Storing any grain this year? You’re not alone – not by a long shot. As of December 2015, USDA-NASS reported 6.83 billion bushels of corn and 1.31 billion bushels of soybeans were being stored on-farm.
In early spring, as temperatures begin to fluctuate more, it’s especially important to keep that stored grain cool.
“Not only are daytime temperatures increasing, but the bin works as a solar collector,” according to Ken Hellevang, NDSU professor of agricultural and biosystems engineering. “This heats the grain to temperatures exceeding outside temperatures, particularly on the south side and on the top of the bin. There is more than twice as much solar energy warming the south wall of a gin on Feb. 21 as there is on June 21 due to the low solar angle.”
Because of that, farmers may want to run aeration fans periodically either at night or in the cooler part of the day to keep grain temperatures down. Temperatures can have a dramatic difference on the shelf life of shelled corn. According to USDA research at Iowa State University, maximum storage time for corn at 13% moisture is 150 months at 40 ˚F, but drops to 26 months at 70 ˚F. At 15% moisture, corn is expected to last no longer than 5.2 months at 70 ˚F.
Hellevang says that while temperature sensors can be an excellent tool, they are not a catch-all solution, either.
“Because grain is an excellent insulator, the grain temperature may be much different just a few feet from the sensor and not affect the measured temperature,” he says.
According to Purdue University research, spring warm-up of grain can prevent “moisture migration” that leads to high-moisture pockets that cause spoilage. Purdue recommends the following:
- Start the fans when the average outdoor temperatures are 10 ˚F to 15 ˚F warmer than grain temperatures.
- Run the fan continuously for a complete warming cycle.
- Don’t stop midway – it will nearly guarantee a deposit of condensed moisture that will lead to spoilage.
- Repeat warming cycles when necessary and bring the grain temperature up to 50 ˚F to 60 ˚F.
- Inspect stored grain on a weekly basis for mold and insect activity.
Hellevang recommends that when inspecting grain, record temperature and moisture content. That could serve as an early warning of insect or mold problems, he says. Insect problems can move from “barely noticeable” to “major infestations” in just 3 to 4 weeks when grain is warm.