Geoscience Reference
In-Depth Information
In the high latitudes and at high altitudes, the low productivity is
linked at the same time to infertility of the soils and to the rigour of
the climates.
CONCLUSION
Let us imagine that we roll up a well-worn, single-piece wall-to-wall
carpet to change it and we are stopped in the middle of the work. At
that moment the bare portion of the floor is, for iron and aluminium,
the equivalent of the E horizon; the part with the roll is the equivalent
of the B horizons and the unchanged portion is equivalent to the C. In
balance-sheet terms, it is fair to say that what is missing from the E is
found in the B. But it would be wrong to state that what is in the B
came totally from the E. Above all, in terms of functioning, it would
be absurd to claim that, when the work is resumed, the E will continue
to nourish the B! It is the B that, while rolling, is nourished from its
own material and that of the C, with building-up of the E as main
consequence. We can see that the arguments are rather subtle. Future,
work in isotope chemistry will help to clear up the difficulties that still
remain (Fritsch
et al
. 2009).
Overall, Podzols present a spectacular morphology. Their Bs and
Bh horizons correspond to a dual weathering front that is gradually
displaced downwards. The two together constitute a sort of micro-
factory working in acid medium and capable of cleaning out everything
except quartz, a granitic arène or a sandy clay. The operation of the
system is regulated by the supply of acids transported from the surface
through the E horizon that is being formed. The age of the Podzol is thus
directly a function of work accomplished, as shown by the thickness of
the residual E horizon (if there is no lateral erosion).
REFERENCES
Álvarez-Arteaga G, NE Gárcía-Calderón, PV Krasilnikof, SN Sedov, VO
Targulian and N Velázquez-Rosas, 2008. Soil altitudinal sequence on
base-poor parent material in a montane cloud forest in Sierra Juarez,
Southern Mexico.
Geoderma
,
144
: 593-612.
Anderson N, ML Berrow, VC Farmer, A Hepburn, JD Russell and AD Walker,
1982. A reassessment of podzol formation processes.
Journal of Soil
Science
,
33
: 125-136.
Andrieux P, 1990.
Influence de la Variabilité Spatiale des Caractéristiques
Physiques des Sols sur le Bilan Hydrologique. L'exemple d'un Système de Sols
sur Barre Prélittorale
(
Guyane
Française
). Thèse, Université Montpellier
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