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It's hard to tell how much corn will yield until it's in the combine hopper.

Tom Bechman 1, Editor, Indiana Prairie Farm

November 23, 2014

2 Min Read

Yield estimates in corn are a big talking point before harvest. This year there is still interest after harvest. How close were the estimates? What caused one hybrid with the same or more kernels per ear to yield less than another hybrid?

One thing that has changed when it comes to yield estimates is the factor to use that relates to number of kernels per bushel. The standard for years was 90,000 kernels per bushel, and the division factor in the formula was 90.

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Bob Nielsen, Purdue University Extension corn specialist, told farmers this fall just before harvest began that with today's hybrids, 80,000 kernels per bushel and 80 are probably more accurate numbers. If grain fill was good and the kernels are deep and full, you might be able to drop it to 75 or even 70. The formula in the Purdue University Corn & Soybean Field Guide used 90 as the factor for years, but now uses 80.

Rumbling in the seed industry indicates some seed companies may be taking a closer look at this as well. Their interest is whether there is a difference amongst the products they sell in kernels per bushel that could make a difference in yield estimates.

Recently, I walked a small field planted with two hybrids form one company. One was somewhat earlier than the other hybrid. Hybrid A consistently had 14 rows around the cob, about 38 kernels per row. Hybrid B had 16 to 18 rows around, 40 kernels per row. Stand counts for both at harvest, counting only stalks with ears, were around 29,000 plants per acre.

The formula for hybrid A: 14 times 38= 532 x 29= 15,428. Divide by 80 and its 193. Divide by 90 and its 172. At 75, it's 206, and at 70 its 220.4.

The formula for hybrid B: 17 times 40 =680 x 29 =19,720. Yields at 80, 90, 75 and 70, respectively, would be: 247, 219, 263 and 282.

Related: Yield Monitors Might Be Smarter Than You Think

Before running the numbers, just walking the plots doing population counts just before harvest, I was very confident Hybrid B was 20 bushels per acre better, and fairly confident it could be 30 to 40 bushels per acre better. The numbers seemed to back me up.

Was I right? Tune in to our lead item tomorrow and find out!

About the Author(s)

Tom Bechman 1

Editor, Indiana Prairie Farm

Tom Bechman is an important cog in the Farm Progress machinery. In addition to serving as editor of Indiana Prairie Farmer, Tom is nationally known for his coverage of Midwest agronomy, conservation, no-till farming, farm management, farm safety, high-tech farming and personal property tax relief. His byline appears monthly in many of the 18 state and regional farm magazines published by Farm Progress.

"I consider it my responsibility and opportunity as a farm magazine editor to supply useful information that will help today's farm families survive and thrive," the veteran editor says.

Tom graduated from Whiteland (Ind.) High School, earned his B.S. in animal science and agricultural education from Purdue University in 1975 and an M.S. in dairy nutrition two years later. He first joined the magazine as a field editor in 1981 after four years as a vocational agriculture teacher.

Tom enjoys interacting with farm families, university specialists and industry leaders, gathering and sifting through loads of information available in agriculture today. "Whenever I find a new idea or a new thought that could either improve someone's life or their income, I consider it a personal challenge to discover how to present it in the most useful form, " he says.

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