the NPK ratios that I have seen in here like 5-10-_ would be synthetic... Another thing about organic fertilizers. They contain a lower concentration of the needed macronutrients and are usually quoted as decimals like 02-.14-.36 .
There are natural products that have been blended and contain all three of the "big three nutrients" rated in whole numbers. I have used a product from Epsoma that is rated at 5-3-3. On a philosophical level I like that this is derived from natural ingredients but it has a tendency to clog my medium. In bonsai culture I strive to maintain a free draining medium and this type of dry, powdery material is not conducive to that end. I would really like to find a natural product that is balanced and granular that does not break down immediately and clog my medium, do you have any suggestions?
And the really great thing about organics is that they don't just contain macrontrients they also contain micronutrients.
I have in front of me packaging from Peters 20-20-20, it lists the micro-nutrients included as Magnesium, Boron, Copper, Iron, Manganese, Molybdenum and Zinc. Perhaps these are not the full compliment and perhaps they are not derived from the sources you would wish but to imply that synthetics lack micro-nutrients is simply not accurate.