Biogold is another popular bonsai fertiliser, which may or may not be cagey about its ingredients since the packaging is all in Japanese which I cannot read. Deploying google translate on their website, and searching online yielded some information:
- It’s a fertiliser with N:P:K ratio NPK 5.5:6:3
- It contains micronutrients iron 0.12%, copper 50mg/kg, molybdenum 27 mg/kg, sulfur 0.5% and also magnesium and calcium (in unspecified amounts)
- It contains chicken manure fermented using bacterial processes
Chicken manure isn’t used directly on plants because the organic matter will ferment and generate heat, usually it is fermented separately along with plant matter such as straw, leaves, cardboard etc, and requires turning or mixing to ensure exposure to air (this is aerobic fermentation which requires oxygen).
So it’s likely that Biogold contains some other kind of plant matter which is unspecified. When looking at other products, plant matter (particularly green or coloured leaves or skins) provided substances which helped the microbial communities in the soil flourish, enhancing root growth and nitrogen uptake. One study found a “positive effect of BioGold® and Compost in increasing the soil microbial population by providing nutritive sources for the growth of soil microbes”ref
Chicken manure is a good source of nitrogen, contains humic acidref, which is a concentrated form of organic matter (also contained in the coal precursors leonardite and peat), and was found to have better growth potential for plants than cow manure.ref
A researcher growing coconut compared BioGold with other fertilisers in this studyref – and found “There were no significant differences (P> 0.005) between treatments in any of the growth parameters tested after a period of six months after planting.” ie. the plants tested had similar outcomes from all the fertilisers tested (which included inorganic fertiliser, cattle manure, ‘Kochchikade biofertilizer’ and compost).
So overall, hard to say, this product appears to be a good fertiliser with micronutrients and humic acid/concentrated organic matter. But since it doesn’t disclose all the ingredients it’s impossible to fully assess it.