
Bryant said "In the world of Soil Science we have defined soil as dirt that contains and nourishes the many microorganisms that live in soil, this includes fungi, bacteria, amoeba, nematodes, and so on.
These soil organisms create a nutrient circle of life, that is there are mineral eaters and then a line of predators.
The way we measure the components is both chemical (Gas Chromatograph or liquid chromatography or mass spectrometry are the best methods) and through microscopic examination and counting of the organisms of the microbiome.