Click on image to view larger version.
Fig. 7. Data from Buckingham's experiments measuring water flow driven by a difference in matric potential. The ordinate is the mean change in water content of a dry and a wet sample of soil brought into contact in a column, divided by the initial difference in the two water contents. This quantity correlates with the flow rate induced by a difference of water contents, in effect representing the soil-water diffusivity. The results here for a Podunk sandy loam suggest that the diffusivity has a minimum at about 16% water content by weight. The symbol A labels these results as being from experiments of 4-d duration. The different point symbols correspond to minor experimental variations. (Buckingham, 1907, p. 59.)
