Southern soybean growers know the value of good seed selection and treatments, along with proper weed, insect and disease control. And once the crop is made, they are ready to reap the benefits of their blood, sweat and tears.

That’s where a timely harvest and correct storage can top off the solid year.

Pawel Wiatrak, Clemson University soybean specialist, says timely harvest is essential in obtaining maximum yield and a high quality crop.

“When harvest is delayed due to bad weather, or when some varieties dry down to seed moisture levels below 11 percent, seed shattering may occur in the field or at the cutter bar at harvest,” he says.

“To reduce the potential for shattering losses, harvest should begin at seed moisture levels of 12 percent to 14 percent. If storage bins have the capacity for drying with air blowers, harvesting at 16 percent is not out of the question.”

Wiatrak warns, however, that for most years in southern states, farmers who wait for ideal moisture around 12 percent often have difficulty harvesting their entire crop without losses in yield and quality, either from shattering, lodging or disease.

Growers should have a harvest plan mapped out before pulling combines to the field, he says. One important factor is to estimate  yield prior to harvest. This will help determine storage needs.

Here are his suggestions to help determine approximate yield:

  • Count the number of plants from 10 randomly selected rows to get the average plant number. For example, count plants in 14-feet, 6-inches long rows for 36-inch row spacing, or 13-feet, 9-inches long rows for 38-inch row spacing (1/1,000 of an acre). Calculate the average and multiply by 1,000. This is your plant population per acre.
  • Count number of pods per plant from 10 randomly selected plants and calculate the average.
  • Multiply plant population per acre by average number pods per plant to get the number of pods per acre.
  • Multiply number of pods per acre by 2.5 (average number of seeds per pod or use your own number) to get the number of seeds per acre.
  • Divide number of seeds per acre by 2,500 (or known number of seeds per pound for the variety) to get weight in pounds per acre.
  • Divide weight in pounds per acre by 60 to get yield in bushels per acre.

Once the yield estimate is made, it’s cutting time. And growers should have their harvesting equipment in peak condition before harvest begins.

Michael Buschermohle, University of Tennessee agricultural engineer, says too many growers leave too many bushels in the field during harvest.

“Growers can prevent such losses with combine adjustments or making sure the combine is operated correctly,” he says.

Excessive speed can be the greatest cause of combining losses, he notes.

“Most combine cutter bar knives move back and forth much slower than mower knives. This slower knife speed, in relation to forward travel, is not so important in small grain harvest such as wheat, but it can cause much loss in soybean harvest unless ground speed is held below 4 mph.”

Also, determine if the combine reel is adjusted to the correct height to properly feed the crop into the combine throat, and that it is turning at the proper speed to minimize harvest losses. Make sure the cutter bar is adjusted to the proper cutting height to minimize harvest loss. Harvest losses can range from a whopping 6 percent to 25 percent.

“Pre-harvest losses will be minimized if the crop is harvested before the bean seed moisture gets to 10 percent,” Buschermohle says. There are two kinds of harvest losses: gathering losses and threshing losses.

“Because soybean plants have pods set from the very bottom to the very top of the stalk and the beans shatter from these pods, gathering losses are the most difficult to control,” he says. 

“To minimize gathering losses, the combine cutter bar must operate near the ground under the lowest bean pods. It must also cut and move the stalks into the combine without shaking them to a shattering degree.”

Threshing losses include straw walker loss, when threshed beans are carried out the back of the machine with the straw; cylinder loss, unthreshed beans remaining in the pods after passing through the cylinder and beans that are cracked by the cylinder; and shoe loss, threshed beans that move over the chaffer and sieve and out the back of the machine.

There can also be header loss, beans that are threshed by the header mechanism and spilled back onto the field instead of moving into the threshing cylinder; and machine handling loss, beans that are spilled back to the ground through cracks and holes in the combine’s skin.

Reel management is also important. The reel holds plants in position while they are being cut and moves the cut plants from the cutter bar.

“It should complete this mission with minimum plant disturbance,” Buschermohle says, “In order to minimize reel disturbance of plants it must operate at the correct speed in relation to ground speed.”

When moving soybeans from the field into storage, growers should take into account the threat of fungi that can harm grain quality, says Sammy Sadaka, University of Arkansas Division of Agriculture agricultural engineer.

“Fungi are the most important cause of damage from the field to storage,” he says. “Everything that is done from that time should help preserve that quality.

“Soybeans may be easily stored and dried in facilities that were designed for rice or wheat. Soybeans are easy to dry because air moves through them more readily than many other grain types.

“They should be dried as quickly as possible to moisture levels of 13 percent or less. A moisture level of 11 percent is desirable if beans are to be kept longer than six months.”

Sadaka says soybeans should also be cooled to avoid moisture collection throughout the winter season.

“Dry and cool beans are relatively safe from fungi and insects — the two primary potential sources for grain damage. The key to excellent on-farm soybean storage is controlling their moisture level. This requires excellent management coupled with an adequate aeration system.”

With the high value of soybeans in the field, growers should double check with their regional Extension agronomist, crop consultant or seed specialist to make sure harvest and handling procedures are followed. This will help assure they’re soybean crop yield.