2010 grain storage will take top-notch effort

FARGO, N.D. -- Farmers in the region are facing high-moisture grain in the bin for a second year in a row. This year, the storage management could be trickier with lower-quality grain that went into the bin, says Ken Hellevang, North Dakota State...

Grain storage
Large bins that have been installed in the past several years often have high-horsepower fans, but farmers need to make sure they're rated at 1 cfm per bushel, or remove some of the bushels for low-temperature drying. (Mikkel Pates / Agweek)

FARGO, N.D. -- Farmers in the region are facing high-moisture grain in the bin for a second year in a row. This year, the storage management could be trickier with lower-quality grain that went into the bin, says Ken Hellevang, North Dakota State University Extension Service ag engineer.

"Storage management needs to be top notch, or we're going to see more problems than normal," Hellevang says.

It's always hard to put a number on how much damage occurs to stored on-farm grain. There sometimes are reports from grain elevators that received poor-quality grain, or even had to reject some of it. Sometimes the damaged grain simply is spread out on a field.

"It's usually done as quietly as possible," Hellevang says. "That's understandable."

Here are some of Hellevang's thoughts on storing corn and soybeans this year.


Immature corn?

Much of the 2009 crop corn that went into the bins in the region in the past several months has ranged from 20 percent to 30 percent moisture. The vast majority went in at less than 25 percent.

Whether this corn actually had reached physiological maturity sometimes was in question, although much of it probably was.

"Last year, we were getting quite a few calls with people combining corn late -- either late winter or early spring," Hellevang says. "This year, they're just waiting for the snow to settle and hoping that just before melting, they'll be able to get out and harvest a lot of this standing corn."

In North Dakota, 24 percent of last year's corn still is in the field.

Many farmers dried wet corn down to 13 percent to 14 percent moisture. Hellevang says it must be at or below 13 percent to be able to store it into the summer and avoid mold growth and deterioration. Once dried to 13 percent, the goal is to keep it cool going in the spring and summer.

The spring likely will be dicey for grain storage, on- or off-farm.

"Any time we have immature corn or any damage to the kernel, such as cracking of the kernel or some degradation on the surface due to molds, they'll be much more prone to problems," Hellevang says.


High-moisture stored corn that isn't dried yet needs attention immediately.

"The dividing line is 20 percent moisture," Hellevang says. "If it's higher moisture than that, the corn needs to come out and go through a high-temperature dryer. In most years, I'd say 21 percent, but this year, we had some potential damage to the surface of the kernels and in some cases, that corn went into the bin moldy."

When farmers harvest high-moisture corn, there is more mechanical damage to the kernels.

When farmers plan to use natural drying, they need to make sure they match the number of bushels in the bin to a minimum of 1 cfm, or cubic foot per minute, per bushel of airflow.

For example, a 20,000-bushel bin must have a fan that delivers 20,000 cfm of air flow.

"We have a number of bins that were, unfortunately, undersized with fans," Hellevang says. "A farmer might say they have good air flow, but when they calculate the rate, it's less than that 1 cfm per bushel rate."

Normally, Hellevang recommends starting the fans in early April when outside temperatures are 50 degrees in the daytime and below freezing at night.

"In the spring, we'll run a 25-degree variation in temperatures, from the highs in 50s in the daytime to the lows to the upper 20s at night."


In any case, if the corn is above 20 percent moisture in a bin it must go through a high-temperature dryer.

"They need to be doing that now in March," Hellevang says.

Drying soybeans

Farmers last fall ended up with a lot of soybeans going into the bins at 16 percent to 18 percent moisture. Soybeans for conventional commercial markets can be run through a high-temperature dryer, Hellevang says.

"The thing is that they need to limit the dryer temperature to minimize damage to the beans. The higher the temperature, the more seed coat cracking and splitting will occur."

Farmers thinking about "natural air" or "low-temperature" drying in the bin -- probably in April and May -- can prepare the way for further drying to 11 percent moisture, for summer storage.

"But what I remind people of is that, with an air flow rate off 1 cfm per bushel, we're looking at about 50 days to dry soybeans that start at 16 percentage moisture and 60 days to dry 18 percent moisture beans."

Unfortunately, until the outside air warms up, it doesn't absorb much moisture.

"With beans, we need to wait until outside temperatures are averaging roughly 40 degrees to natural air-dry. Also, I'm encouraging farmers to air-dry their soybeans only if they have more than an air flow rate of 1 cfm. I think even if we can dry 18 percent moisture beans, if we start early, I feel it's much safer if you're only air-drying beans that start at 16 percent moisture or less."

"With 18 percent moisture beans, you're having to run the fans all of April and May," Hellevang says. "We don't have a lot of experience with that. If we have marginal air flow, we're going to end up not being dry until early June. We can get some pretty warm days in June, and that's going to affect the storability of beans, before we get them dry."

It's safer to run the beans through a high-temperature dryer, or fill the bin two-thirds full to ensure the fan power is sufficient, Hellevang says.

"Many of these bins -- particularly the newer, bigger bins -- the guys are putting in big fans and are moving a lot of air, but when you calculate the (air flow) per bushel, it's a little short of 1 cfm," Hellevang says. "You put in a 42- to 48-foot diameter bin and start hooking up a 40- to 50-horsepower fan, and you think that's got plenty of airflow, but it might not be if you go through the calculations."

Of course, food-grade soybeans for human consumption must be air-dried or low-temperature dried.

He says farmers can use a fan selection program on his Web site or look at the fan charts provided by the fan manufacturers to make sure they have at least 1 cfm. Otherwise, the farmer can fill the bin to two-thirds full to make sure the air flow is sufficient.

But safety comes first, Hellevang says.

Hellevang says farmers should have respiratory protection if they handle moldy grain.

"You get those mold fragments or mold spores being inhaled, you can end up with some nasty allergic reaction to either field molds or spoilage in the bin."

Typically, farmers need a mask that carries an "N95" or higher, according to government standards.

Anytime farmers operate bin fans at temperatures at or below freezing, Hellevang recommends leaving open the "man-hole" or access hole at the top of the bin.

"That should be a release valve in case the vents ice over. In some cases, if the vents ice over, the fans can develop enough pressure to flex the steel and to damage the bin roof."

Mikkel Pates is an agricultural journalist, creating print, online and television stories for Agweek magazine and Agweek TV.
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