Utilization of human excrement in pre-modern China,its theoretical interpretations and ecological significance

The use of human excrement as fertilizer is a characteristic of traditional Chinese agriculture..The application of excrement from urban residents in agriculture since the Song Dynasty has ensured the cleanliness and hygiene of ancientChinesecities.As early as the Ming Dynasty,the Chinese people defined the principle of fertilizing fields with human excrement from the perspective of materialcirculation.The concept Peri-URban ecosystems(PURE)provides inspiration forurban-rural symbiosis regarding circulareconomy.The use of human excrement in fertilization is a major attribute differentiating the Chinese traditional agriculture from the agriculture in other regions around the world.Despite the fact that the exact record showing that human excrement was used as fertilizer in China emerged in the Western Han Dynasty(B.C.202-A.D.8),such records did not become prevalent until the Southern Song Dynasty(A.D.1127-1279).In the Ming and Qing eras(A.D.1368-1912),human excrement was even considered"top-class fertilizerand servedas themost essential fertilizerin farmland fertilization.The importance of human excrement in the Ming and Qing was mainly reflected by farmers'purchase of human excrement from urban areas.As fertilization practices became increasingly popular during the period,men of letters built a localized theoretical system centering on human excrement.Although the use of human excrement had both positive and negative impacts on public health and the ecological environment,the positive overshadowed the negativeas a whole.Today,it is worth pondering on how the utilization of human excrement as an agricultural resource can be improved so that a material cycle system can be rebuilt to re-connect the urban and rural areas.