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Harvesting Soybeans With Green Stems

September 12, 2016

The dry weather occuring in June and July of 2016 and the wet weather we experienced in August have combined to increase the potential for soybean stems to remain green and tough this fall. The combination of green, tough stems and dry and brittle pods may create problems for soybean producers during harvest operations. The most important thing to remember when faced with these conditions is don’t wait until the stems are dry to begin combining. If you wait for the stems to dry, shatter losses occurring at the header or before the combine enters the field will be excessive. The following recommendations should help you reduce shatter losses and plugging problems when harvesting soybean plants with green stems and brittle pods.

  • If shatter losses are excessive, consider combining earlier in the morning or later into the evening when the pods have regained some moisture and are less brittle. However, this may increase plugging problems.
  • Reduce your ground speed to three mph or less if necessary. This will reduce shatter losses and plugging at the cutter bar by providing a crisp sideways cut.
  • Harvest at a 20 to 25 degree angle to the rows. This will improve cutter bar performance and provide more even feeding of the crop into the threshing cylinder or rotor. This may be the single most beneficial practice.
  • Draper heads should also reduce plugging problems when harvesting soybeans with green stems as they provide more uniform feeding into the threshing cylinder or rotor.
  • If the cutter bar is plugging, make sure that all knife sections and guards are sharp and tight. Check the hold down clips to make sure that they hold the knife within 1/32 of an inch of the guards. Adjust the wear plates so that they lightly touch the back of the knife. Check that the speed of the knife is correct and that drive mechanisms such as belts are not slipping. Make sure that the knife is in proper register with the guards. Rotate the knife through one complete cycle and make sure that the tip of the knife sections are centered on a guard at the beginning of a cycle and end up centered on a guard at the end of the cycle.
  • According to Gary Huitink, former agricultural engineer with the University of Arkansas, improper reel speed and reel position cause more shatter losses than any other maladjustment. Maintain the reel speed at 10 to 25 percent faster than the ground speed. Fore and aft reel position is important to reducing slug feeding. Generally, positioning the reel as close to the auger as possible promotes even feeding into the combine. The height of the reel should be adjusted so that it contacts the top one third of the plants.
  • Threshing problems result from worn parts on the cylinder or rotor and improper cylinder or rotor clearance or speed settings. The threshing equipment must be in good condition to handle soybeans with green/tough stems. Adjustments made to the cylinder/rotor clearance and speed is a balancing act between threshing losses and seed damage and split beans. Make one adjustment at a time and inspect the clean grain tank to determine your progress toward minimizing threshing losses and maximizing seed quality.

Again, it is critical that soybean producers continue to harvest soybeans having green stems even though it requires slower travel speeds and closer attention to cutter bar maintenance, and reel and threshing adjustments. Waiting for the stems to dry down will lead to large shatter losses. Careful observation while harvesting will help you identify the problem and where it is occurring. Armed with this information, you can apply the recommendations provided in this article, in your operator’s manual and by your local equipment dealer to solve the problem.

Source: Michigan State University