For centuries, a kingdom in modern-day Peru flourished by leveraging a surprising agricultural resource: seabird droppings, known as guano. New research published in PLOS One reveals that this civilization was applying guano fertilizer to maize crops as early as 1250—nearly 200 years before the rise of the Inca Empire.
The Value of “White Gold”
The islands off the coast of Peru accumulate vast piles of guano, rich in nitrogen and other essential nutrients. This natural fertilizer proved invaluable to the region’s inhabitants, allowing them to sustain larger populations and develop robust trade networks. While the U.S. later exploited guano in the late 1800s for its own imperial gains, the Peruvian kingdom recognized its power long before.
Archaeological Evidence
Archaeologists analyzed carbon, nitrogen, and sulfur isotope ratios in ancient maize cobs from the Chincha Valley. The presence of marine isotopes, combined with regional iconography featuring seabirds, strongly suggests the consistent use of guano as fertilizer. This method builds upon established archaeological techniques but focuses on sulfur, a less common analysis factor.
Why This Matters
The early adoption of guano fertilization is significant because it demonstrates advanced agricultural technology. “The origins of fertilization are important because soil management allowing large-scale crop production would have been key to allowing population growth,” explains Emily Milton, a study co-author at the Smithsonian Institution. Understanding how this kingdom thrived could shed light on their social dynamics and economic power.
Implications for Future Research
This discovery also complicates isotopic analysis used to reconstruct ancient diets. Applying marine fertilizer to terrestrial crops creates “false marine signals” in food products, potentially misinterpreting animal or plant-based diets. The work suggests that ancient agricultural practices may have influenced isotopic signatures in unexpected ways, requiring scientists to refine their methods.
The use of guano by this ancient kingdom underscores the ingenuity of pre-Inca civilizations and the enduring value of natural resources. It highlights how sustainable agricultural practices can drive societal development and raises questions about how access to such resources shaped power dynamics in the region.
