Have you tried using commercially available bagged compost products for your compost tea? I guess I don’t see any reason why it wouldn’t work just as well as homemade compost....
My rose bonsai started going south this past season. I have it in pumice and aged pine bark (Osmocote on the top covered with a thin layer of sphagnum moss). Leaves were yellowing and it didn't want to flower. I eventually scraped the top layer off and put a layer of commercial bagged compost on (its all i had at that stage). On top of that I put a thin layer of composted wood chips.
I only gave it fish hydrolysis from there on. It recovered within a month with new leaves and started flowering. Lush green leaves that i haven't seen on it before.
I then did it with all my bonsais. Will replant everything come spring in a organic mix with my home made compost at the heart of it.
The thing about commercially made compost is you don't know how it was controlled when it was made. It might've gone dry and/or anaerobic. It might contain harmful pathogens. You don't know how long, or if, it has been aged. The aging process is critical because that's when the full spectrum of microbes populates the pile.
Then again, it might be a well made compost filled with humus and all the beneficial microbes needed.
Point is...you don't really know.
A good compost shouldn't be black. It should be dark brown and smell like a forest floor. Should be kept at the right moisture level to. If it dried out, some species might die off while others will go dormant.
I haven't made compost tea yet, although what i've learnt from research is, not all compost teas are equal. The thing about tea is it has to be done right. Assuming the compost does contain a full spectrum of microbes, its not that simple and straight forward to get them into the tea. They thoroughly attach themselves with slime (the same slime that's on your tongue and teeth) to the aggregates within the compost. To loosen them, keep them alive and get them into the tea alive and well, is another process that has to be done right. Done wrong, you'll end up with nothing but muddy water. They are very fragile creatures. The water has to be aerated and agitated just right. Sounds complicated but it really isn't. The right research has been done and is out there. When adding tea to a substrate, you're really only inoculating that substrate with the microbes. They still need a suitable habitat to survive and thrive. What they need most is organic matter and food.
I think I'll use worm castings. Since this is already fermented compost, it will not rot and attract flies. Yes, maybe the larvae is good, but when a bonsai pot becomes a breeding ground for a large number of flies and larvae is at least unpleasant (do Japanese nurseries like flies in their bonsai? Or do they have special fertilizer cakes?). Also, I feed them for free, but they don't give anything in return. Although their excrements may be of some value as fertilizer, but this is a reason for study.
Yes worm castings is an excellent way to inoculate the soil. Again, once they are in there, they need to be kept happy before they can thrive, and the tree can reap all the benefits. Best (and only way really) way to do that is to give them organic matter. They live in it and feed off it.
Again everything comes back (and starts), to the good compost. Once that is in the soil and the microbes are fed and happy, the eco system looks after itself, and can be self sustaining. The ONLY thing we need to do is give the microbes a small amount of supplementing food now and again.
I'm thinking about your larvae again. I think the solution is, to not put the soy meal onto the soil...just work it in slightly. That way the chances of something laying an egg in there is slim. Very little meal is needed to. We tend to over fertilize out of love. We always need to remember...we're feeding the microbes and they are microscopic. The food takes a longish time to break down yes, but also lasts a long time as food for the tree...up to 4 months. So a schedule of a little bit every 2 months makes sense to me.
I don't know what the Japanese has in their cakes. They've been doing organic bonsai for as long as bonsai itself exists..... They've been, where we're going