Morpho-pedology and classification test of soils developed on dolomitic rocks in Taoudeni basin in Burkina Faso

pédogenèse sur roches dolomitiques au Burkina Faso

Abstract

Carbonate rocks have been recognized in temperate and Mediterranean regions as source rocks of
calcimagnesic and Fersialitic soils. The carbonate rocks of Burkina Faso, in tropical region, dominated by
magnesian dolomites dominated by magnesian dolomites, influence pedogenesis of the surrounding soils.
This suggests the probable existence of calcimagnesic and/or Fersialitic soils. However, previous soil
studies in the area have not revealed the presence of soils of these two classes. Uncertainties therefore
remain as to the ability of carbonate rocks of the Taoudeni Basin in Burkina Faso to form calcimagnesic
and Fersialitic soils. The objective of this morpho-pedological study conducted by toposequences from the
three main dolomitic hills of the region is to compare the characteristics of soils derived from dolomite
alteration with those of calcimagnesic and Fersialitic soils known in the literature. The study identified six
soil units including Chromic Dolomitic Vertic Cambisols, which share many of the characteristics of
tropical red soils resulting from fersialitic pedogenesis. The soils encountered show some particularities
(Mean saturation rate, pH < 7; CaO < 2%). These characteristics did not make it possible to classify them
as calcimagnesic soils which are saturated, neutral or alkaline. The hardness of carbonate rocks and rainfall
influence the pedogenesis in dolostones.