The basic idea we are chasing is that, left to their own devices, plants and soil critters really work helluva well together. Plants create sugars through photosynthesis, and share it with the soil critters. In return, the soil critters supply nutrient harvesting and storage services to the plant. For example, they unlock bound up Phosphorus and store Nitrogen harvested from the atmosphere.
Farmers can foster this natural exchange of services or buy substitute services from the fertiliser companies such as bagged Nitrogen and soluble Phosphorus.
It has long been known that the physical structure of the soil is crucially affected by a chemical balance between calcium and magnesium. Tightly bound soil with few air passages can be loosened up by adding calcium, helping them retain moisture and providing habitat for soil critters. There is a lot more to soil mineralisation than the Ca:Mg balance, but its an important starting point.
There is an analog to this in soil biology: the balance between bacteria and fungi. When soil building is just starting (eg from rock) bacteria dominate and fungi are largely absent. Eons later, under mature forests the reverse is true. Every time we cultivate, we slice and dice the soil critters which sets back the fungal elements. The balance can be restored using fungal-promoting additives like fish oil and humates.
When a soil is well mineralised and in biological balance, there is an absolute hive of activity going on down there, all working symbiotically with the plants. The soil becomes more sponge-like, and drought-resistant. Carbon is being sequestered and humus being built. It is also warmer: farmers in snowy regions notice that the snow melts far quicker in places with good biology. That's partly because of heat generated by all the worm sex going on.
Several of the farmers we met had never been exposed to these ideas before and were pretty excited about the prospects. We all came away re-energised and keen to try out some new practices in an effort to get these worm orgies happening.