Soil Management

The key to managing this soil is recognising that the A2 and B2 horizons are making little contribution to the supply of water and nutrients to the trees. The extremely high density in the A2 horizon is expected to prevent root growth and penetration below 36 cm. Furthermore, any roots which do penetrate through the A2 horizons would only have access to a small amount of tightly held soil moisture and almost no readily available soil moisture. Effectively the plant available soil moisture for this soil is around 95 mm, whilst the readily available soil moisture is around 45 mm. This is a moderate to small amount of readily available soil moisture such that this soil would benefit from small frequent irrigations preferably informed by a quality soil moisture monitoring system. In relation to irrigation, the refill point for the A11 horizon is between 28 % (50 kPa) to 24 % (100 kPa) soil moisture. Likewise, the low CEC throughout the soil profile indicates this soil has little ability to retain and supply nutrients, such that frequent fertigation with small amount of fertiliser is advisable to prevent loss of nutrients below the root zone. The hardness of the A2 horizon in part results from its sodicity. Attempts to relieve this harness or compaction through deep ripping are likely to have moderate to short term benefits as this soil will naturally re-compact over a period of months to years.

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