Producers encouraged to keep an eye on stored grain during winter
January 24, 2014
Now is the time to check stored grain thoroughly and take steps to maintain the grain quality.
"Search for small changes that are indicators of potential problems," advises Ken Hellevang, North Dakota State University Extension Service agricultural engineer. "The early snow, cool fall and early cold winter temperatures made 2013 a challenging year for corn and sunflower harvest. Some grain went into storage at higher than recommended moisture contents, and that increases the likelihood of storage problems."
Check to assure that the grain temperature is at 20 to 30 degrees in northern states and below 40 degrees in warmer regions of the country. The allowable storage time approximately doubles for each 10 degrees that the grain is cooled. Also, insects are dormant below about 50 degrees. Cooling corn below about 20 degrees has no benefit and may increase the potential for condensation on the grain when aerating with warmer air. Aeration is not necessary if the grain is at the appropriate temperature.
Solar radiation can warm stored grain, creating an environment for grain storage problems. The daily total solar energy heating the south side of a grain bin on Feb. 21 is more than twice the amount as on June 21. Therefore, grain next to the bin wall may be warmer than the average outdoor air temperature.
Grain warming normally will be limited to a couple of feet near the bin wall and a few feet at the top of the bin. Monitor grain temperature at least in these locations to determine when to operate the aeration fan. Bin temperature cables help monitor grain temperature but only detect the temperature of the grain next to the cable. Grain has an insulation value of about R=1 per inch, so grain insulates the cable from hot spots just a few feet from the cable.
Do not operate the fan during rain, fog or snow to minimize blowing moisture into the bin. Bin vents may frost or ice over if fans are operated when the outdoor air temperature is near or below freezing, which may damage the bin roof. Open or unlatch the fill or access cover during fan operation to serve as a pressure relief valve. Cover the aeration fan when the fan is not operating to prevent pests and moisture from entering the bin and warm wind from heating the grain.
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Hellevang recommends collecting some grain samples and checking the moisture content to assure that it is at the desired level. However, many grain moisture meters are not accurate at grain temperatures below about 40 degrees. When the grain is cold, it should be place in a sealed container, such as a plastic bag, and warmed to room temperature before checking the moisture content.
At temperatures above 40 degrees, the meter reading must be adjusted based on the grain temperature unless the meter measures the grain temperature and
automatically adjusts the reading. Check the operators manual for the meter to determine correct procedures to obtain an accurate value.
Corn at moisture contents exceeding 21 percent and oil sunflowers exceeding 16 percent should be dried in a high-temperature dryer before the end of February to minimize the potential for grain deterioration.
Natural air drying is not efficient until the average outdoor temperature reaches about 40 degrees. The moisture-holding capacity and, therefore the drying capacity, of colder air is so limited that drying at colder temperatures is extremely slow and expensive. When natural air drying, adding supplemental heat primarily reduces the final moisture content of the grain and only slightly reduces drying time.
Always remember safety when working around grain bins. Wet stored grain increases grain-handling hazards. Grain suffocation is likely if entering a bin while unloading. Being engulfed in the grain takes only seconds. Never enter a grain bin without stopping the auger and using the "lock-out/tag-out" procedures to secure it.
Also, a person can be buried instantly if bridging has occurred, grain is attached to the bin wall or it is in a column that can collapse. Read NDSU publication "Caught in the Grain!" (available at http://tinyurl.com/caughtingrain) and view one of the online videos on the hazards of grain entrapment for specific information on the dangers and rescue procedures.
Also, low-level exposure to dust and mold can cause symptoms such as wheezing, a sore throat, nasal or eye irrigation, and congestion. Higher concentrations can cause allergic reactions, and trigger asthma episodes and other problems. In rare cases, symptoms such as headaches, aches and pains, and fever may develop. Certain types of molds can produce mycotoxins, which increase the potential for health hazards from exposure to mold spores.
The type of respiratory protection a person needs will depend on the amount of his or her exposure to dust and mold. Hellevang recommends the minimum protection should be an N-95-rated face mask. This mask has two straps to hold it firmly to the face and a metal strip over the nose to create a tight seal. Some masks have a valve that makes breathing easier for people who wear them for extended periods. A nuisance-dust mask with a single strap will not provide the needed protection because the mold spores will pass through the mask, Hellevang says.
For more information, do an Internet search for NDSU grain drying and storage. F
–NDSU Ag Communications