WINETECH Technical Yearbook 2021

TABLE 1. Grouping of soil forms based on diagnostic horizons and materials.

Diagnostic horizon or material for identification

Soil group

Concept

Soil forms

1

Organic

Wetland peat.

Organic O-horizon

Champagne

Humus enrichment, free drainage, low base status, humid climate.

Kranskop, Magwa, Inanda, Lusiki, Sweetwater, Nomanci.

2

Humic

Humic A-horizon

3

Vertic

Swelling and cracking clay.

Vertic A-horizon.

Rensburg, Arcadia.

Willowbrook, Bonheim, Steendal, Immerpan, Mayo, Milkwood, Inhoek.

4

Melanic

Black clay, high base status

Melanic A-horizon.

5

Silicic

Silica enrichment, arid area.

Dorbank.

Garies, Oudtshoorn, Trawal, Knersvlakte.

Molopo, Askham, Kimberley, Plooysburg, Etosha, Gamoep, Addo, Prieska, Brandvlei, Coega. Estcourt, Klapmuts, Sterkspruit, Sepane, Valsrivier, Swartland. Tsitsikamma, Lamotte, Concordia, Houwhoek, Jonkersberg, Witfontein, Pinegrove, Groenkop. Longlands, Westleigh, Avalon, Bainsvlei, Wasbank, Glencoe, Dresden. Pinedene, Griffin, Clovelly, Bloemdal, Hutton, Shortlands, Constantia.

6

Calcic

Carbonate or gypsum enrichment, arid area.

Soft or hardpan carbonate or gypsic horizon.

7

Duplex

Marked clay enrichment.

Pedocutanic or prismacutanic B-horizon.

8

Podzolic

Metal humate enrichment.

Podzol B-horizon.

Iron enrichment (absolute), mottling or cementation.

9

Plinthic

Soft or hard plinthic B-horizon.

Red or yellow-brown apedal or red structured B-horizon.

10

Oxidic

Iron enrichment (residual), uniform colour.

11

Gleyic

Gleying with accompanying reduction.

G-horizon.

Kroonstad, Katspruit.

Young soils in unconsolidated sediment (colluvial, alluvial or aeolian).

Neocutanic or neocarbonate B-horizon, regic sand, deep E-horizon or stratified alluvium.

Tukulu, Oakleaf, Montagu, Augrabies, Namib, Vilafontes, Kinkelbos, Fernwood, Dundee.

12

Cumulic

Johan de Jager is a soil-science consultant for Vinpro, specialising in soil classification, chemical corrections and the development of long-term fertilisation programmes. 25 subsoil horizons which are used as diagnostic horizons, and the different combinations and sequence of the horizons in the soil led to the identification of 73 different soil forms in the South African Taxonomic System.

13 14

Lithic

Young soil on weathered rock.

Lithocutanic B-horizon or hard rock.

Glenrosa, Mispah, Cartref.

Anthrophic

Human disturbance.

Disturbed material.

Witbank.

the producer and other stakeholders to facil- itate discussions about soils and to simplify the complexity of the subject.

Tomanage this complexity, Martin Fey divid- ed these 73 soil forms into 14 soil groups with the diagnostic horizons as main focus (table 1). This grouping is comparable to interna- tional classification systems used by other countries. Soil groups can help viticulturists,

to which they are classified into larger soil groups. The soil groups can thus help to create a better understanding of the origins of and similarities between the different soil forms. Groups one to four have a distinctive topsoil horizon. Groups five to 11 have

Different soil forms have certain soil forming processes in common, according

WINETECH TECHNICAL YEARBOOK 2021 | 123