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 says.
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 17-18 percent or higher is at extra risk.
One way to deal with the problem is to consider in-bin drying.
"For those who couldn't dry corn to 15 percent in the fall but stored at 17-18 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 1-2 cubic feet per minute per bushel (cfm/bu) and drying should be started when air temperatures are between 40 and 60 degrees Fahrenheit and relative humidity is in the 55-75 percent range.
Some tips Ileleji offered for implementing natural air drying:
* 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 probe.
* Run fans continuously when ambient temperatures average 40-60 degrees with relative humidity not above 75 percent while monitoring the movement of the drying front.
* Be careful not to warm grain above 60 degrees if the intention is to store it through the summer months.
* 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 14-15 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 freely turn."
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.
Ileleji wrote a report titled Check Your Stored Grain Frequently, which can be downloaded here. Additional resources are available through Purdue's Post Harvest Grain Quality Program website at http://www.grainquality.org/.