Geoscience Reference
In-Depth Information
4
Classifications: International
INTRODUCTION
Our aim here is to give the reader the conceptual bases necessary
for using without difficulty the systems presented. But for a rigorous
classification of soils it is necessary to refer to works that have been
written for that purpose. Simplifications have been introduced to
summarize very voluminous technical manuals to a few pages.
There are differences in principle between the classifications, the
taxonomies, the reference bases and the nomenclatures. This issue is
considered in detail in the larger French edition of this topic.
The
genetic
classifications involve external factors (for example,
climate) or at least the processes whose occurrence in the soil under
study leads to an interpretation (for example, decarbonatation). They can
be contrasted to
objective
classifications that only take into account the
observable and measurable characteristics of the soil. But the distinction
between the two types is less distinct than it appears at first sight.
In fact, all classifications have behind them genetic preoccupations
although they endeavour to propose to the user the most rigorous rules
for identifying soils.
4.1 HISTORICAL REVIEW
4.1.1 The Precursors
Suggestions regarding the nature of soils and their classification are
very many with the Latin people. First came
Marcus Terentius Varro
(116-27 BC), author of a treatise on agriculture in three volumes, titled
Rerum Rusticarum libri III
. Later, information on soils was put out by
