The joys of a DIY wheat silo

While many South African wheat farmers continue to complain about unfair wheat grading and high silo costs, Kobus Wessels � 2007 Grain SA�s Farmer of the Year � decided three years ago to build his own grain storage facility. He told Glenneis Erasmus

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While many South African wheat farmers continue to complain about unfair wheat grading and high silo costs, Kobus Wessels – 2007 Grain SA’s Farmer of the Year – decided three years ago to build his own grain storage facility. He told Glenneis Erasmus about the huge benefits.

Building your own grain storage facility is an expensive operation involving huge financial risks. Kobus Wessels, however, who farms near Caledon in the Western Cape, found the advantages more than compensate for the initial costs and actually help to reduce farm risks. His primary motivation for building the facility was to reduce the impact of climate on his harvest. “We have a Mediterranean climate, implying that we should have dry summer conditions,” he explains. “Our long-term rain average in November – when we harvest most of our wheat – is around 28mm every year since 1932. But every now and again there seems to be a glitch in the weather and last year we received 184mm in November.”

Upgrading a drenched crop

Heavy and even mild continuous rain can significantly reduce wheat quality. Last year heavy rains at the end of November decimated the hectolitre mass and fall count of Kobus’s wheat, and a large portion was downgraded to utility grade. This would have been a tremendous setback, but the storage facility enabled Kobus to upgrade the utility wheat to grade B2 by mixing 30% of it with 70% of his B2 wheat. This significantly reduced losses. Utility grade trades for the Safex price minus R225/t, and minus another R310/t for that area’s transportation differential. B2 wheat trades for the Safex price minus R75 and the transport differential. In the end, Kobus managed to supply the market with 3 200t of B2 wheat. Kobus believes most farmers would be able to upgrade crops if the bulk of their crop is of a good quality. In future, he plans to buy in utility grade wheat from surrounding farmers and mix it with his B2 grade. This will enable him to add R225/t to the bought-in utility grade.

A shorter harvest

The facility also contains a cleaning system to upgrade wheat by removing foreign particles like weeds. Kobus also uses it to clean canola, lupins, barley and pea seeds. Residues are used as feed for his sheep. However, the main reason Kobus built the grain-holding facility was to shorten harvesting time. The original facility can dry wheat with natural air with a moisture content of up to 15%. “Farmers usually have to wait until wheat has a moisture content of 13%,” he explains. “Harvesting before that can cause wheat to rot if it isn’t dried. Accordingly, dew prevents us from harvesting until 10am or 11am, as it gives the wheat an unacceptably high moisture content. The drying facilities allow me to start harvesting earlier in the morning.” The climatic risks were reduced even further when he built a new silo with a propane burner. Kobus can now harvest around the clock, provided it isn’t raining. “As a result, the farm equipment is also better utilised,” he says. Kobus currently uses different chambers in the facility and silos to store and dry wheat with different moisture contents. The main chamber, for example, is used to keep wheat with a moisture content of below 13%, while one lean-to is used to dry wheat with a moisture content of 13% to 14%, and the other for wheat with a moisture content of 14% to 15%. The silo with the gas burner also has a stirring apparatus inside to enhance the drying process. Kobus estimates he can dry around 250t of wheat with 18% moisture content within three days at an ambient humidity of 65% and 20ºC. The drying process will obviously be faster if it is warmer outside. He adds that drying such wet wheat hardly involves any risks, as some farmers in Europe even dry wheat with a moisture content of 22% and above. However, he won’t take these risks yet.


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Another advantage of having your own facility is reduced transport costs. Most farmers have to rent extra trucks to transport wheat to cooperatives during harvesting. There’s usually a huge build-up of trucks at the cooperatives because they have to wait their turn to be offloaded. “Time is money and paying people to stand in queues for hours just adds to production costs,” says Kobus. “Failing to move wheat fast enough also forces farmers to slow down the harvesting process, which increases climatic risks.” Kobus can transport all his wheat to his own facility with his own 8t lorry, one tractor and a trailer. The dedicated facility has been designed so a 35t interlink truck can offload in less than 10 minutes and be loaded in under 30 minutes. Cooperation with the co-op Kobus points out that he didn’t build his grain handling facility to be anti-co-op. “For me the main idea was always to add value and optimise production,” he explains. “And now I realise all the benefits for myself – I don’t have to share the profit with anybody else.” He adds that he’s still dependent on his cooperative, as his facility isn’t Safex registered. He needs to get his grain graded at a Safex-registered facility if he wants to trade on Safex. He also doesn’t market his own wheat. “This side of the business should be left to the experts. I don’t have enough time or patience to investigate markets or hunt people down who owe me money,” he says. He therefore uses Bester Voer Beurs to help him with his trading decisions. But Kobus’s storage facility lets him take better advantage of price fluctuations in the market. However, he can’t keep wheat for longer than a year, as the facility needs to be emptied to receive new wheat each year. Contact Kobus Wessels on (028) 261 1922 or e-mail [email protected].

Building a storage facility from the ground up

Kobus Wessels explains that silos are better grain-holding facilities than sheds, because they are closed, making fumigation more effective. Even so, he decided to start with a shed, which could also store equipment, fertiliser and seed. Wessels built the first part of his grain-holding facility three years ago, a 35m x 35m shed with a dump pit, bucket elevator, grain-cleaning facility and three storage rooms. The main storage room has a capacity of 1 500t, and the two others 600t each. The facility has to be immensely strong to sustain such vast amounts of wheat. In addition to the steel in its frame, Kobus points out that 27t of reinforced steel has been used inside concrete to strengthen it. The facility was designed for the optimal use of space. According to Kobus’s research, including discussions on the internet with various international producers and scientific journals, B1 grade wheat with a moisture content of 13% should fall at a minimum of a 27º angle. This figure was used to calculate the pitch of the roof. Most of the wheat is moved by gravity through pipes at a 45º angle. To enable this, a 28m-tall bucket elevator, of which 5,5m are underground, is used to raise grain from the 4m-deep dumping pit and drop it into the pipes. As the wheat piles up to reach the roof, augers in the roof spread it through the chambers for optimal space usage. The dumping pit also lies at a 45º angle to prevent wheat and other foreign matter getting stuck. Kobus explains that insects can easily build up inside small cracks in the walls of the pit, so it’s fumigated and spray-cleaned before each new harvest season. The facility was planned so that Kobus could expand the building. An additional four silos – each with a 270t storage capacity – were added at the end of December last year, but this addition is also designed to leave space for future add-ons. Though the silos differ in structure, and one has a burner, they’re operated in exactly the same way as the rest of the facility. The whole system is fully computerised and each programme can be operated either manually or automatically. As a safety measure the systems are interlinked, so that operations in one part of the facility will shut down if an operation in another part isn’t carried out successfully. Outside humidity and temperature sensors are used as programme guides. There are three main operation stages: drying, aeration and fumigation. Drying is discussed in the main part of this article. The aim of aeration is to cool the wheat. “As a rule of thumb, wheat should be kept as dry, but as cold as possible,” says Kobus. “Warm air is fanned into the sheds to dry the wheat, but the heat can cause the grain to crack and disintegrate so that it’s unsuitable for baking. Warm wheat also tends to attract more insects.” During aeration the computer is programmed to automatically start the fans to blow cool air into the sheds when ambient humidity levels are below 65% and temperature below 20ºC. Fumigation is imperative for insect control. Wheat can be fumigated at any stage, before or after drying. Kobus uses Phostoxin, and the process takes around eight hours depending on environmental factors. The phostoxin tablets are placed inside the fan system, blowing the fumes into the sheds.