Enthusiastic corn growers look forward to this time of year every season, and especially when the season is reasonably friendly for growing corn. It’s time to estimate corn yields!

Wffels Hybrids, Geneseo, Ill., makes estimating yields easier and more precise. You can use a university formula, or you can use the Wyffels yield calculator.

Ryan Gentle, Wyffels agronomy manager for Illinois, says you don’t have to grow Wyffels hybrids to use the calculator. But if you do plant Wyffels, there is a unique option available to make estimates more precise.

“We have devoted time to studying kernel size and comparing average number of kernels per bushel for our hybrids,” he explains. “Now we’ve included an option in our calculator to choose your specific Wyffels hybrid. However, you can also select a generic number — either 80,000 or 90,000 kernels per bushel.”

The primary reason Wyffels emphasizes kernel size is because variation in number of kernels per bushel makes a huge difference in final yield, Gentle says. While weather during grain fill each season impacts final kernel size, genetic differences play a big role.

Traditionally, agronomists assumed 90,000 kernels per bushel. However, Bob Nielsen, retired Purdue Extension corn specialist, began emphasizing a few years ago that modern hybrids tend to produce bigger kernels. Many agronomists now lean toward 80,000 kernels per bushel, although individual hybrid genetics and specific weather during grain fill can skew the number.

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“Our most popular hybrid produces large, deep kernels,” Gentle explains. “Recently, that hybrid grown in a high-yield environment checked in at 59,500 kernels per bushel, which makes a big difference when estimating yields.”

Yield estimate examples

Here are a few examples using the Wyffels yield calculator. To make an estimate, you need to know the following:

Example 1. With 32,000 ears (no comma in calculator entry), 16 rows, 38 kernels per row, generic 90,000 kernels factor, and 200-to-250-bushel-per-acre environment, the estimate for dry corn is 216.2 bushels per acre.

Example 2. With all the same factors as the previous example except for a generic 80,000 kernels instead, the estimate is 243.2 bushels per acre.

Example 3. With all the same factors as the previous example except for the Wyffels 7876 RIB hybrid noted for large kernels instead of a fudge factor, the estimate is 294.8 bushels per acre.

Using the same factors but an over-250-bushel environment, the estimate becomes 327.5 bushels per acre.

Example 4. With all the same factors as Example 3 except for the Wyffels 5510 hybrid instead, the estimate is 266.5 bushels per acre.

Example 5. If you prefer the university method, here is the formula from the Purdue Corn and Soybean Field Guide. It is based on number of ears in 1/1,000 acre, or 17 feet, 5 inches in 30-inch rows. The formula is: Average number of ears × (average number of rows × average number of kernels per row) ÷ fudge factor such as 75, 80, 85 or 90 — representing 75,000; 80,000; 85,000 or 90,000 kernels per bushel.

For example: 32 ears per 1/1,000 acre × (16 rows × 38 kernels per row) ÷ 85 fudge factor = 228.9 bushels per acre.