Water content distributions during horizontal, vertical-up, and vertical-down infiltration into air-dry soil, were measured experimentally using gamma radiation attenuation equipment. A sufficient number of soil columns were analyzed to ascertain fiducial limits of both measured and calculated soil water properties and parameters. The first three coefficient functions of Philip’s solution of the Richards’ flow equation applied to infiltration as well as to the soil hydraulic conductivity and soil water diffusivity as functions of soil water content were ascertained from the measured water content distributions.
