Dissertação (Mestrado) - Universidade Federal de Viçosa, Programa de Pós-Graduação em Solos e Nutrição de Plantas, 2003.

Abstract: The watersheds of the rivers Acre and Iaco, State of Acre, were intensely covered via the main access roads as well as by a panoramic flight, with the following main objectives: characterization of the morphological, chemical, physical, and mineralogical attributes of the main soil classes of the basins hydrological characterization of the basins and establishment of a proposal for a socio-environmental zoning of the two watersheds. Trenches were dug in the main soil classes, the respective morphological descriptions carried out, and soil samples of the horizons collected for the chemical, physical, and mineralogical analyses. Objectives were the evaluation of the nutrient availability in the soils and the characterization of morphological and physical attributes in relation to geology, geomorphology, and the drainage system of the rivers Iaco and Acre, which lie in the southwestern Amazon region. The basin was used as an integrating unit of environments and basis for the definition of a sustainable management of the natural resources. The basins were characterized based on raw data of the historical series of the Agência Nacional de Águas (National Water Agency). This dataset was used in a geographic information system and allowed the consolidation of a socio- xixenvironmental zoning (scale 1:500.000) of the basins. In the Iaco basin, Cambisols, Vertisols, Luvisols, and Alisols are the soil class predominant, while Acrisols, Ferralsols and Plinthosols prevail in the Acre basin. In the Iaco basin, the soils are of greater nutrient availability. However, their physical properties and the presence of high clay activity impede a more intense land use. On the other hand, the soils in the Acre basin offer a greater agricultural potential, in spite of a lower nutrient availability, owing to their superior physical and mineralogical properties. In the Iaco basin, the hydrological variables are more closely correlated, suggesting that the lower degree of disturbance allows the maintenance of the integrity of the basic hydrological conditions. The integration of the soil database with social information, using the basin as integrating element, allowed a separation of the different homogenous units, which consolidated the proposal of socio-environmental zoning. This allows an integrated vision of the basins and might become an efficient guideline to plan future land use in this region of the Amazon Basin.

Orientador João Luiz Lani