Bin Corn Grain Drying Requires Special Attention

Bin Corn Grain Drying Requires Special Attention
A lot of high moisture corn is being binned this year. It is critical to manage this grain so it will keep in good condition until it is moved on to the elevator.
Most grain bins have air pushed through the grain from the bottom and then removed out the top. As the air moves through, moisture evaporates from the grain into the passing air. The grain at the bottom of the bin loses moisture the quickest as it is nearest to the incoming air. Once the grain moisture reaches equilibrium with the air, no more drying will take place. Once corn loses moisture, it does not readily absorb moisture back.
As air passes through the grain, it takes the path of least resistance. Grain top surface should be leveled so air will move through evenly. Secondly, fines may accumulate in the center of the bin where the grain is dropped. Fines will restrict the movement of air and this area of the grain should be watched carefully for heating.
Many use natural air drying, meaning that fans push unheated air through the grain mass. University of Missouri Guide, G1310, Low Temperature In-Bin Drying of Shelled Corn, is a resource that provides information regarding filling depth information. The depth of grain affects air flow and which, in turn, affects the rate of moisture loss from grain.
As the moisture leaves the grain, a drying front is formed and moves upward in the grain. This front should be pushed through the grain mass till the top of the grain is dried.
Research indicates that grain being stirred using natural air increases the time required to dry the grain. The drying front is broken up which causes the air leaving the grain mass containing less moisture.
If stirring devices are used with unheated air, the stirring device should be run during filling the grain to reduce packing and redistribute the fines along with leveling the grain. Then allow the drying front to move through the grain. The bottom of the grain will be somewhat dryer than the top, growers may want to use stirrers to just before the drying front moves through the top of the grain and this will help equalize moisture content of grain mass.
Continuous fan operation is needed when the moisture content of the corn is above 18% and the temperature of the grain is above 40 degrees F. The goal should be to reduce grain moisture to 15.5% if sold during winter and 15% moisture if held over to next year.
Another option is to use heated air to increase drying. Heated air increases the ability to carry away moisture. There are various charts which indicate the relationship between humidity and temperature.
As we move into colder temperatures, grain should be cooled down to prevent convection currents within the grain mass. Run the fan to create a uniform temperature in the grain mass. Convection currents can occur if outside temperatures are low and grain temperatures are high by the air moving along the bin sides downward and then upward in the warm grain center. This can lead to a wet area in the middle top of the bin.
Check grain temperature monthly. If you find problems, run the aeration fan. If you have a stirring device, use this to break up the area of high moisture corn. If you do not have a stirring device, you should remove grain to break up the wet area.
For more information, contact Specialists with the University of Missouri Extension Service, Wayne Flanary, Regional Agronomist at (660)446-3724 or Heather Benedict, Regional Agronomist at (660)425-6434 and Jim Crawford, Natural Resource Engineer at 660-744-6231.