Reducing harvest losses is a simple and effective way to increase soybean yields and profitability. Losses of 10 percent are common and can reach 15 percent. With careful maintenance and operation, harvest losses can be maintained at 3 percent. Reducing harvest losses from 10 to 3 percent in a 45 bushel per acre soybean crop will increase the marketable yield by three bushels per acre. With market prices projected to average nearly $13.50 per bushel for the marketing year, this translates into more than $40 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. This will occur 5 to 10 days after 95 percent 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 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.

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.

Equipment adjustment

Information from the University of Arkansas shows that a skilled combine operator can add more than $200 per hour in additional profits over 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 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 miles per hour or less. Higher speeds are reported to be possible with a draper head or when air is added to the head.
• Set the speed of the reel to run 25 percent faster than the ground speed. If the beans are lodged,increase the reel speed up to 50 percent faster than the ground speed.
• 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. In lodged conditions, operate the reel as low as necessary to pick up plants.

Losses can also occur once the beans have entered the combine. However, the combination of these losses typically accounts for only 1 percent of the total harvest losses.

Measuring harvest losses

In order to make the proper adjustments, the combine operator should stop the combine periodically and check the amount and type of loss that is occurring. Since 80 percent of the losses occur at the header, we will focus on measuring gathering losses.

The first step is to build a frame having an inside area of one square foot. A stiff wire frame painted a bright color works well. Next, stop the combine in a representative area of the field and back up 10 to 15 feet. Use the frame to count the number of beans on the ground in the harvested area in front of the header. Take at least four counts across the entire length of the header. For each count, record the following information.

• Shatter loss. Count all the loose beans and beans in loose pods in the standing crop ahead of the combine and subtract this number from the number of loose beans and beans in pods you find in the harvested area.
• Loose stalk loss. Count all the beans in pods attached to plants that were cut, but not gathered into the combine.
• Lodged stalk loss. Count all the beans in pods attached to plants that were not cut.
• Stubble loss. Count all beans in pods that remain on the stubble.

Determine the average losses in beans per square foot for each category and divide by four (four beans per square foot equals one bushel per acre). Use this information and the recommendations covered in this article to adjust your combine settings. Make one adjustment at a time and stop periodically to evaluate your progress toward reducing harvest losses to 3 percent.

Shatter loss measurement example:

The average shatter loss in this example is 12 beans per square foot, which equals three bushels per acre.

(12 + 11 + 12 + 13) ÷ 4 = 12 beans/ft²
12 beans/ft² ÷ 4 = 3 bushels/acre

Related article:
Estimating soybean yields prior to harvest, Mike Staton, MSU Extension

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. Funding for the SMaRT project is provided by MSU Extension and the Michigan Soybean Checkoff program.