Funny you should say that pal, I looking into making,brewing some nutes ,soil additives with microorganisms , there's some amazing organic products finding thier way on market which have at there heart specific mycorrhiza and bacteria , now it's extremely hard to produce these your self but if you take the product and ferment them in let's say molasses as the food source you should end up with a solution that can be used to add to the soil as feed
I just starting off at this , but will once ime happy with results share ,
oh once you have done it ,it's just a matter of saving some mixture as a starter , bit like yeast for baking sour dough and use it again to produce a new batch