Solo do Rio Grande do Sul e sua relação com o clima

Abstract

The relationship among soil and climate has been for a long time the basis for mapping soils and vegetation on a global scale. In Rio Grande do Sul, there still are few studies that relate soil formation with climate. Soil formation occurs through the weathering of rocks. Rainfall and temperature are major climate factors that determine the nature and rate of chemical reactions in the rocks and define the pedogenesis. This relationship can be studied through edaphoclimatological models and weathering. Thus, the objectives of this thesis were: (i) to determine the influence of climatic availability on the type of weathering and on the formation of soils of the Rio Grande do Sul State, (ii) to determine the relationship between soil and climate in Rio Grande do Sul State through the use of edaphoclimatological models, and (iii) to validate zonal soils of Rio Grande do Sul and to determine their geographical location. To achieve these objectives, three mathematical models were used to determine the characteristics of weathering. In the calculation and graphic representation of models, the average annual temperature and rainfall of 41 meteorological stations of belonging to the 8th District of Meteorology, 1931-1960 period, were used. The relationship between soil of Rio Grande do Sul and regional climate was studied using seven edaphoclimatological models. Results showed that the soils of the State are exposed to conditions of warm temperate zones, which favor chemical weathering and conditions of change and leaching of typical monossialitization zone of the area. The soil of Rio Grande do Sul with the existing regional climate was studied by edaphoclimatological models. According to these models, Rio Grande do Sul State is a region with characteristics of soil with deep and well developed profiles that can support a natural woody-type vegetation. Thus, only a part of the soil area of Rio Grande do Sul State is explained according to the current climate, particularly those which are mapped as being of Oxisols, Chernosols, Argisols, and Nitossols and Argisols, predominantly located in the North-Riograndense Plateau and Central-Depression, respectively. Zonal soils in Rio Grande do Sul State can be grouped as Laterites and Pedalfers, but the relationship between climate and the existing diversity of soil types in the State can not be explained only by climate.