Die gronde van die Karoo

Ellis, Freddie (1988)

Proefskrif (Ph.D. Agric.) -- Universiteit van Stellenbosch, 1988.

Thesis

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.

AFRIKAANSE OPSOMMING: Grondkundige inligting oor die ekstensiewe ariede en semiariede deel (36 miljoen hektaar of 32%) van Suid- Afrika wat as die Karoo bekend staan, is beperk. Hierdie studie is daarop gemik om soveel as moontlik inligting oor die verspreiding, morfologie, klassifikasie, fisies - chemiese kenmerke en grondvrugbaarheidstatus van die gronde te versamel en te beskryf. Die pedosisteemkonsep, wat gebaseer is op die aanname dat daar ' n redelike mate van onderlinge afhanklikheid tussen die omgewingskenmerke, terreinmorfologie en grond is, is gebruik om die terrein en gronde van die Karoo te identifiseer en af te baken . Hierdie inligting is gebruik om 'n veralgemeende grondkaart van die Karoo op ' n skaal van 1: 1 000 000 saam te stel. Hierdie kaart is op so ' n wyse saamgestel dat, benewens die bree grondpatroon, inligting oor die dominante oppervlakkenmerke, die bogrondtekstuurkias en onderliggende materiale ook verskaf en maklik vanaf die kaart afgelees kan word . Inligting oar twee terreinkenmerke, nl. persentasie gelykland en relief, word ook verskaf . Vir die interpretasie van grand- en terreinkenmerke van die Karoo was dit nodig om 'n klein, hanteerbare aantal natuurlike streke, elk waarvan die hulpbronne grand, terrein en klimaat sterk interafhanklik van mekaar is, te definieer en te karteer. Hierdie streke is bree fisiografiese streke genoem. Twintig sulke streke is in die Karoo geidentifiseer. Vir elk van die bree fisiografiese streke word 'n beskrywing van die aard en omvang van die terrein en grondverspreiding, asook beskrywings van die morfologiese kenmerke, klassifikasie, fisies - chemiese kenmerke en grondvrugbaarheidstatus van gronde, gegee. Die gronde van die Karoo is almal in een van sewentien bree grondpatrone ingedeel. Dit was duidelik dat vlak kalkhoudende li tosols, gevolg deur rooi apedale, hoe basestatusgronde, die grootste oppervlakte in die Karoo beslaan. Die rooigronde het gewoonlik sanderige bogronde (A-horison), terwyl die klei- inhoud van die kalkhoudende litosols effens hoer (6- 15%) is. Die diep, swak gestruktuurde gronde wat met ongekonsolideerde afsettings geassosieer word, en wat 'n hoe potensiaal vir besproeiing behoort te he, beslaan sowat 1 miljoen hektaar en kom veral in die sentrale, noordelike en oostelike dele van die Karoo voor.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/66178
This item appears in the following collections: