The Amazon Rainforest is home to thousands of different types of plants, which have been thriving for a very long time. This may make many people think that the soil in the region is rich in nutrients, but that is actually far from the case. The Amazonian soil has been largely leached of nutrients and has been for a very long time. While the native plants can grow in the area thanks to things like deep roots or other adaptations, it makes it very difficult to grow crops that people use for food in this region.

This doesn’t fit, however, with the fact that we know that tribes of people throughout the region have been growing food for thousands of years. When researchers get a closer look, they find patches of what they call dark Earth, which is simply nutrient rich soil. This raised the question of how this dark soil got there and why. A study looked at this exact question and found that native tribes have been engaged in highly effective soil management efforts for thousands of years, and it continues to today.

The study, which was published in the journal Science Advances, also noted that the way this soil management was done helped to trap huge amounts of carbon in the soil and keep it there for long periods of time. This method may be able to be adapted in other parts of the world in an effort to combat climate change, but that is the topic of other studies.

When it comes to the people of the Amazon, study Author Taylor Perron talked about the problem that both ancient and modern indigenous people would have faced:

“If you want to have large settlements, you need a nutritional base. But the soil in the Amazon is extensively leached of nutrients, and naturally poor for growing most crops.”

So, scientists traveled to the Kuikuro Indigenous Territory in the Brazilian Amazon to analyze these areas of dark Earth to see how they got there and how they are sustained.

One of the first things that they noticed was that the Kuikuro II settlement would pile up organic waste in specific areas where they lived. This would include organic waste left over from fishing as well as ash from fires, and more. Over the course of a few years, the materials that they put down in an area would compost and form into dark Earth soil that was excellent for growing crops.

One of the study authors, Morgan Schmidt, explained what the indigenous people were doing to improve the soil they used:

“We saw activities they did to modify the soil and increase the elements, like spreading ash on the ground, or spreading charcoal around the base of the tree, which were obviously intentional actions.”

The team also compared the soil in this area to soil that was from areas where no modern tribes so they could see if the ancient inhabitants used the same strategies for improving the soil. They had some soil samples that were nearly 5000 years old all the way down to just 300 years old.

What they found was that the dark Earth from these ancestral areas was very similar to that of modern tribes. This indicates that the method of improving soil has been used by these tribes and passed down over the generations.

Modern farmers and environmentalists can learn a lot from the soil management strategies that these Amazonian tribes have been using for thousands of years.

If you thought that was interesting, you might like to read a story that reveals Earth’s priciest precious metal isn’t gold or platinum and costs over $10,000 an ounce!