Fruit byproduct, as an example, would be wine from grapes. I don't know what HT was talking about, I didn't read the article, but I would guess they mean adding fruit and veggies to something like a compost heap. Primalseeds - % composition of materials there is a site, with a list of compost material and their levels of phos. acid, nitrogen, and potash. Depending on how acidic or neutral you want your soil is what you put in. I'm new to growing marijuana so I don't really know off hand what the soil ph levels should be, might wanna look that up. But that is a really good site for compost materials and it has tons of stuff listed. Sorry I couldn't be of more help, good luck