Drought Cause and Effect

March 8, 2013 08:33 PM
Drought Cause and Effect

Early drought can produce bigger soybean seeds, which impacts planter prep

The effects of the historical drought of 2012 continue to cause issues for farmers. "Soybean seeds are bigger than normal this year because drought conditions sped up the growth of soybean plants," says Shawn Conley, University of Wisconsin soybean Extension specialist. "The plants stopped producing seed pods about two weeks early, and rains in late July and late August helped expand existing seeds."

"Compared with last year, soybean seed sizes that will be planted in 2013 are definitely larger than average," says Tony White, soybean systems product development manager for Monsanto Company. "However, seed size can vary depending on seed product and the specific environment it was grown in. Monsanto seed brands, including Asgrow, are faced with seed size differences every year, with this season being no exception."

For most planters, minimal adjustments will be needed

Planter provisions. There are logistical implications, such as planter performance, for larger seed sizes, Conley notes. Farmers can prepare by reviewing the tote tag, which should include the seed size, measured in seeds per pound. Seeds normally sold in 50-unit totes might only contain 40 units this year, Conley says. So growers might need 20% more warehouse capacity to store seeds to plant the desired stand.

Virgil Schmitt, Iowa State University field agronomist, says it’s common for 2,500 to 2,700 seeds per pound to result in a 47-lb. bag. But this year, he believes farmers might only get 2,000 seeds to the pound, bulking bags to 70 lb.

Before you head to the field, make sure your planter can handle larger seeds. Talk with your equipment dealers as soon as possible, Conley advises, to allow prep time before the planting window.

DuPont Pioneer is working with planter manufacturers Kinze, AGCO White, John Deere and Case IH to identify best practices for handling larger seeds, says Jeff Daniels, seed technology manager for the company’s production operations division. One in four farmers might use larger-than-normal seed this year, he predicts.

For most planters, minimal adjustments will be needed. Vacuum pressures might need to be slightly higher than normal for accurate planting, Daniels says.

Planter lubricants can also help improve the flow of seeds through the machine.

"Graphite or talc can be used regardless of seed size to help consistently release seed from disks or planting mechanisms," White said. 

Other adjustments might be needed for specific planters. Farmers who use Kinze’s Brush-Type Seed Meters, for example, might need to use a dark blue 48-cell plate instead of the traditional black 60-cell plate, Daniels notes. Those with Case IH seed meters might find a 80- or 100-cell disk will place seeds more accurately than a 130-cell disk.

Producers should also expect to stop more often to fill up during planting, Conley says. Make sure seed delivery to the field is timely.

Check the germ. Lastly, check the percent germination of purchased seed, and adjust planters accordingly, Conley says. Because of the rapid seed drydown this past fall, some elite seed might have reduced germ. Soybean seeds might be sold at an 85% rate this year. While it’s not a big deal, Conley says, growers are reducing seeding rates each year to compensate for increased seed cost. As a result, they’re quickly approaching stand levels where yield loss might occur.

Farmers should also know there’s no evidence suggesting bigger soybean seeds result in better emergence, Schmitt says. The quantity of seed planted, genetics and other factors matter. Above all, follow good agronomic practices.

"Stay with what works because if you get that population too low and we do end up with good growing conditions, you’re limiting yourself," he says.

You can e-mail Nate Birt at nbirt@farmjournal.com.

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