bet365 code newspaper comprehensively reports from foreign media The official website bet365 code University of Oregon recently published a message saying，The research team of Lucas Silva, professor of environmental studies at the school, found that，The fertile black soil in the Amazon region of northwest Brazil is not the result of farming，It is naturally formed。

　　　　，Some scholars believe，The ancestors bet365 code Amazon indigenous people have domesticated plants locally for a long time and burned some areas to wasteland，The ash formed increases fertility，Thereby reducing the well-known high acidity、Nutrient-poor Amazonian soil turned into fertile black soil suitable for farming。

Silva’s research team analyzed black soil samples collected near the confluence bet365 code Solimoes and Negro rivers in northwest Brazil。They found out，Calcium in the soil here、Phosphorus and other nutrients come from the upper reaches bet365 code river。These nutrients may have been formed after the vegetation in the upper reaches was exposed to fire，And was carried downstream because bet365 code flooding bet365 code river。By dating the soil，Researchers found，These nutrients were formed later than 8,000 years ago。After a long dry period from 8000 years ago to 4000 years ago，Climate change drives changes in river direction，The flooding water brought these nutrients to the confluence bet365 code two rivers。

Researchers such as Silva found，The nutritional content bet365 code land around the ancient settlements in this area is much higher than that of neighboring areas，This shows that these ancient residents chose fertile land to engage in agricultural activities，It is not their farming that makes the land fertile。

　(Yan Yong/Compiler)