Food for thought -
https://www.gardenmyths.com/humus-does-not-exist-says-new-study/#more-3384
excerpt -
"Humus Does Not Exist!
A very interesting paper was published in Nature, December 2015, by Johannes Lehmann & Markus Kleber, called “The Contentious Nature of Soil Organic Matter”, ref 1. For those not familiar with the magazine Nature, it is one of the top scientific magazines that tends to publish the creme-DE-la-creme of new discoveries. It is extremely well respected.
I’ll explain the details below, but what this paper says is that we have been looking at humus the wrong way for 200 years. Humus does not exist in the soil. Humus is created during the pH 13 extraction process. The strong alkali creates humus.
There is organic matter in the soil. When it is treated with a pH 13 solution, it goes through a process which creates the large humus molecules."