1. How much Humic Acid 35% powder should I add in respect to the total substrate or per quantity of compost?
It depends on a lot of different factors such as your composting methods, the materials you are composting, other nutrients you are adding, etc.
Compost naturally produces Humic so in some cases, there is no need to add Humic Acid at all.
However, generally, we recommend adding 1% compared to your compost either by weight or volume.
2. Is your Humic Acid water soluble?
No, our Humic Acid is NOT fully water soluble.