Geoscience Reference
In-Depth Information
4.3.5 Qualities and Limitations of Soil Taxonomy
Soil Taxonomy, in spite of its highly hierarchical look with four levels, is
primarily a system for naming soils. Its philosophy, therefore, is not so
distant from what one would think is that of the WRB. As all systems of
this type do, it embodies, regroups and organizes the knowledge of very
many specialists. They play a very useful role in their country of origin.
With a minimum of familiarity, the terminology it proposes is very easily
deciphered. It is less easy to construct! But it has many defects:
It is relatively complex.
Its structure is not always as rigorous as it might seem to be.
Four levels are sometimes too many for characterizing a soil.
But it is very necessary to retain them to preserve the coherence
of the system. The terminology sometimes provides redundant
information. We saw this in the case of 'Lithic Haprendolls'.
At each taxonomic level and undoubtedly to allow the use of
the hundreds of pages of this classification system as a huge
identification key, one starts by examining the soils that are the
simplest to characterize. These are often the most extraordinary
in the exact sense of the term. One then ends up with terms
such as 'other Paleudalfs , 'Typic Calcicryids , etc. This occurs
very many times. In other words, the typical soils are defined
negatively as not having such or such property. The logic is well
understood but it lacks precision.
Considering the structure of Soil Taxonomy, it is enough for
one qualifier to be modified for the name of very many soils to
change as well. In these conditions, the successive editions of
Soil Taxonomy have rendered obsolete the legends of many soil
maps published in USA.
The system facilitates the making of errors in orthography. For
example, why does one write 'Haprendoll' and not 'Haplrendoll'?
It is not very clear.
The system embodies great problems in detail so much so there
is breaking up into different taxa of soils that are close to each
other and must form one natural unit.
The taxonomy considers the seasonal soil climate as an important
criterion, but this climate is often difficult to understand except
in the most typical cases. In particular, some old soils are not
in equilibrium with the present-day climate and it is therefore
unfair to take it as reference; this most specifically affects Oxisols.
