Soil Morphology Revisited; A Comparison of Various National and International Systems.

Soil science, as with all science, is developing globally and there is a growing need to develop a taxonomic system to communication soils information across national boundaries.  Each taxonomic system uses a descriptive system as a parameter for determining the taxonomy of a soil.  The Universal Soil Classification system was proposed, and a committee within the IUSS is currently evaluating soil taxonomic systems and language used to describe soils.  In this project, we compared the descriptive systems used in World Reference Base, US Soil Taxonomy, Brazilian Soil Taxonomy and the Australian soil taxonomic system to determine the similarities and differences between the rules for describing soil texture and structure. The texture classes were similar amongst the soil taxonomic systems; however, there were slight differences. Other researchers suggested that the Australian system adopt the particle-size fraction of 50 micrometers for silt, used in WRB, Brazilian Soil Taxonomy and US Soil Taxonomy. The use of a particle-size fraction of 20 micrometers for silt within the Australian system contributes to confusion when comparing textures. The structure classes were also similar amongst the soil taxonomic systems; however, there were slight differences as well. Soil structure and texture are important soil properties and developing consistent terminology would be beneficial for communicating soil information.