Storage system comes full circle
With 20 years of experience in storing grain on his farm at Killarney, Queensland, Rod Petersen can now unload a semi-trailer of grain in about 10 minutes. “They may do it faster out west, but that’s fast for around here,” Rod says.
The Petersen family crops 1600 hectares, focusing on summer crops of maize, sorghum, soybeans and mungbeans.
Back in the 1960s, they were supplying maize direct to Kellogg’s. These days they supply Defiance Maize Products in Warwick. They also send maize to Brisbane for export. Their storage capacity is about 2800 tonnes.
“One of the main reasons we have a large amount of storage is that we’re too far away from a grain-handling system,” Rod says. “The nearest one is 80 to 100 kilometres away. At that distance, you might as well cart it to port.
“It also takes away some of the pressure of transporting at harvest time. And we don’t have to sell straight off the header – we can sell when it suits us. We currently have two buyers who pay us for storage.”
GRDC grain storage extension project coordinator Chris Warrick says: “The Petersens’ storage works economically for them because they gain value in harvest logistics, as well as a reliable market premium through the arrangement with their buyers. By using best-practice management for their stored grain, they can be confident in maintaining grain quality to meet their buyers’ needs.”
While the silo set-up has evolved over 20 years, the original circular design is still intact, with the 21 silos arranged in two circles.
“You’ve got to start with a design,” Rod says. “A lot of people put silos in a big line but the circular arrangement is working well for us.”
The centre-pivot auger system can move grain from a single unloading point, outside the circle, into any silo. Grain can be moved from any silo to any silo and outloaded from the silos into trucks from a single outloading point.
“It’s like the hands of an old-fashioned clock,” Rod explains. “The little hand conveys the grain into the circle and then the rotating big hand conveys the grain out to the silo you want.”
Not all the silos are gas-tight sealable so, if necessary, grain can be moved to a gas-tight silo for fumigation. Fumigating in gas-tight storage is the only way to control insects at all life stages.
During these warmer months, insects can reproduce in three to four weeks, so fortnightly monitoring is necessary to allow enough time (10 to 17 days) for the batch fumigation process before too much damage is done.
A continuous-flow grain dryer is also part of the design and has been built into the system, allowing the Petersens to dry grain after harvest at their convenience.
“We can take wet grain into one circle and from there through the grain dryer via a bucket elevator,” Rod says. “Then we lift it via a second 20-metre bucket elevator from the dryer to a point high enough to flow to the second circle for storage. We do all this all without trucks, using just the auger system.
“The dryer forces very-high-flow heated air over the grain for a short period of time. It has a capacity of five to 20 tonnes per hour depending on how much moisture is being removed from the grain. A standard aeration fan couldn’t do that reliably, not in this locality anyway.”
With the ability to dry grain, followed by aeration cooling, the Petersens can store grain at the optimum moisture content and temperature, which significantly reduces mould growth and insect reproduction and can even stop it.
Rod says the system is easy to clean, too. “You hose water into the bottom auger and the water goes right to the top and cleans everything out. And because both augers are inclined, the waste water just flows off.”
This meticulous grain hygiene is the first line of defence in preventing a pest infestation.
Rod’s advice for anyone setting up a storage system from scratch is to invest in big capacity augers to allow for expansion.
“When we were setting up, a 7-inch [17.8 centimetre] auger was the industry standard. We went with 11-inch [27.9cm], which is fairly big, and we can handle 120t per hour, but even that’s not big enough now.”
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For more information on storage systems and monitoring see Aerating stored grain: Cooling or drying for quality control, www.grdc.com.au/GRDC-booklet-Aeratingstoredgrain; Grain storage facilities: A grains industry guide, www.grdc.com.au/GRDC-booklet-Grainstoragefacilities; Vigilant monitoring protects grain assets, www.grdc.com.au/GRDC-FS-Vigilantmonitoring
End of Ground Cover Issue 103 (Northern Edition)
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GRDC Project Code PAD00001
Region North, South, West