I was using Servi-tech back then, and they used the Mehlich-3 Phos test. Like I said above, I had single digit P tests come back. I didn't have much for covers back then either, just minimum tillage and COC. My Dad has ground that only gets N and S, it'll kick out 60 bpa beans and 200 bpa corn if it gets the moisture. It tests low teens Bray P-1. The soil tests are terrible in many ways, but it's been no-till with occasional covers for most of this century and it's pretty good yields. This year his beans were about the second highest yield across our entire operation and that's just a really tough pill to swallow when I've been trying to get him to fertilizer more for years.

On the other hand, I've been to conferences where a speaker from Indiana (don't remember the guy's name) said he hasn't applied any phosphorus in 20 years and has soil tests in the upper twenties. He does extensive cover crops.

We don't have low K test soils here, so I have no real experience with that. Potash application of any kind is pretty rare here. I do know that soybeans love banded MAP as well as corn. I did more broadcast attempts to build soils during the high income years because I thought that was a good way to spend money then. Our dry banding machine is pretty slow and labor intensive. So it doesn't get run over very many acres per year. I'd absolutely love an AgSynergy Genesis TRX toolbar with a Montag cart behind it, but that isn't going to happen anytime soon. I don't think I'd ever broadcast MAP again if we had that setup.

And, again, the situation I'm talking about requires yearly applications fertilizer. If you keep all the microbes a little hungry all the time, then it's harder for the young soybean seedlings to establish themselves. Give them a rich band to start off and get the factory built, then they can buy what they need. They're just under capitalized at first.

Maybe I should have started by saying that banding sub-removal phosphorus rates isn't necessarily going to deplete crop-available phosphorus. (in the human lifetime) Whether or not that happens depends on the soil biology.  Without a good soil biology, it can happen pretty fast.