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 a moderately compact with a bulk density of 1.51 g/cm³, however in other respects the A1 horizon appears well structured as the drainable porosity is 10.4 % which is above the desired level of 10 %, and the saturated hydraulic conductivity is high at 150 mm/hr indicating that macropores are well connected. Just under half the water held in the B21 horizon is unavailable for plant use. The B21 horizon is extremely compact with a bulk density of 1.94 g/cm³, yet still retains 6.6 % drainable porosity indicating the presence of large macropores. The B21 and B22 horizons have very little readily available soil moisture at just 3.2 %, and little tightly held water at 4.6 %.

The B22 at 1.40 g/cm³ is less dense than the B21 and the A1 (topsoil). However, despite its low density the B22 has almost no drainable porosity at 1.1 %, and thus no macropores and consequently low oxygen status and will be very slow to drain. The PAWC of the B22 is twice that of the B21 at 15.3 % or 19.9 mm which is good, however only 3.2 % or 4.1 mm is readily available for tree use. The B23 is similar, with a PAWC of 32.6 mm but only 2.6 mm is readily available for rapid plant growth. The hydraulic conductivity of the B23 and presumably the B22 is extremely slow at 0.005 mm/hr. In essence the subsoil is impermeable. Colour and mottling in the subsoil indicate presence of seasonal waterlogging.