Stored Beans With Mixed Moisture Need to Be Aerated

Soybeans put in bins at mixed moisture content could spoil 2008 harvest.

The 2008 soybean crop could create challenges to profitable storage, especially in bins where the ability to aerate grain is insufficient, says Charles Hurburgh, a grain quality specialist and an Iowa State University Extension ag engineer.

"In bins where there's a greater likelihood of having beans with mixed moisture levels, there is also a greater need for aeration," he says. "To stop spoilage, you'll first need to aerate bins to get the beans cold and then pay close attention to moisture levels."

Many farmers in Iowa have harvested areas of fields this fall where replanted soybeans were located in and around beans that weren't replanted. As a result, soybean growers this year will likely have a mix of higher-moisture replanted soybeans in their bins along with lower-moisture, earlier-planted soybeans.

Mixed moisture beans will spell trouble
Even a small portion of high-moisture soybeans can cause a significant storage problem, emphasizes Hurburgh. "If beans start to turn gray in color, or smell rancid, then you should sell them right away," he advises. "It's difficult to stop rancidity from spreading once it starts."

A good aeration system is the key to avoiding unnecessary loss or expense due to mixed soybean moisture levels. "If your soybeans are at 15% moisture or under, you shouldn't need to dry them," says Hurburgh. "Farmers with a decently designed aeration system should be able to drop temperatures inside their bins to keep grain in condition. However, in bins where there is little or no ability to move air through the grain, there is also little or no chance to equalize the temperature in the bin to prevent hot spots from developing."

The ideal aeration strategy will keep temperatures falling with the outside air temperature, adds Hurburgh. "When the temperature difference of the outside air gets to be 10 to 15 degrees F on average, then you should aerate," he advises.

Drying soybeans - it's trickier than corn

Drying soybeans can be both expensive and difficult, in comparison to aeration. "Soybeans can be dried with a gas-fired dryer to reduce moisture content, but the beans will dry very quickly, and you can't get them too hot or they'll split," says Hurburgh. "If you decide to dry soybeans prior to storage, you'll need to pay close attention to drying temperatures and take frequent moisture tests. You don't want the drying air temperature to exceed 130 degrees F or the beans to get hotter than 100 degrees F."

To avoid economic loss, farmers should also be careful to avoid overdrying soybeans. "Inventory management is a lot more critical when prices are higher," says Hurburgh. "A point of moisture could be worth 25 cents per bushel for farmers who priced their soybeans earlier this summer. So, don't dry soybeans much past 13% moisture content and risk losing money on weight. It's always better to take a little bit of discount by being slightly over the moisture standard as opposed to going under the moisture standard."

Consider selling high moisture beans

Farmers may also consider selling high-moisture soybeans right out of the field to save trouble and expense. "In the southern third of Iowa, there were still a fair amount of beans left in the field last week," notes Hurburgh. "At this time of year, those beans likely won't dry down past 15% moisture. With a wet snow, the moisture levels for those soybeans could increase to 15% to 20%."

Any soybeans still left in the field at this late date are also more vulnerable to freeze-thaw cycles which can cause pods to split and soybeans to fall on the ground. Hurburgh recommends harvesting those soybeans as soon as possible.

For more information on soybean drying and storage, go to extension.agron.iastate.edu/soybean.

TAGS: Extension
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