Paraguayan technology saves SA’s apples

For years Pieter Fourie, project manager of the Bethlehem Farmers’ Trust,
struggled with an annual loss of 40% to the project’s apple crop.
Local experts couldn’t come up with any cost-effective solutions,
until Pieter started surfing the internet for a solution. Mike Burgess reports.
Issue date: 20 April 2007

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Packhouse manager, Petrus Dshabangu,
inspecting apples being washed.

For years Pieter Fourie, project manager of the Bethlehem Farmers’ Trust,
struggled with an annual loss of 40% to the project’s apple crop.
Local experts couldn’t come up with any cost-effective solutions,
until Pieter started surfing the internet for a solution. Mike Burgess reports.

The Bethlehem Farmers’ trust was initiated in 1999 when a 110ha farm outside Bethlehem was acquired through the Free State Department of Agriculture and Land Affairs on an individual grant basis.

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Collectively, this secured the farm and the installation of an underground irrigation system for approximately one hundred beneficiaries. Each beneficiary received 1ha on which to farm, with each plot supporting 1 500 trees. The project is funded by the Industrial Development Corporation, the Development Bank of Southern Africa, Afgri (an agricultural services group) and the Free Department of Agriculture and Land Affairs.

The majority of the 110ha of orchards is under drip irrigation and a complete fertigation system. A small percentage is under micro irrigation. Some 94 emerging farmers currently produce export quality apples here. The estimated yield this year is 5 700 tons from five cultivars: Top Red, Pink Lady, Oregon Spur, Braeburn and Royal Gala.

More than 50% of the fruit is exported globally through the export agents Fruitways. They focus specifically on the British supermarket chains of Tesco and Sainsbury’s. The project, however, has never shown a profit. While this is due in part to the withdrawal of some farmers during the start-up phase, the biggest setback has been unpredictable natural challenges. Although the isolation of the Free State can make the control of diseases a great deal easier than some other provinces, harsh weather is the farmers’ biggest adversary.
While violent hailstorms in these areas can be catastrophic to any crop, it is the silent killer, frost, which has caused the most damage to apple production over the years. ”Up to 40% of the crop has been lost to frost each year. It’s difficult to survive such losses,” says project manager Pieter Fourie.
Fortunately, the threat of hail has largely been neutralised by erecting hail netting across the entire orchard. Additionally, after arduous research on possible preventative measures against frost, Pieter was able to source revolutionary and cost-effective frost protection systems with spectacular results. Understanding frost and fighting it Pieter admits when no inexpensive solutions could be identified by specialists in this field, they considered abandoning approximately 40% of their trees.
These were all situated in frost zones in the orchard.

Pieter says there are two kinds of frost, both of which affect the Bethlehem Farmers’ trust orchard. Wind-driven frost forms on a clear or cloudy day during a cold front. It occurs when there is a dramatic drop in temperature with winds above 8km/h. The height of the cold air layer above the ground can be anywhere between 152m to 1 524m, making it very difficult to combat.
Fortunately, this devastating frost is relatively rare and frost prevention mainly focuses on what is called radiation frost.
Radiation frost forms when there is no fog and little or no cloud. There is usually minimal wind and the day’s warmth, trapped in the ground, radiates upwards. This causes an inversion layer to develop, meaning temperature increases with altitude in direct contrast to daytime conditions. As warmer air collects above the cold air on the surface, the inversion level is relatively low, between 9m and 61m. The conditions are now perfect for severe frost. This includes white and black frosts that form depending on atmospheric moisture content. ”If you realise cold air is heavier than warm air, and that it operates in a similar fashion to cold water, then its easier to understand that it will sink to the lowest point and accumulate in hollows, depressions and valleys in the topography, dragged there by gravity, “Pieter says. “Furthermore, this cold air can be obstructed and diverted by numerous structures including roads, vegetation, contours, windbreaks and embankments.” These factors can affect the occurrence of frost.

Combating this freezing cold air can mean the difference between major agricultural losses or profits. Pieter says that traditional techniques of fighting frost are generally very expensive. These include heaters, irrigation, wind machines and heaters burning fuel. In fact, over a five-year period, the Bethlehem Farmers’ trust orchards burnt ethanol at astronomical costs. Save certain passive techniques, the situation seemed hopeless. None of the numerous researchers and experts asked could find a solution.

Then, approximately three years ago, he began trawling the internet. He discovered the Paraguayan Selective Inverted Sink (SIS) Frost Protection System from the SIS Frost Protection Corporation. Last winter, he installed this system. Combating frost The Bethlehem Farmers’ trust now combats dreaded wind-driven frost using special wind-netting.

Last year, they erected it at a 45º angle around the orchards to deflect winds. The main focus of frost protection here is geared towards radiation frost. ”Everybody said to me cold air acts and works like cold water,” explains Pieter. ”I thought logically that if you can pump water surely you can pump air.” Armed with this concept, he began searching cyberspace for a solution to radiation frost in the orchards.
He was sceptical though as the US had for years and with mixed success, employed a system to pump warm air down, and not cold air up. He was understandably surprised, therefore, to stumble on technology from Paraguay. This focused on the principle that cold air drains and can be selectively trapped and mechanically pumped out of orchards at very low costs.
”The SIS Frost Protection System is certainly revolutionary in that it pumps cold air through a simple wind turbine. This can be run on a small 3kW electric or petrol engine, making it incredibly cheap and effective,” Pieter says. About 30 SIS M3.5 turbines are employed by the Bethlehem Farmers’ trust for approximately 46ha, but the smaller SIS M2.5 and larger SIS M25 are also available.
The selective extraction and expulsion of cold air to warmer air at higher altitudes is streamlined by trapping, containing and manipulating cold air. This is achieved by erecting impervious cold air diversion curtains. These have a standard height of 1,5m and can be adjusted according to conditions. The SIS system is specifically designed in relation to a comprehensive regional and local microclimatic analysis and technical study. This includes interpreting local air fluxes, topography and crop and frost damage history. This information is needed to formulate a design of passive frost protection measures and to determine the quantity and specific location of necessary SIS devices in the orchards.

Why use the SIS system?
This system does not impact the environment. It is also personalised and integrated for specific use in specific orchards. SIS is easy to operate and has significantly lower installation and running costs than traditional frost protection units do. “The success of the system has been simply enormous,” Pieter says. “It has been a highlight of my life.” He explains that according to data collected, the SIS Frost Protection System is able to increase temperatures in the orchard by an average of between 3ºC to 5ºC, making it possible for Bethlehem Farmers’ trust orchards to realise their potential for the first time. Joseph Tshabalala, a farmer from the Bethlehem Farmers’ trust, agrees. “The frost was really bad and it was frustrating, but these machines have done a very good job,” Joseph says. Another farmer, Piet Maseko, admits that he was negative about continual frost losses, but that the machines had without a doubt turned the fortunes of all the farmers. Contact Pieter Fourie on (058) 303 5804. Or visit;;; |fw

Mentorship: a crucial ingredient
The Bethlehem Farmers Trust is a uniquely run project. Pieter Fourie, also an apple farmer, devotes 30% of his time giving technical and agricultural assistance to the emerging farmers. His wife now runs his apple farm while he works at the Bethlehem Farmers Trust orchards.
His technical background to apple farming is a vital resource to all emerging farmers involved, which is illustrated by his initiative to find an economical solution to the Bethlehem Farmers Trust frost problem. Despite the development being collective in nature, Pieter says they all try to work on an individual basis and there are no handouts. Nobody lives on the farm and each farmer is responsible for his or her trees. “We try to keep each farmer’s harvest separate,” Pieter says. This way they can assess the quality and volume of each farmer’s fruit and their overall contribution, which will help identify who will have a greater chance of commercial success if allowed to expand – some farmers now work 2ha of land. A management structure has also been created from handpicked individuals who meet each Friday to ensure proper and efficient decision-making processes.