This could be great news for food security and climate change – and it's been around for 700 years

For the last 700 years women in Ghana and Liberia have been using a valuable farming technique that modern-day agronomists have only recently figured out. It transforms depleted soil into “enduringly fertile” farmland.

A team of anthropologists and scientists studied almost 200 sites in the two West African countries and found that women added kitchen waste and charcoal to nutrient-poor tropical soil. The resulting rich black soil, which the researchers call “African dark earths,” could help countries adapt to the effects of climate change as well as improve agriculture not just in Africa but in resource-poor and food-insecure regions around the world.

“This simple, effective farming practice could be an answer to major global challenges such as developing ‘climate smart’ agricultural systems which can feed growing populations and adapt to climate change,” said James Fairhead, an anthropologist from the University of Sussex and co-author of the study.

Food availability has improved almost everywhere since the 1990s, but progress has been slow in sub-Saharan Africa, Central America and southern Asia. In 2015, 795 million people (pdf) around the world were still undernourished—in Africa 23% of the population (pdf. p.3) was still considered hungry, according to the United Nations Food and Agriculture Organization.

African dark earths can handle more intensive farming on less land—the soil stores between 200% and 300% more organic carbon than other soils. It also traps carbon and cuts down on greenhouse gases in the atmosphere, according to the study. Researchers have come across similar soil in South America, there known as terra preta, or”black earths.” (Home gardeners have also been using ash and kitchen waste in soil for years.)

“What is most surprising is that in both Africa and in Amazonia, these two isolated indigenous communities living far apart in distance and time were able to achieve something that the modern-day agricultural management practices could not achieve until now,” said Dr Dawit Solomon, a senior research associate from Cornell University and one of the study’s authors.

Soil scientists have come across African dark earths before but misidentified the soil as a natural feature of the landscape, according to Fairhead. “Tthe question arises: Why has it taken this long for them to be noticed and investigated. After all, soil scientists have been working on the continent for more than a century,” Fairhead tells Quartz.

“We trace the answer back to the colonial period and to…disciplinary practices and funding of soil science that was disinterested in and disrespectful of indigenous farming wisdom,” he said.