Agronomy Talk

Agronomy Talk: Corn and Soybean Early-Season Emergence

Published on Monday, March 25, 2019

So, you’ve planted your crops… now, how long do you need to wait for them to emerge?

A corn crop requires moisture to emerge, about 30 percent soil moisture at minimum. It also needs about 120 Growing Degree Days (GDD) accumulated.

Here is how you can determine your GDD:

    • GDD = (day’s high temperature + day’s low temperature)/2 - 50
    • The maximum high temperature is 86 degrees and the minimum low temperature is 50 degrees

For example, if today’s high is 75°F and the low is 51°F, so (75+51)/2 – 50 = 13 GDD

So, based on this example, the corn will emerge in 9 to 10 days (120/13 = 9.2 days).

It’s important that we protect the mesocotyl! A corn plant will live off the seed until about the V4 to V5 growth stage or until the nodal roots have developed. As you scout your fields, make sure to look at the seed itself and ensure that it is hard and the mesocotyl is white as these are indicators of a healthy plant.

Soybeans, on the other hand, require about 130 GDD for emergence. Their growing point is near the top and comes out of the ground at emergence. 

What about stand counts?

When calculation stand counts for 1/1000th of an acre, follow the below:

  • 30 in. Row Corn = 17 ft. 5 in.
  • 15 in. Row Soybeans = 34 ft. 10 in. (Use 17 ft. 5 in. and count two rows, one on each side of the tape measure)

Hula Hoop Calculations for Drilled Soybeans:

Stand Establishment Concerns:

Always Look for Patterns! Does the problem follow a straight line, low area, certain consistent distance apart, etc.?

  • Straight Lines = Man made, Random Pattern = Mother Nature

If you have any questions, please reach out to your seed advisor or local field agronomist!


Steve Gauck | Field Agronomist 


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