Can soil carbon sequestration contribute to mitigating climate change?

The images here are intended to illustrate two aspects of soil carbon (or organic matter) - firstly the production of good food (on my kitchen bench), secondly the need to reforest and to implement careful management of soil to enhance its organic matter (a slope at our new place). Increasing soil and biomass carbon will decrease atmospheric carbon, thus having a significant impact on global heating.

Dear Friends,
I continue to fret about Climate Change. In January, after the shocking failure of the Copenhagen talks, several of us got together to share our distress and work out what to do next. One person suggested we push for the personal carbon quota. In this system, everyone has an equal share of the total allowable annual carbon emissions. You have a strong incentive to live with less than your budgetted amount, and then you can trade the extra with someone who wants to exceed their budget. The total allowable amount diminishes with time.


Jack wanted to explore the role of global elites - the ultra-wealthy, the media controllers and so on, in blocking action on climate change. Since then he has been conversing with folk in the International forum on Globalization about a possible project on that topic.


I wanted to explore the idea of carbon sequestration through agriculture and forestry - by biological means. It seemed to me that the focus had been on fossil fuel carbon emissions and alternative energy. Several points began to become evident to me, alongside one that is well-known - carbon losses through deforestation.
*Greenhouse gas emissions from agriculture are a significant proportion of the total - 13.5% globally, about 50% of emissions in New Zealand. The global figure rises to 51% if land use and land use change are included in the calculation. That's emissions from deforestation. The emissions comprise nitrous oxide, largely from the enormous and rising use of nitrate fertilisers; methane from the guts of ruminant animals; carbon dioxide from deforestation to clear more land, soil management practices, fertiliser manufacture and fossil fuel use in agricultural machinery. Many readers of this blog will know that nitrous oxide and methane are many times more potent in reflecting solar heat back to earth than carbon dioxide is.
* There are quite well-known ways to cut agricultural greenhouse emissions, and many of them, eg no-till agriculture. . Furthermore, there are multiple ways to build soil carbon. That is, not only cutting emissions, but pulling down CO2 from the atmosphere into the soil. Some of those ways are designed to keep stable carbon in the soil for centuries. Composting would be the best known of this cluster of strategies. Biochar burial in soil is another.

* Better still, all of the practices referred to above shift agriculture from being an unsustainable practice, exhausting the soil over time, to a perhaps perpetually sustainable activity.

* Better yet, some of these practices bear the promise of greater food productivity. Not all of them.



So we should surely talk more about this issue.



I registered for a conference on New Zealand Soil Carbon. With the help of my friend and mentor, soil scientist Don Graves, I put myself through a little crash course on learning about soil. I cycled to Don's one day to pick up a primer in the nature of soil. I had to come back with the car to collect the ten volumes of essential reading Don had for me. What a revelation! It's another world down there! And to think I've been walking around on top of it all, largely oblivious to the teaming life in ultra-complex systems beneath my feet.



The conference was an interesting experience. The participants were mainly farmers, fertiliser makers and soil scientists. Highlights in my quest to answer the question that heads this blog were:

* the presentation by Australian climate activist (and much else) Tim Flannery. Here are his major points:
o Half of avoided emissions to deal with climate change need to come from the biological systems of agriculture and forestry.
o Emissions need to start coming down by 2015; this requires rapid action. (Agriculture doesn’t even enter the NZ ETS until 2015.)
o Carbon can be sequestered in soil in three ways – holistic stock management; enhanced humus production and retention (by a variety of methods comprising biological farming); and charcoal sequestration in soil.
o NZ’s effort in research in this area, $5million per annum, is ‘pathetic’. Much more is needed.
o It’s good that NZ at least has an ETS (compared with Australia) but it needs major revisions to incentivise individual farmers to sequester soil carbon. (I noted that many farmers present were anxious and negative towards the ETS, concerned that they wouldn’t be rewarded for their carbon achievements.)

The other highlight was a ‘break-out session’ hosted by me on the potential of Soil Carbon sequestration to contribute to Climate Change mitigation. These were the major points:
1. There’s loads of potential for increasing soil C in NZ; in fact, it will be dangerous if we don’t do so and fail to retain C in some soils.
2. Biological farming is the way to do it. Get C deep and stable by means of plant choices.
3. We need to be able to measure it.
4. You can make changes that have to do with increasing soil carbon very quickly eg in a year. This contrasts dramatically with the lead time needed for other CC mitigation strategies, eg alternative energy solutions.
5. We need to incentivise the costly transition to biological (different from subsidising production). But note – Carbon and Energy footprint reducing measures are often intrinsically money-saving.
However, on a panel of six speakers later asked about the potential of biochar, several were sceptical because of cost-benefit issues and the carbon costs of transport of feedstock and making the biochar compared with carbon savings in sequestration. One was enthusiastic.

Where do I go from here on this? As soon as I complete another major task I'd like to address this one. It feels very urgent. I'm not sure what the next step is. Probably to get a few minds together. If any reader of this blog wants to go further on this issue, please let me know.

Also, I can send my full notes on this conference to anyone who wishes to see them.

Warmest wishes,
Joanna