Its my understanding that minerals have to undergo enzymatic digestion before becoming useful to plants. Its a poo factor.
Seedcorn is probably the best pretty active member to address that. I certainly don't understand enough of the details to give a good answer. My understanding is that, for most nutrients, the roots release something that separates the ions from the soil so they can be transported into the plant and distributed. They have to be in a chemical condition that allows the ions to be separated. The basic minerals form compounds, often with hydrogen and oxygen, so the bonds need to be weak enough that whatever the roots release can separate those ions. The soil pH has a big effect on this too.
I don't see where there is any requirement that these minerals undergo enzymatic digestion to be in the proper form to be used. The plant roots don't care how the nutrients got into the proper form, just that they are. I'm pretty sure nature can create the right compounds without digestion, though digestion would be a process to do that. That digestion would come about by the bugs that live in compost and make it work. The nutrients in dead plants and dead animals are not in a condition to be absorbed by the roots and they need to (compost, rot, or break down, choose one) and the bugs do that. My guess is that is what they are talking about, converting dead plans and animals to usable form. But lightning can create some of those compounds out of thin air. I'm sure nature has other ways.
This thread started talking about blossom end rot. That's caused by not enough calcium getting to the fruit blossom end. That does not mean there is not enough calcium in the soil, it means there is not enough calcium getting to the fruit. High pH can tie calcium up in compounds that the plant cannot use. Adding calcium like lime can raise pH. That's good in a highly acidic soil, not good in an alkaline soil. The way the plant gets calcium to the fruit (leaves too) is it's absorbed by the roots and transported to the fruit where the moisture transpires, sort of evaporates, leaving the calcium behind. The typical reason you get blossom end rot is that the soil is so dry not enough moisture is being taken up and the end of the fruit is the end of the journey. The fruit blossom end is starved for calcium. Managing moisture in the soil is important, mulching can help. Don't forget that if you suddenly go from a dry soil to a wet soil the fruit is likely to split, especially tomatoes.
There can be other causes. Maybe you don't have enough usable calcium in the soil (a soils analysis is supposed to look at usable calcium, not total calcium). Clay soils usually have plenty of calcium available, sandy soils often don't. If the humidity is so high the water cannot transpire so it doesn't leave enough calcium behind. But usually it is dry soil.
@seedcorn , how badly did I butcher this? Please feel free to correct my mistakes.
