By Liz Stahl

Harvesting soybeans at a moisture content between 13% and 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 60 F, soybeans at 13% moisture can usually be kept for about 6 months without having mold problems. But as moisture levels increase, 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. 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 50 F 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.

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. Note that this article was written for a northern location. In southern Minnesota, natural-air drying usually works for about two weeks longer — until about Dec. 1.