usually its very unsanitory to shit in your crops, because you spread bacteria that is more harmful other people. its different from a cows dung feces over humans. E-coli being one of them, thats why they use manure of herbivorious animals over carnivores/omnivores, meat eaters have more potential to have parasites too, in the old ways. but they use synthetical manufactuered fertilizers to avoid the problems altogether.