Storage tips for corn and soybeans

Moisture content at harvest determines whether to use a grain dryer, a drying bin or natural aeration.

New varieties better adapted for Manitoba’s shorter growing season mean more farmers are growing corn and soybeans for the first time, which means they’ll soon be storing them for the first time.

Like any other grain, the key is moisture and temperature control, says grain management specialist Dave Wall of Wall Grain.

Grain needs to be dry and cool in order to prevent problems with mould and pests. Moisture content at harvest determines whether to use a grain dryer, a drying bin or natural aeration — with management key to getting the crop dried efficiently and safely.

Because of the many variables that govern when to run fans, it’s best to consult with someone very familiar with the options for cooling or drying grain in bins. The options include cooling grain for long-term storage, cooling grain that is coming from a hot air dryer, or drying grain in the bin with natural air or heat assistance. All of these would need different airflows and run times.

Inexpensive monitoring equipment such as temperature and moisture cables inside bins will make it easier to maintain the condition and quality of corn, soybeans or any other grains in long-term storage. Because grain bins are getting larger and crops such as corn and soybeans have a high value, you may want to consider a sophisticated grain-management system which automates the entire grain drying, conditioning and storage processes and automatically turning fans and/or heat on and off as required.

Here are some corn and soybean storage tips from Manitoba growers.


Start with a clean bin and make sure that you clean under the floor to remove residue from previous crops that could harbour disease, pests or rodents, says Lorne Loeppky, who has been growing corn in southeastern Manitoba since 1996.

“If you don’t clean out your bins properly, corn also seems to cause corrosion,” he says.

Corn is considered dry at 14 per cent moisture content, but it normally comes off the combine in the 18 per cent to 28 per cent range, as this reduces damage and losses during harvest.

“Because the weather in Manitoba can be so unpredictable, I usually start harvesting my corn as early as I can to try and limit harvest losses, at around 30 per cent moisture,” says Loeppky. “There have been years when we have been hit by an early frost and the corn didn’t even test. But after it’s through the dryer we still had a good product.”

Most corn in Manitoba is dried prior to long-term storage to get it down to the needed 14 to 15 per cent moisture level.

The bigger the bins, the closer to being dry the corn must be going in, says Loeppky.

“If you have a 5,000- or 10,000-bushel bin, you can probably get away with putting corn in there that could be at 15 per cent and aeration will dry it down the rest of the way. But the bigger it gets, the more dangerous it gets.”

Loeppky uses 20,000- and 30,000-bushel bins, so preparation of the corn is all important.

“We send it through the dryer and then put it in a cooling bin and then move it into the storage bin,” he says. “When your corn comes out of your dryer hot, you want to be probably a point or a point and a half below dry because corn has a tendency to come back on moisture. That problem gets to you if you are dealing with corn that is barely mature when you get the first frost.”

Aerate immediately

Aeration to cool corn should begin as soon as it’s in the bin, and continue periodically until the grain has reached a safe storage temperature.

“When winter comes, if the corn is close to dry, you can cool it down properly before freeze-up and finish drying it in the spring,” says Dennis Thiessen, who has been growing corn in the Steinbach area for 12 years.

“But to be on the safe side, it should be dry going into winter. The most important thing is to have good aeration and run the fans frequently in the fall before freeze-up. In spring, even if it’s dry, it can heat on you if it sits too long with no air on it. So every two to three weeks in summer I run a fan to keep it in condition.

Bins with full aeration floors are best for storing corn and you need to make sure that there are enough vents to get the air to the outside, says Thiessen.

“When you are driving air through the grain mass make sure there is enough ventilation,” he says. “In a hopper bottom bin, I would make sure there is at least a foot or so before the top of the bin so there is room for the air to escape. Don’t fill it right to the very top.”

Fines that accumulate in the centre of the bin can impede airflow and need to be dissipated, says Loeppky.

“The best advice I would have for a new grower is if you have a big bin, put in some sort of spreader system so that your fines don’t end up all in the middle,” he says. “I just have a piece of angle iron dangling from the roof so that when the corn hits it, it spreads out. If you have all your fines in the middle you are not getting the air moving up through the middle and that can end up being a hot spot.”

Soybean storage

When cleaning a bin, sweep or vacuum the floor and walls, and destroy any sweepings containing spoiled or infested grains. Seal cracks to keep out flying insects and prevent rain or snow from getting in, which can form a crust that encourages mould to form at the top of the soybean.

It’s advisable to remove as much foreign material (weed seeds, bean pods, trash, other small grain residues and fines from harvested soybeans) as possible and inspect for mould or insects or for insect-damaged seeds before drying and storing. Any foreign material in the bin can impede or divert airflow during aeration and provide moist, warm areas for mould or insects to thrive or create hot spots.

Soybeans can be harvested at moisture levels below 20 per cent, but must be stored at 14 per cent moisture or lower. Ideally, they should be harvested at 13 to 15 per cent moisture content to help minimize field losses due to shattering of overdried seeds and to avoid the need for anything other than ambient air drying. Harvesting below 12 per cent moisture content increases shattering losses and damage.

Soybeans are sometimes harvested at a higher moisture content due to wet weather or are harvested earlier than expected to reduce combine losses. Any drying method can be used for soybeans but care needs to be taken when using a grain dryer or drying bin with a heater not to overdry the beans to prevent excess shrinkage. Make sure the dried grain is cooled down using fans and/or aeration after drying.

“We have never had to dry soybeans,” says Jason Voth, who has been growing them near Altona for five years. “We cool them off with a fan after harvest. And then when it’s cold out, we turn the fans on to cool them. In the springtime when it warms up, we turn the fans back on to warm up the beans. We use temperature cables in the bins to monitor them. Also in the wintertime I will climb the bins and make sure they haven’t developed a crust on top and that they smell good.”

Insect control

Manitoba’s freezing winter temperatures kill insects in stored grains. But if there is a problem with insect infestation, aerate the bin if outside temperatures are cold enough to kill them or else fumigate with phosphine gas.

Soybeans being dried with natural air are best dried in a bin with a full aeration floor to move the air uniformly through the entire bin. A bin with a partial aeration floor or air duct system can lead to dead areas that can spoil.

The soybean pile should be level at the top and sufficient airflow needs to be maintained to move the drying air through the pile. A minimum airflow of 0.25 to 0.5 cfm/bushel is recommended. The higher the airflow, the better as the faster the beans will dry. One strategy to get adequate airflow is to only partially fill the bin.

Because soybeans are often harvested later than other crops, there is a risk of harvesting too dry, which can cause them to lose quality and value during storage.

“Last year, we had soybeans coming off too dry,” says Wall. “People lost money by selling very dry soybeans. Typically farmers sell soybeans at around 10 per cent moisture and last year we had some producers who had soybeans at 6.5 per cent moisture going into the bin.”

It is possible to rehydrate soybeans with the right system, says Wall.

“We had a customer this spring who had 25,000 bushels of soybeans and because he had a big 25-hp fan on his bin with an Integris computerized grain management system we turned on the fans and put three more points of moisture in there. We gained him over $7,000 by adding moisture into his soybeans.”

Voth physically inspects the soybeans in the bin every so often during the winter to make sure they haven’t developed a crust on top, which can cause mould to develop. If the soybeans still smell good, says Voth, he’s fairly confident that there are no mould issues.

“I would say they should be given the same amount of monitoring as canola,” he says. “I am not shy about leaving the fans on for a while. Hydro is way cheaper than a spoiled bin.”

Any soybeans that become heated or infested should be moved into another bin if outdoor temperatures are cold enough to reduce hot spots and kill insects.

Voth recommends installing temperature cables and advises checking the temperature in the bins every two weeks over the winter, and once a week in spring, until the soybeans have warmed up.

About the author



Stories from our other publications