Symptoms
Vacuum or Radial Bean Meters overpopulate with small soybean seeds.
Situation or Problem
In years that follow extremely poor growing seasons for soybeans, the soybean seeds may be found to be extremely small. For example, in 2004 the majority of soybean seeds were in the 3,400 to 4,300 seeds per pound range.
Traditionally, seeds range from 2,500 to 3,200 seeds per pound, much larger than the available seed in 2004. The John Deere radial bean meter and vacuum meter can plant these small soybeans very effectively. But, as part of pre-season planter preparation, growers will have to prepare the seed meters to plant the small soybeans.
Summary
We have conducted population tests with soybeans sized at 3,600, 3,800, 4,000 and 4,300 seeds per pound. Tests were conducted using the radial bean meter and the vacuum meter. These smaller seeds will overpopulate if the seed meters are not properly prepared.
Solution Steps
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RADIAL BEAN METER: The seed bowl of the radial bean meter has three settings (A, B, C) to adjust for soybean seed size. For smaller seed, the seed bowl will need to be adjusted to position A or B. With the seed bowl adjusted for the correct seed size, the radial bean meter will do an excellent job planting small soybeans.
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VACUUM METERS
Vacuum seed meters will do an excellent job with small soybeans but a seed disk change is necessary. Our tests show that soybeans sized at 3,500 or more seeds per pound will overpopulate (double) with the traditional soybean disks (A42586). Vacuum level adjustments will not eliminate the overpopulation, and a seed disk change is required to eliminate this issue with small soybean seed.
The small edible bean disk gave acceptable performance with the larger seeds in the test group at a vacuum setting of 3 to 5-in. This disk will overpopulate with the smaller seeds in the test group, and vacuum settings will not eliminate this. Sorghum seed disks underpopulate (skip) with all small soybeans, and higher vacuum levels will not eliminate this.
The acid delinted cotton seed disk gave excellent population control with all seeds in the test group. Vacuum levels of 5 to 7-in. were required.
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RECOMMENDATION FOR VACUUM METERS:
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Vacuum seed meters planting soybeans sized at 3,500 or more seeds per pound should use the acid delinted cotton seed disk. Vacuum levels of 5 to 7-in. should be utilized with this disk.
There is one last important issue—seed transmission settings. Because the cotton disk has fewer cells than the soybean disk (64 vs. 108 cells), the planter’s mechanical seed transmission will have to be set to a different sprocket combination to achieve the desired population. A rate chart showing settings for soybean planting using the cotton disk was not provided in the operator’s manual until 2005 production. This rate chart (for 15 to 22-in. row spacing with the cotton disk) is provided with the link below. Ideal ground speed may need to be reduced with the cotton disk compared to the soybean disk. Planting small soybean seed can be done very effectively, but it requires seed meter preparation.
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Affected Equipment
| 1535 drill
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DB series planter
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| 7200 planter
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7300 planter
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| 1700 planter
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1710 planter
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| 1720 planter
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1730 planter
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| 1750 planter
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1760 planter
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| 1760NT planter
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1770 planter
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| 1770NT planter
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1780 planter
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| 1790 planter
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