Harvesting soybeans at a moisture content between 13 to 15% helps maximize weight while minimizing harvest losses. This harvest, however, soybean moisture levels of 16 to 18 % or more have been reported.
Spoilage during storage is a concern when moisture levels are high. If storage temperatures are below about 60F, soybeans at 13% moisture can usually be kept for about 6 months without having mold problems. As moisture levels increase, however, the length of time soybeans can safely be stored decreases. How long can soybeans be stored before mold becomes a concern?
As a general guideline, soybeans in storage tend to act about the same as corn that is 2% greater in moisture content. For example, soybeans at 16% moisture can be expected to act like corn at 18% moisture.
The following table was developed for corn so to adjust for soybeans, simply look at the column for a moisture content 2 percentage points greater than the content of the soybeans in question. For example, 18% moisture soybeans (look at the column for 20% moisture corn) at a temperature of 50F could be stored for about 63 days before there would be enough mold growth to cause price discounts or feeding problems. Note that aeration is always recommended with all storage facilities.
Table 1. Allowable storage time (days) for shelled corn (approximate number of days corn can be held before there is enough mold growth to cause price discounts or feeding problems).
|Corn temperature||Moisture content (% wet basis)|
|Reprinted from: Natural-Air Corn Drying in the Upper Midwest, William Wilcke and R. Vance Morey, WW-6577-GO, Reviewed 2009. http://www.extension.umn.edu/agriculture/corn/harvest/natural-air-corn-drying/|
Artificial drying of soybeans will be needed if soybeans are harvested and stored at a moisture content greater than 13%. The bulletin, "Natural-Air Corn Drying in the Upper Midwest" by Bill Wilcke and Vance Morey, is a useful resource as many of the principles for drying corn will be similar for drying soybeans. Ken Hellevang, NDSU Agricultural Engineer also has a useful article on soybean drying and storage which you can find at: http://www.ag.ndsu.edu/extension-aben/documents/NDSU%20Offers%20Soybean%20Drying.pdf. Note that this article was written for a northern location. In southern MN, natural-air drying usually works for about two weeks longer - until about December 1.