With super soil it needs to biologically active, the more active the better. After checking the pH and figuring out the problem, I would make a mixture of worm castings, some form of calcium, and a form of nitrogen.
For the casting I would use enough to make about a 1-2" layer, for calcium I would suggest either >>PULVERIZED<< dolomite lime or oyster flour, and nitrogen can be a plethora of things but an alfalfa and kelp mix would be ideal/easy.
This would help with microbe population, provide calcium while buffering pH, and give some essential elements/nutrients for growth.