For my work, I spent roughly a year studying the mechanism of roots, on and off. The different routes for nutrient and water uptake, transport, the different types of fungus, the differing ways plants interact with those fungi. And, of course, this is without going into the nematodes and how the plant attracts specific species by emitting tailored carbohydrate packets to both attract the nematodes and feed fungal growth right at the root surface. The very last piece is the ions put out by the roots to electrically attract specific elements, like potassium, nitrogen etc.

It takes hardly any artificial fertiliser (10g per sq meter) to eliminate beneficial fungus from the soil, at which point you are basically running an open air hydro system and have to artificially add nutrients and adjust pH. It takes upwards of 3-5 years to start getting proper results from organic farming methods when switching back and basically involves adding years of organic material to kickstart the organic cycle.

It is totally possible to get comparable results to fertiliser based farming when farming organically, you just need to focus on 'growing' the soil, not just providing nutrient to the plants. In my opinion the former is farming, the latter is hydroponic production. Both have their benefits, it's just that one leaves behind barren soil and the other enriches the soil and is part of a natural cycle that leaves the soil exceptionally fertile.

The RHS (Royal Horticultural Society) sells little packets of mycorrhizal powder that you can put into your garden if you feel it is lacking beneficial fungi. Another more natural route is to bury a kilo of cooked white rice near a very healthy tree, where the soil is soft and 'healthy' then retrieve it after a week. It will be mouldy, but with the right type of mould. Mix that into compost, grow tomatoes in that compost, then when they are finished, chop up their roots, mix it into the compost again, add fresh compost from your compost bin to make seed compost. Mix that seed compost into whatever you want to 'infect'. Some people grow just the fungus using sprouted barley and add the mouldy sprouted barley to their compost.