Ancient Amazonians Likely responsible for Amazonian ‘Dark Earth’

Recent research has resulted in evidence that Ancient Amazonian inhabitants could be responsible for patches of fertile soil in the Amazon known as ‘Dark Earth’.  For many years Archaeologists have been finding fertile soil in hundreds of sites across the Amazon.  These patches have been found mainly around settlements and can date back thousands of years.  Whilst much of the Amazons soil is extremely difficult to cultivate crops on, due to the majority of carbon and nutrients being trapped within decaying trees and plants that is quickly recycled and therefore makes it harder to reach the soil, the ‘Dark Earth’ has high levels of carbon, more than 800 Pg C , as well as many nutrients that allows crops to be cultivated much easier, and therefore makes it more viable for human habitation.  
There is an ongoing debate in Archaeology as well as Anthropology as to whether the Dark Earth was created intentionally by Ancient Amazonian civilisations or rather, created by fires and floods that occurred before settlers inhabited the region.  Recent research undertook by Massachusetts institute of technology suggests that Ancient Amazonians were responsible for the Dark Earth, and even that their descendants, modern Amazonian inhabitants are continuing the process that they undertook to help fertilise the earth1.  The research shows how modern day Amazonians spread organic refuse, such as ash and charcoal, to fertilise the ground to create the Dark Earth1.  The farmers call the Dark Earth Eegepee. An interview with one of the farmers, named Kanu, revealed the locals knowledge of increasing the fertility of the soil via spreading organic waste.
One of the main arguments for Amazonians creating the Dark Earth is the similarity between Ancient and Modern Dark Earth.  Not only were they similar in their composition, but they also both were enriched in the same elements, such as phosphorus and carbon1.  As well as this, the way in which the Dark Earth was found suggests human interference.  The Dark Earth is generally found in radial patterns, with the most fertile found in the centre of ancient and modern settlements.  This data was found by the analysis of Archaeological and modern sites throughout the Upper Xingu region.  
If it is true that the soil was created by the Ancient and Modern farmers then Dark Earth could be used to help control climate control.  As stated earlier, Dark Earth can contain more than 800 Pg C which would mean that this earth could be used to contain carbon as a carbon sink.  If we could figure out how to use the farmers methods on a large scale It could result in an effective way of storing carbon in a way that we can be sure will last for a long time, as the ancient soil has shown.
However, on the other side of the discussion is the belief that the Dark Earth was created primarily by natural events in the area.  This argument does not rule out indigenous peoples influence on the soil as agricultural practices, such as controlled burning, could have helped develop the Dark Earth as well as natural events .  One piece of evidence that goes against the idea that Indigenous people were responsible for the Dark Earth is the Archaeological artefacts that have been found in Dark Earth patches around 7600 years ago.  This would contradict indigenous people being responsible for the soils fertility as it is currently believed that Amazonian people transitioned from being nomadic to sedentary around 6600 years ago.  The research done by the University of Oregon shows that there would have had to been large populations would have had to been managing soil for thousands of years before agriculture emerged in the Amazon.  It seems therefore more likely that indigenous people instead chose to settle in areas with already fertile soil.  
One of the explanations for natural events causing the Dark Earth would be the Amazon river flooding at various points throughout history.  If the river were to overflow, it would cause there to be a difference in carbon and nutrient amounts in flooded and non-flooded areas