Soil Management

This soil holds a substantial amount of plant available water (PAWC) at 170 mm but a much reduced readily available soil water (RAW) at 52 mm. The hostile nature of the A2 horizon is likely to restrict root growth further down the soil profile. Consequently, a more realistic value for plant available water (PAWC) is 105 mm, and 37 mm readily available soil water (RAW). Irrigation will need to be frequent and small to support tree and fruit growth. However, this soil has considerable reserves of soil moisture to prevent moisture stress or drought. The A12 and A13 have high bulk density and all horizons have substantially lower drainable porosity than the ideal value of 10 % which suggests this soil is likely to be prone to poor aeration. Poor aeration is also indicated by the patchy presence of orange mottles (indicating iron rusting) in all A horizons, and grey mottling in the B2 horizon which indicates seasonal waterlogging. The low ESP means these subsoils would be suitable for drainage. Soil carbon levels in the surface soil are quite high, however levels decrease with depth. Management is encouraged to increase return of residues or organic material to encourage carbon cycling in the topsoil. In relation to irrigation, the refill point for the A1 horizon is between 35% (50 kPa) to 29 % (100 kPa) soil moisture.

The low CEC of this soil indicates it has little capacity to absorb nutrients and make nutrients available for tree growth and fruit production. This soil will require fertilizer applications to be small and frequent to meet tree demand without risking nutrient leaching through the soil profile. It is noted that current levels of potassium and phosphorous in the A11, A12 and A13 horizons appear high. It is suggested that fertilizer management should be discussed with your agronomist.

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