Estimation of Soil Water Retention Properties From X-Ray Microtomography Observations.

High-resolution 3-D microtomography visualizations obtained with an advanced desktop scanner with optimized resolution of about 10 microns provide excellent means for quantification of soil macroporosity and associated water retention properties. Different sized samples (0.5, 2, and 5 cm diameter) of undisturbed soils and artificial glass bead mixtures were scanned at different resolutions utilizing a commercial desktop microCT scanner. Equipment setup parameters such as filters (no filter, aluminum and aluminum/copper), total rotation (360o or 180o), and acquisition time were optimized for best image quality and low noise to signal ratios. 3-D reconstructed sample volumes were segmented into solid and liquid phases with advanced, locally adaptive methods. Porosity and water retention properties determined with voxel counting algorithms compare favorably with mercury intrusion porosimetry and tension table measurements.