That’s interesting. I wonder if in a container culture like Earthbox, since one cannot pull minerals from the subsoil if an ideal soil is more important? Most potting soils are not ideal in mineral ratio, but most have adequate minerals for crop removal. Also, sap tests are not economically justified in this particular culture of a couple of growing containers on the patio. Soil tests every year are not economically justified either. Yet it’s probably the quickest way for a family to produce food with the highest level of nutrients on the pyramid! On a side note, the quickest way to increase cec in a container is to add zeolite available at farm stores as Sweet PDZ horse stall refresher. In conclusion, can biologicals when they die, supply minerals/nutrients not in the air and not in the soil?