I am still pretty new to bonsai. Just curious if bone meal would improve on the phosphorus and calcium deficiencies of the plants, it is readily available and affordable. Didn't read through the entire thead...yet.
It would, assuming you have a deficiency in both or either. It may also give you too high levels of either. Phosphate toxicity is a thing. And if you have an actual deficiency in something else, adding too much of the thing you don't need could make the deficiency worse through competition.
Apparently, calcium is one of the hardest thing for plants to take up. Because there is no active transport for it and because both potassium and magnesium directly compete with it, and are usually present in higher levels.
Which is why in the Mirai nutrition video they made a big point of having a higher ratio of calcium to potassium. So the calcium would in practice not be an issue. But too much phosphorus can definitely be one.
In soil, potassium buildup over time is a thing, because it does not flush away as much. Nitrogen for example will both disappear chemically or be washed away by water. I am not sure how in bonsai substrate phosphate buildup can be an issue.
I vaguely remember that in the Mirai video, they actually had phosphate buildup? Is this actually correct, if anyone remembers?
Bone meal by itself is a highly imbalanced fertilizer. So you'd have to be aware of that. It is somewhat cheap, though. You'd use bone meal in the mix with other fertilizers to set the phosphorus level at the correct level. Most other animal-waste fertilizers are mostly nitrogen, like feather meal or blood meal.
You would also require a pH below 7 for bacteria to be able to release the phosphorus from the phosphate minerals in the bone dust.
To my knowledge carbon in reference to nutrients has two meaning, Doc (dissolved organic carbon) and N-Doc (dissolved inorganic carbon). N-Doc as a nutrient will be mainly Co2, without having seen the video I believe they using carbon to reference Doc or dissolved organic carbon that is usually used in the form of carbohydrates (long chain polymer) in farming ex. Molasses.
This long chain polymers usually don’t have any direct affect to the tree although indirectly they will increase the beneficial bacteria in the soil aiding the delivery of Nitrogen and phosphorus and other nutrients to the tree via bacteria.
They would really need to clarify. Calling CO2 'carbon' is quite odd. The only accurate thing would be charcoal. Because sugars are not carbon. Neither are amino acids or any other organic molecules. Carbon is kinda chemically resistant.
So then it is really a physical chemistry thing which I believe was discussed here and in the other biochar thread.
Having a living soil / healthy microbiome while growing a bonsai in substrate is a big question mark to me. Those people that do farming and claim to have very good soils in terms of microbiomes, they don't achieve that by throwing molasses in their soil. They do so by keeping the soil going by having plants grow in them permanently. Because the more roots they have in the soil, the healthier the microbiome becomes. And once you remove the plants/crops, and you leave it bare or you till it, they argue you are killing your microbiome. So you keep using cover crops. Just throwing molasses or even organic fertilizer on bare soil to 'feed the microbes' would not give you the right microbes. The ones you want are the ones that live in symbioses with the plants. You want fungi and bacteria that are fed by the plants through root exudates. For sure you can grow a ton of microbe biomass on things like molasses, manure, blood meal, etc. But what's the point?
When you learn about this farming approach and you try to translate it to bonsai in substrate, there's a lot to wonder about. Does it mean you want some fast-growing like spring oats to sit next to your bonsai? Besides mosses, I have not seen anyone attempt this.