Soil Management

Despite consisting of medium to heavy clay this soil holds relatively little readily available soil water at only 5.0 %. However, due to the depth of the soil this translates to a total of 46 mm readily available soil water, (provided roots are able to access the whole soil profile to 94 cm depth). Management needs to ensure that trees maintain rooting into the B2 and B3 horizons to ensure adequate access to moisture. Small frequent irrigation is recommended to maintain moisture in the A horizons without saturating the heavy clay subsoils, which have very limited drainable porosity and thus are likely to have very low oxygen status to support root function when moist. In relation to irrigation, the refill point for the A1 horizon is between 38 % (50 kPa) to 36 % (100 kPa) soil moisture.  Low levels of sodicity in the B2 and B3 horizons indicate these soils are suitable for subsoil drainage, however water flow to the drains is likely to be slow, and drain installation will need to be closely spaced, and should avoid installation in the slightly sodic B3 layer. The CEC indicates the soil has extremely high capacity to attract and retain nutrients, such that leaching of nutrients below the root zone is very unlikely. The pH in the surface horizons is neutral which ideally should be slightly acid. It is advised that this issue be raised with your local agronomist to ensure liming practices have not overly increased pH beyond the desirable range.

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