With temperatures dropping steadily with the season, the air holds less moisture and will absorb less as it surrounds the corn, whether it is in the field or the bin. The result is much slower drying rates. Hellevang says harvested grain can be stored at higher moisture if it is kept cool with aeration:
- The allowable storage time doubles for each 10 degrees that the grain is cooled. Corn at 22 percent moisture can be stored for 190 days at 30 degrees, but only 60 days at 40 degrees. Aeration fans should be operated to cool the grain to near freezing as quickly as possible. The grain can be cooled later to 20-25F for winter storage.
- Corn can be dried with an airflow rate of 1.35 cubic feet per minute per bushel from 21 percent to 15 percent in about 36 days under normal October conditions of 47F and 65 percent relative humidity.
- With normal November conditions of 27F and 73 percent relative humidity the corn will dry to 18 percent moisture in 70 days.
- Warming the air 5 degrees permits drying the corn to about 15 percent moisture, but it still will take about 52 days.
- Adding more heat will cause the corn to be dried to lower moisture content while shortening the drying time by only a couple of days.
- Drying speed is primarily related to the airflow rate and final moisture content is related to the air relative humidity which is reduced by adding heat.
- Corn can be cooled to 20-25F for winter storage and dried in the spring. The drying fan should be started in the spring when daily average temperatures are about 40F.
The 2013 corn crop may be a challenge to dry because of great variations in moisture from kernel to kernel. Drying may reduce the overall moisture, but not the variation, which can only be resolve with airflow through the grain.
Because of the cooler air in October, reduction of moisture will take longer, since the cooler air moving through the bin will absorb less moisture. The grain can be kept over winter at a higher than desired moisture, if it is cold, but will present issues that need to be addressed when the air warms up in the spring.
Source: Farmgate blog