CHARACTERIZATION AND CLASSIFICATION OF SOILS IN A TOPOSEQUENCE ON LIMESTONE IN THE SERRA DA BODOQUENA, MATO GROSSO DO SUL, BRAZIL

The soils in the Serra da Bodoquena, a mountain chain in the state of Mato Grosso do Sul, Brazil, have peculiar features that differ from other regions of the Cerrado-Pantanal biome. This study aims to characterize soils formed on limestone, based on the physical, chemical and mineralogical properties and organic matter. A toposequence on limestone was selected and profile pits were opened on the summit (P1), backslope (P2), footslope (P3) and toeslope (P4 and P5). The profiles were morphologically described and physical, chemical and mineralogical analyses were carried out in all horizons. According to the Brazilian System of Soil Classification (SiBCS), the studied soils were classified as: (P1) Organossolo Folico Saprico litico - OOs (Litic Ustifolist); (P2) Chernossolo Haplico Ortico tipico - MXo (Typic Haplustoll); (P3) Chernossolo Argiluvico Ortico tipico - MTo (Typic Haplustoll); (P4) Gleissolo Melnico Carbonatico chernossolico - GMk1 (Typic Epiaquoll); and (P5) Gleissolo Mel nico Carbonatico organossolico - GMk2 (Terric Haplosaprist). The color of all studied profiles was dark in the surface horizons, and reddish or grayish in deeper layers, according to the drainage conditions. Base saturation was high in all layers, with calcium as dominant cation in the exchangeable complex. Humin was the dominant organic carbon fraction of the studied soils. A mineralogical analysis showed the presence of calcite in the sand fraction in the soil profiles GMK1 and GMk2 and kaolinite, illite and montmorillonite in the clay fraction of all soils. The occurrence of Ustifolist in non-mountainous environments, different from the characterization by the SiBCS, suggests a greater range of possible environmental conditions for the occurrence of this suborder.