Search

Gamma-ray computed tomography (CT) was employed to study the soil quality of clod samples used to investigate porosity ( ϕ ). Samples with volumes varying from 50 to 100 cm 3 were collected from the soil surface. 2D CT images were obtained with millimetric resolution. Porosity distribution analyses were carried out to infer the soil clod structure. Results obtained provided a new insight on the variability of internal clod structure due to the large amount of data analyzed, information that is not provided by traditional methods used in physics applied to soil. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: The atomic force microscopy (AFM) is a technique for direct three dimensional measurements of the mineral structure in nanometric scale. In the literature, there are studies which approach the characterization of surfaces in atomic scale through AFM, such as humic substances and minerals. However, the number of studies aiming to characterize the clay fraction minerals in soil using this technique is not representative. In this study, AFM was employed to characterize the clay fraction morphology and microtopography in the surface layer of a Rhodic Ferralsol in Brazil, and X-ray diffraction (XRD) together with the Rietveld Method (RM) to characterize and quantify the main minerals. Images analyzed presented particles from 3 to 25nm. Through XRD and RM mineralogical analysis, the minerals found in higher amounts from the most to the least were, gibbsite, kaolinite, hematite, anatase, goethite, magnetite, calcite, vermiculite and rutile. AFM images made it possible to identify, by observing the height and shape, the particles that corresponded to kaolinite, goethite and gibbsite. This study shows the potential of the AFM technique to measure clay in nanometric scale and the possible identification of minerals present in the clay fraction with the use of XRD and RM. [Copyright &y& Elsevier]