As someone who has been large-scale gardening for over 50 years, I have been looking for the best way to build soil long term.
I currently purchase my compost from sources that build it from tree bark. If you have any lumber mills around, you will know that the first thing they do with their logs is to de-bark them so that their saws will not get dulled by the dirt on the bark. Thus, any lumber mill will accumulate mountains of tree bark.
They know that composted tree bark has a market, so you should be able to source it locally. Tree bark does not normally have any crop herbicides on it. By composting it, tree bark will not deplete nitrogen like uncomposted wood or bark mulch does.
I like it because it lasts longer in my soil than any other source of compost. Give it a try.