Guano is the polite word for sea bird droppings, and also refers to bat and seal waste. The term came into use in South America to refer to mineral deposits mined from islands off the Peruvian coast. Guano is full of nitrogen, particularly potassium nitrate used for gunpowder, and phosphorus used for fertilizer. Lack of predators allowed birds to poop on these islands for thousands of years, and the lack of rainfall preserved the guano, leaving dried deposits up to 150 feet deep! The War of the Pacific was fought partially over guano mining rights. Chile, Bolivia and Peru all wanted to exploit the minerals of the Atacama Desert on the west coast of South America, which included saltpeter for explosives and guano for fertilizer and gunpowder.
Guano (from Spanish guano, from Quechua: wanu) is the accumulated excrement of seabirds and bats. As a manure, guano is a highly effective fertilizer due to its exceptionally high content of nitrogen, phosphate and potassium: nutrients essential for plant growth. Guano was also, to a lesser extent, sought for the production of gunpowder and other explosive materials. The 19th-century guano trade played a pivotal role in the development of modern input-intensive farming, but its demand began to decline after the discovery of the Haber–Bosch process of nitrogen fixing led to the production of synthetic fertilizers. The demand for guano spurred the human colonization of remote bird islands in many parts of the world. During the 20th century, guano-producing birds became an important target of conservation programs and influenced the development of environmental consciousness. Today, guano is increasingly sought after by organic farmers.
https://en.wikipedia.org/wiki/Guano
