An operational definition of absolute soil quality and soil health, and why we need both in practice

Abstract. The concept of soil health is becoming increasingly popular. Yet, the way to measure it remains unclear, which hinders its effective consideration in decision-making processes. We propose a general framework to interpret soil data, including the scoring of absolute soil quality (the state of an indicator representative of a soil function regarding an absolute maximum) and (ii) the scoring of soil health (the relative level of an indicator with respect to soil intrinsic potential). We underline that the scoring of soil quality and potential quality is central in land planning and excavated soil reemployment (i.e., matching land future use with soil capabilities) whereas soil health, as the mirror of soil degradation, is essential for soil restoration and sustainable management. We illustrate the approach with saturated hydraulic conductivity as an indicator of soil infiltration capacity for 42 measurements from contrasting soil types and uses, and demonstrate that the approach can be generalized to other soil indicators and functions. Overall, we outline the need to refine target or threshold values for the scoring of both soil quality and soil health, thereby better equipping stakeholders for sustainable soil management and land planning.