Quick analysis of organic matter in soil by energy-dispersive X-ray fluorescence and multivariate analysis

Highlights: • OM and TOC concentrations in agricultural soil were determined. • Samples were differentiated by plateaus and basins using PCA. • EDXRF combined with PLSR is a straightforward methodology for OM quantification. • The novelty is the direct quantification of OM and TOC from soil EDXRF spectral data. - Abstract: The rapid, simple and accurate determination of soil quality indicators is fundamental for improvements in precision agriculture and consequently in production efficiency. The objectives of this study were to determine the organic matter (OM) and total organic carbon (TOC) concentrations in agricultural soil and to discriminate soil provenance by energy-dispersive X-ray fluorescence (EDXRF) combined with principal component analysis and partial least square regression. The conventional methods used for the determination of OM and TOC concentrations are the gravimetric and Walkley–Black methods, respectively. Figures of merit such as sensitivity, detection and quantification limits, accuracy and precision were evaluated. Samples were differentiated by their provenance, and the quality of the prediction model shows that EDXRF combined with multivariate analysis is a promising methodology to fulfil the lack of rapid and accurate analytical methods for the assessment of OM and TOC concentrations in agricultural soils.