A classification of soil solid material for natural and anthropogenic soils

Soil classification systems give an idea which soils are similar regarding their morphology (often developed through pedogenesis) and therefore assigned to the same class, and which are dissimilar and therefore assigned to another class. The morphological criteria are often selected along pedogenetic lines of thinking. Soil functions however often depend on other physical and chemical properties not covered in the same consistent and balanced way, for example neither in World Reference Base for Soil Resources nor US Soil Taxonomy. By using the concept of substrate, a concise and hierarchical soil solid material classification that can be used in parallel to a morphological or morphogenetic soil classification is described. It includes parent material genesis (geogenesis), fine earth texture, coarse fragments, lime and lithic carbon content, and rock type and enables to characterize the soil horizon material—as a complement to the pedogenetic horizon designation—and the entire soil profile—as a complement to the (genetic) soil type. The system covers natural and anthropogenic substrates (as found, e.g., in urban areas, on landfills, etc.). Its hierarchical approach can be used in single profile descriptions, but also in soil mapping, for which it provides a framework for delineation and rule-based aggregation of spatial soil units.