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 (A11 horizon) appears to have slight to moderate compaction, having a bulk density of 1.33 g/cm³ in the A11 horizon and 1.40 g/cm³ in the A12 horizon. In addition the drainable porosity at 8.1 % in the A11 and 5.3% in the A12 horizon is below the desired level of 10 % required for good root function. Despite evidence of compaction and a lack of macroporosity, the hydraulic conductivity at 265 mm/hr is very high, which indicates that while there is not a great deal of soil macroporosity, what is there is functioning well. The A11 and A12 horizons hold similar amounts of plant available water (PAWC) at 27.4 % and 24.5 %. However, as a proportion of the total soil water, these horizons hold little readily available soil water at only 9.0 % and 7.9 % respectively. These horizons do however contain a large amount of tightly held soil moisture at 31.3 % and 21.5 %, which is available for tree function and survival but not rapid growth.

The two B horizons have surprisingly similar water holding properties to that of the two A horizons. However, the B1 and B21 have considerably lower hydraulic conductivity at 45.5 mm/hr and 1.3 mm/hr, which although low, are still substantially higher than many other soils, especially for the B1 horizon. What is notable is the very low drainable porosity at only 1.7 % and 2.3 % which indicates a lack of macroporosity and ability to readily drain once saturated.