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) has very good structure, bulk density is low at 1.19 g/cm³, drainable porosity is ideal at 10 %, and the saturated hydraulic conductivity is high at 91 mm/hr. The topsoil holds 40.5 mm plant available water (PAWC), of which 15.1 mm is readily available to support rapid growth, with a further 25.3 mm of water being available but at a cost to growth rate. The B21 horizon appears more compact than the A1 horizon having a bulk density of 1.31 g/cm, yet it has substantially higher drainable porosity at 12 % than the A1 horizon. The B22 has almost no drainable porosity at 2.0 % and is quite compact at a bulk density of 1.62 g/cm³. The very large difference in hydraulic conductivity between the A1 horizon at 240 mm/hr compared to 2.1 mm/hr in the B22 horizon indicates possibility for temporary waterlogging of the subsoil in winter, which is also suggested by the presence of yellow mottles in the subsoil. The two B2 horizons hold a relatively small amount of readily available water at 19.1 mm or 8.7 % and 15.3 mm or 4.9 % respectively. The B2 subsoils do however hold a substantial amount of tightly held water at 28.9 and 56.5 mm which is available to the tree to prevent drought and support slower rates of growth.