System not just hot air, harvest when you want
GroundCover™ Issue: 44
High flow-rate aeration drying and lower flow-rate aeration to cool and maintain the quality of grain were key topics at recent Northern Region Grains Research Updates. Here John Cameron profiles some of the reports from those updates.
BEING ABLE to harvest when he wants is the big plus of high flow-rate aeration drying silos for a grower from Guyra in NSW's New England area.
In recent years Ian Sole has harvested crops at up to 27 per cent moisture and dried them to delivery standards at a cost of around $3/t for electricity. The drying process uses natural 'un-heated' air, pumped through the silo at a high flow rate to dry the grain.
Farming at 'Avoncliffe', Mr Sole crops feed grains on 300 ha of his 1,900 ha property. The cool and often humid environment means that crops can be difficult to dry in the paddock.
Barley the first to benefit
Barley was the first crop Mr Sole dried. "It was going to yield around 3.3 t/ha and was starting to lodge. With the weather forecast for rain, I decided to start harvesting. Initially, the wet grain was put into a shallow pile in a bunker storage.
"Twenty-four hours later the moisture had evened out but measured a whopping 27 per cent. To make matters worse the grain was now quite hot. Time to test out the new drying silos," he said.
The relatively small crop of 40 tonnes was put into a 60-tonne high flow-rate Kotzur drying silo and the fans turned on. A day later the grain was cool to touch but glasses fogged up when inspecting the grain, Mr Sole said.
"Leaving the fans on for eight hours a day for three to four days dried the grain quickly to 18-19 per cent. Relative humidity at the time was quite high at around 60 per cent."
Although the grain was still at quite a high moisture level, he waited until the relative humidity dropped before completely drying it down to receival standards.
Meanwhile, putting the fans on for two hours each day worked like an evaporative cooler to keep the grain cool and sound — during this period the grain was around 17-18 per cent. After two weeks the relative humidity dropped to below 30 per cent. The high flow-rate fans then went to work full-time and the grain was dried relatively quickly to 12 per cent.
Benefits far outweighed the costs
The cost to Mr Sole was his time and around $3/t for electricity. With power already at the site, the capital costs of a high flow-rate drying silo are only about 10-15 per cent (except on very small silos) more than for normal upright storage. "The benefits far outweighed the costs," Mr Sole added.
He expected losses of 30 per cent due to lodging of the barley, but the drying silo counteracted that with significant benefits such as higher grain weights and lower screenings.
Because grain is harvested wet, there was also minimal cracking, shrinkage was less of a problem, and all but the most wet and immature grain remained plump and on the right side of the sieve.
"Grain quality and weight benefits alone pay for the system," he said.
In addition, Mr Sole was pleasantly surprised when germination tests came in at 98 per cent, substantially higher than his average for farm-kept seed, which is closer to 90 per cent. It is common for seed kept in aerated storage to retain a much higher germination rate.
Aeration drying in the spotlight
'Avoncliffe' has four Kotzur drying silos — two 60 t, one 120 t and one 208 t. The smaller ones have an external lever to enable easy lifting of the lid for aeration, while larger silos are fitted with a perforated ring that sits underneath the lid during aeration operations.
When aeration is finished, the perforated ring is removed and the lid sealed. All Mr Sole's silos can be sealed and pressure-tested — a critical feature if fumigation with phosphine gas is to be used effectively.
Although he has single-phase power, Mr Sole has upgraded his transformer using soft starters and time delays so that not all fans start up at once.
Program 5 Contact: Mr Andrew Kotzur 02 6029 4700
Region North, South, West