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Tue Jan 24, 2012, 12:41 PM

Soil’s Hidden Secrets—Shocking discoveries from the underground may shake up climate science

http://www.sciencenews.org/view/feature/id/337548/title/Soil%E2%80%99s_Hidden_Secrets
Soil’s Hidden Secrets
Shocking discoveries from the underground may shake up climate science

By Charles Petit
January 28th, 2012; Vol.181 #2 (p. 16)



Perhaps more important in the long run, the findings will bring a far deeper understanding of soil’s response to climate change. This new understanding may include whether soil will speed up the pace of warming or slow it down as atmospheric concentrations of carbon dioxide and other carbon-rich greenhouse gases build up. Soil scientists don’t question the urgency of dealing with fossil fuel emissions, but forecasting the course of global warming depends on understanding how the planet deals with carbon. Soil, for now, is a major wild card.

Soil organic material is about 60 percent carbon. Though highly fertile soils may contain only 1 to 3 percent organic material, a few kinds — in peat bogs or Arctic tundra — may be all compacted vegetation. In all, soil holds more than three times as much carbon as the amount found in aboveground vegetation or in the atmosphere. Carbon exists not only in living roots and myriad microbes, worms, fungi and other organisms that live on and near those plant parts, but also in accumulated material left behind by generations of plants that have come and gone.

If the bank of carbon held in the world’s soils were to drop by just 0.3 percent, the release would equal a year’s worth of fossil fuel emissions. But researchers need to answer many questions to learn whether and how the balance could tip. Why do some soil organics, such as rotting leaves near the surface and some several feet down, last only a season or two, while nearby there may be matter tens of thousands of years old or more? Microbes, most scientists agree, are key in decomposing such materials, but the factors that control the species at work, and why they may thrive in one spot and not another, are still mostly a mystery.



Instead, “we are recognizing more mechanisms of feedback,” says Bruce Hungate of Northern Arizona University in Flagstaff. “And most of them tend to make climate change worse.” While much of his time is spent on soil and nutrient dynamics in the southwestern United States, one project that Hungate joined in 1998 at the Kennedy Space Center in Florida sticks in his mind. It was in a stand of coastal scrub oak from which workers occasionally watched space shuttles roar toward orbit. He and researchers from several institutions, led by botanist Bert Drake of the Smithsonian Environmental Research Center in Edgewater, Md., mostly watched what happens to oaks in the air of the future.

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Reply Soil’s Hidden Secrets—Shocking discoveries from the underground may shake up climate science (Original post)
OKIsItJustMe Jan 2012 OP
tabatha Jan 2012 #1
OKIsItJustMe Jan 2012 #2
Tumbulu Jan 2012 #3
OKIsItJustMe Jan 2012 #4
Tumbulu Jan 2012 #5


Response to tabatha (Reply #1)

Tue Jan 24, 2012, 03:09 PM

2. Say, that looks like a cheery read!

Sigh…

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Response to OKIsItJustMe (Original post)

Wed Jan 25, 2012, 12:35 AM

3. I think about this a lot on my farm

I began growing an heirloom wheat about 10 years ago. It is an annual with yields of grain about 1/4 that or modern varieties. But it apparently has the root system of perennial grasses and can be grazed once- thus equal to a partial hay crop. The flavor is unique and significantly different from other wheats. It produces the same amount of grain in a drought year as in a wet year, always low yielding by our modern standards, but it is reliable and requires no input f water or fertilizer. And the soil is left full of root matter.

I keep thinking that we have to go back to plants that sequester lots of carbon. I am afraid that the reduction in what we are used to getting from these crops will make people go into shock, though.

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Response to Tumbulu (Reply #3)

Wed Jan 25, 2012, 09:27 AM

4. Thanks for your perspective

If more productive crops mean less carbon sequestration…

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Response to OKIsItJustMe (Reply #4)

Wed Jan 25, 2012, 12:10 PM

5. well, it seems that way to me....

at least if we define productivity as what is sellable from an acre of land. What can be hauled off of it and sold to others for feed or seed or consumption in some form.

Now perhaps these sorts of low yielding grain- high root matter wheats are appropriate for marginal soils, soils at the edges - the type 3's or worse.... but I was discussing this issue with a soils scientist who just returned from Sweden. She says that there are soils there that 100 years ago were almost pure peat- ie very high organic matter- which now are almost entirely sand. It was the opinion of the agronomists there that the new high yielding grain varieties simply mined the soil of the carbon and turned it into grain......so what happens now that it is all run out?

I fear that this type of ag (green revolution stuff- short statured plants with little root mass and high grain yields) has brought us to a place of unsustainable food production.

I see the problems, but am not at all sure of the answers......

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