@Article{MoreiraTeixGalv:2014:LaSaBr,
author = "Moreira, Luis Clenio J. and Teixeira, Adunias dos Santos and
Galv{\~a}o, L{\^e}nio Soares",
affiliation = "{Universidade Federal do Cear{\'a} (UFC)} and {Universidade
Federal do Cear{\'a} (UFC)} and {Instituto Nacional de Pesquisas
Espaciais (INPE)}",
title = "Laboratory salinization of Brazilian alluvial soils and the
spectral effects of gypsum",
journal = "Remote Sensing",
year = "2014",
volume = "6",
number = "4",
pages = "2647--2663",
keywords = "soil salinity, remote sensing, spectral reflectance, absorption
bands, principal components analysis, electrical conductivity,
continuum removal, band depth.",
abstract = "Irrigation-induced salinization is an important land degradation
process that affects crop yield in the Brazilian semi-arid region,
and gypsum has been used as a corrective measure for saline soils.
Fluvent soil samples (180) were treated with increasing levels of
salinization of NaCl, MgCl2 and CaCl2. The salinity was gauged
using electrical conductivity (EC). Gypsum was added to one split
of these samples before they were treated by the saline solutions.
Laboratory reflectance spectra were measured at nadir under a
controlled environment using a FieldSpec spectrometer, a 250-W
halogen lamp and a Spectralon panel. Variations in spectral
reflectance and brightness were evaluated using principal
component analysis, as well as the continuum-removed absorption
depths of major features at 1450, 1950, 1750 and 2200 nm for both
the gypsum-treated (TG) and non-treated (NTG) air-dried soil
samples as a function of EC. Pearson's correlation coefficients of
reflectance and the band depth with EC were also obtained to
establish the relationships with salinity. Results showed that NTG
samples presented a decrease in reflectance and brightness with
increasing CaCl2 and MgCl2 salinization. The reverse was observed
for NaCl. Gypsum increased the spectral reflectance of the soil.
The best negative correlations between reflectance and EC were
observed in the 1500-2400 nm range for CaCl2 and MgCl2, probably
because these wavelengths are most affected by water absorption,
as Ca and Mg are much more hygroscopic than Na. These decreased
after chemical treatment with gypsum. The most prominent features
were observed at 1450, 1950 and 1750 nm in salinized-soil spectra.
The 2200-nm clay mineral absorption band depth was inversely
correlated with salt concentration. From these features, only the
1750 and 2200 nm ones are within atmospheric absorption windows
and can be more easily measured using hyperspectral sensors.",
doi = "10.3390/rs6042647",
url = "http://dx.doi.org/10.3390/rs6042647",
issn = "2072-4292",
label = "scopus 2014-05 MoreiraTeixGalv:2014:LaSaBr",
language = "en",
targetfile = "remotesensing-06-02647.pdf",
urlaccessdate = "30 abr. 2024"
}