CHARACTERIZATION AND CLASSIFICATION OF SOILS DEVELOPED FROM SANDSTONE OF THE AQUIDAUANA FORMATION

The Aquidauana geological formation consists of a set of up to 500 m thick sediments predominantly composed of sandstone with fine to medium grain size, interspersed with sandy conglomerates. In this environment, the topography is one of the main conditioning factors of the formation of different soil types in the landscape. The objective of this study was to characterize and classify soils developed from these sandstones. Four soils profiles along a representative toposequence of gentle slopes were sampled and studied. The profiles were located on the shoulder (P1), backslope (P2), footslope (P3) and toeslope (P4). The soil profiles were morphologically described and physical and chemical properties of their horizons evaluated. The sand fraction was predominant in all profiles (> 680 g kg(-1)), with textures ranging from sandy loam (P4) to clay sandy loam. The water pH values ranged from 4.2 to 6.5. The cation exchange capacity values ranged from 1.6 cmol(c) kg(-1) (in P4) to 10.3 cmol(c) kg(-1) (in P2), with a predominance of hydrogen ions in P1 and P4, and calcium in profile P2 and P3. The P1 and P4 pedons were dystrophic, whereas in P2 and P3, a high base saturation status evidenced an eutrophic character. Except in P2, the profiles presented low activity clays. In all soil profiles the morphological, physical, chemical and mineralogical properties were conditioned by the parent material and relief demonstrating the influence of these factors on the pedogenesis.