Soil Hydrology
Site
SA6 - Uraidla
Region
Adelaide Hills, South Australia
Soil Type
Brown Chromosol
Soil Hydrology Overview
This data reflects both the quality of the soil structure, the amount of water available for growth and the ease by which these soils are able to be irrigated. The data indicates how much water is available for vigorous tree and fruit growth, as well as how much water is available for tree maintenance and survival. This data can also be used to better schedule irrigation, and compare irrigation requirements between soils.
The surface A1 horizon has remarkably low bulk density at 0.99 g/cm3, very high saturated hydraulic conductivity at 343 mm/hr, and very high drainable porosity at 25.2 %. This indicates this topsoil has remarkable soil structure and macroporosity. The A12 horizon also has exceptionally good soil structure, despite a moderate bulk density of 1.33 g/cm3. The A12 horizon has a remarkable drainable porosity of 19.3 %, whereas the ideal drainable porosity for a topsoil is around 10 %. The A11 and A12 horizons have a high proportion of plant available soil moisture (PAWC) at 22.9 % and 18.7 % however due to the relatively shallow nature of these horizons this only equates to a total of only 34.3 mm, of which only 15.1 mm is readily available for tree and fruit growth.
Compared to the A horizons, the B2 horizon is compacted and poorly structured. The B2 horizon has high bulk density at 1.48 g/cm3, low hydraulic conductivity at 2.38 mm/hr, and a drainable porosity of only 4.5%. The majority of moisture held within this horizon (28.7 % or 45.9 mm) is not available for tree use, whilst the plant available soil moisture content is relatively small at 11 % or only 17.6 mm.
Soil Hydrology Table
Available Soil Moisture
The soil profile to the base of the B2 horizon at 33 cm is able to hold 163 mm soil moisture,of which xx mm is unavailable for tree use. However, of this total moisture the amount of water which is actually available to the trees (plant available water content – PAWC, Green and Orange in figures) is only 52 mm, whilst the moisture used for rapid plant growth (readily available water - Green in figures) is moderate to high at 21 mm. This is a relatively shallow profile in which the possibility exists that tree may be able to access soil moisture in the C horizon which consists of partly broken down bedrock, in which case the plant available soil moisture is likely to be around 95 mm, whilst the readily available soil moisture is likely to be around 43 mm.
Figure 1
Figure 2
Figure 3