Night soil
Night soil is a term most often used to describe the practice of using untreated human waste as fertilizer. This is a highly hazardous practice because of the human disease microbes in human feces. Nevertheless, in the third world it is a common practice. There have been cases of disease-carrying tomatoes, lettuce, and other vegetables being imported from third world nations into more developed nations.
The safe reduction of human waste into compost is possible, but fairly complex. Many municipalities create compost from the city sewage system, but then recommend that it only be used on flower beds, not vegetable gardens. Some claims have been made that this is dangerous or inappropriate without the expensive removal of heavy metals.
India's ancient caste system assigned untouchables with the disposal of night soil. This "manual scavenging" is now illegal in most Indian states, although the practice undoubtedly continues in many rural areas.
The proper disposal or recycling of sewage remains an important research area that is also highly political.
