Combination of 3D Fluorescence/PARAFAC and UV–Vis Absorption for the Characterization of Agricultural Soils from Morocco

The present study, combining UV–Visible absorption and 3D fluorescence supported by PARAFAC chemometric analysis, focused on the characterization of soil water extractable organic matter (WEOM) in the zone of Doukkala located near the Atlantic coast of Morocco. The extracts, in water, of a set of 30 samples covering the four main types of agricultural soils in the region (commonly labeled Tirs, Faid, Hamri and R’mel) were investigated. E 2 / E 3 and E 4 / E 6 absorbance ratios , S 275 - 295 and S 350 - 400 spectral slopes, along with their ratios S R , as well as the fluorescence FI and humification HIX indices were calculated and interpreted. In the four soil types, these parameters revealed, on the one hand, organic materials of terrigenous origin with some biological component, and showed, on the other hand, that these materials are in similar stages of humification with an important humic character. In all the soils investigated, 3D fluorescence crossed with PARAFAC chemometrics highlighted the absence of any protein component and revealed the prevalence of the fulvic acids fraction in the organic matter humic material.