Guano as a renewable resource
Guano is a natural fertilizer derived from the accumulated excrement of seabirds, primarily found on remote desert islands that host large populations of fish-eating birds. Historically significant, guano was first utilized by prehistoric Peruvian farmers and gained popularity in the 19th century as a solution to restore nutrient-depleted soils in Europe, thanks to the advocacy of scientists like Alexander von Humboldt and Georg Leibig. The high demand for guano led to extensive harvesting, notably from the Chincha Islands off the coast of Peru, where the unique ecology supported massive seabird populations.
The extraction and commercial use of guano have complex socio-economic and environmental implications, particularly as overfishing and climate events like El Niño have impacted seabird populations and their habitats. The Peruvian government recognized the value of guano, but challenges from foreign interests and environmental mismanagement led to a decline in production. Today, while Peruvian guano is primarily used for local agriculture, it remains a critical component of sustainable farming practices in other regions, including parts of Mexico and Africa.
Additionally, guano deposits provide valuable insights into environmental conditions and can help scientists study climate patterns over time. With its high nutrient content, particularly nitrogen and phosphoric acid, guano stands out as a potent renewable resource, emphasizing the need for careful management to ensure its sustainability.
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Guano as a renewable resource
Accumulated bird excrement, rich in nitrogen, is known as guano and offers a renewable source of fertilizers.
Definition
Guano is a renewable natural fertilizer. It is found in commercial quantities only on a few desert islands where millions of fish-eating sea birds roost undisturbed.
Overview
There is archaeological evidence that guano was collected and used by prehistoric Peruvian farmers, who called it huano. Nineteenth century application of guano to the exhausted soils of Europe was first advocated by the German agronomist Georg Leibig after its introduction in the 1830s by the noted scientist and South American explorer Alexander von Humboldt. The dramatic increases it caused in wheat, corn, and cotton production created enormous demand for this product, which was soon being dug by hundreds of Chinese laborers forced to work on the Chincha Islands south of Lima, Peru.
These rain-free guano islands are populated by millions of cormorants, gannets, and pelicans that fly out to sea daily to eat anchovies and sardines. The fish themselves feed on plankton they find in the cold, north-flowing Chile-Peru (Humboldt) Current. When this current is occasionally displaced by a warm (El Niño) countercurrent, the entire collapses, and many sea birds begin to die of starvation.
A guano boom began in 1851, when the U.S. Congress passed legislation allowing any American citizen to declare uninhabited guano islands as territory of the United States. Under the provisions of this little-known act, several Caribbean and South Pacific islands were so claimed. One of them, Navassa, located midway between Cuba and Haiti, remains an undisputed U.S. territorial possession to this day under jurisdiction of the U.S. Fish and Wildlife Service. Subfossil guano deposits found there are thought to be the excrement of a fish-eating bat.
Although the Peruvian government recognized guano as a strategic and highly valuable natural resource, little was done to protect the industry from foreign interests and political intrigue. In order to meet financial obligations and service debts, the government mortgaged its guano resources for quick cash loans from foreign business firms selling the increasingly valuable Chincha guano.
Failure to protect the guano-producing birds, as well as ignorance of the complex of their habitat, eventually resulted in the decline of the industry in the face of overwhelming competition from Chilean sodium nitrate deposits discovered in the 1870s. Not until the 1910s was any progress made in reviving the resource. Based on the advice of foreign ichthyologists and the American ornithologist Robert Cushman Murphy, good practices were begun by Francisco Ballen, director of the newly created Compañía Administradora del Guano.
The impact of several disastrous El Niño events beginning in 1925, together with severe overfishing of anchovy stocks, seriously retarded the buildup of new Peruvian guano deposits. No longer exported, Chincha guano is now used exclusively for the benefit of Peruvian agriculture.
Guano is also collected elsewhere in the world and used locally; farmers in Baja California, Mexico, and some regions of western Africa, for example, use it as fertilizer. Bat-guano deposits often occur in caves with sufficiently large bat populations. Seal excrement is also sometimes included in the definition of guano. Bird guano, however, has a higher concentration of fertilizing nutrients (notably nitrogen and phosphoric acid) than either bat or seal guano.
From the study of any deep undisturbed sequence of guano may come a valuable scientific record of environmental conditions that prevailed while it was accumulating. Identifying and dating ancient layers showing disturbed conditions can give statistical clues to hidden climatic cycles and the ability to predict future long-range changes in patterns.
"Bat Guano: A Reliable Record of Climate Change." University of South Florida, 29 Oct. 2017, www.labmanager.com/bat-guano-a-reliable-source-of-climate-change-6201. Accessed 27 Dec. 2024.
"Bird Guano, Is It Hazardous? Absolutely All You Need to Know!" Summit Environmental, 19 Feb. 2022, www.summitenvironmental.co.uk/blog/bird-guano-is-it-hazardous-absolutely-all-you-need-to-know. Accessed 27 Dec. 2024.
Johnston, Paul F. "The Smithsonian and the 19th Century Guano Trade: This Poop Is Crap." National Museum of American History, 31 May 2017, americanhistory.si.edu/explore/stories/smithsonian-and-19th-century-guano-trade-poop-crap. Accessed 27 Dec. 2024.