By Mike Staton
Reducing harvest losses is a simple and effective way to increase soybean yields and profitability. Losses of 7.5% are common, but could be much higher this fall due to the drought and heavy spider mite infestations. The drought reduced overall plant height and the height of the lowest pods on the plants. Both of these conditions increase the potential for gathering losses at the combine head. The pods will also be more brittle and prone to shatter losses in fields that have been stressed by spider mites.
With careful maintenance and operation, harvest losses can be maintained at 3%. Reducing harvest losses from 7.5 to 3% in a 45-bushel per acre soybean crop will increase the marketable yield by two bushels per acre. With market prices projected to average nearly $16 per bushel for the marketing year, this translates to $32 per acre of additional income.
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% moisture. This will occur five to 10 days after 95% of the pods have reached their mature color under good, drying conditions. Try to harvest as much of your crop as possible before the moisture level falls below 12% to reduce splits and cracked seed coats. Shatter losses have been shown to increase significantly when seed moisture falls below 11% and when mature beans undergo multiple wetting and drying cycles.
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.
Information from the University of Arkansas shows that a skilled combine operator can reduce harvest losses significantly when compared to an inexperienced operator or one that is trying to hurry or cut corners. Combine operators should understand how losses occur and how to make the proper adjustments.
Nearly 80% 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 3 mph or less. Higher speeds are reported to be possible with a draper head or when air is added to the head. Pods stripped from the stalks and uneven stubble are signs that the travel speed is too fast.
Set the speed of the reel to run 25% faster than the groundspeed. For a reel with a diameter of 42 inches, this is 10 rpm/mph.
If the beans are lodged, increase the reel speed up to 50% faster than the ground speed (11 rpm/mph).
Position the reel axle 6 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 (generally the top 1/3 of the plants). In lodged conditions, operate the reel as low as necessary to pick up the plants.
Measuring gathering losses after each adjustment is the best way to verify your progress. Please refer to the accompanying article, Measuring soybean harvest losses. Losses can also occur once the beans have entered the combine. However, the combination of these losses typically accounts for only 1% of the total harvest losses.
For more information on reducing soybean harvest losses, join us September 20 for a Soybean Harvest Equipment Field Day and Plot Tour.
This article was produced by the SMaRT project (Soybean Management and Research Technology). The SMaRT project was developed to help Michigan producers increase soybean yields and farm profitability. SMaRT is a partnership between MSU Extension and the Michigan Soybean Checkoff program.
This article was published by MSU Extension. For more information, visit http://www.msue.msu.edu. To contact an expert in your area, visit http://expert.msue.msu.edu, or call 888-MSUE4MI (888-678-3464).
Stanton writes for MSU Extension