Porosity Analysis of Two Acrisols by X-Ray Computed Microtomography

Abstract

Porosity and void characteristics of two major Acrisols (Ferric Acrisol and a Ferri-Plinthic Acrisol) with contrasting pedogenic features from the humid forest zone of Ghana were studied by X-ray computed microtomography. Spatial variability of the porosity of the two Acrisols, as well as the volume of different classes of void size, shape, and orientation, was quantitatively determined. Variations in the void characteristics were interpreted in correlation with the pedogenic features of the two soils. The Ferri-Plinthic Acrisol, with more numerous roots, faunal burrows, and with smaller amounts of rock fragments than the Ferric Acrisol, exhibited a larger total pore volume. The greatest part of the pore volume in the two soils could be associated with the macrovoids class. There was a strong correlation between void size and shape. Regular voids corresponded in general to mesovoids of biogenic origin, especially in the surface horizons, whereas irregular and elongated voids were composed mostly of macrovoids. Void orientation was predominantly inclined, with the exception of the horizons where the root or fauna advancement was impeded by a dense subjacent horizon. Considering soil-vegetation relationships, the computed microtomography imagery showed that root development in the lower horizons of the Ferric Acrisol was probably impeded by Fe-Mn nodules; cultivation of Crotalaria juncea on this soil probably facilitated the root penetration in some of the denser zones within the profile. The Ferri-Plinthic Acrisol structure could be improved by the extensive root system of Chromolaena odorata, a self-established fast-growing perennial shrub. Management strategies of the two major soils need to take into account relevant information on pore distribution, morphology, and orientation.

Effects of Past Copper Contamination and Soil Structure on Copper Leaching from Soil

“…The simple parameter ε m was calculated from the X‐ray CT images. This method improves on the traditional methods because it is faster, noninvasive, and provides quantitative results spatially (Dowuona et al, 2009; Naveed et al, 2013). There was a nonlinear increase in air permeability ( K a ) and K sat with increasing ε m (Fig.…”

Evaluation of Quality of Some Rehabilitated Mined Soils within the AngloGold-Ashanti Concession in Ghana

“…Total nitrogen and available phosphorus contents are very low. The low phosphorus content is partly due to the very small amounts of apatite originally present in the phyllites and the long period of leaching, and also partly due to the element being locked in insoluble or less available compounds of aluminium or iron as noted in similar soils elsewhere [26,31]. Exchangeable bases concentration is very low with Ca and Mg as the dominant cations at exchange site.…”

“…However, this pedological feature was not displayed by soil from the four previously mined sites due to disturbance caused by removal of the soil material. Kaolinite is the dominant clay mineral in this soil [26]. …”

Quantitative evaluation of pore characteristics of sodic soils reclaimed by flue gas desulphurization gypsum using X‐ray computed tomography

“…For example, studies have been widely carried out on segmentation of X‐ray CT images (Baveye et al, ; Iassonov, Gebrenegus, & Tuller, ; Schlüter, Sheppard, Brown, & Wildenschild, ) involving image resolution selection (Sleutel et al, ; Wildenschild et al, ), representative elementary area identification (San José Martínez, Caniego, García‐Gutiérrez, & Espejo, ), and optimal thresholding methods (Elliot & Heck, ; Smet, Plougonven, Leonard, Degré, & Beckers, ; Wang, Kravchenko, Smucker, & Rivers, ); quantification and reconstruction of the pore structure (Marcelino, Cnudde, Vansteelandt, & Carò, ) such as characterization of macropores (Garbout, Munkholm, & Hansen, ; Luo, Lin, & Schmidt, ), extraction of three‐dimensional (3D) typical pore parameters (Al‐Raoush & Willson, ; Luo, Lin, & Li, ), and assessing the spatial variability of soil structure (Carducci, Zinn, Rossoni, Heck, & Oliveira, ); as well as the relationship between pore characteristics and soil functions (Helliwell et al, ) including correlations with soil physical properties (Anderson, Gantzer, Boone, & Tully, ; Munkholm, Heck, & Deen, ) and explanation of the hydraulic conductivity (Luo, Lin, & Halleck, ; Naveed et al, ; Paradelo et al, ; Tracy et al, ). Although the majority of current case studies focus on naturally cultivated soils, there are still some reports confirming that images extracted from X‐ray CT are effective in quantifying pore characteristics of unnaturally soils such as reconstructed, degraded, and reclaimed soils (Dowuona, Taina, & Heck, ; Langmaack, Schrader, Rapp‐Bernhardt, & Kotzke, ; Li, Shao, & Jia, ; Wang, Guo, Bai, & Yang, ). Langmaack et al () reported an interesting case performing X‐ray CT method to study the soil structure rehabilitation of degraded soil caused by compaction.…”