Near Intersection of I-35 & I-90 Southern Mn. | If a yield monitoring system actually measures volume rather than mass (weight) doesn't the Test Weight factor come into play?
We claim to sell "Bushels" of corn and soybeans but in fact we are selling Mass or weight. Never once has an elevator used bushel baskets to measure my loads. They always use a scale to measure the Mass and then divide by the standard factors of 56 or 60.
My point is if 100 bushels of low test weight grain pass through a purely volume based system we would expect the monitor to register 100 bushels. If 100 bushels of high test weight grain were to pass through this same system we would expect the monitor to also register 100 bushels. Take these two 100 bushels batches to an elevator, they will weigh them and calculate the bushels from the scale. The low test weight batch will most certainly result in less bushels than the high test weight batch.
This leads me to believe from a pure standpoint, the mass based systems are self compensating to a point considering test weight. If light test weight grain is being harvested it will impact the sensor with less force than an equal volume of high test weight grain.
But what determines the amount of force with which the grain hits the impact plate? We wish it were only dependent upon the Mass of the grain itself. An old physics formula is Force = Mass x Accleration. So the force that the sensor "feels" is dependent on the Mass (what we're after) and the Acceleration created by the elevator paddles. This acceleration is not constant under varying conditions.
I believe the Ag Leader procedure of using varying flow rates (consistent within each load) for several loads is the best plan. At first thought it would seem better to use large loads to reduce round off type errors. However, it is difficult to maintain consistent flow rates for larger loads.
So do I religiously follow that procedure? I do several loads but probably not as many as I should. I tend to agree with the relative idea more than the absolute precise school of thought. |
Calibrating Ag Leader yield monitors
