August 17, 2022
This time of year, coffee shop talk usually turns to how big corn yields will be. There may be fields that yield well this year despite quirky weather patterns. However, the trend likely will be toward variable yields, area to area, field to field and even within a field. That’s how Brian Saylor expects the 2022 season may shake out.
“We saw some fields near tasseling when others were still at the V8 stage earlier this summer,” says Saylor, an agronomist for Golden Harvest covering Indiana. “In fact, we even had that much variation in plant development within single fields in some areas.
“Most areas saw dry weather in June, which turned into drought in some places. Rain returned quicker in northern and eastern Indiana. Some places even logged too much rain.”
As a result, Saylor expects to see variability in how fast corn reaches maturity. He also expects variability in yield potential, even within a field. If you do yield estimates by pulling ears and counting rows of kernels and kernels per row, check more areas within a field than normal this year to get an accurate estimate.
“You may find ears with 16 rows of kernels around and 40 kernels per row, then find shorter ears elsewhere,” Saylor says. “Kernel depth will be a big factor. That will depend on weather during grain fill, which could extend well into September in many fields.”
The deeper and plumper the kernels, the smaller the fudge factor and the higher the yield, he says.
Here are three examples that illustrate what you might encounter estimating yields in a single field. In each case, harvestable ears for 1/1,000 acre were counted in 17 feet, 5 inches of row in 30-inch rows. Three ears were pulled at random within each sampling area to determine row number and kernels per row.
The standard formula for estimating yield outlined in the Purdue University Corn & Soybean Field Guide was used. The “fudge factor” represents total number of kernels per bushel. Deeper, plumper kernels result in a lower number, while slender, lighter kernels result in a higher number.
Example 1. Ears average 16 rows around with 40 kernels per row, filled to the tip. You count 34,000 ears per 1/1,000 acre. Total kernel count = 16 x 40 x 34 = 21,760 kernels. The fudge factors for lighter, average and plumper kernels are 90, 85 and 80, respectively. Yield estimates for this sampling area are 242, 256 and 272 bushels per acre.
Example 2. This spot was on a moderate slope eroded over time. Corn showed stress first here during dry weather.
Ears average 16 rows around and 34 kernels per row, with 30,000 harvestable ears. Total kernel count = 16 x 34 x 30 = 16,320. With the same fudge factors for kernel size, yield estimates are 181, 192 and 204.
Example 3. Flooding early and dry weather later resulted in a reduced stand and some barren stalks in this low-lying area. Dry weather led to more tip abortion and some blank kernels within rows of kernels.
Ears average 15.3 rows and 30 kernels per row, with 26,000 ears per acre. Total kernel count = 15.3 x 30 x 26 = 11,934. Yield estimates are 133, 140 and 149 bushels per acre.
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