This fall when you’re preparing your grain for storage, all you need to do is remember to SLAM.
That’s short for sanitation, loading, aeration, and monitoring.
The first step — removing any dust or debris from your bins before harvest — is “obviously important,” said Ryan Braun, Canadian sales manager for OPI, a grain storage monitoring company.
Producers should also seal any cracks to prevent moisture from getting into the bin, he added.
Loading is next, and that needs to be done right so that air can flow through the grain.
“Gravity takes all the light stuff and flows it to the outside and leaves all the heavy stuff in the middle,” said Braun.
“That’s all your high-moisture grain, weed seeds, dirt — basically all the stuff you want to put air through. And the more grain there is and the deeper it is, the more pressure there is.”
Airflow “takes the path of least resistance,” he said. And by overloading the bin without levelling the grain out, producers are pushing the air away from the moist centre of the bin.
“You want air moving through the middle, but instead you’ve got air going everywhere but through that middle,” said Braun. “You’re peaking the bin up and not getting any airflow through. By stacking it higher, you’ve basically put 10,000 bushels at risk by getting another 500 bushels in on top of it.”
Producers can remedy that by levelling out their bin with a spreader, shovelling the grain flat, or coring each bin at the end of harvest.
“Whatever you’ve got to do to get those bins flat, it’s going to really help your ability to get air through the grain.”
The next step is aeration and drying — and venting is “critical” to that process.
“When you open a manhole cover on a bin, you shouldn’t have that air blast that blows your cap off. That’s not a good thing,” said Braun. “I know it feels like a lot of airflow, but you’re actually restricting that airflow. You want that air to be cycling through the bin as fast as possible, so you need venting.”
One square foot of venting per 1,000 cubic feet per minute (cfm) is the rule of thumb, he said.
“Just be aware of how many cfm you need. If you’re unfamiliar with what your vents are currently putting out and there’s no label on them, the Grain Guard brochure at UFA or CPS has all the cfms and horsepowers of all the fans listed,” said Braun.
“You can very easily figure out how many cfms you have, how much venting you need, and what you can actually be doing with those fans.”
Producers also need to understand equilibrium moisture content — “basically what the ambient air temperature will do to the grain in the bin.”
“If we have a corn kernel that’s 18 per cent moisture and the moisture content of the bin is 14 per cent, over time that kernel will move to 14 per cent,” said Braun.
But that isn’t static, he added. It changes with the temperature and humidity throughout the day. By understanding equilibrium moisture content, producers can adjust their management to maintain the right moisture levels in their grain.
“It allows you to know when the best time to run your fans is,” he said.
The last step is monitoring.
“A lot of guys I talk to, as soon as it goes down below -10 C, they think they should go back out and check the bins again or they’ll run the fans for a couple of days,” said Braun, adding that that’s the right thing to do.
“Steel is a great conductor, and it cools down the air on the inside of the bin,” he said. “Warm air rises and cold air drops, so you’ve got cool air dropping down the outside of the bin, and it gets warmed by the grain and comes up through the centre.”
Because the centre has a lot of moisture and warm air holds more moisture than cold air, air “picks up all kinds of moisture as it works its way up to the top of the bin.”
“When it gets to the top of the bin, it cools down in the headspace, and just like a pop can that you pull out of the fridge, it condenses and sweats,” he said.
“That’s when you have to shovel the crust off the top of the bin.”
Vents will help let some of that moisture out, said Braun.
“That’s why we try to cool that grain down a little closer to ambient temperatures before winter hits,” he said. “I don’t recommend running fans when it’s -30 out. You should be running your fans before that. When it gets to zero or -10, run your fans for a day or two.”