FARGO, N.D. — Summer temperatures will warm grain, which could lead to insect infestations and mold growth.
“The goal for summer storage should be to keep the grain as cool as possible to extend the storage life and limit insect activity,” says Ken Hellevang, North Dakota State University Extension agricultural engineer.
Insect reproduction is reduced at temperatures below about 60 F.
Hellevang recommends ventilating the top of the bin to remove the solar heat gain that warms the grain. Provide air inlets near the bin roof eave and an outlet near the peak to exhaust the hot air at the top of the bin. It’s much like venting an attic; the heated air rises and is exhausted at the peak.
A ventilation fan to exhaust the hot air is another option. Hot air under the bin roof will heat several feet of grain at the top of the bin to temperatures conducive to mold growth and insect infestations.
Hellevang recommends periodically running grain aeration fans to keep the grain temperature near or below 40 degrees as long as possible during early summer. Night air temperatures are near or below 40 degrees in May.
Running the aeration fan for a few hours to push air up through the cool stored grain will cool grain near the top. Pick a cool early morning every two to three weeks during the summer to run the aeration fan, and only run the fan a few hours to minimize heating grain at the bottom of the bin.
Cover the fan when it is not operating to prevent warm air from blowing into the bin and heating the stored grain. The wind and a natural chimney effect will push warm air through the grain. If the wind blows primarily during the daytime, the grain will be warmed to the daily maximum temperature.
Hellevang encourages producers to monitor the grain temperature.
“Temperature sensors on cables are an excellent tool, but they only measure the temperature of the grain next to the sensor,” he says. “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.”
Common locations to place a temperature cable are near the middle and a few feet from the south wall of a bin.
Grain Summer Storage Moisture Content
Having grain at an appropriate warm-season storage moisture content is very important to store grain safely during the summer. The maximum moisture content for warm-season storage is 13% to 14% for corn, 11% to 12% for soybeans, 13.5% for wheat, 12% for barley and 8% for oil sunflowers.
Mold growth will occur at summer temperatures if the grain exceeds the recommended moisture content. The allowable storage time for 15% moisture corn, for example, is only about four months at 70 degrees and two months at 80 degrees.
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. In addition, the moisture may have changed while the grain was in storage due to moisture migration or moisture entering the bin.
Check Stored Grain
Stored grain should be monitored closely to detect any storage problems early. Check stored grain at least 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.
“Grain temperature cables are a wonderful tool, but do not rely on them to replace inspecting for insects or crusting and detecting odors or other indicators of storage problems,” Hellevang says.
Another option for monitoring grain that is beginning to be used is to measure the carbon dioxide level. Mold growth and insect activity produce carbon dioxide.
Make sure everyone, including family and employees, working around stored grain understands the hazards and proper safety procedures.
“Too many people ignore safety practices and suffer severe injury or death while working around grain,” Hellevang says.
Never enter a bin while unloading grain or to break up a grain bridge or chunks that may plug grain flow. Flowing grain will pull you into the grain mass, burying you within seconds. Before entering the bin, use the “lock-out/tag-out” procedures to assure equipment will not start.
Bridging occurs when grain is high in moisture content, moldy or in poor condition. The kernels stick together and form a crust. A cavity will form under the crust when grain is removed from the bin. The crust isn’t strong enough to support a person’s weight, so anyone who walks on it will fall into the cavity and be buried under several feet of grain.
Determine if the grain has a crust before any grain has been removed. If work needs to be done with a crust, it must be done before any grain is removed.
To determine if the grain is bridged after unloading has started, look for a funnel shape on the surface of the grain mass. If the grain surface appears undisturbed, the grain has bridged and a cavity has formed under the surface. Stay outside the bin and use a pole or other object to break the bridge loose.
If the grain flow stops when you’re removing it from the bin, a chunk of spoiled grain probably is blocking the flow. Entering the bin to break up the blockage will expose you to being buried in grain and tangled in the auger.
If grain has formed a vertical wall, try to break it up from the top of the bin with a long pole on a rope or through a door with a long pole. A wall of grain can collapse, or avalanche, without warning, knocking you over and burying you.
Never enter a grain bin alone. Have at least two people at the bin to assist in case of problems. Use a safety harness and rope that prevents you from descending rapidly more than a couple of feet when entering a bin.
“Take time to think of all options before entering a bin,” Hellevang advises.
— NDSU Extension
For more grain news, click here.