Improve yields and income by reducing soybean harvest losses

Through careful equipment maintenance, soybean harvest losses can be controlled.

Reducing harvest losses is a simple and effective way to increase soybean yield and profitability. Careful equipment maintenance and operation can keep harvest losses at or below 3 percent. Surveys conducted in Ohio and Arkansas found that actual harvest losses averaged around 1.5 bushels per acre; other surveys found that harvest losses of 6 percent (3 bushels per acre) were common. Reducing harvest losses by just 1 bushel per acre will produce more than $11 per acre of additional income this year. 

Harvest timing

Properly timing your harvest operations is critical to reducing harvest losses. Harvest operations can begin anytime after the beans have initially dried to 14 to 15 percent moisture. Under good drying conditions, this will occur five to 10 days after 95 percent of the pods have reached their mature color. To reduce shatter losses, split seed and cracked seed coats, try to harvest as much of your crop as possible before the moisture level falls below 11 percent. Shatter losses also increase significantly when mature beans undergo multiple wetting and drying cycles. 

Equipment maintenance

Before harvest operations begin, inspect and repair the cutting parts on the combine head. Make sure that all knife sections are sharp and tight. Check the hold-down clips to ensure that they hold the knives within 1/32 inch of the guards. Adjust the wear plates to the point that they lightly touch the backs of the knives. 

Equipment adjustment

Information from the University of Arkansas shows that a skilled combine operator, one who understands how losses happen and how to reduce them, can achieve significantly lower harvest losses than an inexperienced operator or one who is trying to hurry or cut corners.

Nearly 80 percent of harvest losses occur while cutting and gathering the plants into the combine. Most of these result from shattered pods dropping beans on the ground. The following recommendations will reduce gathering losses:

  • Operate the combine at a slight angle (about 20 degrees) to the rows. This is especially beneficial with wide rows or plants with tough stems.
  • Maintain ground speed at 3 mph or less. Higher speeds are reported to be possible when using draper heads, when an air system is added to the head, when using 1-1/2-inch knife sections or when the field was rolled. Pods stripped from the stalks and uneven stubble are signs that the travel speed is too high.
  • Set the speed of the reel to run 10 to 25 percent faster than the ground speed. For a reel with a diameter of 42 inches (most reels), this is nine to10 revolutions per minute for each mile per hour of ground speed.
  • If the beans are lodged, gradually increase the reel speed to a maximum of 50 percent faster than the ground speed (12 rpm/mph). 
  • Position the reel axle 6 to 12 inches ahead of the cutter bar. In most conditions, the reel should be positioned as close to the auger as possible to promote even feeding. If the beans are lodged, move the reel forward to pick up the plants. Ideally, the reel should leave the beans just as they are being cut.
  • Set the height of the reel just low enough to control the beans (generally the top one-third of the plants). In lodged conditions, operate the reel as low as necessary to pick up the plants. Raise the reel if cut plants ride over the reel.
  • Measure gathering losses after each adjustment to determine your progress. Information on measuring soybean harvest losses is available from Michigan State University Extension at and from the Michigan Soybean Checkoff at

A Soybean Harvest Equipment Field Day will be held Sept. 25 at Schipper Farms near Martin. The following topics and equipment will be discussed and demonstrated: draper heads, auger heads, air-assisted reels, field roller effects on harvest, harvest loss measurements and ground speed effects on harvest losses. There is no charge for the field day or lunch, but attendees are asked to preregister by calling 269-673-0370, ext. 27, before noon on Sept. 20..

Mike Staton is a Michigan State University Extension educator. He can be contacted at


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