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.

This soil contains a relatively large amount of readily available soil moisture at 69 mm, and plant available soil moisture at 191 mm. This soil profile contains four A horizons or topsoil layers; the A11 at the surface, the A12, as well as the paler A21 and A22c horizons. The A22c horizon is similar to the A21 horizon except it has around 50 % gravel content. The A11, A12 and A2 horizons have similar bulk density at 1.33 g/cm³, 1.44 g/cm³ and 1.44 g/cm³ which indicates these soil layers are slightly to moderately compact. Drainable porosity in the A11 surface horizon is 4.6% whereas the ideal drainable porosity for a topsoil is around 10 %. Whilst the surface hydraulic conductivity at 105 mm/hr is moderate to good, it is less than many other orchard soils measured in this study These values indicate A11 horizon is compact, lacking in macroporosity and will possibly have poor aeration status for root function. The A12 horizon and A2 horizons have 8.2 % and 7.6 % drainable porosity (higher than the A11 horizon) which suggests they have better but not ideal infiltration, drainage and oxygen status for root function in these soil layers. The A21 horizon is also noted to have very low hydraulic conductivity at 0.7 mm/hr which indicates that water infiltrating through the A1 horizon may perch above the A2 horizon resulting in temporary waterlogging in the middle of the soil profile. Although mottling was not noted in these soil layers. The two A1 horizons and the A21 horizon have similar soil water retention properties, together they hold 121 mm plant available soil moisture to a depth of 39 cm, of which 48 mm is readily available for rapid tree and fruit growth. This is greater than many other soils examined in this study. The heavy clay B2 horizon holds a considerable amount of water at 52.7 % however the majority of this at 33.9 % is unavailable for tree use due to a combination of depth, and extreme density of the A22c horizon which is restricting root growth below about 45 cm depth.