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Originally Posted by Michaelangelica
If glomalin stores 1/3 + of the world's carbon. . .?!!!!!!
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Care please. That's
soil carbon. Also the carbon in glomalin molecules is fairly insignificant (4-5% of total soil C at best) compared to the carbon trapped in glomalin-based aggregates. Hence "hiding place" in the USDA article's title. It is the aggregates that matter, just as it is aggregates (whether they turn out to be glomalin-based or not) that matter most to terra preta's properties.
Much of the other 2/3 is in humin (not same as humic acid), which roughly translates as stuff we know is decomposed organic matter but have no idea of its detailed origins. There may well be another couple of glomalins (in terms of importance) waiting to be discovered in humin formation.
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Another extraordinary finding was that elevated carbon dioxide levels encouraged mychorrizae to work overtime. Working with a consortium of scientists from UC-Davis and Stanford, Wright simulated CO2 projections for the year 2100 and observed ramped up glomalin production, with thriving fungi.
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This is out of date now, having been based on a large one-off expeirmental increase in CO2. More realistic gradual increases do not have a significant effect. (Klironomos et al (2005) Nature 433(7026) pp.621-4)
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No one has mentioned worms?
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The bodies of living things (worms, bacteria, mycorrhizae, etc) contribute a lot less than 1% of total soil carbon. (Rillig et al (2001) 'Large contribution of arbuscular mycorrhizal fungi to soil carbon pools in tropical forest soils',
Plant and Soil 233(2), pp. 167-177. Their role is more to make soil a dynamic environment, and in so doing to release global warming gases from it.
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The S.A.Indians say Terra preta soil "grows". I am inclined to believe them. They have been right about everything else.
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I am not, and no they haven't. Laura German catalogues a series of highly variable and sometimes mistaken beliefs in her chapter in
Amazonian Dark Earths, a couple of which I mentioned in my response to Philip. Indeed, what have they been right about? What else besides the garbage disposal and land management strategies that produced dark earths? And in the case of terra preta (rather than mulata) the researchers are divided as to whether that was intentional. Until evidence of soil growth is produced, I think it more likely to be a misinterpretation of strong recovery under fallowing.
M
