Guano
Guano is the accumulated excrement of seabirds, bats, and seals, valued historically and today as a potent natural fertilizer rich in nitrogen, phosphorus, and potassium. It underpinned a global fertilizer boom in the 19th century, centered on Peru’s coastal islands, and influenced geopolitics, labor systems, and environmental management. Modern conservation programs regulate extraction on protected Peruvian islands while research documents guano’s ecological roles and associated health risks.
