Terra preta is in the news today. What is terra preta? It refers to expanses of very dark, fertile anthropogenic soil found in the Amazon Basin. It gets its name from its high charcoal content. It is also called “Amazonian dark earth” or “Indian black earth.” The full name in Portuguese is “Terra preta do índio” or “Terra preta de índio”. This isn’t a subject that I would normally touch, but it is very interesting to understand and realize how vital the Amazon is to us. The search for that pot of gold in the Amazon Rainforest may lie in terra preta. It is a potential gold mine in and of itself. You see, some of the richest soil that can transform poor soil into highly fertile ground lies in terra preta.
So, naturally, I went digging for more information on this fascinating subject. According to Science Daily, scientists have a method to reproduce this soil and say it can pull substantial amounts of carbon out of the increasing levels of carbon dioxide in the Earth’s atmosphere, helping to prevent global warming. That’s because terra preta is loaded with so-called bio-char — similar to charcoal.
“The knowledge that we can gain from studying the Amazonian dark earths, found throughout the Amazon River region, not only teaches us how to restore degraded soils, triple crop yields and support a wide array of crops in regions with agriculturally poor soils, but also can lead to technologies to sequester carbon in soil and prevent critical changes in world climate,” said Johannes Lehmann, assistant professor of biogeochemistry in the Department of Crop and Soil Sciences at Cornell University, speaking today (Feb. 18) at the 2006 meeting of the American Association for the Advancement of Science.
Lehmann, who studies bio-char and is the first author of the 2003 book “Amazonian Dark Earths: Origin, Properties, Management,” the first comprehensive overview of the black soil, said that the super-fertile soil was produced thousands of years ago by indigenous populations using slash-and-char methods instead of slash-and-burn. Terra preta was studied for the first time in 1874 by Cornell Professor Charles Hartt.
Whereas slash-and-burn methods use open fires to reduce biomass to ash, slash-and-char uses low-intensity smoldering fires covered with dirt and straw, for example, which partially exclude oxygen.
Slash-and-burn, which is commonly used in many parts of the world to prepare fields for crops, releases greenhouse gases into the atmosphere. Slash-and-char, on the other hand, actually reduces greenhouse gases, Lehmann said, by sequestering huge amounts of carbon for thousands of years and substantially reducing methane and nitrous oxide emissions from soils.
“The result is that about 50 percent of the biomass carbon is retained,” Lehmann said. “By sequestering huge amounts of carbon, this technique constitutes a much longer and significant sink for atmospheric carbon dioxide than most other sequestration options, making it a powerful tool for long-term mitigation of climate change. In fact we have calculated that up to 12 percent of the carbon emissions produced by human activity could be offset annually if slash-and-burn were replaced by slash-and-char.”
In addition, many biofuel production methods, such as generating bioenergy from agricultural, fish and forestry waste, produce bio-char as a byproduct. “The global importance of a bio-char sequestration as a byproduct of the conversion of biomass to bio-fuels is difficult to predict but is potentially very large,” he added.
Applying the knowledge of terra preta to contemporary soil management also can reduce environmental pollution by decreasing the amount of fertilizer needed, because the bio-char helps retain nitrogen in the soil as well as higher levels of plant-available phosphorus, calcium, sulfur and organic matter. The black soil also does not get depleted, as do other soils, after repeated use.
“In other words, producing and applying bio-char to soil would not only dramatically improve soil and increase crop production, but also could provide a novel approach to establishing a significant, long-term sink for atmospheric carbon dioxide,” said Lehmann. He noted that what is being learned from terra preta also can help farmers prevent agricultural runoff, promote sustained fertility and reduce input costs. Source: Science Daily
This is very fascinating as we strive for green living and viable sustainability measures. Terra preta may very well be the next black gold.
Filed under: Amazon Basin, Black Soil, Charcoal rich, Terra Preta
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