Soil

is there no dirt in your yard even if its mostly sand or clay any place where weeds or grass grows or thats not a pure sandbox i ask cause IMO4 is about using your native dirt to teach the microbes to live in it to acclimate them even if its poor dirt u r adding what it needs for it to go from dead dirt to living soil so that when u add it to your yard or gardens its got a head start on living in that environment and transforming the poor dirt into amazing soil if your yard is a pure sandbox wherever u r collecting IMOs maybe u could grab a few buckets of dirt and make your IMO4 out of that to add to whatever above ground beds u r using ....and if nothing else works and u just have to buy bags of dirt id say get the cheap top soil but this is not recommended and would be a last resort plan Z type thing any kind of native dirt would be better   remember that about 50% of IMO4 is IMO3 so u r adding organic matter and microbes to dirt to make acclimated soil