Living soil or not there are ions in it the plant takes up. The higher the organic matter the lower amount can be as ions become tied up with humus and sequestered in microbes...but there better still be some ions. In fact part of those exudates form h2so4 which is quite good at ionizing ca.
A living soil has to conduct some electrity or it is a dead soil was my point.
Read the work by nova crop control. It is a myth to think you will ever have soil perfect enough to allow the plant to only take up exactly what it needs. What if the sun doesn't shine for a week...that can fuck up root exudates
no sun for a week 6.4 sap aint making it better either