Soil Management

Despite the shallow nature of the soil profile at just 660 mm depth, this soil holds a reasonable amount of plant available soil water at 127 mm and readily available soil water at 32 mm. However, the very high density in the B21 horizon, and extremely low drainable porosity throughout the soil profile indicates that root function will be impaired at depth. Consequently, it is likely that a more realistic plant available water content is in the order of 75 mm, and a readily available soil water content of 20 mm. As such irrigation will be required in frequent, small amounts, in which scheduling is informed by a quality soil moisture probe system. In relation to irrigation, the refill point for the A1 horizon is between 36 % (50 kPa) to 32 % (100 kPa) soil moisture.

Surface soil compaction is evident at this site. Management should ensure that vehicles are prevented from driving on the sides of the tree mounds. Whilst soil carbon levels are quite good, management is encouraged to increase return of resides, clippings and other green waste to improve soil carbon over time. Analysis indicates drainage is likely to be a problem at this site. The limited drainable porosity indicates that low oxygen conditions for root function are likely to exist even before the soil profile is fully saturated. Once saturated this soil will be very slow to drain. Given that subsoils are not sodic, consideration should be given to installation of subsoil drains to improve drainage and aeration. 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. Given high levels of potassium throughout the soil profile and the low CEC it is suggested that options to reduce potassium fertilizer be discussed with your agronomist. In relation to irrigation, the refill point for the A1 horizon is between 37% (50 kPa) to 32 % (100 kPa) soil moisture.

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