Minimizing soybean harvest losses can mean substantially higher yields and profits. Good harvest practices can reduce losses to near 3%, or only 1 to 2 bu/acre. However, delayed harvest or poorly adjusted equipment can result in losses of 10% or more. Since soybeans dry very quickly, close monitoring of grain moisture is required for timely harvest. In addition, combines must be properly adjusted, frequently checked and carefully operated to minimize losses.
Over the last 4 years of a Pioneer Sponsored High Yields Soybean Challenge Contest, they have seen an average yield gain of +7.0 bu./ac by harvesting at 13% moisture vs. 10% moisture. In our area, this is much easier said than done, especially in years where we have warm, dry weather and the soybeans drop moisture very quickly. Soybeans at optimal harvest moistures will likely still have a bit of green color in the stems across the field. In the last several years, Pioneer has consistently seen the highest soybean yields come from the first 7-10 days of soybean harvest.
GUIDELINES:
Typically more than 75 percent of soybean machine harvesting losses are gathering losses, so greatest attention should be given to proper header adjustment and operation. Some of the more important things to remember are:
- Adjust ground speed to avoid long stubble, uneven cutting height and shatter losses due to knife stripping, which are indications that ground speed is too fast.
- Operate cutter bar as close to the ground as possible at all times. A floating flexible cutter bar with automatic header height control is virtually essential for low loss levels.
- Keep knife sections sharp, and make sure guards, wear plates and hold-down clips are in good condition and properly adjusted. Narrow-section knives reduce shatter and may permit slightly higher ground speeds.
- Operate reel 1.5 times the ground speed. Use the following formula: Reel speed (rpm = combine speed (mph)) x 504 / reel diameter (inches)
- Position reel axis eight inches ahead of cutter bar.
- Complete harvest as quickly as possible after beans first reach 15 percent moisture. When beans reach 13 percent moisture or less, take advantage of damp pod conditions brought on by dew, light rain or high humidity to reduce shattering.
- Operate the cylinder at the slowest speed that will give complete threshing to reduce splitting. Check and adjust if necessary as conditions change from damp to dry.
- Remember that soybeans can dry very quickly. Once 95 percent of the pods have reached their mature color, it will only take five to seven good days for the beans to dry enough to harvest.
- Keep forward speed at about 3 miles per hour for most combines. Slow down for uneven soil surface or other abnormal conditions.
- Stubble losses can also be reduced by planting and cultivating practices. Height of lowest pods is increased by growing soybeans in narrow rows or by higher plant populations within the row.
SOURCE: Pedersen, P. 2006. Combine setting for minimum harvest loss. Soybean Extension and Research Program, Iowa State U. Online:
http://extension.agron.iastate.edu/soybean/production_combineset.html
