ETS lifeline: soils capable of absorbing cattle methane

03 Sep, 2009 02:06 PM
Professor Mark Adams says
Professor Mark Adams says "...high country cattle grazing is easily methane-neutral and may even offset cow-methane from other parts of the landscape.”

LIVESTOCK producers may have an emissions trading lifeline with the discovery that Australian soils are capable of neutralising more methane than cattle can produce from the same land.

Although only a preliminary finding, University of Sydney researchers have added a piece to the global warming policy puzzle.

How does methane produced by ruminant animals fit into the biological cycle?

Their research, done on grazing land in the Snowy Mountain region on soils with high organic matter levels of 5-7 per cent, found that these high country soils oxidise methane at a rate of 100 milligrams per square metre per hour, or roughly 8760 kilograms per hectare per year.

By contrast, 100 head of cattle produce about 5400 kg/ha of methane a year.

“In other words, high country grazing is easily methane-neutral and may even offset cow-methane from other parts of the landscape,” said Professor Mark Adams, Dean of Sydney University’s Faculty of Agriculture, Food and Natural Resources.

However, Prof Adams said more work is needed to tighten up his “back of the envelope” calculations, and to determine exactly what is happening in the soils being studied.

Nor is soil oxidation of methane an end to livestock emissions.

Prof Adams explained that a specific class of bacteria uses methane as part of its metabolic process. In oxidising methane, the bacteria produces another greenhouse gas, carbon dioxide (CO2).

But because methane is considered to have 23 times the greenhouse gas warming potential of CO2, the soil oxidation process, if considered part of a biological cycle, has the potential to cut the cost of livestock emissions by 23 times.

Prof Adams described the process as “very significant, and very consistent” across the high organic matter soils studied on the Snowy and Bogong high plains.

The methane finding was an unexpected outcome of a study established to look at interactions between grazing and bushfires.

“We reasoned that we also needed to know a little about how land management was going to affect greenhouse gas emissions, including what we thought would be methane emissions from the soils,” Prof Adams said.

“Lo and behold, we didn’t have methane emissions, we had methane oxidation.”

The study wasn’t the first to observe oxidisation of methane by soil microbes, Prof Adams said, but it is the first to measure the phenomenon in Australian soils.

“We don’t have a good handle on the conditions that promote the growth of methane-oxidising bacteria; we don’t know the exact nature of the microbial communities, we don’t know what else we could do to encourage them.”

“We know little, and in the world’s literature on this, there’s not much more than a handful of publications.”

However, Prof. Adams believes that the soils most capable of oxidising methane are likely to be well-drained, with good structure, rich in organic matter, and will not have been heavily treated with fertilisers known to kill off microbial life.

“Broadacre, low-intensity grazing operations might be something that Australia might well become specialised in as being more carbon-neutral. We could perhaps develop markets for beef or lamb produced using very little fossil fuels, and in a completely carbon-neutral way.”

“There’s much more potential significance to this, if we can get our story right, and our land management right.”

A Sydney University proposal to extend its research into soil oxidation of methane was rejected by the Federal Department of Agriculture.

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3/09/2009 6:53:23 PM

The other fact that nobody has acknowledged yet is that proteins such as meat and wool are net sequesterers of carbon - atmospheric carbon! Foliage, grasses and herbages that absorb CO2 from the air are consumed by livestock and converted into protein. Would Mr Rudd please contact me, a beef, mutton and wool producer, about my forthcoming carbon sequestration royalties!
Jon Noble
4/09/2009 6:25:34 AM

Well this is turn for the good I just happen to own land(tow small farms) in the hillsin the Northern Rivers! What amazing big business this carbon trading is. The scientists that make the discovery could be in trouble as if there is no trouble there is no job.The vast proportion of Co2 comes from the oceans evaporation! We are ready to mix up polution into the issue yes stop poluting the planet and if we could do this we could live in a beuatiful atmosphere like the Romans did until Nero comes around a burns Rome to the ground!Pass the tear glass please!
Jon Noble
4/09/2009 6:26:26 AM

Well, this is turn for the good. I just happen to own land (two small farms) in the hills in the Northern Rivers (of NSW)! What amazing big business this carbon trading is, but the scientists who make the discovery could be in trouble, as, if there is no trouble, there is no job. Yes, stop polluting the planet and if we could do this we could live in a beautiful atmosphere like the Romans did until Nero comes around a burns Rome to the ground! Pass the tear glass please! The vast proportion of Co2 comes from the oceans' evaporation!
4/09/2009 7:39:28 AM

The surface of the planet is carbon neutral in general. If there is a problem, that is only being caused by carbon that has been buried for millions of years being dug up and burnt. The fact that farming is even being spoken about in regards to carbon emissions simply serves to highlight the power of the fossil fuel industry and its attempts to muddy the waters on one hand, aided and abetted by green groups at the other extreme.
Common Cents
4/09/2009 9:00:51 AM

Well done, Professor Mark Adams - it is good to see there are still some learned people at Sydney Uni with common sense as well as brains.
4/09/2009 10:10:05 AM

In this debate, I say green groups are being bought off. Not long ago I was watching a current affairs program. Where what I thought was a PR person for a major petroleum company, was talking up the company's environmental credentials. I was stunned when the spiel finished and the speaker was revealed as a Greenpeace spokesperson.
4/09/2009 10:44:02 AM

Yes, surely we should concentrate on fossil fuels and not get distracted by topics like this. Agriculture is totally irrelevant. Coal and oil are the problem. They are just sequested carbon... it is a joke to think that you can dig up sequested carbon, oxidise it and then, in some magic way, extract carbon from this process and sequester it again.... give me a break. Just stop using fossil fuels... it's not rocket science! We have a solution... it is nuclear power. STOP USING FOSSIL FUELS!
she's my ute
4/09/2009 11:05:53 AM

Well, well, it would appear from this study that evicting the cattlemen from the high country might have been counter productive!! Also, why is the government shying away from making more funding available to follow up on this research? Would it shoot holes in its thinking? And just think off all those dollars that might slip through their fingers in taxing an already overtaxed and overstressed rural sector. Who is right who is wrong? We still need a lot more research. Let's not put the cart before the horse, there is a lot more to learn before we make rash, hasty decisions before this world carbon emissions conference later this year. There is so much unknown about all of this. The earth is millions of years old - surely another couple of years won't make all that much difference to be sure we have it right!
4/09/2009 1:31:18 PM

What I read in these comments is a lot of wishful thinking. Understandable, but let's not allow the way we want the world to be to stop us from seeing the way the world actually as it is. There are a lot of ill-informed myths and straw-clutching doing the rounds: Wool suits sequester carbon so we don't have to do anything... it's all a big green conspiracy, so we don't have to do anything... cows are made of carbon, so we don't have to do anything... methane isn't really a greenhouse gas, so we don't have to do anything... nuclear power is the answer, so we don't have to do anything... it's all somebody else's fault, somebody else's problem, woe is us, poor us... and on and on. This research, as Adams himself says, is in the very early stages. It may turn out to be winner, it may well not. The world is changing. Like it or not, we're all going to have to change, too. It won't be easy but there will be opportunities. If we want a seat at the policy table and not end up on the menu, then we're going to have to get a lot smarter, stop portraying ourselves as victims, and start shouldering some responsibility.
4/09/2009 2:07:11 PM

It sounds too nice to be real. Has this work been done by the professor or does it needs to aknowledge the work of other people? The report sounds flawed or at least incomplete. Is the process happening on the bare surface or in the undersurface, because the 'calculations' reported by this proffesor look like being done on land surface rather than in the soil? Bacterial activity happens from a couple of mm under the surface to deep in the soil profile of course.


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