Corn Yield and Test Weight May Not Be So Related

Corn Yield and Test Weight May Not Be So Related

Corn Illustrated: There's little correlation between corn yield and test weight in most cases.

Test weight remains the mystical factor in all of corn production. Does it matter? What affects it? And most important of all, is it tied to yield potential?

Dave Nanda, consultant for Seed Consultants, Inc. has studied results from test plots for nearly 50 years. He began his career as a corn breeder in the early 1960s.

"There is no correlation between yield and test weight," he says. "Highest yielding hybrids may have low test weight, and low yielding hybrids may have high test weight."

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Good test weight: Poor late-season conditions affected yield in 2013, but didn't appear to affect test weight, at least in some fields, Dave Nanda says.

Nanda says the goal of corn breeders is to select high yielding hybrids that also have high test weights. It's possible because genetics plays a strong role in determining test weight. However, it doesn't always turn out that yield and test weight match up, he notes.

One year ago, Seed Consultants' SCS 1131, a hybrid in the Crop Watch '13 field, produced 207 bushels per acre, even after ending the season in dry conditions and running short of nitrogen. There was die-back on the tips of almost all ears, but the yield was still good. Without tip dieback obviously it would have been much better.

His point is that the conditions that put a lid on yield apparently didn't affect test weight. Corn from that field averaged 60 pounds per bushel for test weight. Under favorable conditions, that hybrid is noted as one with high yield potential and consistent performance, Nanda says. It also has high grain quality compared to many other hybrids on the market.

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This year many fields ran out of nitrogen very late in the season. Diseases also caused many fields to shut down. It will be interesting to see if hybrids in these fields were affected in yield as much as some might think. Watch for more news on that soon.

Note: A previous version of this story indicated corn from the Crop Watch 2013 field made 50 pounds per bushel test weight. The correct figure is 60 pounds per bushel.


For more corn news, corn crop scouting information and corn diseases to watch for, follow Tom Bechman's column, Corn Illustrated Weekly, published every Tuesday.


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