Hydropedology of the Tasmanian texture-contrast soils

The texture-contrast soils are extensively used for agricultural production in Australia, however the processes governing infiltration and soil water distribution in these soils are poorly understood. This manuscript reports surprisingly complex interactions between soil morphology, antecedent soil moisture and preferential flow processes in a series of texture contrast soils. The occurrence of preferential flow was strongly influenced by antecedent soil moisture, not rainfall intensity as is often reported in the literature. In dry soil conditions infiltration resulted from up to five different forms of preferential flow including; finger flow, rivulet flow, macropore flow and saturated backfilling of voids at the base of the soil profile. When soils were at moisture contents near field capacity infiltration was mostly uniform, however wetting front instability and lateral flow in the A1 horizon developed due to difficulty displacing existing soil moisture further down the soil profile.