Characteristic Variations in Reflectance of Surface Soils

TLDR

Soil reflectance variations are linked to soil properties and classification, yet their characteristic patterns across diverse soils remain poorly defined. This study aimed to investigate how soil reflectance varies across a wide range of naturally occurring soils and relate these variations to soil properties and classification. The authors examined 485 soil samples from 30 suborders of 10 Soil Taxonomy orders in the U.S. and Brazil, measuring spectral bidirectional reflectance factor on uniformly moist soils over 0.52–2.32 µm with an indoor spectroradiometer and then classified the resulting curve forms by genetically homogeneous soil properties analogous to suborder subdivisions.

Abstract

Abstract Surface soil samples from a wide range of naturally occurring soils were obtained for the purpose of studying the characteristic variations in soil reflectance as these variations relate to other soil properties and soil classification. A total of 485 soil samples from the U.S. and Brazil representing 30 suborders of the 10 orders of Soil Taxonomy was examined. Spectral bidirectional reflectance factor was measured on uniformly moist soils over the 0.52 to 2.32 µm wavelength range with a spectroradiometer adapted for indoor use. Five distinct soil spectral reflectance curve forms were identified according to curve shape, the presence or absence of absorption bands, and the predominance of soil organic matter and iron oxide composition. These curve forms were further characterized according to genetically homogeneous soil properties in a manner similar to the subdivisions at the suborder level of Soil Taxonomy . Results indicate that spectroradiometric measurements of soil spectral bidirectional reflectance factor can be used to characterize soil reflectance in terms that are meaningful to soil classification, genesis, and survey.