I'm surprised a bit, that you're able to get 200 bushel corn yields with potassium levels that low.   In a way, it is impressive that you can do that.   Don't think I could hit 200 bushel corn with 100 PPM of potassium, and only a 1 percent base saturation of potassium.

Suggestion.... if all your other nutrients are at good levels and at balanced levels.... try applying in a few areas enough potassium to get your K up to 4% base saturation.   My calculations show that would be a need for 1200 pounds of potash.   That's a lot.  Thus, my suggestion to only try it in a few places.   Probably will have to wait a couple years to assess if that much potash proved to be profitable and able to give a sufficient ROI.   But I'm not sure you can know if you truly need a base saturation of K at 4% on your farm, without running some tests.  Try to find out for sure, one-way-or-the-other.  


gordon