The Carbon Farming Solution - Chapter 2: Agricultural Climate Change Mitigation and Adaptation

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The CARBON FARMING SOLUTION - A Global Toolkit of Perennial Crops and Regenerative Agriculture Practices for Climate Change Mitigation and Food Security

by Eric Toesmeier

Part 1: The Big Idea

2: Agricultural Climate Change Mitigation and Adaptation


For this discussion, the emphasis is to be on how we can use the information from the book to mitigate climate change and rising levels of CO2. We're looking for solutions, not debate about whether or not there is a problem. I'd like the discussion to be positive, helping people to make appropriate decisions, encouraging any step in the right direction.

I like this chapter very much. He covers a lot of ground with a broad brush and really sets his out his stall regarding the three pronged approach

- reducing current ag emissions,
- agroecological intensification of existing ag land (hopefully to prevent more land clearing) and
- Carbon sequestration

I must admit I was shocked to discover that transportation in the US is only 3% of emissions. (I would have put that in the 15% or higher range if i'd have had to have guessed). Also discovering that supermarket food often has a smaller carbon footprint than from local farms makes it clear that it's not really what we do, but how we do it that makes the difference to the numbers.

New Zealand (where I lived for several years) is a case in point. In certain cases the produce that was shipped from there to europe actually had a smaller carbon footprint that food produced in europe, this was because of the energy cost of cold storage of apples grown in the UK, that shipping is has a relatively small carbon footprint, and (depending on the product) the fact that much of the electricity in NZ is hydro.

I'd be really curious to know if anyone has any idea about how much current ag emissions could be reduced if we ate seasonal produce only?

Rus Williams wrote:
I must admit I was shocked to discover that transportation in the US is only 3% of emissions. (I would have put that in the 15% or higher range if i'd have had to have guessed).

I think you may have misinterpreted that number (or maybe I misinterpreted what you wrote - if so I apologise). The way I read it is that of food system emissions, transport is 3%. This does seem to imply that most of the reductions can come from approaching other aspects of the problem.

Eric Toensmeier wrote: And transportation is a small fraction of food system emissions, only 3 percent in the United States.

His reference for this is this document: http://pubs.iied.org/pdfs/15516IIED.pdf It's well sourced, but not peer reviewed. I also couldn't find the comment to back up Toensmeier's statement. It's supported in general terms, in the sense that buying local isn't necessarily the best way of selecting foods, but not that specific figure. I may have missed it. Someone please correct me if I did.

That said, I found a reference to this paper in the references: http://pubs.acs.org/doi/abs/10.1021/es702969f

They write:

Christopher L. Weber and H. Scott Matthews wrote: We find that although food is transported long distances in general (1640 km delivery and 6760 km life-cycle supply chain on average) the GHG emissions associated with food are dominated by the production phase, contributing 83% of the average U.S. household’s 8.1 t CO2e/yr footprint for food consumption. Transportation as a whole represents only 11% of life-cycle GHG emissions, and final delivery from producer to retail contributes only 4%. ... Thus, we suggest that dietary shift can be a more effective means of lowering an average household’s food-related climate footprint than “buying local.” Shifting less than one day per week’s worth of calories from red meat and dairy products to chicken, fish, eggs, or a vegetable-based diet achieves more GHG reduction than buying all locally sourced food. - my emphasis

Having had a look at the paper, the distinction between transportation as a fraction of life-cycle emissions and final delivery is that the 4% represents getting the food from the farm to the table, but the remaining 7% relates to the transport of inputs, such as livestock feed and fertiliser. A local herbivorous diet probably tops the lot, but you are still probably better off eating imported soya beans from Brazil than you are local beef (probably fed on Brazilian soya beans to begin with).

Toensmeier seems to be in the right ballpark (UK figures for the latter are 5% according to the original reference), but slightly misleading in that he does not consider those upstream inputs. I suspect the IIED don't either, but I haven't checked those numbers.

According to the US Environmental Protection Agency, total transport emissions are around 26% of total US GHG emissions: https://www3.epa.gov/climatechange/ghgemissions/sources/industry.html

I think this is one of Toensmeier's weaknesses. He references to documents, but often not to original peer-reviewed research. It's bugging the **** out of me.

This is the chapter where Toensmeier introduces Agroecological Intensification. I would like to learn more about this.

Agroecological is a word I've seen bandied about on websites, and a few books, but I'm not sure I know what it means. The way it is used seems to be different depending on the context, which may simply mean it's a term with a flexible use.

Agroecological sounds like a good thing:

Agroecological systems, once established (which can take several years), often yield better than industrial agriculture. Many studies show that agroecological farms have reduced emissions and sequester more carbon than industrial agriculture.

Another thing that came up in this chapter is about how carbon sequestration works - aka, how plants grow.

Plants use the atmospheric carbon in their photosynthesis to build new ... um... plant. The roots are especially carbon dense.

Which tickled something in the back of my mind, and I only now remembered what it is. Irrigation reduces root growth, often drastically. So irrigation decreases carbon sequestration?

R Ranson wrote:
Another thing that came up in this chapter is about how carbon sequestration works - aka, how plants grow.

Plants use the atmospheric carbon in their photosynthesis to build new ... um... plant. The roots are especially carbon dense.

Which tickled something in the back of my mind, and I only now remembered what it is. Irrigation reduces root growth, often drastically. So irrigation decreases carbon sequestration?

My understanding of this runs: yes, sometimes. In heavy (clay) soils waterlogging inhibits ion transport into plant roots. In other circumstances plants will sent out roots looking for water (or other nutrients) where that's a limiting factor. In circumstances where water is the limiting factor, irrigation will help. This may need to be carefully timed where daytime temperatures exceed 30C (slightly higher for crops using the C4 photosynthetic pathway).

Hope that helps.

It does help, thank you Neil.

This is obvious, but it occurred to me that carbon sequestration is a cycle, as all of nature is. So is there no "end-point" that we are trying to reach? Is this dependent upon the purpose of the land use? Is the goal to get most landscapes into a stable climax ecosystem? (and with that idea, can anyone explain if there is truly a stable climax ecosystem?) Or is this goal only for reforestation/conservation areas?


Along with this, Toensmeier's sentence struck me as missing some importance: "although yield is a critical factor in selecting carbon farming techniques, so are social implications, economics, ecosystem services, and of course carbon sequestration capacity" (pg. 21). I know he highlighted the damaging effects of industrial agriculture in general, but he only used one paragraph to highlight that topic. I think this paragraph would have benefited by a brief history on how prioritizing yield has driven choices that are ecologically damaging. Anybody else think this? Maybe in terms of a large scale plan for carbon sequestration Toensmeier is aiming taking a more pragmatic view and not looking to alienate too many readers.

For the topic of above ground and below ground biomass, are there techniques or methods anyone is aware of to incorporate this dead and fallen above ground biomass into the soil? Maybe he will touch on that in later chapters.

On the topic that roots exude about 200 chemicals to feed the microbe life in the soil around them: this seems to me as a good reason to emphasize no-till agriculture and disturbing the soil as little as possible. Also, to restore degraded soils with beneficial microbes. Does anyone know of research showing that microbe life in soils contributes directly to carbon sequestration? Maybe increased microbe life will hasten the productive sequestration time of any given piece of land? Or is there a negative aspect to increased microbe life that I am not aware of?

I did like this sentence: "It is this synergy of fighting climate change while improving farm health and productivity that makes carbon farming such an appealing idea." I hope there is more "motivating speech material" in this book that we can use easily when trying to educate about carbon farming.

Aaron Martz wrote:This is obvious, but it occurred to me that carbon sequestration is a cycle, as all of nature is. So is there no "end-point" that we are trying to reach? Is this dependent upon the purpose of the land use? Is the goal to get most landscapes into a stable climax ecosystem? (and with that idea, can anyone explain if there is truly a stable climax ecosystem?) Or is this goal only for reforestation/conservation areas?

No, the concept of the climax ecosystem has been pretty much superseded. The theoretical end-point in terms of carbon farming would be the point at which any given soil saturates with carbon.

Aaron Martz wrote:
Along with this, Toensmeier's sentence struck me as missing some importance: "although yield is a critical factor in selecting carbon farming techniques, so are social implications, economics, ecosystem services, and of course carbon sequestration capacity" (pg. 21). I know he highlighted the damaging effects of industrial agriculture in general, but he only used one paragraph to highlight that topic. I think this paragraph would have benefited by a brief history on how prioritizing yield has driven choices that are ecologically damaging. Anybody else think this? Maybe in terms of a large scale plan for carbon sequestration Toensmeier is aiming taking a more pragmatic view and not looking to alienate too many readers.

Equivocal yes. I equivocate because we somehow need to work out how to feed ten billion people by 2050 or not much later, preferably without worsening the worst extinction event in 65 million years. This is not a trivial problem.

Aaron Martz wrote:
For the topic of above ground and below ground biomass, are there techniques or methods anyone is aware of to incorporate this dead and fallen above ground biomass into the soil? Maybe he will touch on that in later chapters.

Mulching is the obvious one.

Aaron Martz wrote:
On the topic that roots exude about 200 chemicals to feed the microbe life in the soil around them: this seems to me as a good reason to emphasize no-till agriculture and disturbing the soil as little as possible. Also, to restore degraded soils with beneficial microbes. Does anyone know of research showing that microbe life in soils contributes directly to carbon sequestration? Maybe increased microbe life will hasten the productive sequestration time of any given piece of land? Or is there a negative aspect to increased microbe life that I am not aware of?

I'd agree on the first bit. In terms of microbes, there is a case for introduction of species where these may have been wiped out by, for example, conventional farming or when you are trying to change the habitat from, for example, annuals to woodland. Plant exudates and mycorrhizal functions will then take over the soil ecology with minimal additional microbial input. Some bacteria and some fungi accelerate mineral weathering, and carbon is involved in some of these processes, but that weathering is mostly down to the actions of carbonic acid. Bacteria, fungi and other microbes do not, in general, sequester carbon in their own right. Most of that comes from plants through photosynthesis. A healthy soil microbiota will support faster plant growth, more photosynthesis and more rapid carbon sequestration by that route.

I'm not aware of research quantifying this.

Neil Layton wrote:
No, the concept of the climax ecosystem has been pretty much superseded. The theoretical end-point in terms of carbon farming would be the point at which any given soil saturates with carbon.

Thank you for this. This idea is still very prevalent in permaculture. Is it still useful as a phrase for describing a general pattern? Or would it be better to get rid of 'climax ecosystem' totally and refer to ecosystems at that stage as 'mature'?

Neil Layton wrote:
Equivocal yes. I equivocate because we somehow need to work out how to feed ten billion people by 2050 or not much later, preferably without worsening the worst extinction event in 65 million years. This is not a trivial problem.

Great point. The enthusiasm that vague ideas that fit into the permaculture mold can feed the world just by being permaculture related is prevalent as well. Toensmeier touches on the difficulties by describing the productivity loss that even 2 degrees C increase will result in, let alone 4 or 6 C.

Neil Layton wrote:
Mulching is the obvious one.

Toensmeier says that ~2/3 of the carbon from dead above-ground biomass will enter the atmosphere with the normal carbon cycle. Is there a way to incorporate this carbon into the soil so that less will be released into the atmosphere?

Neil Layton wrote:
I'd agree on the first bit. In terms of microbes, there is a case for introduction of species where these may have been wiped out by, for example, conventional farming or when you are trying to change the habitat from, for example, annuals to woodland. Plant exudates and mycorrhizal functions will then take over the soil ecology with minimal additional microbial input. Some bacteria and some fungi accelerate mineral weathering, and carbon is involved in some of these processes, but that weathering is mostly down to the actions of carbonic acid. Bacteria, fungi and other microbes do not, in general, sequester carbon in their own right. Most of that comes from plants through photosynthesis. A healthy soil microbiota will support faster plant growth, more photosynthesis and more rapid carbon sequestration by that route.

I'm not aware of research quantifying this.

So is the idea that an initial culture in the area should be enough, if the environment is right for them, to populate the area from there on out?

Aaron Martz wrote:
Thank you for this. This idea is still very prevalent in permaculture. Is it still useful as a phrase for describing a general pattern? Or would it be better to get rid of 'climax ecosystem' totally and refer to ecosystems at that stage as 'mature'?

Uh. There are several scientific papers on this subject. Some ecologists are of the view that the term “ecosystem” has had its day. I'm going to risk oversimplifying tens of thousands of words of erudite work here. All ecosystems are, by definition, connected to others, so the boundaries between them are grey areas anyway. You then have to factor in the point that an ecosystem, if you accept the term in the first place, is dynamic, by definition. I talk about horizon habitats, which are points of temporary maturity, subject to management, even a later point of succession.

The concept of the climax community is useful, but there comes a point at which it gets in the way of broader understanding or useful (itself a subjective, loaded, term) management.

Aaron Martz wrote:

Neil Layton wrote:
Equivocal yes. I equivocate because we somehow need to work out how to feed ten billion people by 2050 or not much later, preferably without worsening the worst extinction event in 65 million years. This is not a trivial problem.

Great point. The enthusiasm that vague ideas that fit into the permaculture mold can feed the world just by being permaculture related is prevalent as well. Toensmeier touches on the difficulties by describing the productivity loss that even 2 degrees C increase will result in, let alone 4 or 6 C.

I'm actually not convinced it can even be done, with permaculture or without it. Most analyses use present trends and extrapolate. Once you take into account climate disruption, rates of cropland loss, ecosystem collapse, the possibility of tipping points - which could happen at any time - I think we are in deep trouble. I'm also aware of the possibility that perennial agriculture could be a trap. With abrupt climate change it may be impossible to adapt quickly enough to replace crops that can't cope with the new climate.

I'm not known for being the most optimistic of people, it's true, but I think one possible value of "deep trouble" is extinction. When I first started hillwalking I learned about the concept of the incident pit (I believe it's a concept borrowed from diving). A few small incidents narrow your safety margin. These may be innocuous to begin with: a squall may slightly delay you on your route. You try to make up time, so you twist your ankle, so you skip lunch, which impairs judgement, so you get lost, then another squall makes you wet and cold at a time of day when it's harder to get warm, so your judgement is further impaired so you sprain your ankle so you can't get off the hill so you die of hypothermia around 2am. Any one of these problems would be a non-issue, but one after another kills you.

I suspect we as a species may be falling into an incident pit. Localised crop failures and the odd big storm or drought we can cope with. It's annoying and may kill thousands, even millions of people, but it doesn't threaten us as a species. Enough droughts, enough storms, enough countries imposing export bans to protect their own population, enough water conflicts, enough sea-level rise and so on and the whole thing could turn very, very bad for everybody. I think it's plausible that a reliance on perennials may be a misjudgment born of a realisation of a problem we're not equipped to solve. It might be the far end of the probability tail, but I don't want to discount it.

Aaron Martz wrote:

Neil Layton wrote:
Mulching is the obvious one.

Toensmeier says that ~2/3 of the carbon from dead above-ground biomass will enter the atmosphere with the normal carbon cycle. Is there a way to incorporate this carbon into the soil so that less will be released into the atmosphere?

Not that I know of. Presumably you'd need to till, but that results in the release of soil carbon. Mulch also helps to retain water and moderate soil temperatures. The net effect of that would depend on several variables.

Aaron Martz wrote:
So is the idea that an initial culture in the area should be enough, if the environment is right for them, to populate the area from there on out?

Assuming they are not there already. Most soils contain microbes, often dormant.

Neil Layton wrote:

Aaron Martz wrote:

Neil Layton wrote:
Equivocal yes. I equivocate because we somehow need to work out how to feed ten billion people by 2050 or not much later, preferably without worsening the worst extinction event in 65 million years. This is not a trivial problem.

Great point. The enthusiasm that vague ideas that fit into the permaculture mold can feed the world just by being permaculture related is prevalent as well. Toensmeier touches on the difficulties by describing the productivity loss that even 2 degrees C increase will result in, let alone 4 or 6 C.

I'm actually not convinced it can even be done, with permaculture or without it. Most analyses use present trends and extrapolate. Once you take into account climate disruption, rates of cropland loss, ecosystem collapse, the possibility of tipping points - which could happen at any time - I think we are in deep trouble. I'm also aware of the possibility that perennial agriculture could be a trap. With abrupt climate change it may be impossible to adapt quickly enough to replace crops that can't cope with the new climate.

I'm not known for being the most optimistic of people, it's true, but I think one possible value of "deep trouble" is extinction. When I first started hillwalking I learned about the concept of the incident pit (I believe it's a concept borrowed from diving). A few small incidents narrow your safety margin. These may be innocuous to begin with: a squall may slightly delay you on your route. You try to make up time, so you twist your ankle, so you skip lunch, which impairs judgement, so you get lost, then another squall makes you wet and cold at a time of day when it's harder to get warm, so your judgement is further impaired so you sprain your ankle so you can't get off the hill so you die of hypothermia around 2am. Any one of these problems would be a non-issue, but one after another kills you.

I suspect we as a species may be falling into an incident pit. Localised crop failures and the odd big storm or drought we can cope with. It's annoying and may kill thousands, even millions of people, but it doesn't threaten us as a species. Enough droughts, enough storms, enough countries imposing export bans to protect their own population, enough water conflicts, enough sea-level rise and so on and the whole thing could turn very, very bad for everybody. I think it's plausible that a reliance on perennials may be a misjudgment born of a realisation of a problem we're not equipped to solve. It might be the far end of the probability tail, but I don't want to discount it.

This certainly isn't a popular opinion you just put out. Going on a little rant here, I personally loathe the solutions that techno-utopians put forward as remedies for all problems - "We will invent a new technology to solve the problem." For climate change, this strikes at many ideas being considered by geoengineers. Ideas that we have no predictive capacity to describe whether they would actually work, do nothing with a lot of resources or make issues worse. Do you read the Small Farms Future blog? Chris Smaje is constantly railing against this ideology and the idea that technology will fix all of our issues.

Anyways, I agree with you, though I didn't have any of the theoretical possibilities mapped out that you just gave.Thank you for that metaphor. There is the potential that humans will become extinct. I don't like this idea, but there is a certain amount of relief when I think about the evidence of different mass extinctions in the Earth's history, and the fact that after each event bio-complexity grew again. In some far off future, life will rise again as we once knew it, just without humans. And without humans, the total suffering will remain low in the world.

Your ideas bring up a thought that what we need is not just Toensmeier's approach, but a whole slew of ideas (far-fetched geoengineering excluded). Resilience is brought to mind for me - resilient, small-scale communities that are largely self-sufficient in a diverse number of ways.

Aaron Martz wrote:we need is not just Toensmeier's approach, but a whole slew of ideas

Mostly, I think, we need to implement the solutions already available! Yes, more ideas will be great, but let's at least start with those we already have!