Caracterização e pedogênese de luvissolos e planossolos no núcleo de desertificação de Cabrobó, Pernambuco

Abstract

In the Northeast, the semiarid region presents areas susceptible to desertification. Are areas known as Nuclei of Desertification and these compromotem 20% of the region. The Cabrobó desertification Center, belongs to the state of Pernambuco and is inserted in the geo-environmental unit Country Depression. In this environment the predominant soils and associated with the most impacted areas are Luvisols and Planosols. The study aimed to characterize morphological, physical, chemical, mineralogical and micromorphologically Luvisols and Planosols spread over a segment located in Cabrobó desertification core inserted in the Country Depression from a lithological variation, as well as understand the pedogenic processes involved in the formation of these soils. chemical analysis (pH, exchangeable cations, available phosphorus, exchangeable aluminum, potential acidity, organic carbon); physical (grain size, water dispersible clay and flocculation), selective extractions with DCB and ammonium oxalate; chemical composition analysis by fluorescence X-rays; mineralogical analysis by diffraction of X-rays (fraction sand and clay); micromorphological analyzes and petrographic analyzes. Despite quite different lithologies, soils presented mineralogical composition very similar clay minerals. The sand fraction presented quarzto and feldspar and clay fraction with smectite (beidelita, nontronite and montmorillonite), and mica, vermiculite and kaolinite. The distribution of Luvisols and Planosols in the study area is associated with the lithology, regardless of their position in the landscape, where Luvisols are formed by basic rocks and Planosols by acid rocks. The clay formation in situ (argilic) seems to be the main process responsible for the formation of the B horizon in both soils. The expressive textural difference between the A and B horizons is possibly related to the elutriation and pedimentation process on the horizon training A. The smectite main mineral found in the clay fraction of the subsurface layers Luvisols was nontronite.