Drying Binned Corn

Drying Binned Corn

October 29, 2009

Airflow estimates can be generated using a program developed by the University of Minnesota. Download the program to your home computer to run various scenarios you're considering.

When you use FANS, be sure to click on the Crop Selection tab and select the correct crop. Then click on the Fan Selection tab and pick your fan from the list. If your fan model is not on the list, pick a similar fan from another manufacturer.

Be sure to change the Bin Diameter and Grain Depth to match your situation. Click the Update Estimates tab then click the Airflow vs Depth Table. To print the Airflow vs Depth Table, click on File in the upper left corner and click on Print Airflow vs Depth Table.

More information on grain storage management is available on the UNL in Lancaster County Acreage, Farm & Ranch page.

I have received numerous calls from corn producers harvesting high moisture corn well above the recommended 15% moisture content for long-term storage and/or to avoid being docked by the grain merchandiser. Producers with drying bins and aeration fans capable of producing at least 1 cfm/bu are wondering how long it will take to dry their corn to 15% moisture using ambient (unheated) air.

The time to dry corn, or any grain, depends on a number of variables

  • The initial moisture content of the grain, %
  • The desired moisture content of the grain, %
  • The ambient air properties of temperature and relative humidity
  • The airflow through the grain in the bin as measured in cubic feet per minute per bushel
  • Whether the incoming air is heated before passing through the grain

Using a grain drying program, I ran several scenarios to estimate the time it would need to dry corn (see Table 1). It estimated the days to dry corn in a grain bin using natural air and 1 cubic foot per minute per bushel of grain in the bin.

As you can see in Table 1, weather conditions are a huge factor in how long it takes to dry grain.

Tom Dorn
Extension Educator in Lancaster County

Table 1. Days required to dry corn to 15% moisture with 1 cfm/bushel airflow, using natural air drying. Assumes exhaust air has 85% relative humidity.
Air Properties Initial Moisture (%)
60°F 16 17 18 19 20 21
  Drying Time (days)
60% 4.3 8.8 13.3 18.0 22.7 27.6
 50% 3.2 6.5 9.9 13.4 17.0 20.6
 40% 2.5 5.2 7.8 10.6 13.4 16.3
30% 2.1 4.2 6.4 8.6 10.9 13.3
Air Properties  Initial Moisture (%)
50°F 16 17 18 19 20 21
  Drying Time (days)
60% 5.7 11.5 17.4 23.5 29.8 36.2
50% 4.1 8.3 12.5 16.9 21.4 26.0
40% 3.2 6.5 9.8 13.2 16.8 20.4
30% 2.6 5.3 8.0 10.8 13.7 16.6
Air Properties Initial Moisture(%)
40°F 16 17 18 19 20 21
  Drying Time (days)
60% 6.3 12.8 19.5 26.3 33.3 40.5
50% 4.7 9.5 14.4 19.4 24.6 29.9
40% 3.7 7.6 11.5 15.5 19.7 23.9
30% 3.1 6.3 9.5 12.8 16.3 19.8
Air Properties  Initial Moisture (%)
30°F 16 17 18 19 20 21
  Drying Time (days)
60% 8.2 16.5 25.1 33.8 42.8 52.0
50% 6.2 12.6 19.2 25.9 32.7 39.8
40% 5.0 10.1 15.4 20.8 26.3 32.0
30% 4.1 8.4 12.7 17.2 21.7 26.4

Drying time is proportional to airflow. To adjust for airflow values other than 1 cfm/bu, divide the drying time in the table   by the cfm/bu for your bin, fan, and grain depth. For example, if your airflow is 1.25 cfm/bu and the estimate in the table is 10 days, your estimated drying time would be 10 days/1.25 = 8 days.