One area that generates extended discussion on LP climate change threads is the ability of biological processes – forests, particularly – to remove some of the excess carbon dioxide we’re so thoughtlessly dumping into the atmosphere. It’s a genuinely problematic area, apparently – aside from measurement difficulties, it’s difficult to include in emissions trading schemes because the stored carbon can be released again by fires, land clearing, or soil disturbance.
In that context, a story on the 7.30 report about some new scientific research is quite interesting. Phytoliths are a microscopic structure that forms in many agriculturally useful plants, notably grasses. They’re a little blob of carbon, which is not that unusual in biological structures. However, what makes them interesting is that they have an external skin of silicon – rather tough, hard, and durable stuff. Because of this, the carbon in a phytolith is effectively locked away for a very long time – thousands of years, according to the story. It doesn’t matter if the land use changes, or careless agricultural practices are used. The carbon is effectively taken out of the biosphere. And according to the story, it’s easy to measure the quantity of carbon thus sequestered. Quantifiable, long-term biological sequestration – sounds all good, doesn’t it?
Except for one thing. The quantities are, in the greater scheme of things, not large. The “super bamboo” mentioned in the program sequesters apparently sequesters one tonne of carbon – the equivalent of 3.66 tonnes of carbon dioxide – per hectare, per year. The capacity of the food crop being analysed, sugar cane, to do so is mentioned to be smaller; but one variety is mentioned to be able to capture half a tonne per acre more than another. If Queensland’s entire sugar cane crop switched from a low-phytolith to a high-phytolith variety, it would capture roughly 189,000 additional tonnes of carbon (or roughly 700,000 tonnes of CO2 equivalent) annually – about 0.1% of Australia’s total emissions. If cane farmers are allowed to sell phytolith-based offsets, the financial impact will be small initially. Based on this site’s statistics, the average cane farmer produces around $4,500 worth of sugar per hectare. Half a tonne of carbon – equivalent to 1.8 tonnes of CO2 – will likely be worth around $35-40 initially, rising to about $90 at a carbon price of $50/tonne of CO2. That’s a nice bonus for doing not very much – assuming that the high-phytolith and low-phytolith varieties have the same yield. Even a marginal decrease in yield for the high-phytolith variety is going to make the exercise a financial negative for farmers.
Obviously, careful attention to plant breeding might substantially increase the phytolith production, and as time goes on the carbon price will head up, so there’s plenty of scope for phytoliths to make a contribution both to greenhouse mitigation and farmers’ bottom lines. But it’s going to a be a relatively small one. If the biosphere is going to sequester carbon for us, we’ll need a lot of heavy lifting from other sources.
You mention ‘careful breding’. Is this an area where genetic engineering can come into play. We’ve bred plants that can do all sorts of things. Can we genetically engineer plants in which these critters function really well?
Why leave it up to living plants,in production!?Why not just plant cells,research into by products and the mentioned cells!?Eg., yeasts sugars,plant fibres roots,and growing them in bagasse wastes,to end up being burnt!?!Things grow in compost too!?Compost can be modified pyrolysis.What are the essential growing conditions for these cells,and can they be bred passively whereever the conditions exist,or near exist!?!
One option in relation to genetic engineering might be to transfer phytolith forming genes into other plants. If (yes a big if) all species crops used were capable then the CO2 reduction effect would be much larger. Of course that would raise some interesting questions for those who want to buy organic. Do you eat the ‘CO2 low’ GM crop or the ‘CO2 high’ organic one?
The other option might be to modify common garden plants (e.g. roses) to have phytolith forming genes and so maybe use people’s gardens as carbon sinks rather than using the food supply. But again that raises the issue of spreading these genes into the wider environment and the possible unintended consequences, so garden plants might have to further modified to make them sterile.
I also saw the 7.30 Report article and I also wasn’t particularly impressed by the 1t C/ha figure – every bit counts though I guess, and 700 kt/yr is significant. A more impressive figure is the 290-1170 Mt CO2-e that could be sequestered over 20 years by destocking WA’s rangelands of livestock, which is from Harper, R.J. et al. (2007) The potential of greenhouse sinks to underwrite improved land management Ecological Engineering 29 (4).
There is also the ANU Green Carbon report that has been mentioned in comments threads here before, which estimates that ending logging of Australia’s southeastern forests could sequester up to 7500 Mt/CO2-e.
Both of these activities would have significant ecological cobenefits. Ecosystems are not only important for their own intrinsic reasons, they also have greater resilience than land uses such as monoculture tree plantations, which means a greater probability that they will continue to store carbon over very long time scales.
Fine beat me to it. If we can work out the genes for phytolith creation, we can potentially add it to more useful crops, such as wheat. If the ~12 million hectares of wheat were capturing carbon, that would be what, 3% of our emissions? Just another small step towards a carbon free future.
Of course, if the carbon is locked up or inactivated in the soil, I wonder just how many tonnes can be captured before weird things happen to the soil?
Chumpai: that’s true, but I imagine the yields per hectare for something like wheat is always going to be much less than sugar cane, simply because wheat is a much smaller plant than cane.
Peter Wood: interesting piece on destocking. I wonder what happens to those calculations if agriculture is included in the ETS, and cattle methane emissions start getting costed?
I am not going to bore anyone again, but there are massive issues with the credibility of the Mackey report, and forestry will likely expand if we improve our carbon accounting systems. That refereed Harper paper looks interesting though.
That does sound exciting, Robert. This along with the growing of Kauri forests (a tree that takes many hundreds of years to grow and its wood resists rotting when felled) offer a very real form of carbon credit activity. Another advantage would be that these balls of carbon would be available for mining in some future time, when concentrated carbon becomes scarce. A very interesting relevent technolgy is in July’s scientific american on non tilling agriculture. Growing without disturbing the soil and the many benefits. Suddenly the work that a friend of mine in NZ has been doing on seed drilling makes a lot more sense.
Wilful,
The interesting thing would be how much of the plants photosynthesis (energy capture) is put to the production of the phytophyls. If this does not intefere with the production of grain then it becomes another whole production outcome for the wheat plant. The other relevent technology there is the nitrogen fixing nodules of some plants, a feature that there is a lot of research to include this in many plants including sugar cane.
As for the phytophyls in the soil, I imagine that they would perform in the same way as grains of sand and become an inert part of the soil bulk.
“Peter Wood: interesting piece on destocking. I wonder what happens to those calculations if agriculture is included in the ETS, and cattle methane emissions start getting costed?”
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I gather that destocking or my preferred option lower stocking rates help to build soil carbon when combined with minimum tillage soil rejuvenation techniques.
Courses I’ve attended have proposed that forestry can capture 11-12 tonnes per Ha , soil carbon can be built up about by 13 -14 tonnes per Ha per year but this reaches a limit after some years
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As mentioned fire can release the C so that style of sink is rather risky especially at present where the landowner has to store the C for 100 years and is liable to make up any deficits in the annual accounting that is required.
As fires are predicted to become more frequent obtaining insurance against this loss may be impossible or at least uneconomic.
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Soil carbon can be built up using the two methods( among many others) I mentioned above but will be released in the event of a prolonged dry period. Again these circumstances are beyond the landholders control but if you have entered into a contract to deliver C storage as credits the loss must be paid for .
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I think some rough calculation have shown that a hectare of new gum forestry will balance the methane outputs from 15-20 cows.
Will I then be allowed to sell my cattle as being C neutral? Probably not but
the alternative that I think will work is to have the C costs extracted from consumers at the point of sale ie at the cash register.If you choose to eat red meat then you will effectively pay a tax and this should modify consumption.The C credits I develop have to be sold to middle persons who are termed “aggregators” and it is proposed that these entities will trade the C to the polluting industries. Once again the primary producer delivers the profits to the enterprenuer.
Robert,
Including enteric emissions (farting and burping methane) from agriculture in an ETS (or apply a carbon price to these emissions in any other way) will reduce these emissions by either decreasing the emissions intensity of production (by changes to feed, breeding, biotechnology etc) or by reducing production by reducing livestock numbers. Reducing livestock numbers for extensively farmed livestock (especially cattle) will reduce emissions from “grazeland degradation”. Emissions from grazeland management are not accounted for under the Kyoto Protocol and are hard to measure, but the results of both Harper et al and the Steinfeld et al Livestock’s Long Shadow report suggest that they may be comparable to the enteric emissions.
There are good reasons for not including agriculture and land use in an ETS however:
* Uncertainties in measurement (and in additionality for offsets) could affect the carbon price in the rest of the ETS, and therefore affect the actual amount of emissions associated with a permit. This would undermine the integrity of the ETS. There are also uncertainties in measurement associated with agriculture, especially agricultural soils.
* There is a risk that coverage of only some activities would have perverse effects. For example, covering reforestation could lead to hardwood plantations being used as carbon sinks, which would lead to carbon leakage to the native forest logging sector (which is not accounted for under the Kyoto Protocol). This suggests that coverage of the whole sector, including activities not accounted for under the Kyoto Protocol may be required. Covering all activities in an ETS may make the measurement problems intractable.
While it may not be a good idea to include these activities in an ETS, there are other options for reducing emissions and internalising other externalities (such as biodiversity loss). These include price based approaches (taxes, which could be negative), regulations, and combinations of both. A carbon tax on these sectors would have the advantage that uncertainties in emissions are contained – if agriculture and land use were covered by a carbon tax, there won’t be the risk that uncertainties in emissions in these sectors would affect the ETS that is applied to the rest of the economy.
I’m not sure if the topic of terra preta (biochar) has been covered here before, but it seems a promising option for sequestering carbon in soil:
http://ngm.nationalgeographic.com/2008/09/soil/mann-text
http://peakenergy.blogspot.com/2007/01/black-earth.html
Big Gav, it has been mentioned from time to time, but those links are new, I think. So thanks.
The Rest of the Biochar Story:
Charles Mann (“1491″)in the Sept. National Geographic has a wonderful soils article which places Terra Preta / Biochar soils center stage.
I think Biochar has climbed the pinnacle, the Combined English and other language circulation of NGM is nearly nine million monthly with more than fifty million readers monthly!
We need to encourage more coverage now, to ride Mann’s coattails to public critical mass.
Please put this (soil) bug in your colleague’s ears. These issues need to gain traction among all the various disciplines who have an iron in this fire.
http://ngm.nationalgeographic.com/2008/09/soil/mann-text
I love the “MEGO” factor theme Mann built the story around. Lord… how I KNOW that reaction.
I like his characterization concerning the pot shards found in Terra Preta soils;
so filled with pottery – “It was as if the river’s first inhabitants had
thrown a huge, rowdy frat party, smashing every plate in sight, then
buried the evidence.”
A couple of researchers I was not aware of were quoted, and I’ll be sending them posts about our Biochar group: http://tech.groups.yahoo.com/group/b…guid=122501696
and data base;
http://terrapreta.bioenergylists.org/?q=node
I also have been trying to convince Michael Pollan ( NYT Food Columnist, Author ) to do a follow up story, with pleading emails to him
Since the NGM cover reads “WHERE FOOD BEGINS” , I thought this would be right down his alley and focus more attention on Mann’s work.
I’ve admired his ability since “Botany of Desire” to over come the “MEGO” factor (My Eyes Glaze Over) and make food & agriculture into page turners.
It’s what Mann hasn’t covered that I thought should interest any writer as a follow up article.
The Biochar provisions by Sen.Ken Salazar in the 07 farm bill,
Dr, James Hansen’s Global warming solutions paper and letter to the G-8 conference last month, and coming article in Science,
http://arxiv.org/ftp/arxiv/papers/0804/0804.1126.pdf
The new university programs & field studies, in temperate soils
Glomalin’s role in soil tilth & Terra Preta,
The International Biochar Initiative Conference Sept 8 in New Castle;
http://www.biochar-international.org/ibi2008conference/aboutibi2008conference.html
Given the current “Crisis” atmosphere concerning energy, soil sustainability, food vs. Biofuels, and Climate Change what other subject addresses them all?
Biochar, the modern version of an ancient Amazonian agricultural practice called Terra Preta (black earth), is gainitainability.Terra Preta Soils a process for Carbon Negative Bio fuels, massive Carbon sequestration, ng widespread credibility as a way to address world hunger, climate change, rural poverty, deforestation, and energy shortages… SIMULTANEOUSLY!
This technology represents the most comprehensive, low cost, and productive approach to long term stewardship and sus10X Lower Methane & N2O soil emissions, and 3X Fertility Too. Every 1 ton of Biomass yields 1/3 ton Charcoal for soil Sequestration.
Cheers,
Erich
The best way to offset cow farts is to mix forest with pasture. The more trees the less grass. There is a balance point where carbon absorption from the trees matches the methane release from the cows. NZ did a lot of research on this and found that there was only a marginal loss to farm returns. And if the right trees are planted then there can be a very positive addition to farm returns in the medium term.
Peter Wood, re “carbon leakage to the native forest logging sector”, while this may be the case in theory, in practice it’s basically impossible. There’s no social license to expand native forest harvesting.
Agriculture will be in the ETS before too long. They’re already starting the process of identifying approaches.
Recent comments from Garnaut on biosequestration here.
BilB, i saw an agroforesty project when i was at uni. They were growing radiata pine at 1/3 normal density in strips with healthy pastures in between. Im pretty sure it worked out to be slightly more profitable in the long term than either straight pasture or straight forestry. The livestock were happier and healthier too, as they had shelter from the elements and the block stayed green for longer.
I reckon the best bet though, is to grow fast growing, moderately long lived fodder trees like honey locust or tagasaste with pasture underneath. You get shelter, drought resistance, extra feed and carbon credits.
Anyone interested in farm forestry and the like should look into a guy called Fenton, has a 700 ha farm near near Hamilton, Victoria.
They did a landline story on him a few years back. http://www.abc.net.au/landline/content/2006/s1674809.htm
more than half of Australia’s land mass (448 million hectares) is seasonally dry grazing land. This land is not naturally “tree-friendly” with only limited trees along water courses. While most of it is currently degrading grazing land, it can be regenerated by appropriate management back to strong healthy perennial grasslands. The carbon sequestering capacity of perennial grasslands is as good as forests in many cases.
Importantly, Jan Pokorny (Dissipation of solar energy in landscape— controlled by management of water and vegetation) suggests that “cooling” through revegetation and evapotranspiration will have a greater effect on climate change than carbon sequestration.
So the answer is that changed vegetation and water management as well as sequestering carbon (through that self same vegetation management) and reducing carbon emissions full stop is what is required.
Pls take a look at http://www.soilcarbon.com.au for more on this.
PS – all ruminant animals produce methane – it is a natural part of the carbon cycle. Ruminants include bison, giraffes, wildebeest, water buffalo, and all 90 species of antelope.
soil carbon said:
Although tree densities are low across much of Australia’s arid and semi-arid regions, and while acknowledging that extensive regions of natural grasslands and shrublands occur, soil carbon’s assertion is nonetheless misleading.
In fact, Australia’s arid regions are globally notable for their comparatively high tree densities. For example, Acacia aneura, Acacia papyrocarpa, Alectryon oleifolius, Myoporum platycarpum and Casuarina pauper are small to medium sized trees frequently encountered well away from water courses in lower-latitude regions with annual rainfall under 300mm. At slightly higher rainfall various Callitris and Eucalyptus species become important components of many semi-arid vegetation communities.