Editors' Notebook

The Answer, My Friend ...

Greg D Horstmeier
By  Greg D. Horstmeier , DTN Editor-in-Chief
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High winds affected a widening swath of farm country, according to this image created from DTN wind data. (DTN graphic)

As the DTN/Progressive Farmer Digital Yield Tour, powered by Gro Intelligence, expands each year, we're increasingly wowed by the power of modern yield modeling systems.

That power, and the partnership between DTN and Gro, was on full display early this week as we began to assess the path of the infamous derecho that struck corn country from Iowa to Ohio. That this horrible weather event hit right in the middle of our Digital Yield Tour gave us a lot to react to: First, we counted our blessings that this is a digital/virtual "tour" and we didn't have human yield scouts checking fields in the derecho's path; second, we were uniquely poised to focus on what this windstorm may mean to crop production at a very timely period.

DTN weather experts Nick Lesser and John Baranick jumped in within hours and created a wind path map, focusing on the areas of damaging winds shown by DTN weather data. That information was handed off to the Gro team of Kelly Goughary, Jacques Paye and Steve Bernardi, who layered it over that company's historical crop production data to create a detailed, accurate picture of what the derecho might mean to farmers' yields and to the markets.

That data layering revealed some 18.2 million acres of corn and 15.5 million acres of soybeans were in the path of winds above 60 miles per hour. As we note in Wednesday's Yield Tour article, Gro estimates some 1.47 billion bushels (bb) of corn and 359 million bushels (mb) of soybean production are at risk in Iowa alone.

Gro also examined the five worst-affected counties in the three "I" states, based on average wind speed those areas suffered. That list really begins to bring a storm like this home, several ways. For someone fortunate as myself to have traveled through most of the Corn Belt during my career, it immediately brings up faces of farmers I know in those counties and visions of the land they farm.

It's also an interesting note that these are just five of the worst-hit counties. We all know that derecho damage was far wider than that, and at some point, picking "the worst five" is simply an exercise in drawing a line somewhere. In Iowa, for example, the fifth-worst-hit county, Hardin, had average wind speeds of 77 mph, while the next grouping had winds only slightly less.

In Iowa, wind data showed worst-hit counties were Marshall, Linn, Jasper, Tama and Hardin. According to the latest USDA acreage numbers, they account for 851,000 acres of corn and 429,100 acres of soybean. Production expectations, based on Gro modeling the day before the storm, are about 160 million bushels of corn and 33 million bushels of beans.

Illinois counties were Lee, LaSalle, Vermilion, Rock Island and Will. They had an estimated 823,600 acres of corn and 505,200 acres of soybean, with expected production of 162 million bushels and 44 million bushels respectively for those crops.

In Indiana, the top five counties by wind were Howard, Newton, Allen, Fountain and Carroll. Acres for that area is estimated at 381,700 for corn, 404,300 for beans, with pre-storm production estimates of around 73 million bushels of corn and 23 million bushels of beans.

Now we all wait, from the farmer looking at flattened fields to the satellites high above, to see how the fields respond in the coming days. Some farmers in Iowa have reported corn already springing back. There's speculation in some areas that the wind stress may spur beans to even higher production. But many more growers report snapped or severely shredded plants. As those fields wither, or recover, Gro models will begin to estimate yield reductions, and what that means to the national total.

There's been a touch of scoffing at that wait on social media, with questioners wondering why these high-tech models can't predict the yield hit quickly. For one, those models need fresh satellite imagery from the affected area, and those "bird passes" take time.

To get a feel for how much time, Gro's James Heneghan looked at a previous example of crop damage, a hail event in eastern Nebraska on June 30, 2018. He then went through Gro's Normalized Difference Vegetative Index (NDVI) data to see when that "white combine" damage began to show up in predicted yield losses. While Heneghan stressed that there isn't a lot of knowledge about how hail damage displays in satellite imagery compared to a derecho, in his example, it took until mid-August to accumulate enough NDVI imagery of the area to show significant crop differences from mean or "normal" conditions. So, we may not get the full picture of the derecho "for weeks or even a month," Heneghan said.

But even old-school yield estimation methods are strained by these unusual derecho storms, as Jesup, Iowa, farmer Ben Riensche noted in our Wednesday tour story.

"It's not a simple exercise of counting kernels and ears and coming up with a standard yield estimate like in the past," he said. "This corn was laid over. Some was broken, some was greensnapped, some was stripped -- it was a tassel, a stalk and an ear. How does that fill?" Riensche pondered aloud to our reporters.

In the end, as is often the case, this storm will be devastating at a local level but probably not have a significant impact on the record or near-record corn yields currently being predicted nationally. But examining what effects this storm did and will have, at those area levels, helps us determine that potential with more accuracy and depth than previously possible. And that's not a bunch of hot wind.

Greg D. Horstmeier can be reached at greg.horstmeier@dtn.com

Follow him on Twitter @greghorstmeier

Greg Horstmeier