I found a number of takeaways in Dr Inghams work.
The synergistic action of the soil micro-organisms with the plant roots was one. For the soil to work it has to have roots in it, so cover crops work better than mulch.
It's the diversity of the micro-organisms that make it work. The bacteria content hits a ceiling, then boosting fungi (up to 75%) gives more improvement. But you still need the higher organisms, nematodes and arthropods. It's a dynamic process that is constantly adapting. So, there's no magic inoculant that is going to work for everyone, every time. The best you can do is introduce as broad a spectrum of micro-organisms as you can, and hope you are supplying what's needed, when it's needed. It seems to me that reinoculating periodically might help in case something died out because the necessary habitat for it hadn't yet developed.
Not tilling or disturbing the soil while it is developing it's diversity is important.
A biggie, that doesn't seem to get mentioned in the discussion of "tea's" is that anaerobic is bad. At
there's a guy collecting soil micro-organisms, and it looks like a pretty good technique. But then, he soaks it in water/nutriment for a month which is going to make it go anaerobic and defeat his whole purpose. I think that he could do an active aeration extraction, or just mix the rice into his topsoil, and be way better off.
I haven't heard Dr Ingham address biochar. It seems like it would be beneficial but there is some controversy about it. It's something I want to get into, but I haven't yet. Does anyone have a DIY on building the Kon-Tiki?
There's lots more that could be said on any of these subjects (and many more), but while you focus on any one of them it's important to remember that they all work in a synergistic way. If you change any part of a system you change the whole system. Even something that gives you a big boost isn't good if it throws a healthy system out of balance.