Tomas Munita for The New York Times
For thousands of years, seabirds ate anchovies and then crapped all over islands off the coast of Peru. It got up to a hundred and fifty feet deep and was the world's best fertilizer; wars were fought over it as thousands worked the quano mines. Soon they hit rock, Fritz Haber invented synthetic fertilizers and the party was over.
Now it is a sustainable industry, where they take guano at the same rate as the birds drop it. The New York Times writes "It is a minor miracle that any guano at all is available here today, reflecting a century-old effort hailed by biologists as a rare example of sustainable exploitation of a resource once so coveted that the United States authorized its citizens to take possession of islands or keys where guano was found."
"Guano in Peru sells for about $250 a ton while fetching $500 a ton when exported to France, Israel and the United States. Its status as an organic fertilizer has also increased demand, transforming it into a organic niche fertilizer sold around the world."- from the gorgeous photo essay by Tomas Munita
There is huge demand for the stuff from organic farmers, except that the anchovetta are being overfished, and the bird population is shrinking. ::New York Times