Original story by Tom Dorn, former Nebraska Extension Educator
Reviewed and updated by Paul Jasa, Extension Engineer
If you're looking at storing soybeans harvested at over 13% moisture, you'll want to dry them to 13%, the recommended level for longer term storage.
The time to dry soybeans, or any grain, depends on a number of variables:
- The initial moisture content, %
- The desired moisture content, %
- The average ambient air properties — temperature and relative humidity
- Airflow through the bin — cubic feet per minute per bushel
- Whether the incoming air is heated
Also see
A grain drying program was used to estimate the time it would take 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. When drying in the bin, avoid using the stirator as it can damage soybeans.
As you can see in Table 1, weather conditions are a huge factor in how long it takes to dry grain.
| Air Temperature* | Initial Moisture (%) | |||||
|---|---|---|---|---|---|---|
| 60°F | 14 | 15 | 16 | 17 | 18 | 19 |
| Relative Humidity | 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 Temperature | Initial Moisture (%) | |||||
| 50°F | 14 | 15 | 16 | 17 | 18 | 19 |
| Relative Humidity | 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 Temperature | Initial Moisture (%) | |||||
| 40°F | 14 | 15 | 16 | 17 | 18 | 19 |
| Relative Humidity | 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 |
*The temperatures indicated — 40°F, 50°F, and 60°F — are the average of the high and low for the day.
** Drying time is proportional to airflow. To estimate drying time for airflow values other than 1 cfm/bu, divide the drying time in the table by the cfm/bu for your bin. 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.
