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3 Preseason Soybean Tips for 2019

Consider these three tips before you plant soybeans this spring.

1. pay attention to soybean seed

There is a decent chance the soybean seed you’re planning to plant this spring isn’t as vigorous as you think. Soybean seed supplies for 2019 across the Midwest are showing signs of germination issues, due, in part, to much longer and wetter harvest than normal in the primary seed-producing states of Iowa, Illinois, and Indiana. 

A high incidence of these seed diseases for 2019 include:

  • Phomopsis seed decay. Identified by a chalky white color on the seed surface, seed with phomopsis also will be shriveled or broken. 
  • Purple seed stain. Just like the name says, the soybean seed will have purple blotches or be covered in a purple tint. 

Check the germination percentage on any fresh soybean seed and confirm with germination tests of your own at a state crop improvement association laboratory, recommends Shawn Conley, soybean specialist at the University of Wisconsin-Madison.  

If you saved soybean seed to plant in 2019, make sure it is cleaned thoroughly to get at least 80% germination. The Nebraska Crop Improvement Association, for example, has tested samples ranging from 43% to 98% germination this year.

If the germination rate is lower than normal, plan to add a fungicide seed treatment, which will “generally enhance or improve overall germination rate,” Conley says. 

Fungicide treatment won’t improve germination of dying or dead seeds, but it can help protect seedlings under stress and ensure a better stand. 

Ask your dealer if seed-applied treatments protect against phomopsis seed decay. Many off-patent treatments will not be effective against phomopsis, he says.  

Also, you may want to bump seeding rate to offset the reduced germination percentage, he adds. 

2. Don’t wait for 50°F. dAYs

The default planting date for soybeans tends to be when farmers get done with corn. Since the baseline soil temperature for corn planting is 50oF., soybeans should, therefore, follow suit. Trouble is, that’s not correct. 

Soybeans can handle cold just fine. Sure, short-term freezing temperatures will chill them, and a hard freeze will kill them. But emerged beans can handle 28°F. for four hours. 

“In early-season environments, the soybean plant is more resilient than we give it credit for,” Conley says.

The upshot: You can plant soybeans much earlier than you think, perhaps even ahead of corn.

3. Remember that Soybeans fix N for the next crop

As a legume, soybeans are able to produce a lot of nitrogen through fixation. However, soybeans also use a lot of nitrogen. An 80-bushel-per-acre crop requires 300 pounds of nitrogen per acre, most of which is delivered to the grain elevator as protein.

Most soils, with adequate biological fixation, can meet that demand. Yet, there may not be as much fixed nitrogen carrying over to the next crop as previously thought. 

That’s due, in part, to improvements made by soybean breeders to maximize yield even in tough environments. Conley says  there are more days of the yield-influencing reproduction stage in today’s soybean varieties than those available a generation ago. 

The upshot? Soybean plants will use almost 90% of soil nitrogen, leaving very little for the next crop. Therefore, Conley is reticent to give an N credit after soybeans. At the same time, he also advises against adding too much N as fertilizer. Limit starter fertilizer applications to 30 pounds in a 2×2 configuration. More than 30 pounds of added nitrogen complicates biological fixation. 

“Soybeans are lazy,” he explains. “They would rather get N for free than work for it.”

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