I'm not sure this is worth the trouble, but to each his/her own. I would ask tho' that since you're essentially quoting defined termns, could you pls. provide the source? I'm not sure I'd accept that definition at all.

I think you're confused. 12-4-8 is the same ratio of NPK as 24-8-16 (both are 3:1:2 RATIOS). Both are common MG formulas. The 12-4-8 is just 24-8-16 in a 2:1 dilution. If you dilute the 12-4-8 again at 2:1, you come up with 6-2-4, which totals a 12% fraction of NPK, all from the same fertilizer. That kind of dispels the 15% theory.

The term 'organic' can mean many things. True organic fertilizers are actually more accurately termed soil amendments & REQUIRE the activity of soil organisms to break them down into ionic form so they can pass through semi-permeable cell walls. Organic actually means the material once was living and contains carbon. If it has no carbon, it's not organic.

Because plants don't/can't absorb organic molecules, they absorb elements in ionic form (all plant nutrients are salts - except those that come from the air and pure water), organic soil amendments must be broken down by soil biota before they can be assimilated by plants in elemental form. Soil biota populations are extremely unstable in containers, making nutrient delivery via organic amendments erratic and unreliable. It's just the nature of container culture.

I'm not saying you can't MAKE organic soil amendments as fertilizer work, only that when it comes to knowing what you're applying (in the way of NPK ...), and when it will be available to the plant, there is no comparison between soluble fertilizers and organic soil amendments - there just isn't. You might be able to 'make' the organic fertilizer approach work if you are so inclined, or if your ideology dictates it, but it really is a little like stumbling around in the dark because you have very little control over the 'what and when' of your plant's nutritional needs. Soluble fertilizers offer the clarity of knowing exactly how much of what you are applying, and it's immediately available, regardless of the level of soil biotic activity or lack thereof.

If you're interested, you may wish to consider reading this thread about fertilizing strategies for containerized plants. If you're set in your ideology, just disregard my comments. I just wanted you to realize you'll be choosing to fight cultural conditions for control of your plant's nutrition by choosing an all organic plan, and should probably expect to find it necessary to confront other difficulties en route.

Al

If you want organic fertilizer the only things I can think of are: 1)worm farm 2) fish tank water AKA fish emulsion 3) sea weed 4) provide Calcium with crushed granite, egg shell or oyster shell.

However, like Tapla has said, you won't know what NPK or micronutrients you're providing your plants and what else they might need.