An Integrated System for Soil Indentification in the South African Sugar Industry

Soils of the South African sugar industry were first mapped on the basis of soil parent material and were subsequently grouped into forms and series in the binomial system. An integrated system incorporating both these methods has now been developed to enable the cane grower to identify his soils without difficulty. Introduction In South Africa, sugarcane is grown under a range of climatic and soil conditions and soils in particular, differ widely in their physical and chemical properties, their ability to produce crops and their management requirements. It is also not uncommon to find a number of soils differing in these characteristics on one farm. For three decades soil scientists have been identifying and classifying the sugarbelt soils. The Soils Bulletin No. 19 (SA Sugar Association Experiment Station14) was the result of surveys of the soils on a geological basis Beater.2,3s4,5 A soil parent material map and key is useful and convenient for identifying soil series for young soils near the coast but is not always reliable in detecting differences in soil series resulting from changes in parent material, particularly in the Natal Midlands. Another limitation is that soils with very different properties are derived from the same parent material, eg granite, alluvium, Dwyka tillite, Middle Ecca sediments and Table Mountain Sandstone all give rise to a number of different soil forms. The Department of Agriculture and Fisheries subsequently introduced the more precise binomial system of classification (MacVicar et aP) which involves grouping soils into soil forms and series without necessarily knowing the soil parent material. This has been accepted as the standard system of soil identification for South Africa and it would be advantageous for cane growers to be familiar with this system. The revised edition of the Experiment Station's soils bulletinIs to be published in 1984, will describe both classification systems. The main features of the two classification systems and their integration are described in this paper. TABLE 1 The nature, and extent of soil parent materials in the South African sugar industry Amphibolite IRedcrosshatched( 0,21 1 0,21 1 1 I I I \ , A n SOIL PARENT MATERIAL PERCENTAGE DISTRIBUTION OF TOTAL AREA SURVEYED l v l n r COLOUR GUIDE Pre-Granite quartzite