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.
Paul Szpak has co-authored several journal articles claiming that seabird guano consists of nitrogen-rich ammonium nitrate and urate, phosphates, as well as some earth salts and impurities, and that 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.
However, The Association of American Plant Food Control Officers (AAPFCO) defines Seabird guano as the hardened excrement from marine birds, which contains no organic matter or nitrogen and is a source of phosphates P2O5: "P- Hydroxylapatite - is a naturally-formed phosphate rock mineral with the formula Ca5(PO4)3(OH); the Fluorine content is less than 1%."
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.
In November 1802, Alexander von Humboldt first encountered guano and began investigating its fertilizing properties at Callao in Peru, and his subsequent writings on this topic made the subject well known in Europe. During the guano boom of the nineteenth century, the vast majority of seabird guano was harvested from Peruvian guano islands, but large quantities were also exported from the Caribbean, atolls in the Central Pacific, and islands off the coast of Namibia, Oman, Patagonia, and Baja California. At that time, massive deposits of guano existed on some islands, in some cases more than 50 m deep. In this context the United States passed the Guano Islands Act in 1856, which gave U.S. citizens discovering a source of guano on an unclaimed island exclusive rights to the deposits. Nine of these islands are still officially U.S. territories. Control over guano played a central role in the Chincha Islands War (1864–1866) between Spain and a Peruvian-Chilean alliance. Indentured workers from China played an important role in guano harvest; the first group of 79 Chinese workers arrived in Peru in 1849; by the time that trade ended a quarter of a century later, over 100,000 of their fellow countrymen had been imported. There is no documentary evidence that enslaved Pacific Islanders participated in guano mining. Between 1847 and 1873, there was a significant increase in Peruvian guano exports, and the revenue from this momentarily ended the fiscal necessity of the colonial head tax.
After 1870, the use of Peruvian guano as a fertilizer was eclipsed by saltpeter in the form of caliche extraction from the interior of the Atacama Desert, not far from the guano areas. During the War of the Pacific (1879–1883) Chile seized much of the guano as well as Peru's nitrate-producing area, enabling its national treasury to grow by 900% between 1879 and 1902 thanks to taxes coming from the newly acquired lands. Contrary to popular belief, seabird guano does not have high concentrations of nitrates, and was never important to the production of explosives; bat and cave-bird deposits have been processed to produce gunpowder, however. High-grade rock phosphate deposits are derived from the remobilization of phosphate from bird guano into underlying rocks such as limestone. In 1990 a group of French researchers, from isotope studies, proposed a marine sedimentation origin for some high-grade phosphate deposits on Nauru.
Since 1909, when the Peruvian government took over guano extraction for use by Peru farmers, the industry has relied on production by living populations of marine birds. U.S. ornithologists Robert Cushman Murphy and William Vogt promoted the Peruvian industry internationally as a supreme example of wildlife conservation, while also drawing attention to its vulnerability to the El Niño phenomenon. South Africa independently developed its own guano industry based on sustained-yield production from marine birds during this period, as well. Both industries eventually collapsed due to pressure from overfishing; the importance of guano deposits to agriculture elsewhere in the world faded after 1909 when Fritz Haber developed the Haber-Bosch process of industrial nitrogen fixation, which today generates the ammonia-based fertilizer responsible for sustaining an estimated one-third of the Earth's population.
The ideal type of guano is found in exceptionally dry climates, as rainwater volatilizes and leaches nitrogen-containing ammonia from guano. In order to support large colonies of marine birds and the fish they feed on, these islands must be adjacent to regions of intense marine upwelling, such as those along the eastern boundaries of the Pacific and South Atlantic Oceans.
Bat guano is usually mined in caves and this mining is associated with a corresponding loss of troglobytic biota and diminishing of biodiversity. Guano deposits support a great variety of cave-adapted invertebrates, that rely on bat feces as their sole source of nutrition. In addition to the biological component, deep guano deposits from birds and bats contain local paleoclimatic records and evidence of other environmental changes in strata that have built up over thousands of years, which are unrecoverable once disturbed. However, when done with caution, extraction of guano can be done alongside marine bird colonies without causing them significant harm.
Post-depositional decomposition and ammonia volatilization of penguin guano also plays an important role in the evolution of ornithogenic sediments in the cold and arid environment of Antarctica (McMurdo Sound of the Ross Sea region, East Antarctica).
In agriculture and gardening guano has a number of uses, including as: soil builder, lawn treatments, fungicide (when fed to plants through the leaves), nematicide (decomposing microbes help control nematodes), and as composting activator (nutrients and microbes speed up decomposition).
High in nitrogen, guano was also refined in the early 20th century into a precursor to explosives; this caused guano islands to be of strategic significance before the First World War.
In popular culture
"Guano's historical significance was as much cultural as it was ecological and economic." References to guano in popular culture are an important sign of this cultural influence, especially regarding the ongoing relationship between guano and colonialism. In his 1845 poem "Guanosong", Joseph Victor von Scheffel used a humorous verse to take a position in the then-popular polemic against Hegel's Naturphilosophie; the poem starts with an allusion to Heinrich Heine's Lorelei and may be sung to the same tune. The poem ends however with the blunt statement of a Swabian rapeseed farmer from Böblingen who praises the seagulls of Peru as providing better manure even than his fellow countryman Hegel; this refuted the widespread Enlightenment belief that nature in the New World was inferior to the Old World. The poem has been translated by, among others, Charles Godfrey Leland.
- In Joseph Conrad's 1900 novel Lord Jim the characters Chester and Captain Robinson attempt to recruit the eponymous lead character for an expedition harvesting guano.
- The setting of Ian Fleming's 1958 installation in the James Bond series Dr. No is a Caribbean guano island, and the villain dies at the end buried in guano.
- In Stanley Kubrick's 1964 film Dr. Strangelove, Colonel "Bat" Guano (Keenan Wynn) leads an attack on the airbase responsible for sending a nuclear attack order to bomb the Soviet Union.
- The 1994 film Men of War centers on a band of mercenaries who are hired by an investment firm to seize a tropical island for its extensive guano deposits.
- In the 1995 film Ace Ventura: When Nature Calls, Jim Carrey's character attempts to save an African tribe from being dispossessed of a fortune in bat guano.
- Hungarian painter Judit Reigl had a series of paintings between 1958-1964. She used to protect the floor of her atelier with old and ruined canvasses; when she moved out, she discovered that over these years the paintings developed an interesting surface, and she carved her "Guano painting" from these.
- In the Dungeons & Dragons tabletop game, a small ball of bat guano is a component in casting the fireball spell.
- Cushman, Gregory T. (2013). Guano and the Opening of the Pacific World: A Global Ecological History. Cambridge University Press. ISBN 9781107004139.
- Szpak, Paul; Longstaffe, Fred J.; Millaire, Jean-Francois; White, Christine D. (2012). "Stable Isotope Biogeochemistry of Seabird Guano Fertilization: Results from Growth Chamber Studies with Maize (Zea mays)". PLoS One. 7 (3): e33741. doi:10.1371/journal.pone.0033741.
- Szpak, Paul; Millaire, Jean-Francois; White, Christine D.; Longstaffe, Fred J. (2012). "Influence of seabird guano and camelid dung fertilization on the nitrogen isotopic composition of field-grown maize (Zea mays)". Journal of Archaeological Science. 39 (12): 3721–3740. doi:10.1016/j.jas.2012.06.035.
- "Association of American Plant Food Control Officials Terms & Definitions Committee 2018 Summer Annual Meeting Report". Association of American Plant Food Control Officials (AAPFCO) USA, August 2 2018. Retrieved on 27 January 2019.
- "Bat Guano Definition". Association of American Plant Food Control Officials (AAPFCO), Oregon Department of Agrigulture. USA, 31 March 2016. Retrieved on 12 December 2017.
- "California Department of Food and Agriculture-Notice to Fertilizing Material Licensees-Use of the term 'Bat Guano' on Fertilizing Material Labels". California Department of Food and Agriculture. USA, 11 May 2017. Retrieved on 12 December 2017.
- "Insect Eating (Insectivorous) Bat Guano". RealGuano. USA, 21 September 2017. Retrieved on 12 December 2017.
- Emerson, Justin K.; Roark, Allison M. (2007). "Composition of guano produced by frugivorous, sanguivorous, and insectivorous bats". Acta Chiropterologica. 9: 261–267. doi:10.3161/1733-5329(2007)9[261:cogpbf]2.0.co;2.
- Hutchinson, G. Evelyn (1950). "Survey of Existing Knowledge of Biogeochemistry: 3. The Biogeochemistry of Vertebrate Excretion". Bulletin of the American Museum of Natural History. 96: 1–554.
- Skaggs, Jimmy (1994). The Great Guano Rush: Entrepreneurs and American Overseas Expansion. New York: St. Martin's. ISBN 978-0312103163.
- Méndez, Cecilia (1987). Los trabajadores guaneros del Perú, 1840–1879. Lima: Universidad Nacional Mayor de San Marcos.
- Larson, Brooke (2004). Trials of Nation Making: Liberalism, Race, and Ethnicity in the Andes, 1810-1910. Cambridge: Cambridge University Press. p. 146. ISBN 978-0521567305.
- Crow, The Epic of Latin America, p. 180
- McKelvey VE (1967). "A summary of the salient features of the geology of phosphate deposits, their origin, and distribution" (PDF). Geological Survey Bulletin. 1252-D. D14.
- Bernat M, Loubet M, Baumer A (1991). "Sur l'origine des phosphates de l'atoll corallien de Nauru" [On the origin of phosphates from the Nauru atoll] (PDF). Oceanologica Acta (in French). 14 (4).CS1 maint: Uses authors parameter (link)
- Glenn, Craig, et al., eds. (2000). Marine Authigenesis: From Global to Microbial. Tulsa, OK.CS1 maint: Extra text: authors list (link)
- Wolfe, David W. (2001). Tales from the underground a natural history of subterranean life. Cambridge, Massachusetts: Perseus Pub. ISBN 978-0-7382-0128-3. OCLC 46984480.
- Dwyer, Jim (10 June 2001). "June 3–9; The Root of a Famine". The New York Times. p. 2.
- Gómez-Alpizar, Luis; et al. (2007). "An Andean origin of Phytophthora infestans inferred from mitochondrial and nuclear gene genealogies". PNAS. 104 (9): 3306–11. doi:10.1073/pnas.0611479104. PMC 1805513. PMID 17360643.
- Hong Yan et al., "A 2000-year record of copper pollution in South China Sea derived from seabird excrements: a potential indicator for copper production and civilization of China," Journal of Paleolimnology 44 (2010): 431-442; Hong Yan et al., "Millennial mercury records derived from ornithogenic sediment on Dongdao Island, South China Sea," Journal of Environmental Science 23 (2011): 1415-1423.
- "Guañape Sur trailer", IcarusFilmsNY.
- "Islas Guañape trailer", El Peru canta y baila.
- Nie, Yaguang; Liu, Xiaodong; Wen, Tao; Sun, Liguang; Emslie, Steven D. (2014). "Environmental implication of nitrogen isotopic composition in ornithogenic sediments from the Ross Sea region, East Antarctica: Δ15N as a new proxy for avian influence". Chemical Geology. 363: 91–100. doi:10.1016/j.chemgeo.2013.10.031.
- "h2g2 - Seabird Guano and Bat Dung". Bbc.co.uk. Retrieved 26 January 2013.
- Guano and the Opening of the Pacific World: A Global Ecological History, Gregory T. CushmanCambridge University Press, 25.03.2013, p. 51
- Note: A scan of the Loreley sheet music and lyrics (printed in 1859; note the spelling "Lorelei") are available on the commons in three images: File:Lorelei1.gif, File:Lorelei2.gif, File:Lorelei3.gif
- Charles Godfrey Leland, Gaudeamus! Humorous Poems by Joseph Viktor von Scheffel, Ebook-Nr. 35848 on gutenberg.org
- Cushman, Gregory T. (2013). Guano and the opening of the Pacific world: a global ecological history. Cambridge; New York: Cambridge University Press. ISBN 9781107314030. Retrieved 13 June 2013.
- Hague, James D. (1862). On the phosphatic guano islands of the Pacific Ocean. [New York. Retrieved 13 June 2013.
- Skaggs, Jimmy M. (1994). The great guano rush: entrepreneurs and American overseas expansion. New York: St. Martin's Press. ISBN 978-0312103163.
- Robinson, Solon (1853). Guano: a treatise of practical information for farmers. New York: Solon Robinson.
- Pacific Guano Company (1876). The Pacific Guano Company; its history; its products and trade; its relation to agriculture. Exhausted guano islands of the Pacific Ocean; Howland's island, Chiacha Islands, etc., etc. The Swan Islands; the marl beds and phosphate rock of South Carolina. Chisolm's Island phosphate; the menhaden. Cambridge: Printed for the Pacific Guano Company at the Riverside Press.
- Teschemacher, James E. (1845). Essay on guano; describing its properties and the best methods of its application in agriculture and horticulture; with the value of importations from different localities; founded on actual analyses, and on personal experiments upon numerous kinds of trees, vegetables, flowers, and insects, in this climate. Boston: A.D. Phelps.
- Eden, Thomas Edward (1846). The search for nitre, and the true nature of guano: being an account of a voyage to the south-west coast of Africa: also a description of the minerals found there, and of the guano islands in that part of the world. London: R. Groombridge. Retrieved 13 June 2013.
- Morrell, Benjamin (1832). A Narrative of Four Voyages...etc. New York: J & J Harper. Retrieved 17 December 2009.
- Teale, E.O. (1934). The Limestone caves and hot springs of the Songwe river (Mbeya) area with the notes associated Guano deposits. XII. The East Africa Natural History Society.
- Pissis, Aimé (1878). Nitrate and Guano Deposits in the Desert of Atacama: An Account of the Measures Taken by the Government of Chile to Facilitate the Development Thereof. London: Taylor and Francis.
- Duffield, Alexander James (1877). Peru in the guano age: being a short account of a recent visit to the guano deposits, with some reflections on the money that they have produced and the uses to which it has been applied. London: Richard Bentley and Son.
- Duffield, Alexander James (1881). The Prospects of Peru: The End of the Guano Age and a Description Thereof. With Some Account of the Guano Deposits and Nitrate Plains. London: Newman & Co.
- Hollett, Davi (2008). More Precious than Gold: The Story of the Peruvian Guano Trade. Fairleigh Dickinson. ISBN 978-1611473575.
- Nesbit, John Colis (1856). On agricultural chemistry, and the nature and properties of Peruvian guano. London: Longman and Co.
- "Prospectus of the American Guano Company". 1855. Retrieved 13 June 2013.
- Coker, Robert Ervin (1910). The fisheries and the guano industry of Peru. Washington DC: Government Printing Office. Retrieved 13 June 2013.
- "Report of the Inspector of Guano : Maryland". 1849. Retrieved 13 June 2013.
- United States Department of Agriculture, Office of Experiments (1918). Bat guanos of Porto Rico and their fertilizing value. Mayagüez, P.R.: Porto Rico Agricultural Experiment Station.
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The dictionary definition of guano at Wiktionary