Reducing soybean harvest losses

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

Reducing harvest losses is a simple and effective way to increase soybean yields and profitability. Losses of 10 percent are typical and can reach 15 percent. With careful maintenance and operation, harvest losses can be maintained at three percent. Reducing harvest losses from 10 to three percent in a 45 bushel per acre soybean crop will increase the marketable yield by 3.1 bushels per acre. With market prices projected to be around $12.00 per bushel, this translates into more than $36.00 per acre of additional income.

Harvest timing

Properly timing your harvest operations is critical to reducing harvest losses. Harvest operations can begin any time after the beans have initially dried to 14 to 15 percent moisture. Depending on weather conditions, this is usually about five to 10 days after 95 percent of the pods have reached their mature color. Try to harvest as much of your crop as possible before the moisture level falls below 12 percent to reduce splits and cracked seed coats. Shatter losses have been shown to increase significantly when seed moisture falls below 11 percent and when mature beans undergo multiple wetting and drying cycles. Shatter losses can be reduced by harvesting in the morning or the evening when relative humidity is higher.

Equipment maintenance

Before harvest operations begin, inspect and repair the cutting parts on the header. Make sure that all knife sections are sharp and tight. Check the hold-down clips to ensure that they hold the knife within 1/32 of an inch of the guards. Adjust the wear plates to the point that they lightly touch the back of the knife. Consider switching to quick cut knives if the existing knife sections need replacing or if shatter losses have been high.

Equipment adjustment

Information from the University of Arkansas shows that a skilled combine operator can add more than $150 per hour in additional profits over an inexperienced operator or one that is trying to hurry or cut corners. Despite this, statewide surveys indicate that only 10 percent of combine operators check their combine adjustments regularly and match forward speed to field conditions. Combine operators should understand how losses occur and how to make the proper adjustments.

Nearly 80 percent of harvest losses occur while cutting and gathering the plants into the combine. Most of these are due to shattering. The following recommendations will reduce gathering losses:

  • Maintain ground speed at three mph or less. Slower speeds will be required if the crop is lodged or if the stubble is high and ragged. Higher speeds are possible when using quick cut knives.
  • Set the speed of the reel to run 25 percent faster than the groundspeed. If the beans are lodged, increase the reel speed up to 50 percent faster than the ground speed. Setting the reel speed too fast will cause the beans to be beat out of the pods before reaching the combine. Setting the reel speed too slow will cause cut plants to fall forward and out of the combine.
  • Position the reel axle six to 12 inches ahead of the cutter bar. 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. Positioning the reel too far forward will increase shatter losses due to excessive flailing action. In lodged conditions, operate the reel as low as necessary to pick up plants. Setting the reel too deep in the canopy will also increase shattering and cause plants to ride over the reel. 

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