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Corn may run out of storage life due to warm temps

grain bin dryer setup
DRY CORN: Matching the moisture level of corn going into the bin with how long you intend to store it could prevent a storage disaster, GSI’s Gary Woodruff says.
Be sure you put corn in the bin at a low enough moisture to store it as long as you need to.

You don’t usually harvest corn and bin it when it’s 80 to 90 degrees F outside for several weeks afterward. Yet that’s what happened, especially in the southern one-third of Indiana, this year. Problems can arise anywhere corn was harvested early and a long stretch of warm days set in. Even on Oct. 8, temperatures were 20 degrees above normal in most of Indiana.

“The problem is you can’t manage corn the same way as you would if it was cooler and expect it to have the same storage life,” says Gary Woodruff, district manager for GSI.

Two things affect storage life, he says: grain temperature and moisture content of the grain. Temperature of air flowing over the grain during aeration isn’t the important factor. If grain itself is dumped into a bin at 16% moisture and 80 degrees, shelf life is going to be far shorter than if it’s dried to 15%, 14% or 13% and the temperature in the grain mass is cooler.  

Woodruff refers to a chart prepared by ag engineers as his guide when determining how long you can hold grain at various moisture contents and temperatures. The MidWest Plan Service recently updated its chart showing shelf life for corn based on temperature and moisture content. It’s in the “Grain Drying, Handling, and Storage Handbook.”

The chart is based on storing clean, quality corn that has been through a grain cleaner. Since very few people use grain cleaners, chart instructions recommend cutting storage values in half. For example, if you dump corn in a bin at 60 degrees and 16% moisture and run air, you have about 75 days of storage life before you lose a marketing grade in quality. An example of losing a grade would be dropping from No. 2 to No. 3 yellow corn. At the same time, you would lose 0.5% dry matter.

However, at 80 degrees, more common this fall when many people binned corn, storage life drops as low as 24 days.

“So you only have, at most, 27 days if corn stays at 80 degrees and doesn’t cool and is 16% moisture before you lose a grain grade in quality,” he says. “If you don’t correct it, it only goes downhill from there.”

Corrective action
What can you do? “One option is to install an automatic aeration control if you don’t already have one,” Woodruff says. “It will only let fans run when the outside temperature is lower than the grain temperature.”

The alternative, he says, is to do this manually. When it cools down at night, run aeration fans. Run them overnight and then turn them off if it’s going to heat up during the day. The goal is to cool grain down as fast as possible.  

The other possibility is to put grain that is dry enough into the bin in the first place, depending upon how long you want to store it, Woodruff insists. As a rule of thumb, if you want to store until June 1, make sure it is 15% moisture or less going into the bin. If you want the option of holding through summer, dry to 14%. If you may hold it for a year or more, bin it at 13% moisture. These are maximum values for moisture at these storage intervals, he says.

“This isn’t new information. Ag engineers have told us this for a long time,” Woodruff adds. “It’s just that many have gotten by for various reasons not drying corn that far. Many didn’t get by with it last year, and you won’t get by with it this year.”

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