@Eckhoffw - yes, definitely confusing. Hoping that reading through other pages on the site will explain what is on the chart.
@Colorado - I know nothing about American Bonsai potting media. I've met some of the principals of American Bonsai, I've bought some of their tools, but I have never looked at their potting media. Reason is, I can source adequate materials within a 2 hour drive from my home, so I never considered paying shipping to get potting media. Shipping costs make "dirt" really expensive "dirt".
Akadama and Kanuma are Japan sourced clays derived from volcanic substrates. Clays from, pumice, lava or basalt, or Andesitic basalts or even rhyolites. Regardless, these clays are predominately silica based. There are some metal silicates and metal oxides in the volcanic clays, but the over all amount of calcium oxides is fairly low. The buffer capacity of volcanic derived clays tends to be low. There are deposits of volcanic clays in North America with very similar properties to Akadama and Kanuma, but they are currently not being mined. The expense of mining in USA would result in a media significantly more expensive than the $40 per bag that we are paying for imported Japanese "dirt". For various reasons, the mines in Japan produce "dirt" at a fairly low cost. Most of the current cost is shipping.
In USA many of our clays are limestone derived, eroded, ancient corals, dolomite, and other sources. Here the clays have very high percentages of calcium oxides in various hydration states. This affects pH and buffer capacity. Buffer capacity of limestone derived clays is quite high. Some clays are more inert than others. For example, because Turface is fired (calcined) the solubility is quite low, so functionally Turface is more chemically inert than its parent material before it was fired. Calcined clays are not a replacement for Akadama or Kanuma, they are different products, one is not a substitute for the other.
When I lecture about growing orchids indoors, under lights, one of my sayings is "you can grow in anything, if you understand how to water and fertilize". Everything my 41 years of raising bonsai (at a hobby amateur level) has shown me this saying applies to bonsai too.
A perfectly good blend that I have used successfully is a bark & pumice blend. You can complicate it as much as you like, or you can keep it very simple. Deciduous get a higher percentage of bark, conifers get closer to all pumice. One of my more complicated version of this blend included douglas fir bark, pumice, lava, hort grade charcoal, and a small handful of hardwood sawdust to feed mycorrhiza. My most stripped down is just pumice and douglas fir bark packaged for seedling orchids.
Bark mixes require applying higher nitrogen fertilizer because the slow breakdown of the bark consumes nitrogen. Bark mixes do break down, generally requiring repotting every 3 to 5 years.
Bark-pumice mix is NOT a substitute for Kanuma or Akadama, it is just a different media, it is its own "thing", and it is a good growing media. Nothing wrong with it.
For blueberries I have been using a peat-bark-pumice with a handful of hardwood sawdust blend that as I have become familiar with I like. With regular use of "magical liquid elixirs", meaning extracts of humic acids and fulvic acids, such as liquid seaweed, I found that the fine particles of peat form clumps, therefore retaining good aeration and good water penetration for much longer than the same mix without the addition of humic acid solutions. Great stuff, humic acids, humus, and fulvic acids should be a part of everyone's nutrient programs.
The end take away is, choose a potting mix design that you can afford, and one that you can replenish quickly if you run out. Lean how to water that mix, and how to supplement nutrients. Stick with as few mix designs as you can, keep your potting media as uniform, and as simple as you can, and learn to use it well.
You can grow in anything.
