Adam Clark Estes explores whether human excrement might help address “a food shortage that is directly correlated with a fertilizer shortage”:
Worldwide, human waste produces 70 million tons of nutrients that could account for about 40 percent of the 176 million tons of nutrients needed to produce chemical fertilizer. The value of these nutrients is not lost on the farmers of the world, and in fact, human feces have long been a semi-secret source of fertilizer for centuries.
While culturally acceptable in some parts of the world, it was long frowned upon and even outlawed elsewhere, leading to a cottage industry in selling so-called “night soil.” This richly fertile soil was produced by skimming human waste off of cesspools and spreading it onto fields under the cover of darkness, hence the name. The practice became less popular with the advent of chemical fertilizer in the 20th century, but as those resources dwindle, the old poop fields are starting to look pretty appealing once again.
Indeed, the use of human waste as fertilizer is on the rise. As recently as 2008, nearly 200 million farmers in Asia, Africa, and Latin America depended on feces for fertilizing fields where they grew vegetables and grains. This food, the World Health Organization (WHO) estimated, fed as much as ten percent of the world’s population.