A storage expert says direct and indirect heating systems are essential tools for producers during cool, late harvests
Grain storage expert Joy Agnew says air drying with heat is becoming increasingly essential, given that farmers have recently been facing late harvests.
Speaking at FarmTech Jan. 29, Agnew, formerly of the Prairie Agricultural Machinery Institute (PAMI), said recent harvests indicate farmers are starting later due to poor weather conditions, which makes it more difficult to dry grain naturally.
She said there is little ability to dry grain without heat once temperatures drop below 10 C, noting many farmers found themselves in this situation last fall when temperatures were cool and wet.
“There are a variety of factors that are driving these later harvests,” said Agnew, now the director of applied research at Olds College.
Weather patterns are changing, she said, with late springs and unpredictable falls.
As well, she said there might not have been many heat units in the summer. Smoke obscuring the sun may have also caused problems.
“Whether these poor harvest conditions come in September or October, they do play a large role because more drying is likely needed as more crop is left out.”
She said adding heat to natural drying fans will help producers mitigate issues of cold and wet grain.
She said farmers should ideally add 20 C to 30 C of heat to their fans at a rate of at least one cubic foot per metre (CFM) per bu.
She said the length of time it takes to dry down grain will depend on the grain’s moisture content and the temperature, though it could take anywhere from five to 21 days or longer.
She said either a direct or indirect heating system should work, although producers should keep in mind the efficiencies of those systems.
“System efficiency is important in terms of knowing how much fuel you’re going to be burning,” she said.
No water is being added to the grain with indirect systems, while direct systems do add water, she added.
The amount of water being added in direct systems, however, is marginal when compared to the amount of moisture the system is extracting, Agnew said.
“When you think of overall system efficiencies, direct heating systems are better than indirect.”
She said efficiencies of the systems aren’t entirely known, although PAMI plans to determine efficiencies through further studies.
“Once we understand efficiencies better, we will be able to derive best management practices to improve the overall efficiency and reduce the amount of fuel used.”
During her presentation, she broke down the potential costs of drying grain with heat.
She said propane costs can range from $240 to $1,000 when drying with added heat, depending on the number of days it takes to reduce grain moisture.
She said propane costs for heated air dryers, which are standalone machines that quickly extract moisture at extremely high temperatures, can range from $375 to $605, again depending on the length of time.
The calculations were based on assumptions that two pounds of water per bu. are being removed from 5,000 bu. of wheat.
The wheat in this case is going from a moisture level of 17.5 percent to 14.5 percent, and propane costs are 50 cents per litre.
Agnew said costs would be cheaper if producers had access to natural gas.
“Efficiency matters because your fuel bill will grow if it’s not properly managed,” she said.