Margin Minute: How To Measure Corn Yield Loss

September 12, 2017 03:53 PM

Although northeastern Iowa generally has been a garden spot this year for corn production, a dry August has left the crop to begin shutting down early, says Chris Barron of Ag View Solutions. If you’re wondering how much yield you might be losing at harvest this fall, it’s a good idea to head to the field to crunch the numbers.

Barron’s farm is located between Cedar Rapids and Waterloo and received just 1” of rain during August in increments of 2/10” at a time.

“A lot of the light soil is really starting to shut down. Even what we’re seeing out here in what I would call our best ground, we’re seeing things shut down pretty quickly, too,” Barron says. “The cool weather has saved us, but we need to get some rain to finish this crop off and give us just a touch more test weight. But the milk line is getting down there a ways to where we’re not sure we can add a lot of test weight at this point.”

He uses two test strips to calculate production. Based on his measurements, this year’s yield is down between 20 bu. and 45 bu. per acre—from 205 bu. to 230 bu. this year compared with up to 250 bu. at some locations in 2016. That means he’ll need to capture up to 50 cents more per bushel this year on the reduced production to keep gross income per acre consistent with 2016 levels.

Here’s how Barron did the calculation, in his own words:

  1. Our farm is planted in 30” rows. What we did is we take two sets of rows and we measure out 17.5’ to get a thousandth of an acre. When we did that, we counted 34,500 harvestable ears between the two thousandth-of-an-acre strips, these two rows beside each other.
  2. We randomly picked from either side six ears. We grabbed ear five, eight and 11 from either opposite side so we had six ears to do the kernel counts from, and they’re random.
  3. We ended up with 32 kernel rows for a length, we ended up with 16.7 average kernel rows around. We do the length based on going up to the tip. We don’t take those last couple of rows just to be conservative.
  4. We ended up with 534 kernel count per ear, on average, with 34,500 population.
  5. Really, the big kicker this year, what I think we’re going to have as an issue probably is what do you divide those kernels by in terms of a bushel. Does a bushel mean 70,000 kernels, does it mean 80,000 kernels, does it mean 90,000 kernels? Last year, the crop just finished off really slow and perfectly.
  6. As we look at that and do more of these checks, the concerning thing is this yield is actually coming down a little bit. Here at 80,000 kernels, you’d be at 230 bu. per acre, and then at 90,000, you would actually be at about 205 bu. per acre. That’s a little bit troublesome and scary to me because you start thinking of that in terms of dollars and cents compared to probably where we were last year, we’re talking maybe a difference of almost $200 an acre if you use $3.50 for a price and you’re looking at about 58 bu. less.

As you get out and do these yield estimates, figure out what those numbers mean in terms of price per bushel, Barron advises.

“It might be a situation where we’re looking at almost $1 per bushel more that we would need, as opposed to where we were at last year, to have the same revenue for gross income per acre,” he explains.

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Spell Check

Sharon, IA
9/12/2017 08:56 PM

  According to usda this never happens


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