Soil biology can be easily analyzed by a 400x optical microscope.
For most growing conditions, we want equal parts of fungus to bacteria by weight, which can be easily determined by looking for one strand of beneficial fungus per view at 400x magnification and we can qualitatively pronounce this soil ‘healthy’ and good for growing crops.
This video introduces you to the microscope and goes through some simple identification and analysis.
These are the slides I use for teaching basic soil principles. Creating a Healthier Soil Environment for Mac Nuts in Hawai’i PDF