Disc size influence on tension infiltrometer performance

Abstract

A series of tension infiltration measurements have been made to derive saturated hydraulic conductivities and alpha (a) soil parameter values of a heterogeneous desert soil. Four diameter sizes, 8. 7, 20, 28.2, and 40 cm, were used, yielding saturated hydraulic conductivity values of 0.05, 0.09. 0.10, and 0.11 cm/min, respectively. These increasing mean hydraulic conductivity values with increased disc size are the result of improved sampling of the heterogeneous soil. Standard deviation values are 0.04, 0.03, 0.02, and 0.01, respectively. Respective a mean values for increasing disc size are 0.15, 0.13, 0.11, and 0.10, with respective standard deviations of 0.04, 0.03, 0.03, and 0.02. The decreasing trends of both standard deviations with increasing disc size is attributed to sampling larger areas and reducing edge effects. These results imply that for heterogeneous soils, larger diameter discs have an advantage over the standard 8. 7 and 20 cm disc diameters currently being used.