Great information and links. Thanks so much. We don’t fertilize our lawn at all. Planted it 39 years ago. We run the lawn mower over the leaves and that’s the fertilizer.
If we develop a bare spot that won’t grow anything, we plant a little red clover and fescue or quick grow rye.
Our gardens get plenty of organic amendments, but not chemical. Rotation planting of certain crops helps bring up nutrients, so we try that before we add P or K.
I figured you and a lot of the folks here would find a lot of this info old news and are already doing the recommended practices. Our soil guy would probably give you a gold star since you are not losing your yard clippings and leaves, and amending the soil properly!