The manufacturer of the various ingredients in your media would have to provide the chemical analysis of their product. There is no way for a user to discover that info from some generic
ingredient label. In some cases of substances used to feed animals or people or to be used as soil amendments, the Dept. of Agriculture and other government bodies publish tables of nutrient composition. I imagine it would otherwise be quite difficult to come up with meaningful NPK figures for mixtures that are not specifically marketed as fertilizers. Perhaps a commercial laboratory could help you out with this, as they do with soil samples.
