Peru – the heart of the Inca Empire – and thereabouts is where the potato originated, to be spread around the world after Europeans ‘discovered’ it. Off Peru’s coast a “weird trick of climate and topogrophy” created “[s]warms of anchovies (which) fed the birds that produced the guano that fertilized the fields that yielded such excellent potatoes.” (Evan Fraser and Andrew Rimas, Empires of Food) So valuable was the guano on the Chincha and Lobos islands offshore Peru – which were part of that country – that “[a]s late as the nineteenth century industrial democracies [U.S. and Britain in particular] were willing to go to war to control it.”
The breadbasket of the American Midwest was particularly hungry for fertilizer. In 1850 American President Martin Fillmore declared Peruvian guano so “desirable an article to the agricultural interests of the United States” as to warrant the U.S. employing “all means properly within its power” to obtain it. In 1852 American Secretary of State Daniel Webster asserted: “It may be considered the duty of this Government to protect citizens of the United States who may visit the Lobos Islands for the purpose of obtaining guano.”
America wanted the guano but a British merchant house controlled its sale. American and British gun boats headed for Peru but diplomats managed to prevent open war. This did not stop the U.S. Congress from passing the Guano Islands Act in 1856 “explicitly granting itself the right to use military force to secure bird droppings.”
Amidst the maneovering, the guano, accumulated over thousands of year, and vital to the Incas who long used it in moderation – Ronald Wright in his Short History of Progress calls it “another gift of Inca agriculture” – was mined at an unsustainable rate, using Chinese workers more often than not kidnapped. In its time, guano was the largles export from Latin America to Europe and powered economic growth in Peru.
Artificial chemical fertilizer was developed to replace the natural, though in recent times guano has made a comeback as a fertilizer for organic foods.
(The Nobel Prize winning German chemist Fritz Haber, who invented the process to make the fertilizer, tweaked his invention so as to manufacture poison gas used by Germany against its enemies in the First World War.)
Overfishing, however, has depleted the anchovy and bird population is declining and bird droppings have dropped.
Meanwhile chemical fertilizers have provided the food that has made possible the global population explosion while, at the same time, entrenching fossil-fuel dependency and creating runoffs that are poisoning streams and rivers.
All of which is worth remembering the next time you park your car and return to find that it has been bombed by birds. Heed the Incas: scrape it off to fertilize your garden.