When you say the potash was way different, .....  was the soil analysis different? or just the fertilizer recommendations?     When I say "soil analysis", I mean there should be a K-ppm reading on the soil test, or something similar.  Were these numbers very different?  or were these numbers somewhat close, and just the recommendations different?

It does not surprise me that the recommendations are different. 

I would hope the analysis numbers are much closer.

You didn't comment on the phosphorus numbers.  Were the soil phosphorus analysis numbers close? or were they different?