Proper aeration key to storing moist or sprouted grain

“Grain with a moisture content of more than 12.5 percent will be at risk regardless of test weight, sprouting or quality,” said Edmond Bonjour, manager of Oklahoma State University’s Stored Products Research and Education Center (SPREC).

Moist grain increases the chance of mold, odor and insect damage.

Excess moisture must be reduced as quickly as possible using aeration to ensure successful storage, said Carol Jones, OSU agricultural engineer specializing in stored products.

“During summer aeration, about 0.5 percent of moisture is removed from 12 percent grain during one cooling cycle,” Jones said. “A cooling cycle is the amount of time required to cool the entire grain mass from one temperature to another.”

For bins with aeration systems producing 1/10 cubic feet per minute per bushel (cfm/bu) – the typical aeration for steel bins – about 80 hours to 90 hours is required for one cooling cycle. Approximately 120 hours will be required if the bin is peaked.

The cooling cycle will move twice as fast if the aeration system produces 1/5 cfm/bu, or 40 hours to 45 hours for a level surface top and 60 hours for a peaked surface.

“The moisture content of sprouted grain is actually 1 percent to 1.5 percent higher than the grain moisture meter indicates,” Jones said. “If the moisture meter reads 10.5 percent or less, the sprouted grain will have a moisture content of 12 percent or less and the risk during storage is low.”

SPREC experts recommend that grain with higher contents of moisture be monitored every two days until the moisture content has reduced to safe storage levels.

“Seed sprouted to the point that it has visible plant parts is not a good candidate for storage,” Bonjour said.

If aeration is not available, it is advisable to turn the grain mass to mix layers of moist and drier grain. The grain may be “cored” by pulling the center core grain out of the bin using the unload spout or conveyor hopper.

Storing moist grain comes with another warning as well: Moist grain respires at a higher rate than dry grain. During respiration, oxygen is converted to carbon dioxide that can create a safety hazard for workers entering the storage unit. Extreme caution should be used when entering bins that contain moist grain.

“Carbon dioxide is colorless and odorless, so check for low oxygen or high carbon dioxide levels using proper detection equipment,” Jones said. “Operate the aeration fans for 30 minutes to an hour to exchange unhealthy air in the grain and headspace with fresh air.”

Additional information about grain bin aeration and safety is available by reading OSU Cooperative Extension Current Report No. 1741, “Storing Moist Wheat at Commercial Elevators in Oklahoma,” available at http://osufacts.okstate.edu on the Internet or through all Oklahoma Cooperative Extension Service county offices, usually listed under “County Government” in most local telephone directories.

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REPORTER/MEDIA CONTACT:
Donald Stotts
News and Media Relations Manager
Agricultural Communications Services
143 Agriculture North
Oklahoma State University
Stillwater, OK 74078
Phone: 405-744-4079
Fax: 405-744-5739
E-Mail: donald.stotts@okstate.edu

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