In the previous article, (Soil Organic Matter – the Most Critical Cause and Solution to Climate Change), I showed how the climate models and negotiations completely neglected soil organic matter (SOM) and how its destruction through industrial agriculture is the largest source of carbon dioxide (CO2), more than fossil fuels. Adopting regenerative agricultural systems that reverse this loss, remove CO2 from the air, and store it as SOM will reverse climate change.
In that article, I showed how the models and data used for the Global Carbon Budget were inaccurate, resulting in significant variations in CO2 emissions and removal estimates. The complete absence of the largest terrestrial carbon pool, soils, in the calculations is a fatal flaw that completely invalidates the current policies around the adaptation and mitigation of climate change.
One figure can be used accurately: The amount of atmospheric CO2 has increased by an average of 19 Gt (billion tons) yearly for the last decade. This average is based on measurements from primary research stations, such as Cape Grim and Manua Loa. (Friedlingstein et al. 2023) Most CO2 emissions from fossil fuels, deforestation, and loss of SOM are removed through photosynthesis of plants on land or cyanobacteria in the sea. Maximizing photosynthesis is the key to regenerating our climate.
Removing more than 19 Gt of CO2 yearly will reverse emissions and climate change. This can be done by scaling up best-practice regenerative agriculture. (Cummins and Leu 2024)
Helpful Explanations of Technical Terms
This article quotes from published scientific papers. I have ‘translated’ the information into plain English to make it easier to understand. Most use the metric system. These can be understood by following simple conversions:
2.5 acres to a hectare. Pounds per acre are the same as kilograms per hectare. US tons and metric tons are approximately the same. A gigaton (Gt) is one billion tons.
Industrial Agriculture Cannot Remove Enough CO2
There are claims that no-till systems using herbicides are the best for removing CO2 to mitigate climate change. Researchers conducted a meta-analysis of 74 published studies comparing no-till and full-tillage management. They found many examples of no-till reducing soil organic matter (SOM) and causing crop yield losses. (Ogle, Swan and Paustian 2012)
The most comprehensive study comparing industrial no-till with an organic agricultural tillage system compared multiple parameters. The organic system had better soil quality, including SOM levels. The results found that systems incorporating high amounts of organic inputs from manure and cover crops can improve soils more than no-tillage systems despite reliance on a minimum level of tillage. (Teasdale, Coffman and Mangum 2007)
Research from Ohio State University compared soil carbon levels between no-till and tillage fields. They compared the carbon storage between no-till and plowed fields with the plow depth of 20 cm (8 inches) and found that the carbon storage was generally much more significant in no-till fields than in plowed fields. When they examined to 30 cm (12 inches) and deeper, they found more carbon stored in plowed fields than in the no-till ones. The researchers concluded farmers should not measure soil carbon based on a shallow surface depth. They recommended going as much as one meter (3 feet) below the soil surface to get a more accurate assessment of SOM. (Christopher, Lal and Mishra 2009)
A review of 120 papers on SOM sequestration by researchers from universities in Illinois, Wisconsin, Iowa, and Ohio compared the difference between the no-till and tilled plots. Their findings did not support CO2 sequestration claims of the no-till industry. They found that the no-till subsurface layer often loses more SOM time than is gained in the surface layer. (Olson 2013)
Professor Rattan Lal is a highly regarded soil scientist whose research and review papers on SOM in agriculture are widely cited. He has published articles on the potential of the global scaling up of agricultural systems to sequester CO2 to offset anthropogenic GHG emissions. (Lal 2004, Lal et al. 2007) His maximum estimation is 4.4 Gt of CO2 per year, far below the more than 19 Gt that needs to be removed.
These studies and many others have been used to criticize using agriculture to draw down CO2, as their data sets are from industrial-agricultural systems that decrease SOM or have meager increases. The papers correctly show that industrial-agricultural systems are unsuitable for scaling up to achieve the sequestration levels needed to mitigate climate change. (Amundson and Biardeau 2018, Lam et al. 2013, Olson 2013, van Groenigen et al. 2017, White 2022)
A fundamental weakness in their arguments is that they cherry-picked the studies supporting their viewpoints and omitted the data sets showing good increases in SOM. The authors have ignored extensive published studies showing that regenerative agriculture systems, such as organic agriculture and regenerative grazing, can sequester significant amounts of CO2 and increase SOM over many decades. (Gattinger et al. 2012, Aguilera et al. 2013, Leu 2013, Machmuller et al. 2015, Teague et al. 2016)
Many of the examples cited by the critics are industrial farming systems that use synthetic nitrogen fertilizers, which long-term data shows deplete SOM. Researchers analyzed the results of a 50-year agricultural trial. They found that applying synthetic nitrogen fertilizer had resulted in all the carbon residues from the crop disappearing and an average loss of around 10,000 kg of soil carbon per hectare. It equates to GHG emissions of 36,700 kg of CO2 per hectare (36, 700 lbs per acre) over and above the many thousands of kilograms of crop residue that is converted into CO2 every year. Multiple researchers have found that the higher the application of synthetic nitrogen fertilizer, the greater the amount of SOM lost as CO2. (Khan et al. 2007, Mulvaney, Khan, and Ellsworth 2009, Man et al. 2021)
A simple back-of-the-envelope calculation (see Appendix) extrapolating this on 90% of croplands shows that conservatively, 51 Gt of CO2 is emitted into the atmosphere yearly by the oxidation of SOM. It does not include the extensive emissions from inappropriate tillage, overgrazing, and soil erosion. The loss of SOM is the largest source of CO2, more than fossil fuels (37 Gt), and is not accounted for in the models or climate change negotiations.
The evidence shows that industrial agricultural systems using synthetic nitrogen fertilizers and toxic pesticides contribute to CO2 emissions and cannot remove enough CO2 to mitigate climate change. Reducing fossil fuel emissions and not reducing the large amount of CO2 from nitrogen fertilizer use, soil erosion, overgrazing, and destructive plowing means that the trillions spent on climate change will have no effect.
Research and funding priorities must be focused on evidence-based agricultural systems that can remove large amounts of CO2 and not on systems that contribute to climate change.
Regenerative Agriculture
The best regenerative systems maximize photosynthesis to increase the capture of CO2 and store it in the soil as SOM through organic matter biomass and root exudations. (Prescott et al. 2021) A substantial body of evidence, starting in 1904, shows how root exudates feed organic carbon compounds to the soil microbiome, thereby increasing SOM. The key is to maximize photosynthesis to capture CO2 and convert it into numerous organic compounds. (Leu 2021, Badri and Vivanco 2009, Jones, Nguyen and Finlay 2009, Verma and Verma 2021)
Depending on the management system and the species, root exudates can distribute 10% to 40%, with an average of 30%, of the carbon captured by photosynthesis into the soil while the plants grow. (Verma and Verma 2021) The carbon compounds from root exudates penetrate deeper into the soils due to the depths of the roots than above-ground or tilled biomass. Above-ground and tilled biomass can rapidly oxidize into CO2. Systems with deeper roots are encouraged as their exudates build more durable SOM, as deep soil carbon is more stable. (Christopher, Lal and Mishra 2009, Verma and Verma 2021, Leu 2013, Leu 2021)
The key is ensuring the agricultural systems have photosynthesizing plants for the most prolonged periods in their climates. This is achieved by using a diversity of correctly managed species to ensure they can capture the maximum amount of sunlight per acre as the energy needed to convert CO2 into the organic molecules that build SOM through the soil microbiome. Permanent covers of living plants and limited tillage systems are preferred to increase SOM. (Leu 2021)
Further research has found that synthetic chemical fertilizers produce a higher percentage of the CO2 fixed through photosynthesis of above-ground biomass growth rather than being excreted by roots as exudates to feed the soil microbiome and increase SOM levels. (Prescott et al. 2021) As stated, root exudates build deeper, stable SOM compared to above-ground biomass that readily oxidizes into CO2.
Many long-term trials show that organic farming systems have higher rates of SOM increases than industrial agriculture (Leu 2013). Organic farms do not use synthetic chemical fertilizers, which causes SOM to decline and produce lower percentages of organic carbon-based root exudates.
Examples of Best Practice Regenerative Systems
The evidence shows that agriculture needs to change from chemically intensive to biologically intensive. The new paradigm reduces and ultimately avoids the use of synthetic chemicals. Plant biology and living soil science must be at the forefront of this research.
A general rule is that the soil is covered with the maximum number of living plants for as long as possible during the growing season. Dead plants and bare soil do not photosynthesize, so the most productive regenerative systems avoid killing plants as weeds with herbicides and excessive tillage. Instead, plants are managed as cover crops to build soil fertility by maximizing root exudates. Various strategies are used to manage weeds and use them as cover crops to build fertility. Grazing is one of the most widespread management tools in these regenerative systems. (Leu 2021, Teague et al. 2016)
Regenerative Grazing
A meta-review published in the Journal of Soil and Water Conservation found that transitioning to regeneratively managed ruminant grazing systems can result in more sequestration than emissions, turning ruminant agriculture from a significant emitter to a major mitigator of GHG emissions. The researchers stated: “Permanent cover of forage plants is highly effective in reducing soil erosion, and ruminants consuming only grazed forages under appropriate management result in more C [CO2] sequestration than emissions.” (Teague et al. 2016)
Most studies looking at the emissions from livestock systems do not factor in the SOM sequestration levels that can result from different livestock management systems. Researchers doing life cycle analysis comparing different livestock management systems found that converting to a regenerative grazing method called multi-paddock (MP) grazing resulted in significant increases in SOM and removed more CO2 than emitted. ”In our study, the highest [SOM] stock occurred upon converting to MP [Multi-paddock] grazing, indicates that among the three different grazing practices we analyzed, MP has the highest carbon [CO2] sequestration rate. Combined with its potential to significantly lower GHG emissions, we conclude that MP serves as the best carbon mitigation option.” (Tong et al. 2015)
In a later study, the researchers found similar results and recommended the widespread adoption of regenerative agriculture systems, not just for the increasing SOM; they found considerable ecological and biodiversity benefits. “Incorporating forages and ruminants into regeneratively managed agroecosystems can elevate soil organic C,[SOM] improve soil ecological function by minimizing the damage of tillage and inorganic fertilizers and biocides, and enhance biodiversity and wildlife habitat. We conclude that to ensure long-term sustainability and ecological resilience of agroecosystems, agricultural production should be guided by policies and regenerative management protocols that include ruminant grazing.” (Teague et al. 2016)
Teague and colleagues showed that regenerative livestock systems can remove 11 tons of CO2 per hectare per year (11,000 lbs per acre). Implementing this grazing system on the world’s permanent pastures would remove 37.4 billion tons of CO2 annually. Deployed on 10% of the world’s permanent pastures, it could remove 3.7 Gt of CO2 annually. (Teague et al. 2011)
Researchers using regenerative grazing practices in the southeastern United States removed 29.36 metric tons of CO2 per hectare per year (29,360 lbs per acre). The authors give other examples from worldwide research that have achieved similar levels of SOM sequestration through regenerative grazing. Hence, the results of this research paper are not an isolated outlier. (Machmuller et al. 2015)
If these regenerative grazing practices were implemented on the world’s permanent pastures, they would remove 99.8 billion tons of CO2 annually. By deploying them on 10% of the world’s grazing lands, they could remove 10 Gt of CO2 annually. (See Appendix)
The push to reduce livestock reduction is based on their methane emissions, which are used incorrectly to calculate the greenhouse gas (GHG) contributions to climate change. Most publications will quote them as a percentage of anthropogenic GHGs, not in their measured contributions to trapping infrared (heat) energy as a cause of climate change. The extra trapped energy fuels extreme weather events—floods, storms, droughts, and fires.
The study, which has the most comprehensive datasets and solid methodology, states that CO2 is the principal anthropogenic GHG as it amplifies the GHG effect of water vapor and clouds, the primary GHGs.
CO2 is responsible for 20% of the total increase in GHG infrared energy. Water vapor and clouds are responsible for 75%. All the other anthropogenic GHGs are responsible for 5%. The contribution of methane, at most, is a 1.6% increase in GHG heat energy. (Schmidt et al. 2010)
Most methane emissions come from leaking gas, oil wells, and permafrost melting.
Ruminants are only a percentage. The bulk of this comes from Confined Animal Feeding Operations (CAFOs). While methane and other greenhouse gas outputs are considerable for (CAFOs) and intensive industrial livestock production systems, this is not true for regenerative grazing livestock practices on pasture.
In ranch ecosystems, much of the methane emitted by animals on pasture is degraded by soil and water-based methanotrophic (methane-eating) microorganisms. These organisms do not exist in CAFOs and intensive livestock systems, so 100 percent of their emissions go into the atmosphere. Furthermore, methane is a short-lived greenhouse gas with a half-life of 12 years. It decays into CO2. This CO2 is sequestered into the soil by photosynthesis in correctly managed grazing systems. This does not happen in CAFOs and industrial animal production systems. Scaling up regenerative grazing will reverse climate change.
Pasture Cropping
Pasture cropping is an innovative regenerative agriculture system where the crop is stripped-tilled into a perennial pasture instead of bare soil. There is no need to plow out the pasture species or kill them with herbicides before planting the cash crop.
Colin Seis in Australia first developed this. The principle is based on the ecological fact that annual plants grow in perennial systems. The key is to adapt this principle to the appropriate management systems for specific crops and climates. Pasture cropping can be used on permanent pastures and arable cropping lands. Dr. Christine Jones researched Colin Seis’s property, Winona, and showed he had removed an average of 16.85 tons/ha (16,850 lbs/acre) of CO2 annually. (Winona 2022)
Neils Olsen further innovated pasture cropping. He developed equipment that combines cultivation, mulching, aeration, fertilization, and mixed species seeding into narrow tilled strips in the perennial pasture in one pass. The field is grazed down or mulched before planting to reduce competition with the cash crop.
Pasture cropping is an excellent system for increasing SOM. Olsen was paid for sequestering 11 tons of CO2 per hectare per year under the Australian government’s Carbon Farming Scheme in 2019. He was paid for 13 tons of CO2 per hectare (13,000 lbs per acre) in 2020. (Soil Kee 2019) He was the first farmer to be paid for sequestering soil carbon under the Australian government-regulated system. (Emissions Reduction Fund 2022) If this system was deployed on 10% of all permanent pastures and arable/croplands, it could sequester 6.38 Gt of CO2 annually. (See Appendix)
BEAM
BEAM (Biologically Enhanced Agricultural Management), developed by Dr. David Johnson and Dr. Hui-Chun Su Johnson of New Mexico State University, produces compost with a high diversity of soil microorganisms. The BEAM system aligns with research by Prescott et al., which shows how organic carbon-based inputs such as composts encourage higher proportions of root exudates than synthetic water-soluble chemical fertilizers. (Prescott et al. 2021) Multiple crops grown with BEAM have achieved very high CO2 removal levels and yields. Research published by Johnson and colleagues shows: “… a 4.5-year agricultural field study promoted annual average capture and storage of 10.27 metric tons’ soil C ha-1 year -1 while increasing soil macro-, meso- and micro-nutrient availability…” (Johnson, Ellington and Eaton 2015) These results are currently being replicated in other trials.
These figures mean that BEAM can sequester 37.7 tons of CO2 per hectare (37,700 lbs per acre) annually. BEAM can be used in all soil-based food production systems, including annual crops, permanent crops, and grazing systems, including arid and semi-arid regions. If BEAM was deployed globally on just 10 % of all agricultural lands, it could sequester 18.5 Gt of CO2 per year. (See Appendix)
No Kill, No Till
Singing Frogs Farm, run by Elizabeth and Paul Kaiser, is a highly productive “no-kill, no-till,” biodiverse, organic, agroecological horticulture farm on 3 acres (1.2 hectares) in northern California. The key to their no-till system is to cover the planting beds with mulch and compost instead of plowing them or using herbicides, planting directly into the compost, and having a high biodiversity of cash and cover crops that are continuously rotated to break weed, disease, and pest cycles.
According to Chico State University, the Kaisers have increased soil organic matter (SOM) by 400 percent—from 2.4 percent to 7–8 percent, with an average increase of about 0.75 percentage points per year—in six years. This farming system could apply to more than 80 percent of farmers worldwide, as most have fewer than 5 acres (2 hectares). It is a highly productive system that dramatically increases yield and lowers costs due to the absence of synthetic chemical fertilizers and pesticides. It would assist in ending poverty and food insecurity for most of the world’s farmers.
If the increases in Singing Frog Farm’s soil carbon were adopted by 10% of arable and permanent croplands, it would sequester 17.9 Gt of CO2 annually. (See appendix)
The Agave Agroforestry System
The Flores brothers and Dr. Juan Frias initially developed the agave agroforestry system in the high desert of Mexico. Based on endemic Agave and Mesquite plants, it is a highly productive agroecosystem that regenerates degraded landscapes. The previously indigestible parts of the plants, such as the agave leaves and thorny mesquite leaves, are finely chopped and fermented. This breaks down the toxic compounds such as lectins, saponins, phytates, oxalates, and tannins that plants use to protect themselves from predators, turning them into highly nutritious stock feed.
This is a significant breakthrough as most of the species in other agroforestry systems could
also be fermented to remove the toxic compounds and used as high-quality feed, as has been demonstrated with agave. Selective harvesting for feed would increase the productivity of all of these systems. For example, the agave agroforestry system can be applied to Savory’s Holistically Managed Grazing system to provide forage in the drier and cooler seasons when the pasture grasses do not grow and can be easily overgrazed.
Research by Dr. Mike Howard shows that the agave agroforestry system can sequester 8.7 metric tons of carbon dioxide per hectare per year. This does not count below-ground SOM sequestration or the amount of carbon sequestered by the companion trees. (Howard 2024) The potential for soil carbon sequestration is very high due to the role of deep roots excreting around 30 percent of the carbon compounds created through photosynthesis into the soil. This could sequester a total of 11.3 tons of CO2 per hectare.
A 10% adoption of the agave agroforestry system across the world’s permanent pastures could sequester 3.8 Gt of CO2 annually. This possibility does not include the extra functions that such a system provides, such as cooling the region through regenerating forests and permanent pastures. The shading and rehydrating of the landscape will reduce the ambient temperature.
High levels of SOM increases
The above examples of increases in SOM are much higher than the levels quoted in most of the published literature. (Lal 2004, Lal et al. 2007, Lam et al. 2013, van Groenigen et al. 2017, White 2022)
Consequently, some authors and researchers express skepticism about their credibility. The material and methods used in the above examples are published and can be replicated. They are evidence-based systems. Just dismissing them based on an opinion is the opposite of science. The only way to prove or disprove these results is to replicate the material and methods and see the results. Until this is done, these published results are valid.
There is an urgent need to transform agriculture from a significant source of GHGs to a major mitigator. Agriculture must contribute to the suite of solutions necessary to remove CO2 emissions, reduce the extra trapped energy, and avoid the intensification of extreme weather events it causes.
The above examples of regenerative agricultural systems and other outliers have the most potential. They should be the focus of future research, not rejected because of personal opinions. They should be replicated to see their accuracy in different climates and soil types. If the results are positive, they should be scaled up to remove CO2. Further research should be prioritized to improve these systems.
Conclusion
Using conservative figures, a simple back-of-the-envelope calculation shows that transitioning a small proportion of agricultural production to best-practice regenerative organic systems will remove more CO2 than the current emissions. (See appendix for details and methodology on calculations.)
- 10% of grasslands under the Teague regenerative grazing could sequester 3.7 Gt of CO2 annually.
- 10% of agricultural lands under pasture cropping could sequester 5.3 Gt of CO2 annually.
- 10% of global agricultural lands regenerated by the BEAM organic compost system could sequester 18.5 Gt of CO2 annually.
- 10% of smallholder farms across arable and permanent croplands using Singing Frogs Farm’s bio-intensive organic “no-kill, no-till” system could sequester 9 Gt of CO2 annually.
- 10% of arid and semiarid drylands under the agave agroforestry system could sequester 3.8 Gt of CO2 annually.
This would result in 49.2 Gt of CO2 per year being sequestered. This is better than the 19 Gt of CO2 per year that is currently emitted and would, therefore, start to reverse climate change and regenerate the climate.
Combining these regenerative systems is not double- or triple-counting. Many permanent pastures are unsuitable for cropping and can only be used for grazing. Pasture cropping can be used in most arable and grazing systems where machinery can be safely operated, and there is sufficient soil moisture in the rainy season to grow an annual crop. BEAM can be used in all systems. Singing Frogs Farm’s bio-intensive organic “no-kill, no-till” system can be applied to most of the world’s one billion smallholder farming families. The different systems give landholders flexibility and more options for adoption.
These figures do not include avoiding a conservative 18 Gt CO2 emissions from synthetic nitrogen fertilizers by changing 10% of agriculture to best-practice regenerative agriculture.
Furthermore, 10% adoption rates are realistic goals, especially for working with early adopters. This can be increased over time to regenerate all agricultural systems. This would increase CO2 removal and stop the largest source of CO2 emissions, the loss of SOM through synthetic nitrogen fertilizers, inappropriate tillage, overgrazing, and soil erosion.
The systems quoted in this paper are only five examples of the many regenerative agricultural systems that have the potential to draw down large quantities of CO2 if scaled up on global landscape scales. Many emerging systems, especially perennial agroforestry systems, have the potential to achieve higher increases in SOM. Even if the results were half that of the back-of-the-envelope calculation, the outcome would be impressive and a massive contribution to removing more CO2 than emitted.
In the final chapter of The Regenerative Agriculture Solution, Ronnie Cummins and I explain how this can be scaled up and funded. The following article in this series will summarize this.
Appendix
These calculations are back-of-the-envelope, rough estimations. They are not intended as scientific proof. They are a simple way to understand the potential of these systems.
Synthetic Nitrogen and CO2 Emissions Calculations
United Nations Food and Agriculture Organization (UNFAO) has estimated that the land use:
- Arable cropland: 1.4 billion hectares (3.5 billion acres)
- Permanent crops: 0.15 billion hectares (0.38 billion acres)
Total 1.55 billion hectares
90% of this uses synthetic nitrogen fertilizers = 1.39 billion ha x 36.7 tons of CO2 per hectare = 51 billion tons.
This means a conservative estimate of 51 billion tons (Gt) of CO2 are emitted into the atmosphere yearly by industrial agriculture’s oxidation of soil organic matter. It does not include the extensive emissions from inappropriate tillage, overgrazing, and soil erosion. The loss of SOM is the largest source of CO2 and is not accounted for in the models or climate change negotiations.
Calculations for Achieving Negative Emissions
Global Agricultural Land Figures
The United Nations Food and Agriculture Organization estimated that the total land used to produce food and fiber is 4.9 billion hectares (12.2 billion acres).
This is divided into:
- Permanent pastures: 3.4 billion hectares (8.5 billion acres)
- Arable cropland: 1.4 billion hectares (3.5 billion acres)
- Permanent crops: 0.15 billion hectares (0.38 billion acres) (FAOSTAT 2015)
Regenerative Grazing Calculations
To explain the significance of Machmuller’s figures: 8.0 Mg ha−1 yr−1 = 8,000 kgs of carbon stored in the soil per hectare per year. Soil Organic Carbon x 3.67 = CO2, which means that these grazing systems have sequestered 29,360 kgs (29.36 metric tons) of CO2/ha/yr. (Machmuller et al. 2015)
If these regenerative grazing practices were implemented on the world’s Permanent pastures, they would sequester 98.6 Gt CO2/yr. 29.36 X 3.4 billion ha = 99.8 billion tons of CO2
If this system were deployed on 10% of the world’s grazing lands, they could sequester 10 Gt of CO2 annually.
Teague et al. achieved 11 tons per hectare annually. 11 X 3.4 billion ha = 37.4 billion tons of CO2. Deployed on 10% of the world’s permanent pastures, it could sequester 3.7 Gt of CO2 annually.
Pasture Cropping Calculations
Olsen’s pasture cropping system achieved 13 tons and 11 tons a hectare. I have chosen to use the more conservative number of 11 tons. If applied to permanent pastures and arable/croplands, it would sequester 63.8 Gt of CO2 per year. (Permanent pastures and arable croplands 4.8 billion hectares x 11t CO2/ha/yr = 52.8 Gt annually
If this system were deployed on 10% of all permanent pastures and arable/croplands, it could sequester 5.3 Gt of CO2 annually.
BEAM Calculations
BEAM sequestered 37.7 metric tons of CO2 per hectare per year in a documented field trial.
If BEAM were extrapolated globally across agricultural lands, it would sequester 185 Gt of CO2 annually. (37.7 t CO2/ha/yr X 4.9 billion ha = 185,168,175,790t CO2/ha/yr)
If this system were deployed on 10% of agricultural lands, it could sequester 18.5 Gt of CO2 annually.
No Kill, No Till
Paul and Elizabeth Kaiser of Singing Frog Farm have managed to increase their soil organic matter from 2.4 percent to an optimal 7 to 8 percent in just 6 years, an average increase of about .75 percentage points per year. According to Dr. Christine Jones, “An increase of 1 percent in the level of soil carbon in the 0–30 cm soil profile equates to sequestration of 154 tons CO2/ha with an average bulk density of 1.4 g/cm3.”³ It follows that .75 percent organic matter = 115.5 metric tons of CO2 per hectare (115,500 pounds an acre per year). This system can be used on arable and permanent croplands for a total of 1.55 billion hectares (3.9 billion acres). Extrapolated globally across arable and permanent croplands it would sequester 179 Gt of CO2 per year (1.55 billion hectares × 115.5 metric tons of CO2 per hectare = 179 billion tons.) If this system were deployed on 10 percent of arable and permanent croplands, it could sequester 17.9 Gt of CO2 annually.
The Agave Agroforestry System
Research by Dr. Mike Howard shows that the agave agroforestry system can sequester 8.7 metric tons of carbon dioxide per hectare per year. This does not count below-ground SOM sequestration or the amount of carbon sequestered by the companion trees. The potential for soil carbon sequestration is very high due to the role of deep roots excreting around 30 percent of the carbon compounds created through photosynthesis into the soil. This could sequester a total of 11.3 tons of CO2 per hectare.
Extrapolated globally across the 3.4 billion hectares (8.5 billion acres) of permanent pastures, the agave agroforestry system could sequester 38.42 Gt of CO2 annually. 10% adoption would sequester 3.8 Gt annually.
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