Bat guano

Guano (from Quechua "wani" via Spanish) 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. The 19th-century guano trade played a pivotal role in the development of modern input-intensive farming practices and inspired the formal human colonization of remote bird islands in many parts of the world. During the twentieth 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.

Seabird guano consists of nitrogen-rich ammonium nitrate and urate, phosphates, as well as some earth salts and impurities. (Ammonium nitrate is a chemical compound, the nitrate salt of the ammonium cation. It has the chemical formula NH4NO3, simplified to N2H4O3. It is a white crystal solid and is highly soluble in water. It is predominantly used in agriculture as a high-nitrogen fertilizer.) Unleached guano from favored locales, such as the Chincha Islands off the coast of Peru, typically contains 8 to 16 percent nitrogen (the majority of which is uric acid), 8 to 12 percent equivalent phosphoric acid, and 2 to 3 percent equivalent potash.

Bat guano is fecal excrement from bats. Commercially harvested bat guano is used as an organic fertilizer. All commercially sold bat guano is derived from insect eating bats. A study was done that demonstrated that, for fruit bats and insect bats, the composition of their guano was largely the same, and differed mainly based on their diet.

The word "guano" originates from the Andean indigenous language Quechua, which refers to any form of dung used as an agricultural fertilizer. Archaeological evidence suggests that Andean people have collected guano from small islands and points located off the desert coast of Peru for use as a soil amendment for well over 1,500 years. Spanish colonial documents suggest that the rulers of the Inca Empire assigned great value to guano, restricted access to it, and punished any disturbance of the birds with death. The Guanay cormorant has historically been the most abundant and important producer of guano. Other important guano producing species off the coast of Peru are the Peruvian pelican and the Peruvian booby.

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