Soybean School: Adding Moisture Back to Too-Dry Soybeans


Too wet isn’t good, but neither is too dry for growers looking to get the most value for soybeans.

According to researchers at North Dakota State University, on a 40 bushel-per-acre crop, harvesting soybeans at 9 percent moisture rather than 13 percent will cost the farmer around 1.8 bushels per acre. At $10 per bushel, that’s an $18 per acre difference.

NDSU’s Ken Hellevang joins RealAg’s Kelvin Heppner in this audio Soybean School episode to discuss how to “recondition” or add moisture back into soybeans while in storage.

“We’re doing the opposite of what we would do with natural air drying,” he explains. “If the beans are exposed to air that is dry, moisture moves from the bean to the air. If it’s exposed to air that’s at a higher humidity than the beans, it goes from the air to the soybeans.”

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He recommends turning fans on when relative humidity is averaging around 70 percent. Running fans when it’s foggy or when humidity is very high can make part of the bin too wet to store safely. As with drying, the reconditioning process can take weeks, depending on outdoor air temperature and humidity, but Hellevang notes it’s possible to recondition beans in spring if a grower runs out of time before winter.

Adding moisture will cause the beans to expand, which he notes can damage bin walls. Although little research has been done in this area, he suggests unloading beans periodically or using vertical stirring augers to reduce pressure, noting there is risk of damaging dry beans by handling them.

Hellevang shares his insight into reconditioning beans, aiming for 13 percent moisture for marketing:

The numbers behind reconditioning too-dry soybeans (from NDSU — soybean price adjusted):

30 days of fan operation = 720 hours.

Achieving an optimal airflow rate of at least 0.75 cubic feet per minute per bushel on a 42-foot-diameter bin filled 20 feet deep with soybeans would require a 15 horsepower fan (~15 kilowatts of electricity per hour of operation). The cost to operate the fan, assuming an electricity cost of 10 cents per kilowatt-hour, is $1,080.

Raising the moisture content from 9 to 13 percent would increase the quantity of soybeans by 1,019 bushels. At a price of $10 per bushel, this is worth $10,190.

Related: Soybean School: An Inside Look at Grading Soybeans


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