I don't need to know what else is in the mix , it doesn't matter.
I've already touched a bit on why.
If you want good compost you need to make it yourself and really manage it ...
It isn't feasible to do for the amount of soil you throw at a full term plant.
Some of mine are in five yards. So I turn to an outfit like worm soil factory for green waste compost blended with worm castings ...but the base is really peat moss , perlite, and lava rock...
Some compost outfits start with mill waste too and call it "forest humus" which is laughable ...
Compost can be a good way to deliver biology and other positive attributes , like increasing water retention...but it can kill you just as easily,
I was wondering when someone would say this, just make your own damn compost and soil, know your inputs and build it to spec. Buy a mighty mike turner and never look back.
We do 4 yard batches of compost per pile which makes 24 or 25 yards of soil depending on strength desired. Two people can shovel turn a pile in 15 minutes, once a day for 15 days before its cooled.
Even if you use a lot of soil you could make it yourself, I know its very doable for two skinny dudes to make and turn by shovel 100 -200 yards of soil in two months(15-20minutes per day).
A big help is some sort of mixer for the initial mix of ingredient.