Mauritania exhibits five types of soils. As rain is as insignificant
as irregular in the great part of the territory’s landmass and
the magnitude of the gap between maximum and minimum temperature being
such as physical modification of rocks remains mainly unchanged, Mauritanian
earth is mostly without vegetal life. Thus, soils are typically characterized
as “weathered raw-mineral soils” or lithogenic soils.
These weathered raw-mineral desert soils are classified in two parts,
namely; 1) desert deposited soils and, 2) desert ablation soils. The
first type of soils is found in the great ergs; which are widespread
surfaces of sands deposited by wind and superimposed one on the other
without any stratification. The second type of soils develops on rocks
which have been altered in the past. They shape regs of coarse sands,
gravels or pebbles as a result of wearing rocks by and through wind
activities (Eolian weathering). These activities have been very differentiated
throughout ages. Accordingly, certain soils formed in the quaternary
under conditions of humidity which are presently not existing. Thus,
in the north-west, there are regions with paleo soils, brownish resulting
from calcareous earth or covered by a limy crust. In this same region,
these desert ablation soils are often found together with so-called
deposited soils, laid down through ancient rivers which have presently
In the neighboring category, there are the so-called “raw mineral
soils’’ resulting from alteration of diverse less or not
decomposed rocks. Qualitatively, they are very poor, less thick and
roots of plants have great difficulties to penetrate their ground.
Practically, they have no value for any plant life
A part from the above type of soils, much younger soils constitute
the second category. They are still in their process of growth which
are thicker, resulting either from climatic origin taking shape on
sedimentary rocks or on sandy ground brought by wind. And there are
those developing on sandy coastal sands independently of climate.
The third category is found in the semi-arid zones. They are known
as isohumic and are characterized by a relatively higher proportion
of humus resulting from the decomposition of vegetal and animal elements
apart from a sufficient content of iron giving it a reddish color.
They are younger soils or less developed soils.
The fourth class of soils is that whose characteristics are due, in
great part, to the temporary or permanent presence of water. They
are, thus, called hydromorphous soils. It occurs only in the Southern
part of the country in the form of a band stretching along the Senegal
river. They are known as hydromorphous soils.
Finally, the fifth class is made by halomorphous soils meaning characterized
by the presence of sodium, potassium and/or solvable chemical composition.
They are found in the coastal region or in some basins without flow
to the ocean. As such, they are very compact and waterproof and the
presence of the above signaled chemicals makes them totally inappropriate