GEOPEDOLOGY OF THE NORTHWEST SECTOR OF THE BAJOS SUBMERIDIONALES BASIN, ARGENTINA

Abstract

The geopedological study of a sub-basin in the Santiago del Estero-Chaco limit, on the northwestern edge of the Bajo Submeridionales basin, is carried out, with the aim of deepening the knowledge of the factors and formative processes that control the type and distribution of the soils of the region. For this purpose, a geomorphological map is made, representative pits of each delimited landscape unit are studied and sampled. In the laboratory, routine physical and chemical analyzes are carried out for each profile. The results obtained allowed the identification of four landscape-soil units at the categorical level of "Landform": 1) Gently undulating plain, with little-developed Molisols and numerous lithological discontinuities. The dominant pedogenetic processes correspond to surface melanization and deep carbonation; 2) Slope (0.5 to 1.5%), where more developed Molisols are recognized, in addition to Alfisols, subject to water erosion processes. Pedogenetic processes correspond to melanization, argiluviation, and carbonation; 3) Low plane, where well-developed Vertisols dominate and that had not been documented so far in the cartography available for the Chaco sector. The pedogenetic processes in this unit are melanization, carbonation, argiluviation, vertisolization, and oxide-reduction; and 4) Drainage path, in which, in addition to Vertisols, Alfisols were identified. The dominant processes correspond to oxide-reduction, given by the fluctuation of the layer, while in the Alfisols the sodification is added. The study carried out provides a new interpretation of the genesis and distribution of soils in the region. Likewise, the information generated is useful for future semi-detailed surveys in the Santiago sector of the BBSS basin, where agriculture advanced and decision-making is necessary to mitigate degradation processes, such as water erosion and salinization.