When Grain Heats Up

ST. LOUIS (DTN) -- Spring seems impossibly far away in many snowy parts of the Midwest, but stored grain could be feeling the heat already.

"Late winter and early spring is a really critical time to start monitoring grain temperature," said Ken Hellevang, an agricultural engineer with North Dakota State University Extension.

In late winter, the sun's rays might seem weaker, but its low position in the sky can make it a potent force, he explained.

"Because we still have relatively cool temperatures outside, sometimes we forget that the amount of solar energy hitting the south wall of bins right now is twice what it will be during the summer months because of the solar angle," he told DTN. "Once we start getting outside temperatures warming up added to that solar heating, the grain might be warming up more rapidly than we would expect."

Keeping stored grain cool and dry will be increasingly important as low commodity prices encourage growers to hold on to their 2014 harvest for longer than usual.

"The market has been giving farmers incentive to store," noted DTN Markets Editor Katie Micik. "Farmers are likely waiting on a spring rally to sell what's unpriced -- and there's a lot that's unpriced."

On-farm corn storage reached 7.09 billion bushels in December 2014, an 11% jump from the previous year, according to the USDA's most recent quarterly report on grain storage published in January. Soybeans stored on the farm swelled to 1.22 billion bushels in December 2014, up 28% from the same month in 2013.

MONITOR GRAIN DURING THE WAITING GAME

Pete Pistorius, of Blue Mound, Ill., is among those farmers holding out for a spring price rally. After a bigger-than-average crop in 2014, his bins are fuller than usual. He sold contracted corn through the winter months, but 40% of his harvest remains unpriced and in storage.

Pistorius is setting selling targets in the $4.50 to $4.60 range and hopes to use basis contracts to cut his stored grain stocks in half in the next month or two.

Should the market not cooperate, he is prepared to hold on to the rest of his grain into the summer. "We've had pretty good luck storing corn through summer months," he told DTN. "It just means we have to keep an eye on it."

As temperatures rise during the spring months, the priority will be keeping grain cool; once the summer months get underway, drying grain down to the low recommended moisture levels for summer storage becomes more critical, Hellevang explained.

THE SPRING COOL DOWN

For every 10-degree rise in grain temperature, the grain's storage lifespan is roughly halved, Hellevang said. For example, 18% moisture corn has a storage life of about 200 days at 40 degrees Fahrenheit, 90 days at 50 degrees, 50 days at 60 degrees, and just 30 days when the temperature reaches 70 degrees.

This decline is due mainly to mold growth, which picks up as temperatures rise. Hellevang recommends that growers run their aeration fans at cold parts of the day and the night to keep grain cool during the spring months. Northern growers can aim for 30-degree grain temperatures, while Southern growers will have to be content with 40 degrees.

Temperature cables and sensors can monitor grain temperature, but only in the spots where they are placed, Hellevang warned. "Grain is a very good insulator," he explained. "If you move just three to four feet away from the sensor, you can have a hotspot or a very different temperature."

Grain on the south side and center of the bins tends to get the warmest, so Hellevang recommends placing temperature sensors in those locations if possible.

THE SUMMER DRY DOWN

Farmers hoping to hold their grain into the summer months need to aim for low moisture content, Hellevang said. For corn, grain should be around 13.5% to 14% moisture, soybeans should be as low as 11% and wheat should be around 13%.

Growers can take the grain out of the bin and run it through a dryer to reach these goals. Once temperatures start consistently averaging 40 to 50 degrees, natural air drying can also begin to slowly lower the moisture content, Hellevang said.

Mold can thrive in overly moist grain during the steamy summer months. Pistorius says he aims to check bins every two weeks on his operation. Observing the temperature, flow and odor of the air he runs through his bins often gives him a good idea of whether moisture and mold levels are a concern, he said. He also occasionally pulls a couple thousand bushels out of storage to check for mold, moisture, and insects before selling it off.

Because cooler temperatures can distort moisture readings, Hellevang recommends pulling small samples of grain from the bin, putting them in a sealed container and allowing them to reach room temperature inside before checking their moisture. Frost or moisture accumulation on the bin roof can also signal a moisture problem, he added.

Mold can often be detected by visual inspection of kernel samples or odor, Pistorius noted. To check for insects, Hellevang suggests sprinkling kernel samples on a light- or white-colored cloth, which will make tiny grain pests more visible.

Keeping summer grain stores cool is a challenge. Aeration for a few hours at sunrise can help, as can installing good ventilation in the headspace of grain bins, which can heat up in the daytime sun.

Covering the fan and air duct openings to your bins when they aren't in use is a good all-year practice that becomes especially important during summer months, Hellevang added. Leaving them open can allow hot, humid air to seep into the bins.

Finally, market your highest moisture grain first, along with any grain stored in temporary or less-than-ideal storage units, like ag bags or buildings, Hellevang said.

Pistorius made a point to sell off his farm's wettest corn in the early winter months. He also emptied the farm's 15 ag bags, which held overflow grain stocks, by the end of February. "The grain we have left has pretty much been dried down as far as it needs to be," he concluded. "We can keep it in storage for a while, as long as we take the time to maintain it."

For more information on monitoring stored grain, see this University of Nebraska guide, written by Hellevang: http://bit.ly/… and this North Dakota State University Extension guide: http://bit.ly/….

For more information on managing molds and insect pests in stored grain, see this Purdue guide: http://bit.ly/….

Emily Unglesbee can be reached at emily.unglesbee@dtn.com

Follow Emily Unglesbee on Twitter @Emily_Unglesbee

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