i have an extremely small growing area of anything not fungus or hydroponics, and its sand, but the fertilizer area cannot be dragged over sand, the rocky stone next to it can, but not the sand, first i thought maybe the irrigation sprinkler would make wet sand to fertilize, but maybe thats not it. i dont have any research further than "sewage sludge composter" and "irrigation". the biosolids directly say, "Biosolids produce a large boost to fertility of sand which can make it fertile
when combined with irrigation"
normal sand, i don't think a cosmetic mod replaces the sand