Doctoral Degrees (Soil Science)

Permanent URI for this collection

https://scholar.sun.ac.za/handle/10019.1/569

Browse

Browsing Doctoral Degrees (Soil Science) by browse.metadata.advisor "Lambrechts, J. J. N."

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    Die gronde van die Karoo
    (Stellenbosch : Stellenbosch University, 1988) Ellis, Freddie; Lambrechts, J. J. N.; Stellenbosch University. Faculty of AgriSciences. Department of Soil Science.
    ENGLISH ABSTRACT: Soil information pertaining to one of the most extensive arid and semi-arid areas of South Africa is limited. This area, known as the Karoo, comprises 36 million hectares or 32% of the surface area of South Africa. The purpose of this study was to gather as much information as was possible regarding the distribution, morphology, classification, physical, chemical and fertility status of the soils of this area. The pedosystem concept was used to identify and demarcate the terrain and soils of this study area. This assumes that a fair degree of interdependence exists between the environmental characteristics, terrain morphology and the soil. From this a general map (scale 1: 1 000 000) of the Karoo was produced. This illustrates broad soil patterns, while topsoil texture classes and underlying materials can easily be read from the map. In addition, terrain characteristics (i.e. percentage level land and relief) are also given. For the interpretation of soil and terrain characteristics it was necessary to define a small number of natural regions of the Karoo. In these regions the natural resources of soil, terrain and climate are strongly interdependent. They have been called broad physiographical regions. Twenty such regions have been identified in the Karoo. For each broad physiographical region a description is given of the nature and extent of the terrain together with the distribution of the soils with their morphology, classification, physical and chemical characteristics and fertility status. The soils of the Karoo can conveniently be arranged into seventeen broad soil patterns. It was clear that shallow calcareous lithosols and red apedal soils with a high base saturation occupy the largest area of the Karoo. The red soils usually have sandy topsoils (A horizon) while the clay content of the calcareous lithosols is slightly higher varying from 6- 15%. The deep, weakly structured soils which are associated with unconsolidated deposits and which should have a high potential for irrigation, occupy ca. 1 million hectares and occur mostly in the central , northern and eastern parts of the Karoo. Approximately 22 million hectares (60%) of the soils of the Karoo are stony and a further 14% are covered by desert pavement.