Temporal changes in fractal dimensions of soil cracks with desiccation

If shrinking and swelling soil is predominant in the field, cracks in the soil may be one of the major contributors to preferential flow altering water and solute contents. Air-dried and sifted Brookston clay loam was packed (24.6 cm in diam. and 2 cm thick) in a plastic pan. The packed soil on an electronic balance was saturated with deionized water and allowed to dry with evaporation. Temporal changes in cracking patterns were captured every 30 min with a computer controlled CCD camera in the laboratory. Fractal dimensions of cracking patterns were determined from binary images based on the captured images. The fractal dimension increased with decreases in soil water content up to theta approximate to 0.2 kg(-1) and reached a constant value approximate to 1.23 with further decreases in water content. Due in part to slaking of aggregates by wetting, the fractal dimension at the minimum water content increased with increases in the number of wetting-drying cycles.