Soil Management

This is a well-structured soil with excellent drainable porosity and thus oxygenation capacity for root growth and function. Despite the excellent structure of the topsoil, it holds a relatively small amount of water for tree growth. The combination of moderate cation exchange capacity and moderate hydraulic conductivity indicates there is potential for applied nutrients to leach below the tree root zone if applied at large rates. Consequently, normal judicial fertilizer application practices involving small regular fertigation should be sufficient to prevent leaching of nutrient beyond the tree root zone. The subsoil is strongly acid which has resulted in exchangeable aluminium levels exceeding the toxicity threshold for apples. Aluminium toxicity is expected to reduce root growth and function. This is supported by the lack of roots observed in the B2 horizon. Consequently, the readily available soil moisture and plant available moisture values reported in this study are likely to be greater than those available to the tree. Management is advised to irrigate in small to moderate amounts frequently, preferably with the aid of soil moisture monitoring sensors / probes. In relation to irrigation, the refill point for the A1 horizon is between 32% (50 kPa) to 29 % (100 kPa) soil moisture. Given low pH and probability of aluminium toxicity it is recommended that application of lime be discussed with your local agronomist. In addition, management is encouraged to continue current practices that promote residue return and carbon cycling in the topsoil.

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