A recent study by the Iowa State University Grain Quality Laboratory indicates that for the years 1987 to 1990, Minnesota soybeans had higher moisture content, more foreign material, more splits, and more DKT (total damaged kernels, which is largely mold damage) than soybeans from other states in our region. (See C.R. Hurburgh, Jr., 1996, "US soybean quality related to costs and benefits of soybean cleaning," Applied Engineering in Agriculture 12(3):379-382, ASAE, St. Joseph, MI.)
Given our short growing seasons and narrow windows of harvest opportunity, Minnesotans frequently encounter more difficult conditions for harvesting soybeans than do our southern neighbors. This doesn't mean that we can't produce as high quality beans as our neighbors, it just means that we need to work a bit harder to do so. With the expected high prices for soybeans this year, it would be worth investing a little more time, effort, and fuel (electricity and perhaps gas) this year to make sure you have high quality beans available for sale.
The first step in producing high quality soybeans starts with combine operation. Check the condition of harvested beans frequently and change combine settings as needed to minimize the number of split beans and amount of foreign material in the grain tank. It might be best to leave replanted spots or other parts of fields that have unusually wet or immature beans for later harvest, rather than mixing them in with beans that are clean, dry, and fully mature.
If soybeans are 13% moisture or less, they can go directly into storage. All storage bins should have some kind of aeration system--especially for a high-value crop like soybeans. Use the aeration system to cool beans down to 20 to 30°F for winter storage. Storage at this temperature reduces the likelihood of mold growth and reduces the chances of natural convection currents which can cause moisture migration and spoilage at the top of the bin.
If soybeans are wetter than 13% moisture, they need to be artificially dried for safe storage. Natural-air drying (no heat) should work well if you have a bin that has a full perforated floor and fan power of about 0.75 hp per 1000 bu of beans (for bins less than 18 ft high). Heated-air drying can also be used for soybeans, but keep the temperature down (less than 140°F) to avoid splitting seeds. Turn the temperature down even further (less than 110°F) if you plan to keep the beans for seed.
Best wishes for a profitable soybean harvest!
This page is part of the Biosystems and Agricultural Engineering Department web at http://www.bae.umn.edu/