The German Soil Systematics and the Rationale Behind Its Revision
Einar Eberhardt, Karl Stahr, Peter Schad, Alexander GröngröftABSTRACT
Background
The German Soil Systematics is a pedogenetic classification based on the morphological expressions of pedogenic processes and has been developed over several stages since 1952. The system has successfully been in use for soil classification and soil survey for almost 70 years. Pedogenic processes are identified in most cases with parameters recognizable in the field. Almost 20 years after the last edition, a revision of the soil systematics and its horizon definitions has been made..
Aims
The revision was done in order to include (i) soil geneses which logically did not fit into the previous structure of the system, e.g. soils with accumulation from lateral influx (Rheosole), (ii) soils resulting from environmental change, e.g. former peat soils whose peat degradation has progressed so far that they are no longer organic soils (Abmoor Subtypes of several mineral soils), and (iii) the Andosole and Umbrisole (similarly defined as in the WRB). Besides, some logical inconsistencies should be addressed. Guiding ideas for the rearrangement and additions were to make the pedogenetic principles better visible, to have a more homogeneous, balanced structure, and to cover all soils relevant for soil survey and mapping.
Results
The pedogenic processes that formed the soil are identified in most cases with parameters recognizable in the field and encoded with an extensive system of horizon symbols. The presence and (to some extent: the absence) of certain horizons in a certain depth in the profile and some thickness criteria are used to class the soil in a seven‐level Soil Systematics with: Divisions (2, mineral and organic soils), Subdivisions (7, related to water and oxygen availability), Classes (23, main genetical pathways), Types (56, genesis and intensity of processes), Subtypes (ca. 300, including Norm, Deviating and Transitional Subtypes), Varieties (2000, qualitatively diverging from their subtypes) and Subvarieties (quantitative additions to the Variety information). The logical inconsistencies were resolved by dissolving some former Classes and Types into now Types or Subtypes. The number of Types did not increase.
Conclusions
A new, consistent structure with all required new entitities could be achieved that will serve current and future needs. To include more objective criteria in the delimitation of soil systematic units is a common endeavor of the development of many national systems. A closer proximity to WRB was not a primary goal here, in contrast to other national system updates of the last years. This was to keep the clear advantages of the German Soil Systematics, some of them setting it apart from WRB and/or US Soil Taxonomy, in particular a more consistent justification for its higher‐level classes.