Geoscience Reference
In-Depth Information
The very great modernity of the system is remarkable. The idea of
horizon is accepted; the usefulness of soluble salts in characterizing
more or less leached environments is understood. In the climate column,
not reproduced here, Dokuchaev compared the annual rainfall to the
transpiration (water demand of the atmosphere) for characterizing the
moisture of soil. Lastly, he does not lack lucidity when he wrote: '
Owners
of the best soils of the world, we find ourselves in an intolerably painful situation
when we see the sad state of agriculture in the Chernozem and steppe zone
'
(Dokuchaev 1900).
But all soils do not obey the law of latitudinal zonality. Besides
normal
soils (Table 4.1), Dokuchaev mentioned
transitional
and other
abnormal
soils. His followers have clarified the concepts and exceptions
by introducing
zonal
,
intrazonal
and
azonal
soils.
4.1.3 Qualities of a Good Classification
In soil science, as in other disciplines, a classification or reference base
should have the qualities summarized in Table 4.2.
A good classification must also respect the principle of priority,
whereby the first author who recognizes an element of the taxonomy
and names it attaches his name to it. For example, in botany, the
common yew
Taxus baccata
L. is recognized, the 'L.' signifying that the
classification of the Swedish scientist Carl von Linné is referred to. But
plant and animal scientists are fortunate to have to classify distinct
entities. Soil scientists, on the contrary, create taxa by introducing rather
arbitrary divisions in a continuous soil cover. In these circumstances,
it is at times customary to modify a name that was much used in
order to show clearly that certain concepts were changed and that the
content of the taxon in question has been enlarged, or even reduced and
made more specific. For example, the term 'laterites' was abandoned in
favour of 'Ferralsols'. Nevertheless, soil scientists have used and abused
this freedom. Simple terms have been abandoned and terminology has
become needlessly complex.
4.2
WORLD REFERENCE BASE FOR SOIL RESOURCES (WRB)
4.2.1 Introduction
In 1974, at the instance of R. Dudal, the FAO published its Soil Map of
the World on 1:5 million scale, accompanied by a legend that constituted
a well-structured but still schematic inventory of the soils of our planet.
Origin and objectives
