We are in a situation this fall where we need to do some extra drying of the corn and soybean crop in order to store the crop over the winter months. Hopefully we will be wrapping up the soybean harvest this week and heading full-force into the corn. Following are a few comments about drying both corn and soybeans.
Soybeans: We need to do some artificial drying of soybeans if they are harvested at moisture content over 13 percent. If we use a high-temperature dryer we need to limit the temperature in order to avoid damage to the soybeans. Typically, the maximum temperature for drying non-food soybeans is around 130 F. Even at that temperature, some skins and beans will be cracked. Seed beans will have to be natural-air dried to avoid damage. Once soybeans are dried to 13 percent or less they need to be cooled and can safely be stored for about six months without having mold problems. The suggested winter storage temperature for oilseeds in the upper Midwest is 20 to 30 F. If the soybeans have been dried using high temperatures they will need to be cooled down. It is best to cool them in 10 to 20 stages as average temperatures drop in the fall. For example, daytime highs right now are in the 50's. Run the fans for a few days until the beans are cooled down. Wait a few weeks until daytime highs are in the 30s to 40s and then run the fans again to bring the final storage temperature into the 20 to 30 range. Be sure and check the beans on a regular basis over the winter months. Natural-air drying works well with soybeans when daytime temperatures are in the 60s or higher. This year we had few if any beans in the bins when the current stretch of cool wet weather hit.
Corn: We will need to use a high-heat dryer if the corn moisture is higher than 22 percent. Most years, corn does well with natural air drying, and some producers may still be able to dry corn this year by blowing some slightly heated air up through their grain bins (air heated to about 10 degrees higher than outdoor air temperature). If the corn moisture is higher than 22 percent there may be little choice but to use a high-heat dryer. Dryer designs vary, so see instructions for temperature recommendations. Start with the lower end of the temperature recommendation if corn quality is a concern and turn it up if corn drying capacity is not sufficient. Using energy for heated-air drying is expected to add to overall costs for producers this year.
Reconditioning Overdry Soybeans: If you end up with some beans that get too dry after using added heat to get them down to storage levels you can bring the moisture levels back up given enough time and a high enough airflow per bushel. What we are doing here is, in effect, increasing the moisture content by aerating them with humid air. It is also important to state that it is illegal to add liquid water to increase soybean moisture. The process of reconditioning soybeans is quite slow-even with high airflow per bushel (0.75 to 1.0 cfm/bu) available on bins equipped for drying. It would be difficult to accomplish significant reconditioning using the low airflow aeration systems common on most storage bins. Fan control is tricky and some beans could end up too wet for storage. You could end up with layers of wet beans and dry beans unless you find some way to mix or stir them in the bin or unloading of the bin.