MSU Extension Soybeans

Soybean harvest began in many fields this past week in Michigan, and although most fields appear to be a couple weeks away from harvest, the hot and dry conditions prevalent in the southern half of the Lower Peninsula are pushing crops to maturity ahead of schedule. Most areas south of Highway 10 are 10-14 or more days ahead of normal with respect to accumulated heat units. At the same time, most of the Lower Peninsula has received 2–4 inches less rainfall than normal over the past 30 days aside from a pocket centered on Livingston and Washtenaw counties. The next chances for widespread rainfall will be early this coming week with totals of 0.5-1 inch for most of the state. However, according to the 6–10 day and 8–14 day outlooks from the National Weather Service’s Climate Prediction Center, the hot and dry conditions are predicted to persist through the end of September, and the 3–4 week outlook predicts more of the same through the first half of October.

If these predictions hold true, soybeans will finish and dry down rapidly, and moisture levels can easily drop below 10%. Reports from local elevators have come in already of beans arriving at 9% moisture. This increases the potential for shatter losses, higher discounts due to split beans and reduced delivery weight. When moisture levels fall below 10%, producers will need to decide if they should harvest the overly dry soybeans or wait for rain to add some moisture back into the beans. This is an individual decision. This article will provide information that should help guide this decision.

Advantages of continuing to harvest overly dry soybeans:

• Timely wheat planting
• Reduced soil compaction
• Fall tillage operations can be completed sooner
• Ability to switch over to corn sooner which will also likely dry down quickly this fall

The main advantage of delaying harvest and waiting for rain is that the net value of each bushel harvested may be increased (see Table 1). However, there is some risk associated with this strategy. Harvest losses may increase as soybean pods typically become more brittle with each wetting and drying cycle. Today’s varieties are more resistant to shattering, but the risk increases with repeated wetting and drying cycles.

You should also consider the following factors when making the decision to continue harvesting overly dry soybeans or delaying harvest operations.

What is the calendar date and weather outlook?

It is still early in the harvest season and the 6-10 and 8-14 day weather outlooks are projecting a high probability of higher than normal temperatures and normal to slightly below normal precipitation.

How will the soybeans be marketed?

Soybeans grown for seed should be harvested at moisture levels near 13% to optimize seed quality. The risk of reducing seed quality increases significantly as the moisture level in the seed falls below 10%, so seed producers should wait for rain if moisture levels are below 10%.

Producers growing food-grade or non-GMO soybeans under contract should check with their contractors to get their current recommendations for harvesting this year’s crop. Some contractors want producers to begin harvesting food-grade beans early at moisture contents above 13% to avoid the potential for quality to decline due to rapid field drying.

Producers raising commercial soybeans have no marketing restrictions regarding moisture content as long as the moisture levels are below 18%. Some elevators reserve the right to reject loads above 16%.

Are the fields well drained or poorly drained?

Consider harvesting poorly drained fields while soil conditions are optimal.

Can the overly dry soybeans be harvested without excessive shatter losses or splits?

Shatter losses can be reduced by beginning harvest operations earlier in the day, reducing ground speed and reel speed and paying close attention to reel position. Most elevators will not assess discounts on loads containing less than 20% split beans.

Do you have the capability to recondition the overly dry soybeans?

It is illegal to add water to any grain crop. However, it is legal to increase the moisture level of the beans by running aeration fans only when humidity levels are high. Be aware that adding too much moisture may damage the bins. Ken Hellevang at North Dakota State University (NDSU) has written several articles on reconditioning soybeans: “Consider Reconditioning Too-dry Soybeans and Other Grain,” “Soybeans May Need Rewetting” and “Reconditioning Soybeans in Storage Poses Problems.”

For more information about reconditioning, drying, handling and storing soybeans, see NDSU’s Grain Drying and Storage website.

This article was produced by a partnership between Michigan State University Extension and the Michigan Soybean Checkoff program.