Isn it a good idea that the plant nutrients in urine and feces be returned to farmland ?
Yes, certainly. Urine and feces are the concentrated nutrient remains of the food we have grown. Urine and feces are naturally very low in heavy metals and contain micronutrients from diverse food sources. Many soils lack these micronutrients because they have been “mined” and not returned as the result of poor agricultural practices. These micronutrients — such as Selenium which we predominantly get through fish –are rarely present in chemical fertilizers. But the practice of mixing urine and feces with large amounts of municipal tapwater–(leaving aside for the moment the question of what it means to add them to municipal sewage)–adds unnaturally high amounts of heavy metals to sewage treatment sludge. This contamination of excreta with heavy metals is part of the reason why urine and feces should be kept separate from municipal sewage.
