de Oliveira J. F. auteur aut IRD Brossard Michel auteur aut IRD Corazza E. J. auteur aut IRD Guimaraes M. D. auteur aut IRD Marchao R. L. auteur aut IRD text journalArticle eng text/pdf born digital access Visible and near-infrared (Vis-NIR) spectroscopy is a tool to determine soi l spatial variability and has been used to map soils and their properties. Considering that physical , chemical , mineralogical , and morphological soi l properties can affect the intensity and the depth of the spectral reflectance band in the Vis-NIR region, the objectives of this work were to: (i) evaluate the potential of the reflectance inflection difference (RID) to discriminate soils; and (ii) veri f y potential spatial correlations of the RID with soi l properties, compared with the f u l l spectra, in order to build thematic maps at a fiel d scale. In a farm of 375 ha, 78 soil samples from the 0.87-0.92-m depth were collected in a regular grid of 200 m, with a focus on the soi l diagnostic horizon (Bw horizon). The sampled soils were a Latossolo Vermelho-Amarelo & PRIME;acrico (Haplic Ferralsol) and a Latossolo Ver-melho distr & PRIME;ofico (Rhodic Ferralsol). Twenty-two physical , chemical , mineralogical , and morphological soi l properties were determined, and the Vis-NIR spectra between 400 and 2500 nm were measured. Considering the presence of an inflection band and its relationship with soi l properties, the spectral bands used to calculate the RID were between (base 1/base 2): 400-510, 730-930, 1290-1450, 1800-1950, 2000-2218, and 2218-2290 nm. The RID failed to map the spatial variability of soi l properties, with a Kappa inde x of 39%; therefore, it is not a good parameter for building thematic maps of soi l parameters. In addition, the complete spectru m (mainly in 400-510, 730-930, 1290-1450, 1800-1950, 2000-2218, and 2218-2290 nm) was better spatially correlated with soi l properties than the decomposition of the spectrum by the RID. Soi l classification and level of dis-cretization as affected by spectral variability were also discussed here. Three soi l groups were discriminated mainly by the Ki and K r indexes and clay content. Moreover, the variability of the spectra was conditioned by the spatial variability of the mentioned variables. The clay content for soils with a discrepant particle size (group 1 compared with groups 2 and 3) and the Ki and K r indexes for soils with a homogeneous particle size (between groups 2 and 3), associated with the f u l l Vis-NIR spectral analysis, allowed building thematic maps with a good precision, without the need of mathematical models; this was possible by the modification of the reflectance intensity and the size of the concavity of the spectral band. specialized Ki and K r indexes Reflectance inflection difference Soil spatial variability Soil spectra BRESIL GOIAS 068 30 e00532 [13 ] 2022 2352-0094 https://www.documentation.ird.fr/hor/fdi:010085332 10.1016/j.geodrs.2022.e00532 2352-0094 [F B010085332] https://www.documentation.ird.fr/hor/fdi:010085332 https://www.documentation.ird.fr/intranet/publi/2022-09/010085332.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2022-09-02 2025-02-24 fdi:010085332 fre