I'm 74. I've gardened for many years---in many soil and climate types. This current situation has me baffled.
This is my 5th summer at this location. I moved from Coastal Oregon with it's sand. My "garden" was 4 and 5 gallon buckets and some 4'x4' raised beds. I had a lot of wonderful help moving and was able to bring much of it with me. Everything that first summer of re-establishing the beds looked normal. The next year, plants struggled. I put it down to the damage done by a mole---air pruning with it's tunnels. It took me a month to trap it. The next year, I dug around to collapse the tunnels. Plants still struggled.
I have 4 cubic-yard compost bins. One is always being emptied, another being filled and two decomposing. I had two tiered worm farms, but the moles kept invading to eat the worms. I now have a worm box.
I have a composting toilet. 3-4 5 gallon bucket contents go into each bin. I thought the urine might be causing a salt build up---even with 40" of rain a winter.... So I quit adding it, although it hasn't caused any problems with other gardens that I know of..
There are many oak trees here and I wondered if the leaves weren't great for the bins because of tannin. The grass growing under the trees is not lush.I switched to local grass hay for my carbon source.
I don't have a car and order many things online. The cardboard goes into the bins.
I first read the Solomon book when I moved to OR many years ago, but didn't register the K info. I rented from a lady with goats and I remember she bought alfalfa from the eastern part of the state, because it was necessary for milk production---vs buying local grass hay. So, I knew about the deficiencies of the hay, but didn't consider it could impact my gardening. She also supplemented with Selenium.
I don't believe in the usefulness of soil teats; they say nothing about availability of plant nutrients. My neighbor's tomatoes don't have cat faces. So Ca is fine....
Having dealt with symphylans in the past, I've developed the practice of starting seedlings off in 4x4 pots with good soil. It hasn't been enough to produce the results you would expect after transplanting.
I've ordered some liquid fertilizer that is 5-5-1. My next experiment.