Full text
| |
| Author(s): |
Jairo Calderari de Oliveira Junior
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2014-12-19 |
| Examining board members: |
Pablo Vidal Torrado;
Lucia Helena Cunha dos Anjos;
Selma Simoes de Castro;
Ricardo Marques Coelho;
Tiago Osorio Ferreira
|
| Advisor: | Pablo Vidal Torrado |
| Abstract | |
Sodic soils are commonly associated to semi-arid climates, closed drainage systems (endorheic) and evaporative environments. In Brazilian Pantanal, knowns as the largest continental flooded area in the earth, sodic soils have significant expression in terms of area and environmental functionality, the specificity on plants development and soil intentional consumption (geophagy) by several animals, also playing as a refuge along the flooding events. These soils are located in the higher ground of the landscape (paleodiques), different from common situation. Pedogenic processes on north Pantanal sodic soils were studied in the Private Natural Heritage Reserve (PRNP) SESC Pantanal, in Barão do Melgaço-MT, performed on \"paleodiques\" from five sectors at different dissection stages. Pedogenic process was studied by means of morphologic descriptions was done in various scales, 14C dating on carbonate precipitates and optically stimulated luminescence (OSL) in sediments, geochemical and mineralogical modeling, spatial analysis of chemical and physical properties of the soil, apparent soil electrical conductivity performed by sensor electromagnetic (EM-38) and multivariate statistics. Soil profile from more conserved sectors shows typical features of lentic sedimentation environment, calcium carbonate layer and diatoms occurrence, suggesting that the formation of these features occurred by water concentration. Current condition is the opposite from earlier, wherein the flood plains remained isolated, with limited lateral and vertical drainage promoting water loss by evaporation and therefore concentrating the ions in solution. Simulation of the evaporation of water from São Lourenço and Cuiabá rivers points out similar results, suggesting that water evaporation from both could result in calcite precipitation and Na+ saturation in exchange complex. However, the features observed in both, field morphology and thin sections suggested that sodic soils are currently in degradation. The argilluviation is very intense and stands out as the main transformation process of these soils, occurring from the most preserved even in the most advanced dissection stage of. The ferrolysis is evident in the most advanced stage processing at E and Bt transition, where it establishes a cavity porosity depletion by both mechanical and chemical. Carbonates associated with channels, old pores and channels, without a cortex, suggests the current conditions do not favor sodic soil formation. Mineralogical analyzes indicates smectite presence in the paleodique of the most preserved sector, while present conditions promotes a smectite-kaolinite interestratification. Current hydrology promotes the gradual erosion of paleodiques that previously isolated the lakes from each other, becoming a slight open drainage system. The principal component analysis (PCA) identified the redox process as major process in the study area and, along the flood events, are primarily responsible for soil transformations. Pathway of sodic soil transformation in the RPPN SESC Pantanal paleodiques was Typic Natrudalf-Glossic Natraqualf. The latter are very susceptible to erosion process, promoted by flooding and tend to disappear, narrowing the paleodique progressively. Erosion process results in smalls and circulars elevations, named mounds, with high levels of Na+. (AU) | |
| FAPESP's process: | 11/11905-9 - Spatial characterization and genesis of sodic soil in the region of Barão do Melgaço, Pantanal Mato-Grossense |
| Grantee: | Jairo Calderari de Oliveira Junior |
| Support Opportunities: | Scholarships in Brazil - Doctorate |