It’s necessary in order for nutrients to be broken down and made available for uptake, but with the soil you are making, you’re already growing your own.
I use Promix as my base for new plants and it’s mainly just peat moss. I add dry organic nutrients (Roots Organics) for the plant but I also need the microbes to make those nutrients available to my roots. Humic acid is also the soil conditioner that aids in that process. peace