In order to evaluate the impact of agricultural practices on soil functions we need methods to quantify these soil functions. One difficulty is that there are no simple sensors for the different soil functions. They are the result of many processes in soils and their interactions. One approach for the evaluation of soil functions is to identify suitable key properties (indicators) together with a method to related such indicators to the individual soil functions.

With this regard, we differentiate between the natural potential of a soil to fulfil the various soil functions and its current soil function state. The assessment of the potential of a soil is based on inherent soil properties (soil depth, horizonation, texture, mineralogy), whereas the assessment of the actual state is based on variables that can be manipulated by soil management (soil organic matter, nutrient content and availability, bulk density, pH value, hydraulic properties, biological activity). Overall, this allows for the site-specific assessment of (1) the soil function state, (2) its change due to agricultural management, and (3) its capacity for improvement.

Reference:
Vogel, H. J., Eberhardt, E., Franko, U., Lang, B., Ließ, M., Weller, U., Wiesmeier, M. & Wollschläger, U. (2019). Quantitative evaluation of soil functions: potential and state. Frontiers in Environmental Science, 7, 164