INTERPRETING TENSION-INFILTROMETER DATA FOR QUANTIFYING SOIL MACROPORES - SOME PRACTICAL CONSIDERATIONS

A tension-infiltrometer offers a practical means for obtaining informa tion on soil infiltration characteristics at low soil moisture tension s in the field. This study examines interpretation of tension-infiltro meter results. Saturated hydraulic conductivities (K(s)) calculated fr om unconfined tension-infiltrometer measurements were not statisticall y different from conductivity measurements made with a velocity-head p ermeameter. K(s) values determined with the tension-infiltrometer were greater than conductivities measured with a Guelph permeameter. Tensi on-infiltrometer measurements of infiltration made through a 20-mm lay er of sand were an order of magnitude less than ponded infiltration me asurements at the same location. Increases in antecedent soil moisture decreased infiltration values, but parameters for equations fitted to the hydraulic conductivity versus tension curve were similar. Unconfi ned infiltration rates when adjusted to give vertical conductivity did not change appreciably the values of parameters fitted to a hydraulic conductivity versus soil moisture tension curve.