"Thank you, and if you'd like to expand on that thought"
I'm no biochemical expert, first off
.
However, you have to give up thinking about fertlizers as "natural" and "unnatural." That is just political crap. The ingredients your plant is after doesn't care about ferts being "natural" or "chemical" or whatever. The Nitrogen, Potassium and Phosphorous are what it's interested in. Elements are elements. There are no "brand name elements" or "natural elements."
Fertilizers based on animal products (bone meal, blood meal, etc) and ferts that come in prepared powdered water soluable forms are both perfectly valid ways to "feed" your trees.
The differences in how the two are absorbed by the plant is the key. While the basic ingredients used by the plant are the same in each, they are not "available" to the plant in the same way.
With organics, the NPK is there in very low doses, but in cake form, they are available over a longer period. Some of the ingredients require organic decay to occur before the plant can use them. I always find concern over mold and insects on fert cakes to be amusing, since you WANT that to happen to break down the stuff into useable form for the plant...Some ingredients might not become available at all--studies have shown that bone meal doesn't break down much at all and could really be usesless (that's another story though). Anyway, "organic" ferts are best used on older developed trees because their NPK is lower and constant. That means it generally doesn't stoke a burst of new growth on trees. That can mean a world of difference to a tree that is mostly developed with fine twigging and developed root mass. You don't want a lot of fuel available to the tree to outgrow that fine development. A lot of fast-acting, readily available fert results in larger leaves, more intense new shoot development (mostly in place where it isn't needed).
Powdered ferts, like Miracle Grow, are manufactured for optimal plant performance. They are made to be fast-acting and the NPK in them is tens of times higher than in "organic" ferts. These mixes are good for developing plants that can use everything you can give them to develop primary branching, expand nebaris, increase foliage -- which fosters even more new growth, etc. Readily available NPK will spur new growth and support it in quantity. It is literally fuel for the fire that makes bonsai. By the way, most any prepared fertlizer will work--plants can't tell NPK in Miracle Grow from that in Peters.' However, it can be a good idea to switch off between two prepared ferts in a summer because mixes tend to have different levels of trace elements.
He agrees with you completely. I think you're right about the chemicals: what is different (as you allude to) is the rate of delivery and the concentration-at-delivery. I also agree that both slow-release organics and quick-release ferts have their appropriate uses.
