By Mike Staton
Soybean seed is very fragile and susceptible to mechanical injury – the leading cause of poor germination in soybean seed. The reason for this is that the seed coats are typically thin and the embryo is located near the seed coat. When the embryo is bumped, jarred or hit, the radicle (embryonic root tissue) can be injured, causing root growth in the germinating seed to be impaired. Depending on the severity of the injury, the plants will die immediately or continue to grow with a weakened root system. While the incidence and severity of mechanical damage increases as seed moisture levels drop below 12 percent, all soybean seed should be handled carefully.
This is especially true for bulk soybean seed as there are more opportunities to damage the seed when transported through augers and conveyors. Researchers at the Ohio State University conducted a project studying the impact of bulk seed handling equipment on soybean germination rates. The transport systems evaluated in the study are listed below.
- 18-foot rubber-paddled belt conveyor in a 6-inch diameter steel tube
- 16-foot brush auger in a 6-inch diameter steel tube
- 16-foot steel auger in a 6-inch diameter steel tube
- 16-foot plastic-cupped auger in a 6-inch diameter steel tube
Grab samples were collected at the discharge end of each of these systems. The samples and a control sample that was not transported through the equipment were subjected to a warm germination test.
The researchers found that the average germination test for all the handling systems combined was 5.2% lower than the control. They also demonstrated significant differences between the transport equipment when operated to deliver 10 bushels per minute. The plastic-cupped auger was very gentle and the germination rate was comparable to the control. The brush auger and the steel auger both reduced germination by nearly 7% when compared to the control. Damage was significantly reduced with these systems when the auger speed was reduced from 525 rpm to 370 rpm. The belt conveyor performed poorly in this study. It was discovered that no padding existed at the nose of the conveyor, so the seeds hit a steel plate before exiting the conveyor.
Recommendations for reducing mechanical damage when handling soybean seed:
- Operate augers at lower speeds and keep them full.
- Install or upgrade padding at the nose of the conveyor or auger to reduce impact damage to the seed.
- Replace worn augers as damage increases with wear.
- Keep bearings and tubing in good shape.
- Reduce the height that the seed falls using bean ladders or other systems. Seed should not free fall more than 10 feet.
- Handle bagged seed gently. Dropping a bag of soybean seed on a concrete floor can reduce germination by up to 10%.
The Ohio State University research is summarized in a publication, "Impact of Bulk Seed Handling on Soybean Germination Rate."
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. The SMaRT project is a partnership between MSU Extension and the Michigan Soybean Checkoff program.
This article was published on MSU Extension News. For more information from MSU Extension, visithttp://news.msue.msu.edu. To contact an expert in your area, visit http://expert.msue.msu.edu, or call 888-MSUE4MI (888-678-3464).
Staton is a Michigan State University Extension Educator