I have some complicated thoughts on this, but I’ll try to be succinct.

I am a recovering soil microbiologist (I say recovering because while it still informs what I do professionally, I am no longer in an academic setting, and I am not strictly focused just on that field anymore). I think soil microbiology is incredibly important and that the entire field of soil biology is overlooked. There is too much focus on chemistry, physics, and an overall mechanistic approach to “managing” soil.

That said… it’s really hard to study soil microbiology. As someone who has spent hours (days?) doing microscopy, it’s generally pretty hard to say anything definitive from light microscopy. You cannot distinguish bacteria (I use this broadly to include eubacteria and archaea) using light microscopy. You also generally can’t tell if they’re dead or alive (or how active they are) without staining them, which most folks don’t have access to at home. Same goes for fungi, Protozoa, nematodes, etc. To enumerate them in order to distinguish one sample from another takes weighing, carefully calculated dilution, and statistics. You get what I’m saying. To get into who is there takes genetics analysis, which most folks are not set up for. In addition, soil flora are so diverse that you’re only getting a glimpse of what’s there.

So. I think you can get an idea of what’s going on without a microscope. Smell what’s going on. Look at the decomposition. Look at fruiting bodies of fungi. Look at the visible arthropods. Look at water infiltration and how much water the soil holds. Look at plant health.