Indigenous people of the Amazon produced rich agricultural soil by adding charcoal, manure, and animal bones to the otherwise nutrient-poor dirt of the world’s greatest rainforest. The inputs allowed early indigenous people to farm their terra preta, or dark earth, sustainably in the Amazon. To date such practices are only known from the the Amazon and parts of Africa. But in a recent paper in the open access journal Forests scientists in Indonesian Borneo report on the first evidence of terra preta in Asia.
“Our surveys in East Kalimantan identified several sites where soils possess an anthropogenic [human-caused] development and context similar in several respects to the Amazon’s Anthropogenic Dark Earths. Similarities include riverside locations, presence of useful fruit trees, spatial extent as well as soil characteristics such as dark color, high carbon content (in some cases), high phosphorus levels, and improved apparent fertility in comparison to neighboring soils,” the researchers write, adding that, “local people value these soils for cultivation but are unaware of their origins.”
 Left: nutrient-poor Amazon natural soil. Right: terra preta, rich dark earth, produced by human impacts in the Amazon. Photo by: Bruno Glaser. |
Scientists and experts have become profoundly intrigued by terra preta since replicating the complex and still beguiling process could be a major solution to many of the world’s environmental and hunger problems. Enhancing nutrient-poor tropical soil could decrease deforestation through slash-and-burn agriculture, produce more food on less land, sequester significant amounts of carbon, and lessen the need for environmentally-damaging fertilizer.
Sampling several hundred sites near Malinau, Kalimantan researchers found intriguing evidence of possible terra preta on the island of Borneo, but say further research is necessary.
“Human activity appears to be the only plausible explanation, yet we are uncertain about the age of the soils, who created them, by what processes and in what historical period(s),” the researchers write. “Farmers recognize the dark soils and favor them for both annual and perennial crops, yet they do not know what led to their formation.”
CITATION: Douglas Sheil, Imam Basuki, Laura German, Thomas W. Kuyper, Godwin Limberg, Rajindra K. Puri, Bernard Sellato, Meine van Noordwijk, and Eva Wollenberg. Do Anthropogenic Dark Earths Occur in the Interior of Borneo? Some Initial Observations from East Kalimantan. Forests. 2012. doi:10.3390/f30x000x.
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