[HN Gopher] A soil-science revolution upends plans to fight clim...
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A soil-science revolution upends plans to fight climate change
Author : theafh
Score : 93 points
Date : 2021-07-27 16:37 UTC (6 hours ago)
(HTM) web link (www.quantamagazine.org)
(TXT) w3m dump (www.quantamagazine.org)
| omegaworks wrote:
| Makes sense, and underscores why the loss of permafrost is
| catastrophic. Cold conditions impede the activity of microbes
| that metabolize soil.
| strait wrote:
| Another example of an article selectively picking bits and pieces
| to support a sensational and false conclusion. The discussion of
| oxygen exposure was conveniently left out. Why focus so much on
| the concept of recalcitrant carbon when microbes will break down
| rock and even petrochemicals under the right conditions?
|
| Oxygen is a dominant factor in accelerated decomposition. Carbon
| is continually sequestered in healthy soils where plant roots
| will die back periodically, both seasonally and from grazing
| action. Much of the spent root carbon is sequestered in the soil
| as the limited local oxygen is used in partial decomposition,
| replaced with gases that serve to preserve and dilute whatever
| small amount of oxygen may later infiltrate the soil, depending
| on depth in soil.
|
| This is the same concept seen when lacto-fermenting vegetables in
| a jar. Enough salts would effectively halt decomposition, but
| just a fraction of the salt is needed when the CO2 generated from
| the lacto bacteria flushes out the oxygen. The rising acid and
| falling oxygen gradually drive the microbial activity toward
| zero.
| Robotbeat wrote:
| Lack of oxygen may make it even worse. Evolution of methane
| from decaying organic matter in soil in an anoxic environment
| would be much worse than CO2 in terms of global warming.
|
| However, I'm not a soil scientist.
| hosh wrote:
| Biochar.
|
| It lasts for at least a couple thousand years, and is considered
| a long-lasting soil amendment.
|
| The presence of biochar creates habitats for those microbes and
| conserves nutrients, making the soil fertile, even in areas like
| the Amazon where rainfall normally washes away nutrient
| accumulations. It can be made with processes that sequesters
| carbon, both in the charring stage (via gassifier designs
| optimized towards sequestering) and during the inoculation stage
| where it can capture greenhouse gases emitted by a compost pile.
| throwaway894345 wrote:
| This sounds really interesting. Do you have any reading
| recommendations (links or books)?
| kaybe wrote:
| I can also recommend this wikipedia article and its
| surroundings:
|
| https://en.wikipedia.org/wiki/Terra_preta
| Jenkins2000 wrote:
| I found these videos very interesting:
|
| https://www.youtube.com/watch?v=svNg5w7WY0k&t=5s
|
| This is on my to-do list:
|
| http://climatechangeacademy.com/courses/carbon-removal/4
|
| https://bootup.airminers.org/
|
| I found a lot of information from comments here:
|
| https://news.ycombinator.com/item?id=27822694
| jbotz wrote:
| There is one way of storing carbon in the soil for the long term:
| biochar[0]. Biochar is organic matter heated anaerobically
| (pyrolysis) until it turns into something like charcoal. Biochar
| is stable for a long time. You can then bury that in the soil...
| it seems to improve the soil by providing surface area for soil
| micro-organisms and to store nutrients. This could be done on a
| very large scale, and pyrolysis can actually be energy positive
| because you can burn the hydrogen that's released to perform the
| pyrolysis and still have energy left over.
|
| This may be one of our best options, and we should accelerate
| more research in that area.
|
| [0] https://en.wikipedia.org/wiki/Biochar
| chris_va wrote:
| > still have energy left over
|
| ... if it's dry biomass.
|
| A bit of humidity would likely tip that the other way, unless I
| am doing the math wrong.
| nine_k wrote:
| Money quote:
|
| _<<But over the past 10 years or so, soil science has undergone
| a quiet revolution, akin to what would happen if, in physics,
| relativity or quantum mechanics were overthrown.
|
| ...
|
| Soil researchers have concluded that even the largest, most
| complex molecules can be quickly devoured by soil's abundant and
| voracious microbes. The magic molecule you can just stick in the
| soil and expect to stay there may not exist.
|
| ...
|
| The consequences go far beyond carbon sequestration strategies.
| Major climate models such as those produced by the
| Intergovernmental Panel on Climate Change are based on this
| outdated understanding of soil. Several recent studies indicate
| that those models are underestimating the total amount of carbon
| that will be released from soil in a warming climate. In
| addition, computer models that predict the greenhouse gas impacts
| of farming practices -- predictions that are being used in carbon
| markets -- are probably overly optimistic about soil's ability to
| trap and hold on to carbon.>>_
| beerandt wrote:
| This is being used beneficially at some superfund sites- they
| basically wait for some natural microbe to emerge that
| neutralizes or otherwise treats the prevailing contaminant,
| sample it, figure out how to maximize it's metabolism, then
| devise a way to assist the in situ conditions to become ideal.
| Maybe some wells, pumps, plants, or chemicals are
| installed/introduced, and then it's just a monitoring expense.
| [deleted]
| 8note wrote:
| I'm surprised that they didn't find long lasting plastics in the
| soils
| Jenkins2000 wrote:
| Is biochar a potential solution?
| legulere wrote:
| The first study I found on google seems to suggest that biochar
| lasts for a pretty long time but also decomposes:
| https://www.sciencedirect.com/science/article/abs/pii/S00380...
| Jenkins2000 wrote:
| If I'm reading that correctly, they say it should last about
| 4,000 years which should get us pretty far.
| kickout wrote:
| Bluntly, yes it is.
| phkahler wrote:
| This totally ignores what happens to dead biomass in the very
| long term. It turns into coal. If that's not sequestering carbon
| I don't know what is.
| jbotz wrote:
| Aside from time, you also need a stricly anaerobic environment
| under pressure for that to happen.
| CorrectHorseBat wrote:
| Isn't coal from before dead biomass could be decomposed?
| collaborative wrote:
| Yes
| waterheater wrote:
| "One teaspoon of healthy soil contains more bacteria, fungi and
| other microbes than there are humans on Earth. Those hungry
| organisms can make soil a difficult place to store carbon over
| long periods of time."
|
| The natural respiration of soil microbes is small compared to how
| much carbon can be naturally sequestered in healthy soil due to
| sustainable agricultural practices.
|
| Healthy soil is well-known to hold substantial amounts of carbon,
| right along side such organisms. The development of unsustainable
| agricultural practices (monocultures, single-planting seasons,
| letting fields lie fallow, tilling, chemical sprays, essentially
| Monsanto's entire business model) has destroyed soil biodiversity
| and health. Healthy soil can absorb an inch of rain every few
| minutes. Fields flood (and crops are subsequently lost) because
| the ground is hard and crusty, preventing soil absorption. If
| more cropland soil had the healthy consistency of cottage cheese,
| flooding wouldn't be an issue.
|
| Yes, forced carbon sequestration might not work in the presence
| of healthy soil. However, fixing the deficient soils created
| across the world from unsustainable industrial agriculture
| practices will naturally sequester carbon. I would love to know
| exactly how much carbon no longer is trapped in our soils that
| once was due to the last 100+ years of unsustainable
| industrialized agriculture.
|
| https://www.youtube.com/watch?v=uUmIdq0D6-A
|
| https://microbiometer.com/improving-soil-health-and-carbon-c...
| jbotz wrote:
| As someone who has practiced (or tried to) sustainable
| agriculture in the tropics, I have to say that I've long ago
| become dubious about the whole idea of storing carbon in the
| soil. I think in cold climates, under dense forest growth,
| maybe more carbon accumulates than the microbial life can
| consume, up to a point, but in the tropics that sure doesn't
| seem to be the case. Most of the soils I've seen have
| essentially no carbon content below the first few
| centimeters... all the nutrients are in the litter layer above
| the soil, and most of the native plants will grow their feeder
| roots right into that litter (mulch). With a lot of effort and
| a lot of mulch, you can start to accumulate a bit more carbon
| in the soil, and a lot of crop plants sure appreciate that, but
| by far most of your mulch is going to disappear amazingly fast
| if you don't keep applying more, and then that bit of soil
| carbon quickly disappears, too. You can't build those deep,
| black, "healthy" soils you see in temperate climates in the
| tropics. At a guess I would say 99% of the carbon in tropical
| rain forests is in the living matter.
|
| And the problem is that with global heating, the tropics are on
| march toward the poles.
| [deleted]
| Jenkins2000 wrote:
| It seems that the rich black soil in the Amazon was man-made
| and has lasted thousands of years:
|
| https://en.wikipedia.org/wiki/Terra_preta
| jbotz wrote:
| Right. That's biochar. See my top-level comment.
|
| But note that this is not all or most of the soil in the
| Amazon, by a long shot... the "terra preta da Amazonia"
| exists in isolated patches where humans had been conducting
| slash-and-burn agriculture for hundreds of years. _Most_ of
| the soil of the Amazon region is just like any other
| topical soil, nutrient and carbon poor.
| aaron695 wrote:
| > Indeed, radioactive dating measurements suggest that some
| amount of carbon can stay in the soil for centuries.
|
| This is the only quote that matters. We literally know it works.
|
| Yet the world is so so broken the facts don't matter.
|
| We have the observable working model, but the environmental
| industrial complex needs to keep its minions in a constant state
| of panic which allows it to keep its control.
|
| A healthy human being would see this article as how amazing our
| understanding of soil science is getting.
|
| Just last week there was an article on increasing plant root
| length and increasing productivity that's working in field tests.
| Increasing soil depth just a little in farmland is a huge change.
| Nothing is upended.
| https://www.nature.com/articles/s41587-021-00982-9
|
| This is interesting around invasive species
| https://onlinelibrary.wiley.com/doi/10.1111/gcb.15769
| DennisP wrote:
| What that quote doesn't tell me: if I bury carbon today, will
| 99% or 1% of it stay for centuries?
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(page generated 2021-07-27 23:00 UTC)