The Application of Pedology As an Environmental Science in South Africa.

Soil Science has traditionally been an agricultural science.  Soil classification therefore also focused primarily on the classification of soil for agricultural purposes.  Soil Taxonomy - A Taxonomic System for South Africa has been used effectively for soil classification since 1991.  Recent developments in South Africa, however, challenged this preconception, resulting in substantial reconsideration of the classification system.  First was the development of hydropedology.  This led to the incorporation of soil taxa in the ACRU hydrological model, greatly improving the soil interflow component of the model.  Next was the application of soil classification as primary criterion in wetland delineation for urban and industrial development.  Lastly was the application of soil classification in carbon sequestration studies.  A recent development of note was the initiation of a study to determine if there exists a relationship between wetland soil properties and the aestivation of the Rift Valley Fever Virus.  These developments had obvious impacts on the soil classification system.  Firstly the depth limit had to be removed, while it is currently 1.5 m.  This means that the system is, in essence, open-ended and that all horizons can be recognised in the classification of the soil.  Only one additional diagnostic (gypsic) was added, while numerous diagnostics were improved.  In many cases and where possible, these diagnostic changes aimed to better align South African diagnostics with Soil Taxonomy and/or the WRB.  The South African classification system will now have two levels taxonomic levels additional to the current two.  One will be a higher ‘Soil Group’ level aimed at lay person use and another, the lowest level, aimed at better describing soils.  The lowest level will use predefined ‘qualifiers’ to be used as required, while the highest level will be a grouping of the soil forms.