Humic acid is supposed to boost how quickly things become available to the plants...you can get humic acid from any old decaying organic matter...so...when I add compost to my old soil, I am adding humic acid...I don't see how it can kill the microbiology..another hit in this armor...I use the GO line with other organic soil amendments, given I don't often use the Diamond black, but once or twice a year my soil will get a dose...I keep reusing the same soil I started with 3 years ago...of course it isnt recognizable as the same soil, but I am absolutely sure it is chock full of microbes...simply because if I add any nutes to my plants other than carb boosters they act like they are overfert and also because I grow a good deal of mycelia on the top of my soil...when a large plant finishes I rip out the plant and leave the roots..I add all manner of things good for plants, guanos, and compost, worm castings, worms, lime, leaves, composted manure, etc...then I let that sit til i need it...If all my soil is in rotation then I will go buy a new bag of roots organic of FFOF...most of my soil started out as FFOF, but overtime as I said it is now just a mismatched blend of awesomeness as far as me and my plants are concerned...
So, if the Diamond Black is killing my bennies, then why are my pots still growing mushrooms?