Ask an Agronomist
Calibrate equipment to adjust for variable soybean seed size
Apr 08, 2014
Reports of larger-than-normal soybean seed are fueling some concerns about planting this spring. While smooth planting with larger soybean seed may not be a snap, it shouldn’t be a problem, either, according to Seth Naeve, University of Minnesota Extension soybean specialist.
"It's not nearly as big of a deal as in years past because seed is now generally sold by the number (140,000 seeds) instead of by the weight," says Naeve. "Farmers will just need to be aware that they will have larger volumes (and weight) in seed if seed size is large."
He adds: "Some producers even prefer larger seed. A larger seed does have more stored energy and mineral recourses for the emerging soybean plant. However, the larger cotyledons can be more difficult to force up through the soil. So, soil type does impact whether large or small seeded soybeans emerge better, but overall it's a wash."
Seed size is greatly affected by the environment, but there is little interaction with variety, he notes. So, when seed size increases, it’s usually across soybean lines (of the same maturity).
He adds that very large seed is usually the result of poor conditions during seed-set, paired with much better conditions during late seed-fill.
While there are reports of larger-than-normal seed size in some parts of the country, Naeve points out that the 2013 U.S. Soybean Export Council survey indicates that last year Iowa farmers produced average to below-average sized seed except in the northwest corner of the state, where seed size was much larger than normal.
As in any year, the important thing is to calibrate your soybean planter or drill as you head to the field, and remember to recalibrate between varieties to make sure you plant the intended amount of seed. If you have any concerns, contact your seed supplier and equipment dealer about setting your equipment to handle this year’s seed sizes.
Four Tips to Give Soybeans a Good Start
The time you spend monitoring soil moisture, planting depth, seed-to-soil contact and planting equipment calibration will be rewarded with uniform and rapid soybean emergence.