Tuesday, February 10, 2009
I apologize if I upset anyone by posting about the immediacy of global warming yesterday. Goodness knows we already have enough to worry about without having to be concerned about the planet as well. Unfortunately, no matter what happens with the economic situation, we and our children still expect to wake up here every morning so that appears to make it the most important concern of all.
James Lovelock mentioned carbon sequestration in the interview so I went back to look up what I'd remembered reading about a novel concept, even though it's very old, you may not have heard about.
The Amazonian rainforest has some of the globe's richest soil that can transform poor soil into highly fertile ground. Scientists have a method to reproduce this soil - known as terra preta, or Amazonian dark earths - 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. Terra preta is soil that has been enhanced by black carbon, derived from charcoal, and other organic matter.
It is estimated that as much as 10 to 20% of the soils in the Amazon basin are terra preta soils. Only after realizing these numbers did archaeologists finally understand how there had been a sufficient agricultural base to support the vast ancient civilizations in the Amazon basin, civilizations that, until recently, had largely been written off as myth. Of course, we'd be somebody else's myth too if the plagues had wiped out all of us instead of only 90% back in 1300AD.
The super-fertile soil was produced thousands of years ago by indigenous populations using slash-and-char methods instead of slash-and-burn. Slash-and-char, on the other hand, actually reduces greenhouse gases by sequestering huge amounts of carbon for thousands of years and substantially reducing methane and nitrous oxide emissions from soils.
Johannes Lehmann of Cornell University, who has written books and numerous articles about bio-char says, "The result is that about 50 percent of the biomass carbon is retained and by sequestering huge amounts of carbon, this technique constitutes a much longer and significant sink for atmospheric carbon dioxide than most other 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."
So it really could be done. What do you think? Are we wise enough yet as a race to actually do something constructive to not only heal the earth but make her more beautiful and fruitful too?