Evaluation of Saturo infiltrometer for determining field-saturated soil hydraulic conductivity

Pressure infiltrometer (PI) experiments are commonly applied for determination of field-saturated soil hydraulic conductivity, Ks, by the analysis of steady-state infiltration rate from within a single ring. Basically, two approaches can be used for determining Ks: the One-Ponding-Depth (OPD) approach, that uses a single depth of ponding and requires an a priori estimate of the α* parameter, and the Two-Ponding-Depth (TPD) approach, that allows simultaneous estimation of Ks and α*, the ratio between Ks and matric flux potential. Recently, SATURO infiltrometer (METER Group, Inc., USA) was developed as an automated version of the PI method. SATURO automatically calculates Ks by the TPD equations but its functioning presents some specific peculiarities. In particular, the higher pressure head on the soil surface is established before the lower one, and the steady-state infiltration rates required for TPD calculation are sampled after a soaking phase and one or more pressure cycles.