[farmergann]

I test and fertilize per test annually, as in 170# k.

Wouldn't Phosphorus be the more relevant indicator/deficiency in this case?

 

[farmergann]

Could be, but I typically use 65-90# p2o5

Let me preface by saying I'm an old lab tech, so I get my rocks off to different stuff than most. That said, plant available P where you want it for orchardgrass can vary tremendously independent of input. You probably already know that, but just in case you didn't, had to say it. Have you tested available P? It'd be a worthwhile excercise for me if I were economically dependent on hay production.

 

[farmergann]

I just like making good quality hay and hate buying crap at usury rates.

Same lol.

Coincidentally, I'm pan frying a quart of smashed egg shells right now to mix with 5 qts vinegar. I'd wager that 21 days from now (once the desired reactions have slowed to a crawl), that is exactly what you'd need on your field - though mixed with a lot of water... Make some home brew cal-phos like that and throw it on a mowed strip of your infested pasture late summer/early fall. $$$ says it will favor the OG next spring green up. Hell, it might even help now, depending on temps and ph (seems to me like you'd be on top of liming given your previous comments, so no worry there).

I know you've got a frustrating and unexpected problem, but that's kind of the thing I love about being where I'm at and doing what I'm doing

Good luck!