3-D VISUALIZATION OF SOIL MACROPOROSITY USING X-RAY CAT SCANNING

Computer assisted Tomography (CAT) offers considerable potential for r eliable and nondestructive in-situ characterization of macropores occu rring in agricultural soils. Several researchers have used CAT techniq ues for characterizing soil macropores of small undisturbed soil cores . However, then is still a need to develop comprehensive algorithms to automate the analysis and interpretation of macropore geometry direct ly 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 inter connecting macropore structure. A total of 240 scans of 3-mm depth wer e taken for each column. After conversion of the raw CAT scan data int o density matrices, two-and three-dimensional soil density reconstruct ions were generated. With the elaboration of numerous computer program s in the PV-WAVE language, this analysis gives a detailed representati on of the spatial variations of the macropore structure and heterogene ity of soil.