Bin Drying Soybeans

Bin Drying Soybeans

October 27, 2009

I have received numerous calls from soybean producers who have decided they shouldn't wait any longer for the soybeans to dry in the field. They want to start harvesting or have already begun harvesting beans and plan to dry them in the bin. Of course, the main question is "How long is it going to take to get the beans dry enough to take to the merchandiser or dry enough to store on the farm?"

The time to dry soybeans, 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 — temperature and relative humidity
  • The airflow through the grain in the bin — 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 soybeans (see Table 1). It estimated the days to dry soybeans 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 soybeans to 13% moisture with 1 cfm/bushel airflow, using natural air drying. Assumes exhaust air has 85% relative humidity.

Air Properties  Initial Moisture (%)
60°F

14

15

16

17

18

19

  Drying Time (days)
60% 4.6 9.2 14.0 18.9 23.9 29.0
 50% 3.4 6.9 10.5 14.1 17.8 21.7
 40% 2.7 5.4 8.2 11.1 14.1 17.1
 30% 2.2 4.4 6.7 9.1 11.5 14.0
Air Properties  Initial Moisture (%)

50°F

14

15

16

17

18

19

  Drying Time (days)

60%

6.0 12.1 18.3 24.7 31.3 38.0
50% 4.3 8.7 13.2 17.8 22.5 27.4
40% 3.4 6.8 10.3 13.9 17.6 21.4
30% 2.8 5.6 8.4 11.4 14.4 17.5
Air Properties  Initial Moisture (%)

40°F

14

15

16

17

18

19

  Drying Time (days)
60% 6.7 13.5 20.5 27.7 35.0 42.5
50% 4.9 10.0 15.1 20.4 25.9 31.4
40% 3.9 8.0 12.1 16.3 20.7 25.1
30% 3.3 6.6 10.0 13.5 17.1 20.8

  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.