Near Intersection of I-35 & I-90 Southern Mn. | With the Ag Leader system, the Test Weight should not be much of a problem unless it varies greatly.
At first it would seem that a variation in test weight would cause problems. Everybody knows that a full truckload of corn will weigh less with poor test weight corn than with good test weight corn.
This whole area of confusion relates back to history and how grain was first measured. Grain was measured in terms of volume (bushels) and relates to the old bushel basket. Later in history scales were used since measuring a large quantity of grain with bushel baskets was impractical.
It didn't take too long for folks to realize that a bushel basket of oats was lighter than a bushel basket of corn. Thus the standardized bushel weights were created. Apparently it was observed that a bushel basket full of good quality corn weighed about 56 pounds. Thus the standard of 56 pounds was asssociated with corn. So when you sell corn at the local elevator you are really selling weight or mass but it is converted to volume or bushels for the paperwork.
When you sell the corn, the test weight doesn't really "hurt" you unless is is unacceptably low and you are discounted. It is the total weight that you are really concerned with.
With a force impact system such as Ag Leader's, the system is actually measuring the force that it experiences as the grain is "thrown" against the impact plate. This means that the test weight variation is inherently built in to the system.
Think about it this way - If 1000 kernels of good test weight corn hit the impact plate in a certain amount of time a force would be produced, measured and recorded. If 1000 kernels of poorer test weight corn hit the impact plate in the same amount of time, a lesser force would be produced, measured and recorded. Thus the yield which is based on this observed force would be less in the second situation. The yield shown on the monitor is based on a combination of factors which include the actual force observed, the flow range in which the sample was observed, area covered and then finally corrected for moisture.
It is true that these 1000 kernels may take up the same amount of "space" or volume but their weight (mass) would be different. So does a conversion need to be involved? No since the force observed by the impact plate will be less.
This brings up another old argument. Several years ago many small farmers in our area used bin dryers for their corn. As operations got larger many switched to high heat continuous flow dryers. The argument against the faster dryers was that "the test weight will be poorer".
This statement would seem to indicate that the corn lost weight which would seem to be a bad thing. I couldn't figure out why the weight should be poorer with the higher heat/faster dryers. After all the only thing removed was supposedly the moisture.
So it seemed to me that if we dried 1000 kernels of 22% corn to 15% with a slow bin dryer that these 1000 kernels would have a certain weight after drying which would be less (due to the removal of some of the moisture) then when we started. Likewise if we took these same 1000 kernels of 22% corn down to 15% with a faster dryer that they would have a certain weight after the drying process. If in fact only some moisture has been removed then the weights after drying should be the same.
I believe this is in fact the case. So why does the test weight seem to be poorer with the fast dryer? The weight of those 1000 kernels would still be the same. I believe it lies in the fact that if you dry the corn more quickly, the kernels do not shrink as much as they would if you dry it more slowly. Then when the test weight is observed more kernels of the slow dried batch will fit in the test container since the kernels have actually shrunk down more. If there are more kernels in the cup, the weight will be higher and the test weight appear better. So yes, the test weight might be poorer but the total weight would be the same. As long as the test weight is still "good enough" then the dollars received for the crop should be equivalent.
This also explains why after you dry corn slowly you may "pick up Test Weight" which sure sounds good. This is quite often true because more kernels now fit in the cup. You have lost "total weight" but gained "test weight" by the drying process.
This Test Weight discussion has purposely avoided any references to grain quality. I think most of us would agree that slow dried corn would probably be more desirable in terms of quality. |
Insight Yield Monitor
