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Fertilizer supplies key nutrients to plants, including nitrogen, phosphorus, and potassium. In the early 20th century, chemists learned to synthesize nitrogen fertilizer in the lab, sparking the Green Revolution.
Before this development, farmers fertilized with manure from farm animals or other sources. And therein lies the tale of a fascinating chapter in American agricultural history.
In the 19th century, ocean exploration revealed the presence of Pacific Islands occupied only by seabirds. They were piled high with nutrient-rich guano. In 1856, Congress passed the Guano Islands Act, which allowed U.S. citizens to take possession of any uninhabited, guano-covered island not claimed by another country. The U.S. military could be called upon to defend these claims.
More than 100 islands were claimed and mined, loosening a monopoly held by South American countries that were charging American farmers steep prices for guano fertilizer.
There are reports that guano mining activities discouraged seabird activity on these islands. The mining activities ended at the turn of the twentieth century – about the same time synthetic fertilizer was discovered.
The Guano Islands Act, which is still on the books, created a new category of U.S. territories outside the continent that were not earmarked for statehood. Many of the former guano islands are still under U.S. jurisdiction, and several are now part of the U.S. Pacific Island Marine National Monument.
Established by President George W. Bush, the monument encompasses the islands and the sea surrounding them. These remote refuges protect fish, corals, marine mammals, invertebrates, and, of course, the seabirds that caused all of the fuss in the first place.
Web Links
http://basementgeographer.blogspot.com/2011/01/guano-islands-act.html
http://www.fws.gov/marinenationalmonuments/index.html
Photo, taken on October 19, 2011, courtesy of Jose Silva via Flickr.