C'mon man theres got to be more than one guy that uses soil here. WTF
It depends on what you have at your disposal. I have stuff here that they putt through a process that is more complex than microbrewing beer...stuffs amazing(Solid Gold). But if you dont have these you can make a good mixture and then that would matter on how much you need to make for how many plants...if these questions are answered i can help yah.
this is what i use and i mix in big blue tote
year old organic cow manure fill half full
then 2 bags of perlite
bm1 or promix to fill almost to top leaving room to mix
lime
i guess i'm lucky living in the emerald triangle i can get about anything that has to do with weed, any time.