Enhanced Pedon Horizonation Using Portable X-ray Fluorescence Spectrometry

Abstract

Soil pedons are commonly differentiated into a succession of horizons based on observable differences in soil color, texture, structure, or other characteristics, which are essentially associated with or determined by the chemical composition of soil materials. Portable X-ray fluorescence spectrometry (PXRF), which provides scanning results in ∼60 to 90 s, offers a rapid means of quantifying elemental concentrations in the soil. This research evaluated the use of PXRF on 10 soil pedons in Louisiana for enhanced identification of soil horizons based on differences in elemental concentrations. Three quantifiable measures, difference of clay contents (DC), difference of laboratory analysis results (DLA), and difference of PXRF elemental concentrations (DE), were established based on principal component analysis for evaluating PXRF for soil horizonation. The results showed the variations of PXRF elemental concentrations (DE) in the pedons matched with described horizons better than those of laboratory (DLA) or clay (DC) measures in terms of horizon uniqueness. Furthermore, the PXRF scans conducted under field, lab, or monolith conditions achieved almost the same results. This will allow the use of PXRF as a means of discreetly differentiating elemental differences in archived monoliths with implications for adjustments to their taxonomic classification and land use recommendations. In summary, PXRF was shown to be an effective tool for enhanced soil horizon differentiation on alluvial soils in Louisiana.