Biochar: looking better all the time

Interesting biochar research is reported in a news release from the American Society of Agronomy.  An Australian research team has been testing the effects of biochar on nitrous oxide emission and nitrogen leaching from two different soil varieties. Their results are reported (no charge for this month) in the Journal of Environmental Quality.

The study demonstrates that biochar, applied to soils to capture and store carbon, can reduce emissions of the potent greenhouse gas nitrous oxide and inorganic nitrogen runoff from agriculture settings.

It apparently takes time for the biochar to interact with the soil in this way. The scientists subjected soils samples to three wetting-drying cycles, to simulate a range of soil moistures during the five-month study period, and measured nitrous oxide emissions and nitrogen runoff. Initially the effects were inconsistent. Several early samples produced greater nitrous oxide emissions and nitrate leaching than the control samples. However, during the third wetting-drying cycle, four months after biochar application, all biochars reduced nitrous oxide emissions by up to 73%, and reduced ammonium leaching by up to 94%. The researchers suggest that reductions in nitrous oxide emissions and nitrogen leaching over time were due to “ageing” of the biochars in soil.

Senior author Bhupinder Pal Singh comments:

“The impacts of biochars on nitrous oxide emissions from soil are of interest because even small reductions in nitrous oxide emissions can considerably enhance the greenhouse mitigation value of biochar, which is already proven to be a highly stable carbon pool in the soil environment.”

Research is on-going to investigate the causes of the reductions in nitrous oxide emissions, especially under field conditions, and to determine optimal rate and timing of biochar and fertiliser applications to agricultural soils to maximize the greenhouse mitigation value.

The effect of biochar on nitrous oxide emissions is not a new discovery. A Hot Topic post eighteen months ago mentioned early indications that biochar appeared to cause the soils in which it was buried to give off less carbon dioxide than normal and much reduced levels of nitrous oxide. Geoff Bertram and Simon Terry in The Carbon Challenge, in arguing that farmers have means for reducing greenhouse gas emissions, mention biochar both for its carbon sequestration value and also for its reported suppression of nitrous oxide emissions. The research reported here appears a confirmation of this, especially if it proves robust over time. Longer testing will be needed, but the signs seem promising.

8 thoughts on “Biochar: looking better all the time”

  1. For sure, biocharring soils with the proper micro-organisms should speed this process up, this is the one geoengineering scheme I’m confident isn’t easily misused and is relatively cheap.

  2. To take a specific example, if there was very robust movable (*maybe on a truck*) biocharring engines the Gulf distaster cleanup could be done at least partly with these and the charred remains of the crude could be used as biochar on some forestry landscape.

  3. I urge everyone to take a look at this report on Biochar –

    Biochar might lock in carbon in your garden, maybe on your farm, but as a climate solution at a grand scale its a dangerous project that should be stopped before it gets started. The NZ biochar network and its affiliates is strongly linked in with the International Biochar Initiative, a massive industry lobby group representing some of the worlds biggest polluters and aimed at getting Biochar into Carbon Markets. Offsetting real, permanent emissions from smokestacks with unstable non-permanent carbon in soils will render the entire process useless as far as the climate is concerned and will provide polluters with on-paper emissions reductions that meke no real difference to the climate. Be careful of those promoting biochar, they are vultures.

  4. Agreeing with jyyh this is a cheap geoengineering solution, but it also seems to be the ONLY one that doesn’t have knock on consequences, or ignores the problem, i.e. it removes CO2 and doesn’t just mask it. Also agreeing with Gary, seems to be ridiculous to manufacture a fuel and bury it, just so you can dig up a fuel and burn it.

    As for the article, I suspect we have a surface catalytic effect here, and it takes a few cycles to open up that surface area.

  5. knock on consequences…

    + ‘Biochar’ advocates are promoting ‘targets’ which would require the use of 500 million hectares or more of land to be used for producing charcoal plus energy. Industrial monocultures of fast growing trees and other feedstocks for the pulp and paper industry and for agrofuels are already creating severe social and environmental impacts which worsen climate change. This very large new demand for ‘biochar’ would greatly exacerbate these problems.

    + There is a risk that ‘biochar’ could in future be used to promote the development of genetically engineered (GE) tree varieties specifically engineered for ‘biochar’ production or to try and extend the range of fast-growing trees, both of which could have very serious ecological impacts.

    + There is no consistent evidence that charcoal can be relied upon to make soil more fertile. Industrial charcoal production at the expense of organic matter needed for making humus could have the opposite results.

    + Combinations of charcoal with fossil fuel-based fertilisers made from scrubbing coal power plant flue gases are being promoted as ‘biochar’, and those will help to perpetuate fossil fuel burning as well as emissions of nitrous oxide, a powerful greenhouse gas.

    + The process for making charcoal and energy (pyrolysis) can result in dangerous soil and air pollution.


  6. We got into this mess one coal fire/driven mile/factory at a time, if we get out of it again it will be one wind farm/solar farm/biochar acre at a time. Why does everybody assume that there can only ever be one solution? 500 million hectares, fine, why do we have to do it all at once? Why does it have to all be in the same place? Why not simply start off with agricultural waste?

    There is a risk re. GM. Talk about borrowing trouble, we haven’t got biochar farming yet. Eventually the sun will go red giant, why bother at all?

    Who says it makes soil more fertile? I didn’t, and I didn’t really care, it was about burying carbon.

    Fine, so educate people. There is no point burying the stuff if we are just going to dig it up again in a different form.

    And other forms of geoengineering treat the symptoms and mask the problem, so for example the oceans continue to acidify.

    So of all your knock on consequences the only real one is monocultures and the scale of the problem. And only if you try to solve the problem in one stroke.

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