The objective of this work was to evaluate the efficiency of spectral reflectance in the detection of different erosion levels present in soils. Four soils, corresponding to a Red-Yellow Latosol (Oxisol), Latosolic Terra Roxa Estruturada (Ultisol), Cambisol (Inceptisol) and Vertisol, located in a toposequence in Piracicaba, São Paulo, Brazil, were evaluated for their chemical, physical and mineralogical attributes. The spectral reflectance was measured between 400 and 2,500 nm using an Infra Red Intelligent Spectroradiometer. Each soil was collected according to the depth-increments 0-5, 10-20, 40-60, 60-80 cm, which were considered as no erosion (control), slight erosion, moderate erosion and severe erosion, respectively. Spectral data obtained under laboratory conditions, which simulated data from the TM-LANDSAT-5 satelite, were then correlated with the soil erosion process. As the degree of simulated erosion increased, alterations in the soils occurred, mainly with the organic matter content, causing modifications in the spectral characteristics. The more eroded the soil, the higher was the spectral reflectance intensity between 600 and 2,400 nm. The absorption bands, due to iron oxides (850 nm), water (1,400 and 1,900 nm) and kaolinite (2,200 nm), were more intense in the eroded soils. Spectral data from LANDSAT were less detailed, for discriminating erosion levels in soils and, consequently, less efficient. Even under these conditions, bands 3, 4, 5 and 7 discriminated the non eroded soils from the eroded ones.
remote sensing; soil erosion; radiometry