%0 Journal Article
%T Use of Imaging Spectroscopy for Mapping and Quantifying the Weathering Degree of Tropical Soils in Central Brazil
%A Gustavo M. M. Baptista
%A Rodrigo S. Corr¨ºa
%A Perseu F. dos Santos
%A Jos¨¦ S. Madeira Netto
%A Paulo R. Meneses
%J Applied and Environmental Soil Science
%D 2011
%I Hindawi Publishing Corporation
%R 10.1155/2011/641328
%X The purpose of this study was to test the feasibility of applying AVIRIS sensor (Airborne Visible/InfraRed Imaging Spectrometer) for mapping and quantifying mineralogical components of three Brazilian soils, a reddish Oxisol in S£¿o Jo£¿o D'Alian£¿a area (SJA) and a dark reddish brown Oxisol and Ultisol in Niquelandia (NIQ) counties, Goi¨¢s State. The study applied the spectral index RCGb [kaolinite/(kaolinite + gibbsite) ratio] and was based on spectral absorption features of these two minerals.The RCGb index was developed for the evaluation of weathering degrees of various Brazilian soils and was validated by the analysis of soil samples spectra imaged by AVIRIS and checked against laboratory mineralogical quantification (TGA:Thermal Gravimetric Analysis). Results showed to be possible mapping and quantifying the weathering degree of the studied soils and that the two selected areas presented different weathering degrees of their soils even for a same soil type. 1. Introduction Soil is a product of forming factors such as parent material, climate, time, organisms, and topography. The great variability in soils results from interactions of these factors and their influence on the formation of different soil profiles. Mineral types and their proportions in soils are also dependable on soil-forming factors and have strong influence on agriculture, forestry, soil engineering, among others [1]. Tropical soil scontain mineralogical variations that cannot be perceived in field works.The determination of soil mineral composition depends on laboratory analysis of soil samples collected in field, and an extrapolation of the representativeness of the results to a broader area depends on landscape morphological characteristics and accuracy of the field work [2]. For cartographic purposes, the spatial distribution of values from point-sampled minerals is done by using morphological criteria in correlation with topography, parent material, and other parameters. Reliable criteria to discriminate soils with varied amounts of kaolinite and gibbsite do not exist, and the quantification of these two minerals in soils demands systematic samplings with high-density points. Because this procedure greatly increases costs of soil surveys, new techniques and resources that can ease pedological surveys are strongly desirable. Recent advances in remote sensing with the image spectroscopy appear to be a promising alternative in soil science. However, most of the optical remote sensing means cannot detect the entire soil body (¡°pedon¡±) that extends from the surface to the parent
%U http://www.hindawi.com/journals/aess/2011/641328/