Monitor Fall And Winter Stored Grain To Prevent Problems

Both a warm fall and rapid change to winter increases the potential for stored grain problems, says Ken Hellevang, professor emeritus and retired North Dakota State University Extension agricultural engineer. Grain needs to be dry or cool to prevent mold growth.

For example, cereal grain at 18% moisture content can be stored for up to about 200 days at 40 degrees Fahrenheit or about 90 days at 50 degrees, but only about 15 days at 80 degrees. For each 10-degree increase in grain temperature, the allowable storage time is reduced by about half.

Of course, the allowable storage time increases at lower grain moisture contents. At 70 degrees, the allowable storage time increases from about 30 days for 18% moisture grain to 45 days at 17%, 70 days for 16% and 200 days for 14% moisture cereal grain.

The potential for insect problems also increases at warmer temperatures. Insects are dormant below about 50 degrees, so it is important to keep grain temperature below 50 degrees if possible, says Hellevang. If grain temperature is kept below freezing during winter storage, insects can be killed.

Moisture migration in the grain occurs when about a 20-degree temperature difference occurs between the grain and average outdoor temperature. Moisture migration increases the moisture content of the grain near or at the top of the bin. This can increase the moisture content by several percentage points and lead to crusting of the grain. Therefore, the grain should be cooled with aeration when there is a 10- to 15-degree difference between grain and average outdoor temperatures. Grain should be cooled to 20 to 30 degrees for winter storage.

Hellevang recommends to check dry grain at least every two to three weeks as long as the grain is at winter storage temperature. Check at least every couple weeks if it is warmer. Measure and record the grain temperature, watching for trends that indicate problems. Check the grain moisture content and examine the grain in several locations. Moisture measurements of grain at temperatures below about 40 degrees are not accurate.

Verify the accuracy of the measurement by warming the grain sample to room temperature in a sealed plastic bag before measuring the moisture content. Search for small changes that are indicators of potential problems. Collect a sample, warm it to room temperature and place the grain on a light-colored or white surface to look for insects.

Grain temperature near the bin wall and on the top surface depends both on the outdoor temperature and solar radiation.

"The amount of solar energy on the south wall of the bin will be two to three times as much on Feb. 21 as on June 21 due to the low solar angle," Hellevang says.

During late winter and spring, monitor the grain temperature, particularly near the south wall and near the grain surface, and periodically run the aeration system to keep the grain cool. The goal in northern states should be to keep the grain temperature below 40 degrees as long as possible during the spring and early summer.

There is the potential for bin vent screens to become iced over when operating fans at temperatures near or below freezing. Hellevang recommends to leave a bin fill hole or manhole unlatched as a pressure relief valve if the air is being pushed up through the grain.

Hellevang emphasizes the importance of always remembering safety precautions when working around grain bins. Grain suffocation is likely if someone enters a bin while unloading. It only takes seconds to be engulfed in the grain. Never enter a grain bin without stopping the auger and using the "lock-out/tag-out" procedures to secure it. A person can be buried instantly if grain attached to the bin wall releases or grain in a column collapses.