Soybean fields maturity variable

There are areas in fields where the soybean plants are approaching maturity adjacent to areas with green plants.

Editor’s note: The following was written by Shawn Conley, University of Wisconsin Extension Soybean and Small Grain Specialist, for the Extension Cool Bean website Sept. 23.


Variable soil types, flooding and ponding, variable planting dates and random pest pressure have left many growers with extreme in-field variability of soybean maturity in 2019. It’s the worst I have ever seen.

There are areas in fields where the soybean seed is approaching maturity adjacent to areas with green seed.

The prevailing question is, “When should the grower harvest?” Obviously there is no simple answer because each field is different.

But there is a set of guidelines to consider.

The easiest answer is to harvest the field at two different times. Take what is dry today. Then come back in two weeks to harvest the rest.

The challenge with that approach is that today’s equipment is large and not easily moved from field to field. Furthermore, many growers rent or own land across large areas where that’s impractical and the whole field must be taken at once.

The next simple answer is to wait until the whole field is ready to go. But we are seeing areas across the Midwest where shattering is occurring. The general rule of thumb is four seeds per square foot equals 1 bushel yield loss. At local cash prices hovering at about $8 per bushel, that’s difficult to see happen and not harvest.

Waiting will also lead to moisture loss in the field. As we learned the past few years, producers aren’t compensated for harvesting at less than 13% moisture.

If growers are concerned with shatter and/or other harvest losses, the next logical approach is to harvest as soon as possible. That opens a whole new can of worms. Harvesting as soon as possible will lead to a mixture of dry, wet and immature or green soybean seed.

Be aware if that mixture is harvested regardless of the ratio, the combine moisture sensor may not detect the correct moisture. Be prepared for an initial shock when the elevator tests the grain. Next be prepared for the dockage.

Most combines will leave more beans in the pod when they are wet or immature. Those beans may land on the ground or in the grain tank as unthreshed soybeans.

Harvesting seed with that variability will be similar to handling frosted soybean seed. Discounts may occur due to moisture shrink, damage — green beans are considered damage — foreign material, test weight and heating. A producer might choose on-farm storage to address some of the dockage concerns.

The last consideration I would bring forward is that the mature areas are likely going to be reduced-yield pockets due to early senescence. The yet-to-mature areas will likely be the better-yielding areas within the field. So consider which yield environment a producer would rather focus time and efforts to protect.

The question ultimately comes down to the bottom line and where to make the most money. If shatter is not occurring and a producer has good equipment that doesn’t incur significant harvest loss, consider whether harvesting grain that is over-dry will make more money than harvesting seed that may incur significant dockage. My guess is yes.

Sign up for our Daily Headlines newsletter

* I understand and agree that registration on or use of this site constitutes agreement to its user agreement and privacy policy.