Human manure, known as "night soil," was a traditional form of fertilizer in China and Japan. In the United States, heavily treated products derived from municipal sewage are sold for use as fertilizer, one example being Milorganite.<ref>[http://www.milorganite.com/about/history.cfm Milorganite: Our History]</ref> | Human manure, known as "night soil," was a traditional form of fertilizer in China and Japan. In the United States, heavily treated products derived from municipal sewage are sold for use as fertilizer, one example being Milorganite.<ref>[http://www.milorganite.com/about/history.cfm Milorganite: Our History]</ref> |