Quantification and discrimination of Soils Developed from Basalt as Evaluated by Terrestrial , Airborne and Orbital Sensors

The aim of this investigation was to evaluate orbital, airborne (simulation) and terrestrial spectral reflectance data of two soils developed from basic rocks on a topossequence in the state of Paraná, Brazil, focusing especially on soil spectral characterization and attribute content estimation. Rhodic Haplortox (RH) and Typic Argiudol (TA). Soil samples were submitted to a laboratory 4002500 nm spectroradiometer for reflectance data, which were used to simulate data from TM/Landsat and AVIRIS bands. Real data from TM was also obtained. Although the spectral curves of the soils were similar, TA curve presented higher reflectance intensity than RH curve, between 800 and 2500 nm, and both showed differences in absorption features at 850 nm (iron forms), at 1900 nm (mineralogy) and at 2265 nm (gibbsite), due to granulometry and mineralogy. Spectral data obtained in laboratory were important to validation of orbital data, which also discriminated the soils especially through band 7. We may conclude that reflectance reflectance extracted from spectroradiometer and orbital data represent soil spectral information more accurately than digital numbers. It was possible to estimate clay and silt contents and silt/clay relation through the analysis of soil samples reflected energy.