~6 years ago after decades of crop mining it tested very very low on K. I did two years of a rye and sorghum sudan rotation with an estimated replacement rate plus a little K and then put it to grass. I've been putting on a healthy replacement rate with 40-50 extra lbs of K since then. I don't know where it is now, but two years ago it had moved up to testing at the high end of low. A grass nerd stopped by this summer to look at it during second growth and said even though the yields are acceptable I was probably still below the K levels required to grow a healthy high production plant. That's when he suggested I also really needed to start breaking fungal cycle with late winter cuts.  

The grass under that roan cow is one of the new extra special fescues on low K soil. It's about a mile from the brome/orchard field and was under the same management for the previous 40 years. I never had it tested, but it didn't even really turn green for the first three years while getting a little N until I threw a bunch of money in K at it. I honestly think it's just a terrible variety though because I also have it on some good fertile dirt and it still sucks.