Agriculture Reference
In-Depth Information
it is imperative that series should be deÝned as soon as possible, especially for the higher potential
soils.
INTRODUCTION: THE PIONEER AND LEADERS OF SOIL CLASSIFICATION IN
SOUTH AFRICA
Before embarking on a discussion of soil classiÝcation in South Africa, it is Ýt to pay tribute
to the pioneer and subsequent leaders of soil classiÝcation in the country. There is no doubt that
Dr. C.R. van der Merwe was the pioneer of soil classiÝcation in South Africa. In the foreword
to the report on South African soil series by MacVicar et al., (1965), it is stated:
Others have made important contributions from time to time, but in the Ýeld of soil classiÝcation and
soil genesis in South Africa, he stands supreme. È Concepts will change with time, old ideas will
be discarded, names will be forgotten, but not the name of C.R. van der Merwe.
ApproximationÒ (Soil Survey Staff, 1960) confronted the world with a new
approach to soil classiÝcation and brought a new impetus to soil classiÝcation, Drs. C.N.
MacVicar, R.F. Loxton, and J.M. de Villiers became the leaders of a new movement to develop
a systematic soil classiÝcation system, according to the new lines of thinking, for South Africa.
Their strength was a combination of brilliant intellectual understanding of pedology coupled
with extensive Ýeld experience. One of their biggest challenges was to develop a useful soil
classiÝcation system for a country that forms part of the internationally little understood ÑThird
Major Soil RegionÒ of the world.
When the Ñ7
th
THE “THIRD MAJOR SOIL REGION”
When I became involved with international soil classiÝcation, as a member of the World
Reference Base for Soil Resources (WRB) Working Group of the International Soil Science
Society (now the International Union of Soil Sciences), I battled with the question of why so
many of the most important soils in Southern Africa (and Australia) are not catered for adequately
(or at all) in the two major international soil classiÝcation systems, namely, the USAÔs Soil
Taxonomy (Soil Survey Staff, 1975) and the FAO system (FAO, 1988). Looking at a world map,
it then dawned upon me that the world can be divided into three broad different Ñmajor soil
regions.Ò These are the following:
1.
The soils of the relatively high to high latitudes of the big continents of the northern hemisphere,
i.e., those at latitudes 35
, the whole of Europe, and nearly
the whole of North America and the former Soviet Union. These soils have been well studied and
their classiÝcation has been developed to a high degree of reÝnement. In the southern hemisphere,
there is almost no land at these latitudes, not forgetting the ice-covered Antarctica, of course.
Habitable land at these latitudes in the southern hemisphere includes virtually only New Zealand
and minute parts of Australia and South America.
ο
N and higher. These include,
inter alia
2.
The soils of the humid and subhumid tropical areas. These soils have been fairly well studied,
documented, and classiÝed by soil scientists from Europe, and to some extent from the U.S.
Between the two aforementioned major soil regions is found, in both hemispheres, the interna-
tionally quite unknown and relatively poorly understood Ñthird major soil regionÒ of the world.
3.
S latitudes. It includes the
whole of Southern Africa and almost the whole of Australia. These include large desert and semi-
desert areas. Where it rains somewhat more, potential evapotranspiration greatly exceeds rainfall.
Rainfall is also strongly seasonal and unreliable. Moist periods and periods of intense desiccation
In the southern hemisphere, it lies between approximately 20
ο
and 35
ο
