WEST LAFAYETTE, Ind. — Farmers who have grain from last
growing season still in storage this spring need to closely monitor its
condition — especially if corn was stored at moisture contents higher than 15
percent, a Purdue Extension agricultural engineer said.
While the cold winter likely kept mold and insect problems
at bay, the threat of both increases as temperatures rise. Grain stored at
moisture levels of 17 percent to 18 percent or higher is at extra risk.
One way to deal with the problem is to consider in-bin
“For those who couldn’t dry corn to 15 percent in the fall,
but stored at 17 to 18 percent, the warm spring temperature offers the
opportunity to dry to a safe storage moisture using natural air, in-bin
systems,” Klein Ileleji said. “Farmers need to begin to implement natural air
drying immediately if they haven’t started already.”
Natural air, or ambient, in-bin drying can be used to dry
corn with up to 20 percent moisture in the spring. Ileleji said growers should
use an airflow rate of 1 to 2 cubic feet per minute per bushel and drying should
be started when air temperatures are between 40 and 60 degrees and relative
humidity is in the 55 percent to 75 percent range.
Some tips Ileleji offered for implementing natural air
* Sample grain in the bin to determine moisture content and check for signs
of spoilage on the surface and at several depths up to 6 feet using a grain
* Run fans continuously when ambient temperatures average 40 to 60 degrees
with relative humidity not above 75 percent while monitoring the movement of the
* Be careful not to warm grain above 60 degrees if the intention is to store
it through the summer months; and
* Ventilate the bin headspace at night to prevent condensation at the
surface that could lead to crusting or spoilage.
Ileleji said it’s best not to warm grain that was dried to
14 percent to 15 percent in the fall and cooled over the winter — especially if
that grain will be held through the summer.
“Because grain is a good insulator, the cool temperatures
achieved through winter aeration can be maintained during the warm spring months
into summer,” he said.
According to studies at the Purdue University Post-Harvest
Center for Research and Education, leaving bin fans off through the spring to
keep grain cool from winter aeration slows the growth of maize weevils.
“Warming grain would start biological processes earlier,”
Ileleji said. “That includes growth of both mold and development of insect
pests. It is also advisable to place a cover over the bin fans to prevent
passive aeration of the grain bulk with warm air when wind enters a fan that can
Finally, as temperatures increase, so should the frequency
of stored-grain monitoring. Growers need to monitor grain bulk and ambient
temperatures, as well as any signs of spoilage.