In November 1802, Alexander von Humboldt was the first European to encounter 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.
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.