https://thenutrientcompany.com/blogs/horticulture/npk-value-of-everything-organic-database
I’ve got the Attra organic potting mix pdf here; https://permasteader.com/cloud/index.php/s/FWMeE2tz2LGf6Zf
Has recipes for seed starting and potting soil mixes. Some are for making a mix way better than anything you can buy but may not save you money. Some are special purpose like soil block mixes and some are pretty basic with less than 6 ingredients. They mention how the old timers used leaf mold in lieu of peat moss before peat moss was a thing. Takes 6 months to a year to make leaf mold so start now for next year or start this Fall when you rake the lawn and use it two Springs later.
Bone meal for phosphorus can be made. https://duckduckgo.com/?q=How+to+Make+Bone+Meal
For Potassium
Ground charred corncobs are 0, 0. 2
Comfrey is 1.8, 0.5, 5.3
Any kind of ash is super high and fast acting and will also raise the soil pH. Doesn’t last a long time. Various rock and granite dust are high in K and very slow acting.
Nitrogen from manure and many other things. Coffee/tea grounds. Fish.
As I clear land here, I burn off the leaves and then scrape the remaining leaf mold/humus to the garden area and till it in a little. Best potatoes ever on those years. Baseball sized Yukon Gold and cleaner and more uniform in shape than anything from the store. Everything else did good those years and it made the clayey loam into loam for two years. Also made grass some up faster where I had scraped. I had noticed where I had dragged brush and it scraped leaves, leaf mold and humus off and left bare soil, I had grass come up quick so that’s when I decided to scrape the rest off with the riding mower with a grader blade.
If you’ve got the land and the tools and the smarts and the strong back, there’s plenty all around us in Nature to use to our advantage.
Why, it’s almost as if it were ‘designed’ that way! Go figger! ;)