Night soil refers to untreated human waste used historically as fertilizer. It is known to cause illness, especially among those not accustomed to eating food grown in this way.
Human waste is an extremely rich source of soil nutrients and soil microorganisms, and treating it as waste discards a valuable resource. (See also No such thing as garbage) However it must be properly treated in most cases and applied according to safety guidelines.
Safety in reuse of human waste[edit | edit source]
It is an important principle in risk management to take several safety measures together, to minimize risk. For food safety:
A much safer alternative is to apply mature humanure to an empty garden bed first, then apply layers of safer soil and mulch.
Strict care must be taken even with matured humane. A good strategy is to use thick mulch, and only apply where the edible parts of the plant are well above the ground - fruit trees or vines on trellises, for example.
Exceptions to treatment requirements[edit | edit source]
Treatment and application requirements will be less strict where the soil will not be used for food crops for some years, and where there is little exposure to humans and human disease vectors, e.g. in timber plantations which are fenced off and far from human settlements. In such cases, appropriate workplace safety measures are essential for workers, including protective clothing and masks, and washing facilities.