Just the other day, I took the lid off a five gallon bin, into which I'd been putting comfrey, nettles and several handfuls of 6X, (chicken manure fertilizer).
It came out the colour of thick black coffee, and as I'd actually forgotten that I'd put the 6X in afterwards, in a holed plastic bag to steep it all, the residue was really quite benign! (It'd been there two years)!
I'm now wondering if I might top it all up with the new nettles and comfrey, but goodness knows how much to use when diluted...
Trial and error I guess, but maybe just a wine glass with a gallon should be the starting point!
(I'll wash the glass afterwards of course)!