Test Weight

What weighs more, a pound of feathers or a pound of bricks? 

That’s the analogy I use when asked about test weight. During this week’s agronomy newsletter discussion, someone noted that everyone seems to have their own opinion on test weight. But here’s the reality: we drive trucks across scales, not into precisely measured volumetric boxes. We convert pounds into bushels. And ultimately, the weight we haul off the field is what truly matters.

That said, in most cases we desire a denser kernel if possible. Typically, denser kernels endure grain handling better and thus avoid the “fines” we may get in bins. A denser kernel also stores in a smaller area. Let’s refer back to the article title. A pound of bricks will fit easily into a shoe box while a pound of feathers may not. 

What determines test weight? Kernel size and kernel density determine test weight. When I think about test weight, I envision popcorn smaller kernels and more orange or very dark yellow color. Big fluffy light-yellow kernels typically don’t have a lot of kernel density. The challenge while looking at corn preharvest can be estimating just how heavy each kernel is and how many it will take to make a pound. This is the reason we use the conversion of 90, 100 or 110 sometimes in our yield calculations. Test weight represents a significant aspect of corn characteristics, particularly in relation to grain handling and storage. The more important trait is pounds across the scale at #2 yellow dent grades.