UC Santa Barbara researcher conducts first-ever global-scale evaluation of the role of soil minerals in carbon storage
University of California – Santa Barbara
One answer to our greenhouse gas challenges may be right under our feet: Soil scientists Oliver Chadwick of UC Santa Barbara and Marc Kramer of Washington State University have found that minerals in soil can hold on to a significant amount of carbon pulled from the atmosphere. It’s a mechanism that could potentially be exploited as the world tries to shift its carbon economy.
“We’ve known for quite a long time that the carbon stored on minerals is the carbon that sticks around for a long time,” said Chadwick, co-author of the paper, “Climate-driven thresholds in reactive mineral retention of soil carbon at the global scale,” published in the journal Nature Climate Change. How much carbon the soil can take and how much it can keep, he said, are dependent on factors including temperature and moisture.
“When plants photosynthesize, they draw carbon out of the atmosphere, then they die and their organic matter is incorporated in the soil,” Chadwick explained. “Bacteria decompose that organic matter, releasing carbon that can either go right back into the atmosphere as carbon dioxide or it can get held on the surface of soil minerals.”
Water plays a significant role in the soil’s ability to retain carbon, say the researchers. Chadwick and Kramer consulted soil profiles from the National Ecological Observatory Network (NEON) and from a globally representative archived data set for this first-ever global-scale evaluation of the role soil plays in producing dissolved organic matter and storing it on minerals. Wetter climates are more conducive to formation of minerals that are effective at storing carbon, therefore much of the Earth’s estimated 600 billion metric tons of soil-bound carbon is found in the wet forests and tropical zones. Arid places, meanwhile, tend to have a “negative water balance” and can thus store far less organic carbon. According to Chadwick, the findings suggest that even a small, strategic change in the water balance could drive greater carbon storage.
“That’s not as easy as it sounds, because water is dear,” Chadwick said, and in places where a shift in soil moisture could tip the water balance from negative to positive — like the desert — there’s not enough water to begin with. “So, it doesn’t actually make any sense to spread a lot of water out over the landscape because water is hugely valuable,” he added.
Climate change is another driver to consider. As the Earth warms, microbial activity increases and, in turn, so does the potential for carbon to be released back into the atmosphere at a greater rate than photosynthesis can draw it out. Increased evaporation due to a warmer climate also decreases the amount of water in the soil available to dissolve and move carbon to minerals deep below the surface.
There is still a lot to investigate and several hurdles to overcome as soil scientists everywhere consider ways to tip the balance of the Earth’s soil from carbon source to carbon sink, but according to these researchers, understanding this relatively little-known but highly significant carbon storage pathway is a start.
“We know less about the soils on Earth than we do about the surface of Mars,” said Kramer. “Before we can start thinking about storing carbon in the ground, we need to actually understand how it gets there and how likely it is to stick around. This finding highlights a major breakthrough in our understanding.”
Among the next steps for the scientists is to date the mineral-stored carbon in the soil to better understand how long these reactive (typically iron and aluminum) minerals can keep carbon out of the air. “Which is really important if we’re going to put effort into trying to store carbon in the soil,” Chadwick said. “Is it going to stay there long enough to matter? If we put it in and it comes out five years later, it’s not solving our problem, and we ought to be barking up a different tree.”
###
Any scientist that says “we know less about the soils on Earth than we do about the surface of Mars” has immediatly and obviously removed themselves from serious consideration. Stop trying to change the Earth, or at least figure out how to only change the part you want to live in and leave the rest alone.
Wait a minute. Didn’t they say that increasing carbon dioxide in the atmosphere raises the temperature and therefore increases the amount of water vapour? Wouldn’t that result in an increase in soil absorption on its own?
No no. It’s like when you go running and you inhale more. Your lungs blow up and explode. Well I never ran anywhere, but I studied about in my post doc.
“and in places where a shift in soil moisture could tip the water balance from negative to positive — like the desert — there’s not enough water to begin with. “
Perhaps when Kramer said ‘we’ he meant himself and Chadwick. As a soil scientist myself for several decades, I personally know much more about the soils on earth than the surface of Mars. But, I do love to read about Mars and I love the pictures from Mars even more so.
There is simply no way to introduce the quantities of CO2 that they want to sequester into soil. What? We are going to be running around jabbing pipes into the soil all over the place, pumping in CO2 for a time and then move on. It’s a joke, particularly as they seem to think it’s a serious observation.
Any policy or project based on the idea of reducing CO2 emissions or sequestering CO2 is wrong. Maybe do the policy or project to save money or be more efficient. Because CO2 cannot detectably warm the climate, if at all, and is instead greening the planet, the war on CO2 is just wrong. We need more CO2 not less.
Biofuels is a great example of misguided policy, also a great example of crony capitalism, and has nothing to do with decreasing emissions. It actually take more energy to make ethanol for gasohol than you get back from burning it.
The reason nuclear energy is not suggested is that there are already nuclear power plant companies that can do the construction. The point of crony capitalism is to create new businesses that do something no one else is doing and give the start up funds to friends, family, and fellow politicians. We have new wind turbine, solar panels, solar collection, and biofuels—all worthless but worth millions to the cronies.
“It actually take more energy to make ethanol for gasohol than you get back from burning it.”
That would be a true statement. There are no free lunches. No perpetual motion machines exist, except maybe the Univetse itself.
Yes, yes, yes ~~ so wonderfully refreshing to read your comment. I am not a scientist but I go have a very inquisitive mind! In my later years I have learned to never trust but to investigate everything, even then I’m still, at times, caught in a hoax. Discouraging at best, pissed off most of the time with the crap being spewed all over social media as truth. Even more discouraging is the fact that Americans latest crop of university graduates can’t even name countries on a map! And these uneducated lemmings are voting and making decisions for our lives. And most all believe the sky is falling, the earth will be totally under water within the next 10 years and CO2 is killing us!
GID HELP US!
Rant over
Ron Long,
Yes! We know very little about the subsurface profiles on Mars. It seems to e mostly regolith and blowing sands instead of soils with well-defined horizons. We don’t know for sure if there are perchlorates on the surface of Mars or not. He seems to be someone misstating the facts to appeal for more funding.
Actually the best form of long term Carbon storage has been in the form of carbonate rocks. So much carbon was sequestered via carbonate rocks that we almost did not have enough carbon available for plants during the past ice age for life to continue. Our burning of fossil fuels has helped to lessen the carbon crisis without any effect on the Earth’s climate. Some day in the future to allow life to continue on this planet we will have to convert carbonate rock into CO2 on a large scale so that plants will have sufficient CO2 to survive.
Thank you William – very well said.
I first wrote about CO2 starvation circa 2012 or earlier.
http://wattsupwiththat.com/2012/08/30/north-american-energy-independence-by-2020/#comment-1070931
[excerpt]
(Plant) Food for Thought:
One reasonable scenario for the end of life on Earth is insufficient atmospheric CO2 to support photosynthesis, as CO2 is permanently sequestered in carbonate rocks, hydrocarbons, coals, etc.
Since life on Earth could actually end due to CO2 starvation, should we be paying energy companies to burn fossil fuels to increase atmospheric CO2, instead of fining them due to the false belief that CO2 from fossil fuel combustion causes catastrophic global warming?
Could T.S. Eliot have been thinking about CO2 starvation when he wrote:
“This is the way the world ends
Not with a bang but a whimper.”
Regards, Allan
Correction:
I first wrote about CO2 starvation circa 2009 or earlier.
https://wattsupwiththat.com/2009/01/30/co2-temperatures-and-ice-ages/#comment-70691
It seems that George Carlin was wrong.
https://m.youtube.com/watch?v=7W33HRc1A6c
His supposition was that our purpose in life was to create plastics. It seems that our purpose could be to remove CO2 from sequestration so that life as we know it can continue.
A question please William:
In order to make CO2 we will have to roast a lot of limestone, and make a lot of CaO, and then what do we do with the CaO? If we use it to make concrete, the concrete will over time absorb CO2 from the atmosphere to cure, and then we are back where we started from – in terms of atmospheric CO2.
Maybe we would be better to (shock and awe) burn fossil fuels!!!
Best, Allan 🙂
“….and then what do we do with the CaO? ”
We could spray it on crop stubble to increase pH, break up the stubble and improve organic structure of the soil. Just a thought.
Mr Haas, I appreciate this argument very much and enjoy the expressions of absolute disbelief and horror on the faces of warmistas when I employ it.
https://wattsupwiththat.com/2017/03/15/study-why-co2-levels-are-lower-during-global-cold-periods/comment-page-1/#comment-2453942
I think we could be looking at an instant of geologic time. Even if I am out by a few million years, it still points out how utterly foolish it is to worry about CO2 being too high – it is clearly too low – and CO2 abatement schemes are utter nonsense.
Atmospheric CO2 is inexorably declining as it is being sequestered in carbonate rocks. In the last Continental Last Ice Age, atmospheric CO2 declined to about 180 ppm – next time it could drop lower, even closer to the extinction point of C3 plants at about 150-160 ppm.
It is a bit more complicated – a few plants (less than 1%) use the C4 photosynthesis pathway, including corn and sugar cane – but I doubt terrestrial life could survive for long on Sugar Frosted Flakes – notwithstanding the persistent rumour that “They’re Great!” 🙂
There are also CAM plants, so we can look forward to having pineapple with our Sugar Frosted Flakes.
Regards, Allan
__________________
Dr. Patrick Moore, a co-founder of Greenpeace, has also written on this subject:
https://wattsupwiththat.files.wordpress.com/2016/06/moore-positive-impact-of-human-co2-emissions.pdf
Executive Summary
This study looks at the positive environmental effects of carbon dioxide (CO2) emissions, a topic which has been well established in the scientific literature but which is far too often ignored in the current discussions about climate change policy. All life is carbon based and the primary source of this carbon is the CO2 in the global atmosphere. As recently as 18,000 years ago, at the height of the most recent major glaciation, CO2 dipped to its lowest level in recorded history at 180 ppm, low enough to stunt plant growth.
This is only 30 ppm above a level that would result in the death of plants due to CO2 starvation. It is calculated that if the decline in CO2 levels were to continue at the same rate as it has over the past 140 million years, life on Earth would begin to die as soon as two million years from now and would slowly perish almost entirely as carbon continued to be lost to the deep ocean sediments. The combustion of fossil fuels for energy to power human civilization has reversed the downward trend in CO2 and promises to bring it back to levels that are likely to foster a considerable increase in the growth rate and biomass of plants, including food crops and trees. Human emissions of CO2 have restored a balance to the global carbon cycle, thereby ensuring the long-term continuation of life on Earth.
***********************************
Carbonate rock sequestration is the method mother nature’s been using for eons to pull CO2 out of the atmosphere. Interestingly, because of the stability of the alkaline earth bi-carbonates in COLD water, more carbonate rocks form and more CO2 is sequestered in warm the tropical oceans. I suspect that if the amount of CO2 sequestered in shallow parts of the tropical oceans was comparted to the amount sequestered in wet tropical forests, the oceans would account for orders of magnitude more.
Hopefully that’s a long way off. When the time comes though, we can use cheap abundant fusion power as a power source to make cement out of limestone and save the planet. I reckon in 2-3 thousand years fusion will only be 30 years away.
When cement (in concrete) cures it absorbs CO2 again – probably a zero-sum game.
“Climate change is another driver to consider. As the Earth warms, microbial activity increases and, in turn, so does the potential for carbon to be released back into the atmosphere at a greater rate than photosynthesis can draw it out. Increased evaporation due to a warmer climate also decreases the amount of water in the soil available to dissolve and move carbon to minerals deep below the surface.”
Don’t bother to mention that photosynthesis will increase,
and microbial activity will always be dependent on the level of photosynthesis.
And a warmer climate will mean more rainfall.
Nope, silly science denier! Warmer temperatures only evaporate water and dry the forest. Then there will be huge forest fires. The water accumulates in the atmosphere. That’s what gives us an ECS of 6K.
Everything here on Earth, in the solar system was not created/done by accident. Why is it that climate ‘scientists’ believe they can do better than THE CREATOR. ~~ GOD
They think they are King Canute.
https://wattsupwiththat.com/2018/02/04/the-fantasy-of-accelerating-sea-level-rise-just-got-hosed/comment-page-1/#comment-2734412
[excerpt]
Leo above referred to a global warming hysteric as “a modern day Cnut”.
I still think a spell-check is in order.
Regards, Allan
They are not doing anything, just trying to determine Her moods, with no more success than anyone.
Prepare for any and all eventualities, don’t assume Her first try was just a one-off.
She’s relentless.
https://tallbloke.wordpress.com/2019/01/05/climate-models-fail-climate-warming-experiment-finds-unexpected-results/
It’s almost like you have to do a study to find out a study’s legitimacy. What cracked me up about this study is they used fake heaters on the control plots. That’s hilarious.
If we follow the money, they do studies to get grants. That is why we are caught in an endless cycle of studies. Arriving at politically correct findings opens up more government grants, gets you past peer review and gets you published allowing you to request more money for the next study. Sufficient publishing gets you paid speaker positions with per diem to the best conferences held at the best conference centers located in the best vacation spots in the world. Some alarmists think this is all about science. Silly alamists.
Well said. In others words, a racket, not science; unless one defines science as a bureaucracy of systematized knowledge used to facilitate economic/cultural privilege. Techno-mediocracy is probably a better term for that.
Yet another multiplier effect to be exploited by the warmist models.
More heat = less ability of the soil to hold CO2 etc. etc……
Allan Macrae “I first wrote about CO2 starvation circa 2012 or earlier”.
There is a symbiotic relationship between volcanic action (particularly the oceanic volcanoes) and life on earth.
Without volcanic activity the CO2 would become rapidly (paleological timneframe) sequestered into limestone and life on earth as we know it would cease.
We are doing the environment a favour by burning fossil fuels to liberate the sequestered carbon as plant food.
But it still gets back to the false belief that CO2 can retain heat, therefore the more CO2 in the atmosphere the higher the worlds temperature.
Snag is that it does not happen in the real world, but only in the models and the vivid imagenatiopn of the True Believers.
MJE
And here i was thinking the science was settled,
now what?
” therefore much of the Earth’s estimated 600 billion metric tons of soil-bound carbon is found in the wet forests and tropical zones. Arid places, meanwhile, tend to have a “negative water balance” and can thus store far less organic carbon.”
So tropical zones store most carbon abd are the warmest places on earth.
The poles are the coldest, most arid, with no photosynthesis and no carbon storage from plant decomposition.
How can they say that a warmer planet will have less soil carbon storage ?
There’s no end to the fun we can have ridiculing the “science” briefings from EurekAlert!
If arid places have a “negative water balance”, how long before they become bone dry? If moist areas have a “positive water balance”, how long before they become lakes?
Seriously, who writes this tripe?
the dry arid low nutrient aussie soils that are being “saved” by no till chem ag..
do NOT have the ability to rot down the left debris or even to maintain dungbeetles in many places.
by midsummer all activity ceases without rains
our soils do best with burning and the residue ploughed in adding carbon directly as well as other minerals and benefits of killing weed seeds and fungals moulds etc, as well as some pests.
all of which are an issue in left stubbles.
the mob doing this “study” should have read widely and realised a lot of older soils people know fr more than they do
you have/had/ some brilliant soils researchers in america and their works easily accessible
this crew is NOT in the running!
Excerpted from commentary:
“Yup”, and as the Earth warms, the outgassing of CO2 from the surface waters increase accordingly, ….. and at a far, far greater pace (and quantity) than the CO2 emitted by microbial decomposition.
And the 60-year Mauna Loa CO2 Record is testament of the above stated fact.
“… soil can hold on to a significant amount of carbon …”
Is there some reason why the climate cult insists on “carbon” instead of “carbon dioxide”? I’m guessing the number one reason is because carbon is black, and in terms of Dr. Stephen Schneider’s famous quote it’s more scary. There is no number two.
No – it is because the soil does not store the carbon as CO2.
I know the alarmists often say carbon when they mean CO2, but not in this case.
BillP – 7:36 am
No – it is because the soil does not store the carbon as CO2.
Guilty as charged )-: Post enough stuff on the internet and sooner or later you’re gonna step in it. So my turn in the barrel.
Oh, thanks for the reply – I guess.
Admirable response.
I wish climate alarmists would admit when they are wrong – or even that they might be wrong.
Steve C, in actuality, iffen they are talking sequestered C (carbon) in soil then the “climate scientists” and “greenies” should be referring to it as ……..
carbohydrates (sugars) – Any of the group of organic compounds consisting of carbon, hydrogen, and oxygen, usually in the ratio of 1:2:1, hence the general formula: Cn (H2O)
cellulose (C6H10O5)n
incomplete oxidation of carbon is “black” ……. crystalline carbon is translucent (diamonds)
“I’m guessing the number one reason is because carbon is black, and in terms of Dr. Stephen Schneider’s famous quote it’s more scary. ”
Well there ya go. Staring us right in the face. Carbonphobes are racist.
It’s all starting to make sense now. Climate solutions is just a dog whistle to trigger carbonphobes’ insidious closet racism.
sigh
where to begin
(and those who let this carbonoxide horse bolt by conceding the ‘trapped heat’ GHGE really do need their backsides kicking. to put it mildly)
Let’s go in here:
The problem here is that humans are Perfect Little Angels. They couldn’t *possibly* do anything wrong.
If they really imagine they wanna do what they say, it is very very very easy.
…..Quit ploughing
…..Quit throwing nitrogenous fertilisers around
…..Quit irrigating deserts to create ‘farmland’ (it only makes the desert larger in the medium term and poisons the soil with salt….
Places like… Aral Sea, Dead Sea, Sea of Galilee, Lake Baktigan(sp??), Whittlesey & Cambridge Fen, East Anglia as a whole, Aswan Dam (is gonna kill the Nile Delta), sucking water out of the Ogallala, etc etc etc
I saw a wheat farmer (epic yield he was getting – volcanic soil innit) from Punjab on TV some years ago.
He originally had a borehole that was 50 metres deep.
It dried up. Sank a new one to 300 metres.
At time of interview, it was drying up and he was planning a new borehole to 550 metres,
Sea level rise anyone?
I assert, yet again, that the so-far observed Climate Change is entirely due to the practices outlined above.
Of course, The Alert Reader ( sometimes I do wonder if anyone on this planet is awake, especially in what passes for ‘scientists’ ), the alert reader will see a ‘slight’ problem.
But of course, in their eagerness to have Excellent Fun checking willy sizes and in bar-room brawls, will trash the thoughts of a certain guy who predicted ‘A Problem’
Fine. Your way.
But another slight monster is appearing from behind the hill, inside our heads and caused in its entirety by the consumption of the very stuff that the ploughs, fertilisers and irrigators are producing…
The Apple Shaped bodies you see everywhere nowadays is another equally damaging monster (different sides of the same coin)
Is-cruel-consider-Dementia-divorce
Heartbreaking, would you treat an animal like that?
half-of-all-women-will-develop-dementia
At any one time, a sixth of the population in England aged 16 to 64 have a mental health problem
From here
Sense of humour (fail?)
How’s *your* Dry January going?
No alcohol safe to drink
Do be absolutely aware you are doing 2 consecutive Januaries (2019 and 2020)- with drought conditions prevailing between
Call it a Ridiculously Dry Dryness if you like, call what you like but but at some point in the 2nd half, you will become inspired to write a book about alcohol.
It will be a big book and there will Not Be One Single Good Word about the stuff between its covers.
If no pop is causing you grief, trust me, not least as I worked out this little bit of science all on my lonesome.
Silent Disco Parties Aren’t Just For Fun, They Can Also Help With Social Anxiety
The kids in the 80’s actually worked it out for themselves, they actually found a healthy use for computers via the electronic drum machine.
Otherwise, computers are as damaging as guns and knives in the hands of drunks.As Time Berners Lee effectively said recently.
Unfortunately, the chronically chemically depressed parents/teachers/elders/betters entirely misunderstood and thought the kids might actually be simply just ‘enjoying themselves’
Thus it had to be ruthlessly stamped out, at the time.
Now what have got? (see links above)
And the depletion of and subsequent lack of soil carbon is the root cause.
Now what?
(Call me paranoid if you think it helps.)
I am a bit worried if all those links work……
I’ve just worked it out…
All those Fat People are actually trying (and succeeding) to capture carbon.
Who Would Have Thunk?
Wonderful world.
Slightly of topic but Gordon Bennett…
‘ the only hope for avoiding catastrophic global warming is for a nuclear war to reduce human population and consumption.’
https://www.powerlineblog.com/archives/2019/01/green-weenie-of-the-week-nuclear-war-will-save-us.php?
The Amazon Indians practiced soil enrichment with charcoal on a very protracted basis, so much so that they terraformed a substantial amount of the basin.
Look up ‘terra preta’, they showed a way forward for large scale carbon capture on a sustainable basis.
Etudiant, in no way can the terra preta accumulation of carbon be extended globally. This accidental build-up occurred over thousands of years under relatively unique circumstances.
‘Arid places, meanwhile, tend to have a “negative water balance” and can thus store far less organic carbon.’ But with the greening of the planet arid places are becoming smaller little by little. Then when plants die off arid soil will give need matter to grow more plant life. It may take thousands and thousands of years but it will happen.
“As the Earth warms, microbial activity increases and, in turn, so does the potential for carbon to be released back into the atmosphere at a greater rate than photosynthesis can draw it out.”
As CO2 rises, plants grow larger and faster sequestering more “carbon” from the air. Carbon in, carbon out. Could there be a balance?
My thought as well. A good reviewer would have required that they attempt to quantify that balance before approving the paper for publication.
There is too much money in academic life.
And the the way to get some of it is shown in the above piece.
“Willikin jellikins guys–let’s dream up something that will attract grant money.”
I love that show!
🙂
The Weather Channel sez thar gonna be mo’ days above 86 degrees if we don’t git CO2 outta the air!
This seems to suggest geoengineering of the ground, rather than the atmosphere.
The result will be the same: billions will die.
Well the experiment was very poorly designed. 1) The warming expected is supposed to be accompanied by higher specific humidity (i.e. relative humidity would remain constant ~100%, but in warmer tropical air, it would contain more water). She might as well have put a bag of this stuff in her apartment and turned up the thermostat to get these results. Had they watered the plot, they probably would have got roughly what they thought they would.
2) It is admirable that actual empirical, real life, experiments (not what the clime syndicate call an experiment) were done, but experimental design is not a slap dab exercise. It requires rigorous attention to details, modelling scales and realistic magnitudes of the parameters of the tests. Science-lite generalist researchers like ecologists should consult seasoned experimenters, inside and outside of their fields to be sure you haven’t left something important out. Just like you should talk to a seasoned statistician about proper reduction of data.
Even the elevation of temperature was heavy handed. Let’s recap the theory: in a warming world, the tropics will remain essentially unchanged in temperature! The polar regions will warm the most. 4C increase in temperature for a tropical forest is far flung from any reality. Even, God forbid, if you were using Fahrenheit (and didn’t state it!).
An article here on WUWT a few years ago by a sea science specialist from Australia opined that almost all experiments involving affects of higher CO2, acidification, and elevated temperatures as stressors on sea life were totally invalid. He gave a tutorial on proper design, care of the sea creatures and plants and so on. Idjits were virtually cooking, pickling poisoning and traumatizing shellfish with their ham-handed designs and reporting ridiculous results.
They have cause and effect backwards. In the prairie, the plants grow extensive root systems to capture and hold water. The root systems die off and regrow annually, putting more organic carbon in the soil. Soil with large amounts of organic carbon holds more water.
” As the Earth warms, microbial activity increases and, in turn, so does the potential for carbon to be released back into the atmosphere at a greater rate than photosynthesis can draw it out.”
Really? So the soil is able to “create” carbon out of an undiscovered fusion reaction going on under out feet?
There is a limited amount of carbon in the soil…if it is depleted then carbon stops coming out of the soil. So if a warmer Earth is able to use more carbon from the soil, the amount used rises only until reestablishing a balance. The more carbon you can release, the more carbon in the cycle, the more lush the planet becomes.
These people sit around and wring their hands over a Natural Cycle that has existed (without man’s help) for hundreds of millions of years (assuming the presence of land plants here, you could argue it goes back several billions of years in the sea).
Sub-soil worldwide is well known already to be holding ~ 70% of soil organic carbon. It needs to be understood that top soil & sub-soil don’t behave the same to carbon made available.
Sub-soil holding carbon is a function of the size of aggregates made with carbon being larger than the size of aggregates made in top soil; it is “macro-aggregates” that are more stable in water. The macro- aggregates have more aggregated components which configure conformations of occlussion that contribute to the macro-aggregate’s stability in a way that acts to counter simple decomposition.
Most of soil organic carbon is derived from plant roots’ dead/sloughed cells & exudates/mucilage. The water parameter works in that with increased soil moisture there is greater soil microbial activity, while at the same time more root exudates spur more microbial growth.
Fungi use root exudates more than soil bacteria & as soil water goes up the ratio of soil fungi goes up in relation to soil bacteria. In top-soil root exudates do not diffuse as far from the roots as root exudates diffuse in the bulk of soil roots not occupying.
Root exudates include poly-saccharides that act as glueing agents for soil aggregates & so do fungi. Away from the immediate root zone (sub-soil) the fungi that lyse (die opening up) after multiplying on lots of far travelling root exudates then release their fungal glueing agents.
In other words sub-soil fungi create greater binding strength in carbon aggregates. Thus we note the counter-intuitive situation where tropical soils, which are notoriously prone to weathering & low fertility from repeated high rainfall, can actually be holding a lot of the global soil carbon – it’s the fungal factor.
Desert roots only add their diverse forms of organic matter in relatively lower amounts; without soil moisture to carry many of these away from the top-soil they are utilized more in the immediate root zone. What occurs in those conditions is smaller “micro-aggregates” which do not have substantial stability against decomposition.
As for elevated CO2 impact on soil organic carbon levels: remember that top-soil & the bulk of other soil do not automatically form aggregates the same. In an experiment where CO2 was increased 20% there was definitely more carbon aggregates formed in the top 15-45 cm of soil. However this increase of soil organic carbon did not carry through to the deeper soil & I contend it is not sensible to extrapolate the CO2 fertilization effect will lead to heaps (👓 Australian terminology) more carbon stably sequestered in the bulk of global soil.
Nice write-up, but why no reference to glomalin related soil protein? GRSP accounts for about 1/3rd of global soil carbon. GRSP is sloughed off by arbuscular mycorrhizal fungi which in turn get their carbon from root exudes:
http://char-grow.com/wp-content/uploads/pdf/Nichols.pdf
Glomalin is 30-40% carbon. There is relatively more glomalin in top soil than deeper soil; however, despite it’s lower proportion in deeper soil it is that deep glomalin which has the property of making macro-aggregates of soil organic carbon more stable. Glomalin dynamics are not easy to simplify as a linear factor since the conditions where the specific case considering it’s occurance vary.
What might be of general interest is that although chemical fertiliization (N-P-K type of products) reduce glomalin (by limiting some glomalin source fungi) if there is also soil ammendment with long term (on-going) manure application (in addition to the chemical N-P-K fertilizer) then there is still substantial glomalin contributing to an increase in soil organic carbon macro-aggregates. However, the glomalin dynamic in the case when excessive amounts of manure is utilized for soil ammendment everything does not play out the same; as in terms of desirably promoting the more desirable macro-aggregates (ie: more manure occassions more of other dynamics). See free full text on-line (2015): “Long-term manure ammenment produced soil aggregate stability via distribution of the glomalin-related soil protein in macroaggregate”
An earlier commentator posted indications for tilling/ploughing the soil as being a desirable tactic due to some side effects of the no-till practice. Just in terms of glomalin, the tillage breaks a lot of it’s (glomalin) fungal synthesizer; whereas no-till remnant crop straw left in place over time favors fungal producers of glomalin.
We have known for a fairly long time that soils can store a lot of carbon. We can do that now by adding things like charcoal to soil, which also improve its basic soil structure and growing abilities. Zero till agriculture is another major benefit while maintaining soil structure, excessive erosion as well as moisture and nutrients. Carbon soil sinks are relatively easy to initialize and maintain with sensible development. We have seen that in spades just the last 50 years of agriculture as well as responsible forestry.
What we need now is a ‘Carbon Bank’. We should be stock piling fossil fuels, while we have the resources and the ability to do so. Creating a massive fossil fuel bank of trillions of barrels of oil, coal and NG would stabilize global prices, much like the Strategic Petroleum Reserve provides security for oil supplies. If something goes wrong geopolitically that causes the price of oil to rise exponentially, we dip into the Carbon Bank. When oil prices are low, we buy oil and add it the Carbon Bank. When prices are high, we sell it to maintain the annual price we set, so we can plan our economies without being held hostage to global extortion practices by hostile forces. We currently have a glut of cheap fossil fuels, and by having a security of supply at a set price would promote economic stability.
While we will probably max out at about 560-570 ppmv by 2100 but for the vast long term future, we will need to convert from fossil fuels to synthetic fuels. There is no argument that fossil fuels are a finate resource, only how long they will last a given price. And one with a price point that at some point will perhaps find alternative fuels to be competitive. It is important to think about that inevitable day because it represents a new opportunity to continue with carbon based fuels, which clearly have provided civilization with so much opportunity. We are carbon based life forms and will utilize ‘carbon’ as essential to life for as long as humans exist. We really need to end the war on ‘carbon’ with information that Carbon and CO2 are not pollution.
Charcoal as bio-char may not be a lineal benefit in agricultural soils’ context far into the future. Hopefully the selection of biochar substrate & pyrolysis processing temperature variables can be discovered that avoid the following quoted finding ” … elevated CO2 decreased the ability of biochar [{pine wood @ >600°C}] addition … inspiring plant growth.” As per (2017) “Biochar addition induced the same plant responses as elevated CO2 in mine spoil.”
Every time someone claims ‘as the earth warms’ it should be contested, the earth has NOT warmed since 1998 despite a 30% increase in CO2