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.

Overall the A1 horizon appears to have moderate to good soil structure. The A1 horizon has a low to moderate bulk density of 1.24 g/cm³ and a moderate to high saturated hydraulic conductivity of 125 mm/hr. This indicates the soil to be non-compacted or low compaction with good macropore structures. However, the drainable porosity is only 4.9 % which suggests the topsoil has poor aeration status. The topsoil has a very large plant available water content (PAWC) at 36 % or 64.9 mm of which 24 mm or 13.3 % is readily available for rapid treegrowth. Only a very small proportion of moisture held in the A1 horizon 9.3 % or 16.7 mm is not available for tree growth. The A2 horizon is similar to the A1 except that it has higher bulk density at 1.39 g/cm³, yet has slightly higher drainable porosity and slightly lower PAWC at 29.2 %.

The B21 and B22 horizons are moderately compact with a bulk density of 1.34 g/cm³ and 1.46 g/cm³ respectively, and have low drainable porosity at 3.6 % and 3.7 % respectively. The saturated hydraulic conductivity of the subsoil is very low at 0.30 mm/hr. Over half the soil moisture held in the B21 and B22 horizons is not available for use by trees, with only 5.9 % to 6.2 % or 10.6 mm to 18.9 mm soil moisture being readily available for rapid tree growth. The low drainable porosity and hydraulic conductivity of the two B2 layers indicates that ‘perched’ water tables are likely to develop in winter.