The Sharp Edge: Kernel weight, not test weight, key to understanding corn yield


Throughout corn harvest, much attention is paid to test weight as the crop works through the combine, into the bin, and off to market.

But does test weight really matter? On this episode of The Sharp Edge, Maizex Seeds agronomist Greg Stewart explains why he believes growers would be better rewarded if they focused on their crop’s kernel weight rather than the test weight.

As Stewart notes, test weight is not a yield indicator, it is really a volumetric measure indicating how corn kernels fit together and matters most in areas like transportation where trucks can more efficiently haul more bushels of high test weight corn compared to low test weight corn.

Kernel weight, however, is the true measure of yield. Stewart points out that the components of corn yield include, ear count, number of kernels and kernel weight. Big test weight does not add yield but the difference between 51 pound and 55 pound kernel weight can move a crop from 222 bu/ac to 265 bu/ac, says Stewart.

“When it comes to yield, test weight isn’t even part of the discussion,” says Stewart. “At harvest, everybody is measuring test weight but we really need good thousand kernel weight measurement to learn about how hybrids performed during the year,” says Stewart. (Story continues after the video.)

In the video, Stewart and RealAgriculture agronomist Peter Johnson demonstrate how hybrid genetics impact kernel weight. In many cases, hybrids will produce larger and heavier kernels than others hybrids, but the trade-off is fewer kernels.  Stewart also discusses how knowing kernel weight can play a key role in understanding the impact disease has on a crop as well as the effectiveness of fungicide in protecting yield.

Click here for more episodes of The Sharp Edge.

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