Understanding Corn Test Weight

Mike Rankin, Crops and Soils Agent, UW Extension-Fond du Lac Co.

Corn test weight (TW) is an often discussed topic of conversation among corn growers. The topic moves to the forefront in years when corn has been stressed at some point during the grain filling period or when the growing season is ended by frost before physiological maturity is reached. In many cases, the concept of test weight is misunderstood. Test weight is volumetric measurement. An official bushel measures 1.244 cubic feet. To measure TW, we usually take the weight of some smaller unit of measure and make a conversion. The official minimum allowable TW for U.S. No. 1 yellow corn is 56 lbs. per bushel, while No. 2 corn is 54 lbs. per bushel. It's unknown how this all started hundreds of years ago, but perhaps it was easier and more fair to sell things based on volume (length x width x height), something a person could see, instead of weight. Today, of course, corn is sold by weight and often in 56-pound blocks that we, for some reason, still call a bushel. Because weight is contingent on moisture content, grain buyers base their price on a "standard" moisture of (usually) 15 or 15.5 percent.

*To Continue Reading this Article Click Here*