As harvest finishes up, a high-stakes management process is getting underway inside countless on-farm grain bins. Farmers are working to keep corn and soybean crops in good condition until marketing opportunities hopefully improve.
Two key factors farmers will need to manage throughout the months ahead are temperature and moisture. Here is a number of recommendations Extension specialist offer to help growers in the process:
Temperature: A Guardian Of Grain Quality
Managing temperature in the bin is a cornerstone of effective grain storage. By carefully managing temperature levels, Ken Hellevang says farmers can significantly extend the quality of their stored grain and minimize the chance for incurring losses over winter.
“I like to say that for every 10 degrees that we cool the grain, we double the storage life,” notes Hellevang, emeritus professor of agriculture and biosystems engineering at North Dakota State University.
According to Iowa State University Extension, the ideal temperature range for storing grain during winter is between 30° F and 40° F.
If grain drops below 30° F, the risk of freezing and forming large chunks increases, which can cause problems when trying to empty the bin later, adds Reagan Tibbs, University of Illinois Commercial Agriculture Educator.
Monitoring and managing the grain temperature is a critical piece of grain storage, emphasizes Hellevang, who addressed the topic on a recent Crop Science Podcast Show.
He says maintaining an optimal temperature offers a couple of critical benefits:
1. Spoilage prevention: Hellevang says temperature variations within the grain mass can create convection currents, leading to moisture migration and spoilage. Consistent temperature control helps maintain grain quality by minimizing the risks associated with moisture buildup and heat retention.
2. Insect control: Most insect activity significantly decreases below 55°F, and insects typically enter dormancy at temperatures below 50°F, Hellevang says.
“For those farmers in the northern country, where we have cold temperatures, if we bring the temperature down to freezing or even a little below that, we can actually kill insects,” he adds.
Aeration should be done routinely throughout the winter to maintain cool and even temperatures in the bin, according to Iowa State University Extension. Uneven temperatures in the grain bin can occur when the grain mass isn’t cool enough going into winter, resulting in cooler grain along the bin walls and warmer grain in the core. This temperature difference can cause convection currents that deposit moisture on the grain surface, causing spoilage and crusting.
Other reasons for uneven temperatures in the bin include solar heating of grain under the roof and along the bin walls, as well as heating from insect and mold activity. Iowa State recommends leveling the grain surface to improve aeration and prevent issues caused by accumulated fines by spreading grain or coring the bin.
University of Minnesota Extension recommends covering fans when they are off to prevent severe weather and temperature changes from affecting the bin. Covers made of canvas, tarp, or even plywood can be used for this purpose.
Moisture Management Is Essential
Hellevang likes to remind farmers that there’s a difference between market moisture and storage moisture.
For corn, he says the market moisture is about 15.5%. But corn going into long-term storage, at or beyond 6 months, needs to be maintained at 13% to 14% moisture.
“We also need to be a little concerned about not getting grain too dry, because the drier it gets, the more brittle it becomes, and we see more breakage issues,” he says, adding: “The market really doesn’t reward you for bringing in 10% moisture corn. They’d like to be handling that 13%, 14% moisture corn.”
Hellevang adds that every region of the country is a “little different” on what they find are ideal moisture levels for grain in storage.
As part of maintaining ideal temperature and moisture levels, Tibbs tells farmers to keep an eye on potential moisture migration in the bin.
“What can happen is when the temperature difference between the outside and inside the grain bin exceeds 20° F, the moisture content in the bin can increase toward the top. That raises the risk of grain crusting, which can reduce grain quality and pose safety concerns when checking bins,” Tibbs explains.
Monitor Grain Throughout The Storage Period
Hellevang suggests checking stored grain every two weeks. While checking on the grain, measure and record the grain temperature and moisture content. Rising grain temperature may indicate insect or mold problems. Insect infestations can increase from being barely noticeable to major infestations in three to four weeks when the grain is warm, he adds.
Checking the grain moisture content is important because moisture measurements at harvest may have been in error due to moisture gradients in the kernel, grain temperature, and other factors. When checking the moisture content of stored grain, Hellevang advises following the manufacturer’s procedure for obtaining an accurate moisture measurement.
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