Using the latest research and development technology, a Mpumalanga-based crop maintenance advisor says creating a nutrition plan and sticking to it means macadamia farmers could now accurately calculate the supplementation needs in their orchards to get the best out of their trees.

While it may seem obvious that the best harvests achieved from macadamia trees are dependent largely on climatic conditions and soil type, independent consultant and expert, Stephan Schoeman says using high-tech systems to accurately measure what nutrition the trees lacked was now crucial for first grade kernels and wholesome oil production.

At a recent study group held on the KwaZulu-Natal south coast and hosted by the Green Farms Nut Company, Schoeman said it was ideal for nutrition planning to start at the design phase of an orchard.

The decisions made at this phase, he said, would dictate the level of control the grower could have over optimising management, nutrition and water-use over the orchard’s life span. And recent advances in technology; in particular, ultra-low-flow drip, fertigation systems, variable-speed pumps and automated soil moisture probes, now allowed farmers to manage their orchards at levels and frequencies that were impossible or impractical just a few years ago.

“For macadamia trees to produce first grade kernel and good wholesome nut oil not only do they require water but the full nutrient spectrum. The trees also need energy provided by light plus carbon dioxide to complete the flowering to fruiting maturation process,” Schoeman said.

A macadamia tree takes 30 weeks from full bloom to harvest and it is in the intimate knowledge of this process, and how to balance existing growing conditions to create an ideal flowering and nut formation climate, that should form the basis of a sound nutrition management plan, he said.

To get the most out of an orchard Schoeman stressed that growers should be managing individual blocks of trees rather than entire orchards.

He said they must decide how much nutrition they are going to supply to those trees and when they are going to supply that nutrition and how?

Schoeman said it was ideal to develop the plan before an orchard was planted.

And important questions at the pre-development should start with an understanding of what types of soils are present in the orchard.

“The aim is to create balanced growing conditions for the trees. If the soil is found to be acidic then there will be major nutritional deficiencies present which can impact negatively on the nut development cycle. The physical character of the soil further influences the soil fertility and an amelioration plan will detail how those deficiencies should be fixed,” he said.

The next question was to ask what cultivars were ideal for the soil type?

Once that was established, Schoeman said, it was critical to buy top quality seedlings as the next most important step.

He said any nutrition plan would effectively fail regardless of the precision feeding programme if trees were poor.

Next growers should establish how their trees should be fed and what irrigation system would be most suitable for ideal growing conditions such as drip irrigation or micro-jets.

“When you get to this point in your orchard planning then the grower must determine what he is going to feed his trees, how much and when that food will be applied.”

For an existing orchard, Schoeman said the results from regular leaf, water and soil tests should be used to accurately calculate fertiliser requirements in conjunction with nutrient replacement values.

“Again, this must be based on the cultivar and whether the trees are young or old trees. Fertiliser application history is also important when calculating what reserves remain in the soil,” he said.

Schoeman said technology platforms were providing an exciting environment for growers wanting to ensure the best possible planning process in the establishment of new orchards or in improving the management of existing trees.

AgriWiz is one of those technologies. It is a cloud-based research and development platform which I use. Using this platform creates a comprehensive plan by integrating all the orchard factors and conditions. It evaluates and calculates water use, yield, climate, history and soil types.  The programme then takes all these factors and integrates them through the system to create a weekly management diary which is moderated by the expected rainfall for that week. Sticking to a nutrition plan creates a management environment that is efficient, effective and results in optimal yields in any growing conditions,” Schoeman said.

For further information contact Stephan Schoeman on


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