3-D Visualization of Soil Macroporosity Using X-ray CAT Scanning

ABSTRACT

Computer assisted tomography (CAT) offers considerable potential for reliable and nondestructive in-situ characterization of macropores occurring in agricultural soils. Several researchers have used CAT techniques for characterizing soil macropores of small undisturbed soil cores. However, there is still a need to develop comprehensive algorithms to automate the analysis and interpretation of macropore geometry directly from CAT scan data. Four undisturbed soil columns (800 mm long x 77 mm diameter) were extracted from a loamy sand field in central Canada and scanned for the visualization and characterization of their interconnecting macropore structure. A total of 240 scans of 3-mm depth were taken for each column. After conversion of the raw CAT scan data into density matrices, two and three dimensional soil density reconstructions were generated. With the elaboration of numerous computer programs in the PV-WAVE language, this analysis gives a detailed representation of the spatial variation of the macropore structure and heterogeneity of soil.

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