Soil Management

This is a good soil, and a remarkable achievement. The exceptionally soil structure is undoubtably related to the extraordinarily high organic carbon content of the soil profile. Yet high organic carbon content does not appear to have overly influenced the cation exchange capacity as would normally be expected. Management is encouraged to continue current management practices that promote residue return and carbon cycling in the topsoil. The high drainable porosity and hydraulic conductivity combined with only low to moderate cation exchange capacity means this soil profile has lower than anticipated capacity to store and retain nutrients. Consequently, fertilizer will need to be applied regularly in small amounts via fertigation.

The whole soil profile is strongly to very strongly acid, which has resulted in exchangeable aluminium levels in all soil horizons exceeding the toxicity threshold for apples. Aluminium toxicity is expected to reduce root growth and function. Note the lack of roots observed in the B22 horizon. Given this toxicity and lack of roots in the B22 horizon the plant available soil moisture, and readily available soil moisture are more likely to be in the order of 86.4 mm and 41.6 mm respectively, rather than the values reported for the whole soil profile. Consequently, 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 34 % (50 kPa) to 32 % (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.

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