Hydroponic citrus in south africa

September 29, 2008

Citrus grow hydroponically in South Africa
Travel broadens the mind, even on the narrow topic of irrigating citrus.

So discovered Larry Parsons, a professor of horticulture at the Citrus Research and Education Center in Lake Alfred, from his recent trip to South Africa. He was still excited about what he found there when we discussed the trip last week.

Americans have a tendency to think we’re the world’s most technologically advanced country, and that’s true often enough. But Parsons told me many South African growers are far ahead of their Florida counterparts in using advanced irrigation techniques.

In particular, the South Africans are way ahead of Florida in employing “open hydroponics” irrigations systems, Parsons said. One Florida growers, Pete Spyke of Arapaho Citrus Management Inc. in Fort Pierce, has been experimenting with open hydroponics, and you can read about his experiences on his website.

Briefly, open hydroponics uses drip irrigation to “spoon feed” the trees with the proper amount of water and fertilizer, Parsons said. The system will run about six to seven times a day for perhaps an hour at a time – that schedule can be adjusted based on local climate and soil conditions – so that trees get only enough water and nutrition as they can absorb at that time.

That reduces the amount of water used in conventional irrigation systems, which run long enough to keep the soil moist so the trees absorb water when it’s not running, he said.

“That way you are definitely keeping water in the first 2 inches of soil,” Parsons said. “The idea is growing a tree more rapidly because it is not water-stressed.”

That means trees produce a commercial crop sooner, he said.

Open hydroponics also allows for higher density plantings, said Parsons, who saw densities in South Africa as high as 1,300 trees per hectare, or about 525 trees per acre. It would not be possible to get such densities in Florida because it leaves not room for equipment, but densities higher than 140 trees per acre are definitely possible.

Both factors may be particularly valuable in the future for Florida citrus, at least until it finds a way to control citrus greening, he said. The higher densities limits per-acre yield losses due to removing greening-infected trees, and the resets come into production sooner.

There are drawbacks, mostly financial, Parsons acknowledged.

Higher densities mean higher up-front costs in planting a new grove on the open hydroponics model, he said.

And the system requires computerized controls, monitors and other hi-tech equipment to work most effectively, Parsons said. He estimated that would add another $1,000 to $2,000 per grove in up-front costs.

Growers would save on water and fertilizer, the latter a significant factor given the exploding price of fertilizers in the past year. Parson’s colleague, economist Ron Muraro, told growers at the Sept. 11 Citrus Packinghouse Day to expect fertilizer costs to continue rising into next year and perhaps further.

“This is not for everybody,” Parsons said. “The areas where it has worked have generally been the more arid regions, such as Israel, South Africa and Spain.”

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Written by Matt · Filed Under hydroponics