Farmer builds his own oven for drying macadamias

Valley Macadamia’s Farmer of the Year, Bill Bales-Smith, has built a drying oven for less than K7 000 and it saves him about K200 000 in the drying costs of his macadamias.

For most macadamia nut farmers, the cost of erecting and operating electric drying units is extremely high, or they have to pay a processing plant to do it for them. Bill Bales-Smith, a macadamia nut farmer from the Sabie Valley South Africa, sought another solution and built his own drying oven for a mere ZMW 6800. Now he dries his own macadamias and reduces the moisture content from 20% to about 3.5% without paying another cent.

The heat from the two ovens is drawn into a simple pipe and chimney system through the drying unit. The pipe leading from the oven is about 250 mm in diameter and passes through a cavity below the macadamia drying tanks, explains Bill.


The hot air passing through the pipes is kept contained in the cavity by corrugated iron sheets that enclose it. Extractor fans then draw the heat into drying tanks where the hot air rises up through the macadamias, drying the nuts.


Bill, who previously farmed in Zimbabwe, says his oven is basically a modification of the Malawi tobacco oven. It was designed to be extremely economical. The V-shaped fireplace inside the ovens draws oxygen through the centre of the fire. This means the oven uses 30% less wood than one which draws fresh air over the fire.

Bill uses the wood which is pruned from his 38 ha macadamia orchards every year to power his drying unit. This is more than enough wood, he explains. He says it would cost him about K200 000 in drying costs if he sent his macadamias to Valley Macadamias’ processing plant to be dried.

Allan Sutton, chairman of Valley Macadamias, is impressed with the quality of the product which Bill delivers annually. “Bill’s macadamia nuts are processed so quickly and easily through the system it seems almost unreal sometimes. In a country where we have a problem with electricity, this oven makes so much sense. If I could, I would convert our plant to this type of system but I don’t think our municipal zoning permits furnaces.”

1. This pile of wood is used to dry 300 tons of macadamias during harvest time.


2. The ovens which feed Bill’s drying unit were modified from an old tobacco oven that became known as the Malawi oven.


3. The V-shaped base of the oven draws air from below the flames, a design feature that allows the oven to use 30% less wood.


4. Heat passes through a thick pipe from the oven; the pipe then goes to a chimney that ensures optimal flow of hot air for the drying unit. These pipes are enclosed with corrugated iron to ensure as much heat as possible is drawn by the extractor fans to the drying tanks.

ENQUIRIES: Bill Bales-Smith +2782 771 6986.

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