Ancient Amazonians created mysterious ‘dark earth’ on purpose

Mysterious patches of fertile black soil pepper the verdant Amazon rainforest. They sit in stark contrast with the reddish, eroded soil that dominates the basin. Researchers have long thought this Amazonian dark earth—or terra preta —was created by pre-Hispanic Indigenous civilizations, which have inhabited the region for millennia, but it wasn’t clear how. Now, a multidisciplinary team of scientists and Indigenous partners suggests the ancient Amazonians intentionally created the rich soil thousands of years ago to better foster their crops, and that their modern-day descendants are still making new terra preta today. “This could change everything,” says Lucas Silva, an environmental scientist at the University of Oregon who was not involved in the new study. If the study holds up, he says, it would be the first demonstration of modern creation of dark earth that others can replicate. But he’s not convinced the process is as fast and simple as the new study suggests. “I don’t think we’re there yet.” The Amazon’s terra preta is much darker—black or dark brown—more fertile, and holds much more organic carbon than most of the region’s soils. Crops grow better in it because of its high phosphorus, nitrogen, and calcium content. And because of its supercharged carbon content, scientists consider it an important carbon reservoir that sequesters greenhouse gases. Terra preta is usually found near ar...
Source: ScienceNOW - Category: Science Source Type: news