Indigenous individuals might have deliberately created Amazon’s ‘black soil’

chicago —Indigenous peoples of the Amazon may have been deliberately creating fertile agricultural soil for thousands of years.

At archaeological sites in the Amazon basin, mysterious and unusually fertile soils dot the land. Scientists have long debated the origin of this “dark soil,” which is darker and more carbon-rich than surrounding soil.

Now, researchers show that the indigenous Kuikuro people of southeastern Brazil intentionally create similar soils around their villagesThe discovery, presented Dec. 16 at a meeting of the American Geophysical Union, provides evidence for the idea that long ago Amazonians also intentionally created the soil.

The fact that Kuikuro people made a dark Earth today is a “pretty strong argument” that people also made it in the past, says Duke University geochemist Paul Baker. He was not involved in the study.

In doing so, these early inhabitants may have inadvertently stored large amounts of carbon in the soil, said study leader Taylor Perron, an MIT geoscientist. The technology could provide a blueprint for developing ways to sustainably lock up atmospheric carbon in tropical soils to help combat climate change, he said.

Over millennia, indigenous peoples have transformed the Amazon

The Western world has long viewed the Amazon as a vast wilderness, relatively unexplored before the arrival of Europeans. Central to this argument is the idea that Amazonian soils are as nutrient-poor as other tropical soils, preventing its inhabitants from developing agriculture at the scale needed to support complex societies.

But a plethora of archaeological discoveries in recent decades—including Ancient urban centers discovered in Amazon in modern-day Bolivia – has shown that people were actively shaping the Amazons thousands of years before the arrival of Europeans (Serial Number: 5/25/22).

Most scientists today agree that the presence of black soil near archaeological sites means that Amazonians used this soil to grow crops long ago. But while some archaeologists believe people created the soil intentionally, others believe the dark Earth was formed through geological processes.

Perron and his colleagues reviewed a 2018 interview with Kuikuro people by a Kuikuro filmmaker. These conversations indicate that the Kuikuro villagers actively crafted Dark Earth— egpe In Kuikuro – using ash, food scraps and controlled combustion.

“When you plant where there is no eegepe, the soil becomes weak,” Elder Kanukekuro explained in an interview. “That’s why we throw ash, cassava skin and cassava pulp.”

The researchers collected soil samples from around the village of Kuikuro and the archaeological site in Brazil’s Xingu River basin. The team found “striking similarities” between Dark Earth samples from ancient and modern sites, Perron said. Both were much less acidic than the surrounding soil—likely due to the neutralizing effect of the ash—and contained higher levels of plant-friendly nutrients.

A dark Earth could store vast amounts of carbon in the Amazon

These analyzes also showed that dark soils contain, on average, twice the amount of carbon as surrounding soils. Infrared scans of the Xingu region showed that the region was covered with black dirt, and as much as about 9 megatons of carbon — the annual carbon emissions of a small industrialized country — could Its whereabouts are unknown in the area. Meeting.

That number, while preliminary, could swell to roughly the annual carbon emissions of the United States when all the dark Earth across the Amazon region is taken into account, Perron said.

Figuring out how much carbon the Amazon is actually storing could help improve climate simulations. But the researchers’ estimates are “huge extrapolations from very small data sets,” Baker cautions — a sentiment echoed by Perron.

Antoinette WinklerPrins, a geographer at Johns Hopkins University who was not involved in the study, said more data is needed to determine the true value of carbon stored in the Amazon’s black soil. Still, she said the research has profound implications for Amazon’s “past and future.”

On the one hand, the technology highlights how ancient peoples thrived in the Amazon by developing sustainable agriculture that also doubles as carbon sequestration. Darkening the Earth — or something like it — could be a way to mitigate climate change while supporting tropical agriculture as more and more greenhouse gases enter the atmosphere.

“People in ancient times figured out a way to store large amounts of carbon for hundreds or even thousands of years,” Perron said. “Maybe we can learn something from it.”