Just reading my copy of the Jan 2019 issue of Successful Farming magazine.  There is an article in it on soil microbes. It is focused on research being done by David C Johnson at New Mexico State University.  I can't find a link to the article or else I would post it.

One thing I picked up in this article.  Dr. Johnson found a tremendous amount of fungi under compost piles that were not turned.  He is saying when compost piles are turned, it limits the production of fungi, and these fungi are important in helping roots to pick up nutrients.  Interesting.