Right. That's biochar. See my top-level comment.

But note that this is not all or most of the soil in the Amazon, by a long shot... the "terra preta da Amazonia" exists in isolated patches where humans had been conducting slash-and-burn agriculture for hundreds of years. Most of the soil of the Amazon region is just like any other topical soil, nutrient and carbon poor.

But biochar establishes the fact that carbon can be (semi-?)sequestered by a sustainable human agricultural process, this scheme has been implemented on a large scale in the past, and similar schemes could be implemented in future ag systems. That’s not a trifecta you hit very often in complex systems of any sort.

Upshot: if you are a young scientist/engineer/agronomist/ag economist and want to do real hands-on exploratory science where everybody is in the dumb club, and still make a significant direct middle/long-term difference in the world and its population, soil science could be your ticket.

PS: The content of the article is great. The click-bait title is absurd.