Soil classification systems: World reference base and soil taxonomy

Abstract

This chapter considers the characteristics of the two soil taxonomies that have made them world references: World Reference Base, WRB (IUSS Working Group WRB, 2015) and Soil Taxonomy, ST (Soil Survey Staff, 2014). Diagnostic horizons that serve to classify soils are mentioned, after recalling the genetic horizons. The first hierarchical levels of both taxonomies are described: the Reference Soil Groups of the WRB and the Orders of the Soil Taxonomy. Finally, the procedure for classifying and naming a soil is described using, as an example, the field observations and the analytical data from a soil profile of Toledo, Spain.