well soil growstyle is based upon beneficial micro-organisms that break down your biological nutrients to absorbable,chemicly available nutrients
for example : you take 100% sterilised coco and add bionutes like algae based or wormcastings and more like that ... without adding Mycorrhizae the nutrients will not be absorbable by the plant cause its locked in a more complex biological form, so without bacteria in a sterile subtrate like coco youll get a dead plant as soon as its reserves are depleted... now the bacteria they predigest these organic nutes and breaks them down in more chemically absorbable nutrients and infact trades with the plant roots these nutrients for a small amount of sugars and starches from the root in a symbiotic relationship ..; thats why ppl tend to reffer to their mix as "living soil"