Minding Ag's Business

2019 Puts Yield Models to the Test

Katie Micik Dehlinger
By  Katie Micik Dehlinger , Farm Business Editor
Test weight is likely to be a determining factor of this year's yield potential. USDA weighs corn as part of its yield methodology (above), but most satellite-driven models rely on plants' vegetative health for clues on kernel fill. (DTN File Photo)

Combines are beginning to roll in pockets of the Corn Belt, but whether harvest is ready to start in earnest is another thing entirely. Most of the nation's corn is still racing to make it to black layer before it freezes.

But if there's one thing this hot and steamy week in middle Tennessee has made clear to me: Mild weather is giving this crop a chance to make it to the finish line. That, in turn, is being reflected in satellite-data yield models as well as production forecasts from the USDA.

"Yield prospects are looking better, but whether we're able to get all the benefit of that is going to depend on how things get through the balance of the season," DTN Senior Ag Meteorologist Bryce Anderson said during a recent webinar on pre-harvest yield expectations. "If there's any question about corn or soybeans' ability to finish, to make it through the season without any real cold weather incident, I think it's probably in the soybean scenario."

For the week ending Sept. 8, only 11% of the corn crop was mature, compared to 33% last year and the five-year average of 24%. But on soybeans, USDA said 92% of are setting pods. At this time last year, 31% had already dropped their leaves.

Anderson said the long-range forecasts offer some encouraging news for yield potential. For the rest of September, expect above average temperatures. A wetter pattern looks likely to set in during October while temperatures remain on the high side of normal.

"Warm temps in October should help crops reach or get close to maturity before the first freeze," Anderson said, but a rainy weather pattern is likely to delay and/or prolong the harvest season. Field conditions should improve in November as the pattern dries out and mild temperatures linger.

If you'd like to learn more about the long-range forecast and the differences by region, please watch "Pre-Harvest Yield Expectations," here https://www.dtn.com/….

The beneficial turn in weather was reflected in yield models from Gro Intelligence, which partnered with DTN on the webinar and the DTN/Progressive Farmer 2019 Digital Yield Tour, which was conducted during the week of Aug. 12, 2019.

On Monday, Gro's models called for a 170-bushel-per-acre yield on corn and 47-bpa yield on soybeans. The models update everyday as new weather, precipitation, vegetative health and other data become available. The most recent yield forecasts are higher than they were in mid-August, when DTN dug into Gro's Data for the Digital Yield Tour. You can find more about the tour and its results here: https://spotlights.dtnpf.com/…

Gro Intelligence senior vice president for financial services Steve Mathews said the move reflects the weather pattern's shift to more favorable, or at least not negative, conditions.

While Gro's yield estimate went up, USDA's came down, albeit not by as much as the market expected. USDA estimated the national average corn yield at 168.2 bpa, down from 1.3 bushels from last month but still above the 166.7 bpa pre-report estimate.

Over the past few years, Gro's final corn yield estimate has ended up quite close to USDA's final estimate, with the primary difference being that Gro releases its number in November while USDA waits until January.

The outstanding question about this year's corn crop is test weight, particularly if it does freeze before the crop reaches maturity. Earlier this week, DTN Staff Reporter Emily Unglesbee explained the relationship between fall cold snaps, plant health and dry matter in her article, "Freeze Facts: What Happens When Corn and Soybeans Get Hit With a Freeze?"

So much of the outcome depends on a how close the plant is to black layer and the severity of the frost or freeze event. For instance, light frost can drop yields by 35% if it hits at soft dough, by 27% at full dent, and by 6% if it occurs at the half-milk-line stage -- about two to three weeks before black, Unglesbee reported. That's a significant difference.

You can find her full article here: https://www.dtnpf.com/….

Gro's model doesn't directly account for test weight, instead relying on vegetative health readings to indicate if the plant has the potential to continue adding yield.

While forecasts are more favorable, especially for corn, there's a long way to go until the crop is in the bin, and anything could happen, especially with the kind of year it's been. Yield models are just one more thing 2019 is putting to the test.

Katie Dehlinger can be reached at Katie.dehlinger@dtn.com

Follow her on Twitter @KatieD_DTN



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