sustainable management of soil resources. These methods and tools, however, have been developed in isolation from each other using different conceptual frameworks such as soil health or soil quality, which in turn have evolved over time. This currently results in a diversity of available terminology and definitions to represent the objectives of evaluation and to describe the information on soil functions that is produced in the quantification process. For actors interested in soil function evaluation, this diversity is a source of confusion. In this paper, we develop a conceptual framework to describe the types of information on soil functions that can be searched for and link them with soil functioning and user needs. These concepts are soil function supply, soil dynamic capacity for a function, and soil inherent capacity for a function. The framework is then used with a set of publications on soil function evaluation to identify the information on soil functions they produce and helps rank these publications in terms of objectives and produced information. We highly recommend authors to use our framework to explicitly link their objectives with the information on soil functions that is sought and the method used to obtain this information, in relation to the specific context of the study. The framework also helps to open up a discussion on the fundamentals of monitoring soil functions for the sustainable use of soil resources. • Numerous methods are available to assess soil functions. • We propose a framework to understand what information on soil functions can be produced. • Three types of information on soil functions can be obtained: supply, dynamic capacity, and inherent capacity. • The framework is used to explain the differences in methods and information from the literature. • The framework will aid developing future methods that explicitly link user needs, objectives of evaluation, information of interest on soil functions, and applied quantification methodology.