In situ separation of soil types along transects employing Vis-NIR sensors: a new view of soil evaluation

• Published in: Ciência agronômica 2014-09, Vol.45 (3), p.433-442
• Main Authors: Fiorio, Peterson Ricardo, Demattê, José Alexandre Melo, Nanni, Marcos Rafael, Genú, Aline Marques, Martins, Juliano Araujo
• Format: Article
• Language: English
• Subjects: AGRONOMY; Reflectance; Remote sensing; Soil spectroradiometry; Soil survey
• ISSN: 1806-6690; 1806-6690
• DOI: 10.1590/S1806-66902014000300002

Soil components, such as organic matter, the levels and form of iron oxides, moisture and texture, influence the interaction of the soil with electromagnetic energy, so that knowledge of the energy reflected by different classes of soil is therefore of help in their discrimination. The aim of this study was to evaluate the possibility of differentiating classes of soils along two transects, by means of the field spectral behaviour of different classes, using both visual and multivariate statistical analysis. Equidistant points were marked along the transects, 100 m apart, where geo-referenced soil samples were collected from the surface layer at a depth of 0 to 0.20 m. In the area under study, ten classes of soil were described by means of laboratory analysis of surface samples and a morphological description of the profiles, with each soil being classified according to the Brazilian System of Soil Classification. For separating soil units and establishing their boundaries in the landscape three methods were used: a) traditional, evaluating the correlation between soil and landscape; b) qualitative assessment of the spectral curves; c) multivariate analysis for discrimination of the classes of soil. Comparison of these methods made possible the use of spectroradiometry in differentiating the classes of soil, with the statistical method separating a larger number of classes. It was possible to delimit the boundaries of the soil units in the area under study, as well as differences in texture, colour, total iron and organic matter between units, by varying the spectral responses of the soil samples being tested.