[Influence of soil iron oxide on VNIR diffuse reflectance spectroscopy].

The influences of iron oxide on soil reflectance, soil line parameter, organic matter spectral characterization and the shape of soil reflectance spectra were studied in the present paper with thirteen samples in several soil types, which covered a range of iron oxide content obtained from various combination of original and iron-removing samples. The results highlight that (1) a decrease on 350-570 nm and an increase on 570-2 500 nm were showed in the reflectance spectra with increasing iron oxide content. However, there was no significant correlation between iron oxide and spectral reflectance quantitatively; (2) iron oxide content had a negative linear correlation with soil line slope and a positive linear correlation with intercept, both were significant, which illustrated the feasibility of iron oxide prediction using soil line parameter; (3) the spectral characteristics of soil organic matter could be covered by iron oxide on 622-851 nm; (4) iron oxide in soil had influence on the shape of reflectance spectra after continuum removal and calculating statistical F and spectral angle.