With a looming water crisis and an expanding macadamia industry, the obvious question arises: where will the water for the new orchards come from? A recent groundbreaking study shows that farmers have been grossly over-irrigating and that dryland macadamias in high-rainfall areas actually provide better yields. Lindi Botha spoke to Theunis and Armand Smit, specialists in irrigation and optimal water usage.
The ongoing prosperity of the macadamia industry has led to a rapid increase in orchards, with the industry adding about 2 000ha each year.
With water shortages increasingly becoming the norm, however, concern has been expressed about the availability of irrigated water for these new orchards.
LACK OF RESEARCH
As the industry is still relatively new in South Africa, little research has been conducted here on the many factors that ensure a macadamia farm’s sustainability and profitability.
In particular, relatively little is known about the crop’s wateruse efficiency and maximum irrigation requirements. Theunis Smit, owner of Darwin Consulting, puts it more bluntly, saying that no research has been done in South Africa on how much water a macadamia tree really needs.
“Much of the existing research originates in Australia and the majority of orchards there are dryland, as studies show there’s little benefit to irrigating in high-rainfall areas. We know how much water the trees can use; the biggest challenge is to determine the minimum amount we can get away with. Because the profitability of macadamias is high, farmers are not pressed to adopt new technologies to increase efficiencies.”
OVERWATERING RESULTS IN LEACHING OF MACRONUTRIENTS SUCH AS NITROGEN
One obstacle in determining optimal water use is that there is no one-size-fits-all approach.
“Trees aren’t uniform,” explains Theunis. “You can have one tree drowning and another droughtstressed in the same orchard! What’s more, most farmers don’t know how much water they’re giving their trees. They can tell you how long they irrigate, but not how much, and a lot of the water is flushed away, taking all the nutrients with it.
This story is from the August 16, 2019 edition of Farmer's Weekly.
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This story is from the August 16, 2019 edition of Farmer's Weekly.
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