Recognition of natural soil bodies using textural properties of red freely drained soil profiles from KwaZulu-Natal and Mpumalanga

Abstract

The research examines the range of variation of soil texture for red freely drained soils associated with six of the major geological formations of KwaZulu-Natal and Mpumalanga. The soil profile information is derived from particle size analyses of over 4 000 geo-referenced profiles with links to the soil form classification class and the underlying geological formation as stratification criteria. Ranges in soil texture are plotted on a soil texture triangle diagram. Well-defined natural soil bodies could be identified and their range in textural properties determined for each geological formation. Such natural bodies appear unique and consistent for that geological formation. When considered over a range of geological formations, the boundaries of soil texture regularly overlap. Stratification of some kind is essential if the natural soil body concept is to have its practical significance extended to the lower taxa of a formal soil classification system. Principles to define natural soil bodies are discussed using the coastal belt of KwaZulu-Natal as an example.