Carbon Sequestration into Soil via Enduring Glomalin?
Carbon Sequestration into Soil via Enduring Glomalin?
Agronomy & Policies to Reduce Net GHG from Farms.
By: Grant Rigby grantrigby.ca January 26, 2024
Filamentous mycorrhizae fungi grow symbiotically into plant root cells, supplying phosphate, minerals etc and water to the plant, sourced via the mycorrhizae's long hyphae filaments. In exchange the plant supplies energy and carbon via sucrose and lipids. Mycorrhizae are thought to produce "glomalin-related-soil-proteins" as a coating envelope protecting the long hyphae from bacteria attack. Glomalin proteins are insoluble and seemingly resistant to bacterial enzymes, and thus endure in soil after death of the mycorrhizae, as accumulating sequestered carbon.
Roles of Arbuscular Mycorrhizal Fungi on Soil Fertility: Contribution in the Improvement of Physical, Chemical, and Biological Properties of the Soil
Key point is that enduring glomalin proteins appear to be the product of biological synthesis, using photosynthesized sucrose provided by living plant roots directly into living symbiotic mycorrhizae fungi, and not derived from dead plant residue.
Some recent glomalin science references (from scholar.google.com, search "glomalin"):
- Enhancing Carbon Sequestration in Mediterranean Agroforestry Systems: A Review
- Mycorrhizal product glomalin: a proficient agent of nutrient sequestration and soil fertility restoration under jeopardized agroecosystem
- Does Glomalin Hold Your Farm Together?
- Mapping the scientific knowledge of glomalin-related soil protein with implications for carbon sequestration
- A critical review of 25 years of glomalin research: a better mechanical understanding and robust quantification techniques are required
- Facets of AM Fungi in Sequestering Soil Carbon and Improving Soil Health
- Extraradical Mycorrhizal Hyphae Promote Soil Carbon Sequestration through Difficultly Extractable Glomalin-Related Soil Protein in Response to Soil Water Stress
- Contribution of Arbuscular Mycorrhizal Fungal Communities to Soil Carbon Accumulation during the Development of Cunninghamia lanceolata Plantations
- Faster accumulation and greater contribution of glomalin to the soil organic carbon pool than amino sugars do under tropical coastal forest restoration
- Evaluation of the relation between soil biomass of arbuscular mycorrhizal fungi and glomalin-related soil protein in conservation agriculture
An Agriculture Canada experiment at ten sites, placed carbon-isotope-labeled barley litter on the soil surface, or incorporated to 10cm depth, and monitored its decomposition over ten years: "Loss of C via decomposition occurred quickly - more than half was lost within 1 year and only about 5-12% remained at the end of the experiment…. Comparison of litter application treatments showed that no-till slowed decay of plant litter, but only for a short time (~1 yr)…. If only 10% of added plant litter C remains in soil beyond a few years, regardless of climate, residue placement, or soil type, then rates of soil gain are limited without substantive increases in residue inputs." https://doi.org/10.1016/j.geoderma.2023.116608
Farmers ended burning and summer fallow, and have been annually adding dead crop residues to soils for a half century now, yet their soils have not regained the coal blackness I remember blowing onto snow in the ditches during the 1960's.
My guess is much of that original carbon in native prairie soil might have been of enduring glomalins from mycorrhizae, plus biochar from the base of plant stalks where insufficient oxygen for combustion during prairie fires, plus carbon residues from dead microorganisms sorbed onto clays? Soil microbiologists could sleuth that 12000 year story much better than I.
I therefore think we farmers shall fail to adequately sequester enough carbon in soils to help halt excess climate warming, unless we focus on enduring microbial-resistant glomalin production.
Greenwashing? of Net Greenhouse Gas Emitted from Grain Farms:
Canada's Sustainable Agriculture Strategy discussion document:
Sustainable Agriculture Strategy: Discussion Document
- Down in it is a map of Canada showing the Prairies to have accumulated carbon since 1990. In the reference #5 for the map, all that is stated is that it is a "Custom map created using data from Canada's National Inventory Report 2022", with no scientific authors having put their names to it, nor any explanation of carbon measurement technique (was it really from the identical sites back in 1990 before GPS recording?), nor of assumptions, such as if data was derived from soil samples taken for nutrient recommendations, then the new lowlands salinity patches created since 1990 that are now devoid of plants would not likely have been sampled and are thus ignored in the map?
- There are no yellow spots within the contiguous dark green area, despite likely being some large zones of tillage-fallow-using organic farms, and of highly tilled vegetable cropped areas, and of salinity flats likely large enough to have generated a yellow spot?
- Ag Canada's apparent conclusion that common "no-till" farming is achieving a net accumulation of relevant carbon in the soil, might I suspect have been based upon merely measuring the carbon in the top six inches of soil without considering what form it is in. I suspect soil samples were merely oven-heated to volatize hydrocarbons and measure the loss of mass to determine soil carbon, which includes the labile carbon in fast decomposing dead roots of annual plants as though it is an enduring storage for carbon. But most plant residue likely ultimately ends up being respired by rodents, insects, fungi and bacteria or chemically oxidized back into the atmosphere as CO2, methane and nitrous oxide. Adding fungicides on most farms has likely delayed respiration/decay of plant residue by fungi, yet all residue remains just temporary carbon storage vulnerable to near-term harrowing-induced respiration or oxidation and thus ought not to be counted as enduring "sequestered" stable carbon?
- Or worse, Agriculture Canada and/or Environment and Climate Change Canada's modelers, who are not likely soil microbiologists, might have simplistically assumed that if there is no cultivator tillage, then each crop grown will contribute a positive increase to soil organic matter, with no regard for the oxidation of soil carbon via aggressive surface harrowing down 1/2 inch into erosive dust, and no regard for the likelihood of all the dead plant residue being fully decayed and respired back into atmospheric CO2 as it possibly always has been? We don't know because their assumptions and calculations are not publicly reported?
- Or perhaps there were no actual soil carbon measurements and it is all biased conjecture having the goal of finding something good to report to the UN climate panel?
- But my main questions are whether the new carbon in non-saline uplands is highly resistant to degradation, or merely plant decay that is now delayed by several months compared with 1990 when most fields were promptly tilled every fall or spring, and whether any of the soil carbon improvement is protected in subsoil below possible future tillage, and whether the current practices can continue to accumulate more carbon in soil sufficiently to climb towards maximum enduring carbon sequestration, or will it plateau low as I have read a soil scientist acknowledge?
- Is the difference between the dark green improvement of total soil carbon on the Prairies, and the pale green yellow decline of total soil carbon elsewhere, merely due to the change on the Prairies from fall tillage incorporation of residues, to a fall harrow-only delay of residue decay regime, and not indicative of a significant change in enduring glomalin carbon? Might the introduction of fungicides on most grain fields have resulted in less glomalin synthesis via killing mycorrhizae in recent years, which is masked by the labile carbon accumulation due to obviously a simple time delay in the respiratory decay of unincorporated crop residue?
- Might a no-fall-till yet row-tilled corn /row-tilled soybean/ herbicided-wheat rotation, actually yield more enduring soil glomalin, than would a fungicided no-till canola /wheat rotation?
- Of concern would be that the delayed decay on the Prairies is also due to the preservative activity of fungicides, or of glyphosate tie-up of essential metals essential for growth of decay organisms, like applying a varnish on stubble every year, meaning we farmers would be compelled to continue applying such preservatives uninterrupted for many decades ahead?
- Modern chemical grain farming routinely controls fungal diseases via fungicide sprays that are translocated within the plant, including down the root along with sucrose likely out into mycorrhizae fungi which the fungicides likely also kill thus halting the synthesis of its enduring carbon-rich glomalin. Some herbicides may also have fungicidal activity, such as the root translocating and exudated glyphosate which is sprayed on growing canola, corn and soybean, and on most wheat and canola before harvest to poison deep rooted perennial weeds, yet is known to chelate (tie-up) several metal atoms that are essential for the construction of the enzymes of all life. I suspect glyphosate translocates into and along mycorrhizae filaments and is toxic to it, and perpetually deprives all life forms down in subsoil via chelating essential metal atoms, because the subsoil will remain absent of possibly evolving glyphosate-metabolizing bacteria living in topsoil?
- Given that annual crops only have living roots of moderate depth for a short portion of the summer, it thus seems unlikely there is enough time in the short period following the fungicidal seed treatments and prior to foliar fungicide application on typical chemical grain farms, for carbon sequestration in glomalin to be significant. Surplus nutrients added close to roots or foliar fed might have already negated any need for the plants to supply sucrose to any mycorrhizae for sourcing nutrients anyways?
- Canola and other brassica crops do not directly support any mycorrhizae, so in the years of monoculture canola, no carbon-rich enduring glomalin can be synthesized?
- On typical organic grain farms that disc under green manure crops at flowering, and thus create mid-summer fallow conditions, there would similarly be little glomalin synthesized that year?
- The addition of nitrogen such as ammonia gas dispersed as molecules in the fall, risks much nitrogen being grabbed firstly by soil bacteria before crops germinate and extend roots. To utilize the abundant added nitrogen for their own growth, bacteria must first digest and respire soil carbon into CO2 to obtain energy. Thus, adding some nitrogen chemicals can result in the release of ancient soil carbon into the atmosphere as respired CO2, which has been suggested to be why the adding of nitrogen chemicals for many years has not resulted in blacker carbon-richer soils? If nitrogen was coated with cane sugar, then soil bacteria would get energy and carbon from it, but instead farmers steal ancient carbon from soil for bacteria to first utilize the added nitrogen!
- Being ionic, the high concentrations of ammonia cations are known to displace calcium and magnesium cations from montmorillonite clays, out into the soil solution, permanently degrading the clay and adding cations available to pair with anions such as added sulfate to yield the white salinity salt calcium-sulfate that annually visibly accumulates to levels preventing plants from growing to sequester carbon (grantrigby.ca). (Perhaps such harsh destructive substances have been fraudulently called "fertile"izers, and ought never be listed in the 4R's as a "Right source"?)
- Some farms in the minor organic sector conduct excess oxidative soil tillage that surely continues to release ancient and recent soil carbon via stimulated microbial and erosive carbon oxidation into the atmosphere, same as did same old practices since sod-breaking as evidenced by beige soils now that at homesteading time were black?
- The same must be true for many chemical farms that have added high speed disc tillage implements to pulverize/oxidize soil carbon thrown up into wind erosion vulnerability. And also must be true for the pretend "zero-till" chemical farms that actually high speed tine harrow (till) the top 1/2 inch surface soil into pulverized desiccated oxidized dust plumes every fall and again in the spring, and roll clogs into erosive dust, as standard practice on many Prairie grain farms?
- However, tillage that merely severs the long hyphae of mycorrhizae might plausibly increase total glomalin synthesis if it results in growth of replacement hyphae and its synthesis of more of its protective glomalin, such as might occur via inter-row coulter-disc tillage to kill weeds to advantage the growth of a mycorrhizae-associated long growing season crop such as corn?
- Six inches of virgin black soil was discovered in 1980's by Dad and I on two knolls on neighbouring farms that we rented, in locations where there could never have been wind eroded soil drifts nor plowed high fencelines nor straw stacks left to decay. All knolls were thus black soil at homesteading! A recent road ditch cut into a neighbour's eroded upland revealed no black carbon in the now brown soil, nor any visible roots at all in the yellow clay beneath the top 5 inches, after a half-century of continuous-grain-cropping, and the last two decades in chemically-managed-zero-tillage wheat/canola/soybean - thus revealing zero visible sequestration of carbon.
Nitrous Oxide (non-carbon) GHG Emission from Soils:
- Also, when the soil is anaerobic via water inundation, as occurs every early spring in the low slopes and flat lands, some fall applied chemical nitrogen is converted by bacteria into the potent GHG nitrous oxide? (Having no carbon in it, nitrous oxide is ignored in carbon greenwashing statements such as Agriculture Canada's that only mentions "carbon" sequestration.)
Unnecessary Methane from Liquid Swine Manure:
- Food grade grains are now fed to factory swine, resulting in human food energy being mostly wasted as CO2 respiration by the swine, meaning most of the GHG from fossil fuels and added chemical nitrogen and the drying of late season corn that would not have been grown if not for the new swine barn, as well as GHG from the barn concrete, and the GHG from natural gas used in feed processing and the GHG from propane used for barn heating, all becomes very concentrated per unit of food in the form of factory swine meats. And then liquid urine-feces is unnecessarily stored deep (anaerobic) thru hot summer enabling warm bacterial fermentation of GHG methane gas (Measured versus modeled methane emissions from separated liquid dairy manure show large model underestimates https://www.sciencedirect.com/science/article/abs/pii/S0167880916303292), and neurotoxic, viral immunity suppressing H2S gas (Ambient hydrogen sulfide exposure increases the severity of influenza A virus infection in swine https://doi.org/10.1080/19338244.2021.1896986). Swine excrement could instead be banded daily under soil whenever not frozen, and only stored when winter's cold prevents creation of H2S and the GHG methane.
(If the methane from grazing cattle is the same as was the methane from grazing bison for 12000 years, then net new GHG from true grass-fed beef is much lower than from typical hog?)
Swine barns could easily be heated without GHG emitting fossil fuels, via ground source heat pumps, or via biomass energy sources such as grain straw, cattails or willow coppicing, plus exhaust air heat exchangers (enabling UV treatment at night to destroy viral aerosols such as the 1918 swine flu emitted from barns, to prevent humanizing a barn epidemic).
And, of course, the GHG from Farm Machines:
- Grain farmers burn fossil fuel for seeding and harvesting and marketing. Most organic farmers burn extra fossil fuel for tilling dry soil in the fall, like most chemical farmers burn extra fossil fuel for frequent pesticide applications. Plus the common reprogramming of new tractor engines after purchase, to negate need for buying an additive to prevent the elevated nitrous oxide created by the higher temperatures in newer diesel engines. Plus the GHG embedded in purchase decisions for the manufacture/delivery of fertilizers, pesticides and new machinery.
When to Grow Glomalin?
I suggest the greatest opportunity for significant new carbon sequestration into our carbon-depleted soils, in the form of enduring glomalin-related-soil-protein, to be during the high angle solar radiation, warm long days of each summer, via our growing mycorrhizae-associating grain crops. New mycorrhizae hyphae can be grown every year to help deliver nutrients and water to our crops, also synthesizing more of the enduring glomalin to protect its hyphae, achieving sequestration of carbon into microbial-resistant glomalin every year, some of which may be further protected via sorption onto clay minerals?
Idealized Agronomy for Enduring Carbon Sequestration on Grain Farms
1. Intercrop non-mycorrhizal brassica crops with peas/barley/soybeans/corn/timothy/clover etc that can associate with mycorrhizae, to thereby sequester some carbon via glomalin synthesis by mycorrhizae during canola growing years.
2. Reject seed treatments that delay the nutrient-supplying "rhizophagy cycle" and mycorrhizal symbiotic associations with the seedling's roots. Avoid any foliar fungicide that translocates to roots and into mycorrhizae fungi where plausibly lethal halting the synthesis of enduring carbon-rich glomalin.
3. Limit root-translocating herbicide use to the topsoil (>4 inch) shallow-rooted early stage of plants, so toxins cannot enter the subsoil below the tillage zone where it is most beneficial for enduring glomalin to be synthesized. (Thus avoid glyphosate application unless the deep roots of perennials have first been severed to prevent its translocation down via deep roots and out into mycorrhizae in subsoil where permanently tying-up scarce metals essential for life's enzymes.)
4. Avoid application of nitrogen chemicals in fall due to greater risk of nitrous oxide GHG emissions from warm anaerobic soils in spring before crop root uptake of N. Choose N sources that do not emit GHG in manufacture, that do not salinate soil by displacing cations out of clays into the soil solution, and that do not induce bacteria to first use the added N via respiring CO2 GHG from ancient soil carbon for the energy for bacterial growth. (Possibly first buffer harsh ammonium ions such as via pre-adsorbed onto mined clays, or grow into yeast cells before field application, or imagine new benign chemistries for manufacture.)
5. Place most phosphate at enough distance from seed to encourage symbiotic mycorrhizae growth to be first to access the P for supply to crop, thereby also synthesizing glomalin.
6. Ensure all soils on farm grow plants-mycorrhizae every summer, and diligently prevent, desalt and re-vegetate bare salinity patches which otherwise only net respire ancient soil carbon into CO2. (Hypotheses about salinity causation: http://www.rigbyorchards.com/soil_salinity.html)
7. Limit tillage to the time of crop seeding to preserve mycorrhizae. Avoid tillage when windy, and retain wind-resistant soil clogs and intact surface vegetation cover, to prevent evaporative capillarity salination that inhibits plant growth, to shield soil from heat and UV, and to prevent wind erosive oxidation of soil carbon into CO2 GHG.
8. Crops are grown to be eaten and respired back into only non toxic CO2, so reject sales of grain for livestock feed if the excrement is stored anaerobic emitting neurotoxic hydrogen sulfide and the more potent GHG methane.
Government might implement a public registry into which farmers could voluntarily self attest by signed affidavits that they have met any or all of these 8 ideals.
Last year, in December 2022, the above was communicated to approx 50 Canadian soil scientists and agronomists, and to the Sustainable Agriculture Strategy Advisory Panel:
- Pulse Canada
- Dairy Farmers of Canada
- Egg Farmers of Canada
- Canadian Agri-Food Policy Institute
- Canada Organic Growers
- Farmers for Climate Solutions
- Canadian Canola Growers Association
- Fertilizer Canada
- Canadian Cattle Association
- Fruit & Vegetable Growers of Canada
- Canadian Pork Council
- Grain Growers of Canada
- Canadian Wildlife Federation
- National Farmers Union
- Canola Council of Canada
- Nature United
- Chicken Farmers of Canada
- Union de producteurs agricoles
- Ducks Unlimited
- Soy Canada
- Panel Co-chairs: Agriculture Canada, Canadian Federation of Agriculture
- And to Environment and Climate Change Canada, and to Canada and Manitoba Ministers
No corrective response has been received.
Practical Government Actions to Reduce Net GHG from Farms
To enable farmers to accept lower cash profitability in order to sequester carbon, without risking decline of credit service from bullying lenders, legislate the Profession of Business Lenders with a code of ethics requiring professional ethical service of the capital needs for all businesses, regardless of scale, or profitability relative to other farmers, or any other discriminatory criteria (same as professional dentists serve the public's needs to cure tooth pain, and not to cause pain).
Machinery Power Conversion to Non-GHG:
Fund graduate students at engineering and mechanical schools to design and improvise replacing diesel engines of threshing combines and sprayers with electric motors, powered by:
- lithium battery;
- sodium battery, to be swapped out with another freshly charged via on-farm solar;
- hydrogen fuel cell battery,
- using on-farm solar for hydrolysis to generate hydrogen, then into ammonia for storage and back to hydrogen at fuel usage;
- and the conversion of existing diesel engines to direct usage of ammonia as fuel.
Canada Fossil Fuel Charge / Climate Action Incentive Payment / AgriInvest:
Exempt all homes built before 2024. Or the provinces via Planning Acts could disallow unabated GHG-releasing fossil carbon fuels in all new construction. (New builds by the affluent can easily be geothermal heated.)
Apply the Fossil Fuel Charge to new barns and new greenhouses, but not paid into the CAIP fund paid out to others. Instead retain this GHG pollution charge into a new AgriInvest account to be used for reducing net farm GHG emissions (similar to the Conservative platform of last election).
Extend the FFC on GHG pollution, and its retention in AgriInvest accounts, to all farm fuels emitting unabated ancient fossil carbon GHG, in 2028 by when equipment conversions are likely feasible, to ensure an economic incentive to reduce GHG. Or implement a minimum wholesale or retail price (somehow?) for GHG emitting fossil fuels, that in 2028 exceeds the market price for non-GHG energy.
Exempt Perennial Vegetation from Property Tax:
For the public costs for water drainage such as all culverts, bridges and ditches, tax only those lands which have ceased to evapotranspire rainwater thru plants, thus tax all public and private roads and parking lots, roofs and saline patches. This also incentivizes carbon sequestration into enduring glomalin. Assess annual growing crops at 50% rate, perennial vegetation at zero rate.
To enable farmers to enhance mycorrhizae growth and its glomalin production every year via growing intercrops (such as adding mycorrhizal peas into canola), offer simple cheap weather data-based extreme heat and frost insurance for any intercrop mixture. Also assess any crop mixture by designating it to be the dominant crop and counting all dockage as being that crop.
AgrStability and AgriInvest Subsidies:
Commencing 2025, exclude liquid manure producing farm businesses if the excrement is stored through warm summer allowing the fermentation of toxic H2S and methane GHG. (Barn owners can easily arrange for local farmers to accept liquid manure direct from barns thru summer, such as for banding under soil between rows of corn.)
Commencing 2027, from AgriInvest only, exclude crops which cannot associate with glomalin-synthesizing mycorrhizae, unless the farmer attests that it was intercropped or after harvest cover-cropped or otherwise managed to support mycorrhizae growth to increase total soil glomalin carbon every year.
Evaluate all pesticides for risk of translocating into the crop's mycorrhizae and impeding glomalin synthesis, and then publicly report and review license.
Evaluate and rank all licensed fertilizers for
- GHG emissions in manufacture,
- cation exchange in soil causing soil salination via displaced Ca, Mg, toxic Al etc into soil solution,
- loss of ancient soil carbon via respiration into CO2 GHG via bacteria needing energy and C to first utilize the added N,
- possible supplying nitrogen direct to mycorrhizae and increasing glomalin production?,
- and nitrous oxide emissions from soil,
then publicly report differences between all N sources.
Soil Resource Knowledge:
Use aerial imagery to map annual changes in salinity patches, to record wind erosion events, and to record bare soil, and publish the maps. Plants cannot be grown and thus carbon cannot be sequestered in saline patches, which thus only net emit CO2 from ancient soil carbon. Wind erosion oxidizes soil carbon into GHG. Hot bare soil likely kills mycorrhizae, and UV radiation of surface carbon might oxidize it into CO2? Public awareness will encourage better stewardship of the soil resource essential for the public's long term sustainable food supply.
Recognition and Revenue:
Express Canada's appreciation of farmers who's practices are likely to increase carbon sequestration into enduring glomalin in soil, via:
Glomalin Growing Days Program:
Voluntarily, farmers may report, by acreage and location and annual crop, the total Glomalin Growing Days (GGD) that a mycorrhizae-associating crop species was growing and likely nourishing mycorrhizae resulting in glomalin synthesis.
A national committee of university tenured fungi scientists could be funded to annually advise which, if any, pesticides would likely significantly diminish glomalin production, such that the GGD would thus be limited to the period when such pesticides are absent from the roots.
Farmers voluntarily self attest their GGD and acres via signed affidavit.
This program would issue a payment for acres where GGD exceeded 90% of the region's typical frost free growing days, and soil remains mulch covered and not tilled until spring to preserve living mycorrhizae and to prevent winter wind erosion and early spring salination.
The location/acres/crops/GGDays attested are listed on a public registry 28 days prior to issuing payments before Easter, thereby allowing for community scrutiny to help avert fraud.
This public registry of lands and crops capturing carbon into enduring glomalin would be expected to aid marketings to some buyers who may compete to purchase these identified carbon-capturing crops, for branding initiatives earning consumer support via higher prices, and to facilitate preferential exports to countries requiring such practices for imports.
The funds for this program could be those already allocated to AgriInvest, transforming it from a gross income subsidy into an acreage payment to encourage carbon capture in soils.
(This article ranges beyond my science education, thus it may err. Critique is thus required.)
Summary: I suggest farmers grow glomalin, and scientists ask new research questions.
I am a participant in Farmers for Climate Solutions hosted 'Prairie Farmer and Rancher Forum', 2024, which shall attempt to achieve consensus recommendations.
January 26, 2024
homestead farmer near upper Pembina towards Turtle Mountain, The Prairies, Earth.
(made by mycorrhizae)
GHG Agric Policies?- your critique requested.
(Advertisement placed in four SW Manitoba newspapers mid January 2024.)