Near Intersection of I-35 & I-90 Southern Mn. | I believe your conclusion is pretty well accepted fact. Here is my theory as to why this happens. It boils down to the confusion of talking about TEST WEIGHT and TOTAL WEIGHT.
Using your example, the kernels in the 500 bushel batch dried with just air (dried more slowly) will shrink in size more than the kernels in the 500 bushel batch dried with heat.
If both batches were the dried to the same level, the resulting weight (converted to bushels) would be the same in either case. So from that standpoint there is no difference between the two batches. In either case you had 500 bushels wet which will result in two batches of the same weight when dry. If only the moisture is removed, the weight reduction must be the same in both batches. So the resulting TOTAL WEIGHT should be the same.
So why does the batch dried slowly have better test weight? Test Weight is really a measurement of density (how much do the kernels weigh when the container if filled).
When the test weight container is filled with the slow dried corn which has had more time to shrink, more kernels will fit into the container. Since more kernels will fit in the container the weight will be greater resulting in a higher test weight value.
I maintain in your example that in comparing the two batches the TOTAL WEIGHT before drying and after drying will be the same. The TEST WEIGHT before drying and after drying will be different.
My Dad always used to say: "We'll pick up some test weight after we run it through the dryer". This always puzzled me as I knew we were removing weight with the reduction in moisture. How could the weight improve? The TEST WEIGHT increased but the TOTAL WEIGHT decreased.
A Gravity box of the dry corn weighed more than the same Gravity box of Wet corn. Why? Once again there were more kernels in the dry load although each kernel actually weighed less than it did before drying.
Everybody (including me) seems to love high test weight. But if the test weight is acceptable (no penalties) what is the difference from a selling point? We sell TOTAL WEIGHT (not volume even though we call it bushels). We are penalized for low test weight but not rewarded for high test weight. Of course you can get more on your truck and more in your bins when the test weight is higher.
I know of a party that checks all their corn varieties for Test Weight and uses that as the major determining factor in variety selection for another year. I maintain that I am interested in Total Weight (as long as the Test Weight is acceptable) rather than Test Weight. I fully agree that very low test weight indicates a bad situation but that abnormally high Test Weight does not necessarily result in more money although it makes you feel good. |
Does test weight change if drying by air only vs. heat?
