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 topsoil (A1 horizon) appears to be well structured having a low bulk density of 1.16 g/cm³, a moderate saturated hydraulic conductivity of 95 mm/hr, and a very high drainable porosity of 18.0 % which is well in excess of the ideal level of 10 %. Despite the excellent structure of the topsoil, the A1 horizon holds a relatively small amount of water for tree growth. The A1 horizon contains 18.1 % or 45.2 mm plant available water (PAWC), of which 7.3 % or 18.3 mm is readily available to support rapid growth (green in Figure 3), an additional 26.8 mm soil moisture is available to the tree but at a cost to growth (Orange in Figure 3), whilst 52.5 mm is not able for use by trees (Red in figure 2).

The B2 horizon is substantially more compact than the A1 horizon, however it holds a similar amount of readily available soil moisture. The B2 horizon has a moderate bulk density of 1.32 g/cm³, a very low saturated hydraulic conductivity of 0.96 mm/hr, and a low to moderate drainable porosity of 5.7 % which all indicate the subsoil is moderately compact and that air and water flow are restricted. The readily available soil moisture of the B2 horizon of 6.7 %, which is similar to that of the A1 horizon at 7.3 %. And the tightly held moisture of the B2 horizon of 12.7 %, is similar to that of the A1 horizon at 10.7 %. The primary difference between the two horizons is the reduction in drainable porosity within the subsoil.