King Kutter Spreader Application Rates

[MNBobcat]

I have a 3-point King Kutter spreader that I used for the first time yesterday. I checked the tractor speed with a GPS and used the application rate chart on the spreader to determine the setting. It ended up being off by probably 80% Instead of spreading once on the field I had to go over it about 6 times because apparently I wasn't putting the fertilizer/lime on heavy enough. That sucked.

I got to thinking....using this analogy.....you could have a 5 gallon bucket of material where a full bucket weight 5 pounds or a full bucket weighs 15 pounds. Based on that concept, it seems to me that you can't use just the tractor speed and the gate setting on the spreader to determine application rate. There has to be another value in the calculation to determine where to set the spreader where you make 1 pass on the field and apply all of the material at the proper application rate. The "volume" of the material has to come into play because weight and volume together come into play, don't they?

Am I missing something?

 

[LouNY]

There are several adjustments on that type of spreader.
The chart has several different application rates for different materials.
Are both of your shutters opening the same, are the vanes set for the proper distribution, is the spreader being carried level when spreading.
Usually after making one pass on a field then refilling (weighing or counting the number of bags) the hopper to the same amount as you started with will let you calculate the actual application rate.