Newsletter

October: 2007

Annual General Meeting

Sunday 21st October following a BBQ Lunch at Tom and Sarah Guthrie’s property , 366 Mafeking Road, Mafeking. (Mafeking is southwest of Ararat and east of the Grampians near Mt William) For catering purposes please advise the Secretary Peter (03 5352 1530) if you are attending. Friends of EFN are welcome.

Activity since last Newsletter: Several written submissions have been made, one to VEAC concerning Management of Redgum Forests on the Murray River and another to DSE concerning Managing Land and Biodiversity in a time of Climate Change (White Paper process). The President and Secretary also took the opportunity to personally present EFN views to the latter process. An opinion piece on Biofuels was submitted to the Weekly Times but has not been published. Biofuels and Biodiversity Policies are being drafted.

Our Web site has been upgraded thanks to David Cummings and Travis Price.

The Following Article was forwarded by one of our members Mark Wootton (Jigsaw Farms and the Climate Institute): The author is Tony McMichael.

Greenhouse gas emissions from agriculture

Current drought conditions and water shortages experienced across Australia are stimulating plenty of discussions about climate change. Are we experiencing a taste of what is predicted or is it just a natural cycle from which we’ll emerge back into more “normal” climatic conditions?

The media is giving this debate plenty of coverage so the focus of this article is not climate change itself, but possible causes behind it; emissions of greenhouse gases associated with our modern ways of living. Carbon dioxide (CO2) from fossil fuels is a well-known emission source, but what is the profile for Australia’s agriculture sector and what opportunities are there for agriculture to reduce (abate) emissions without compromising production?

The Australian Greenhouse Office (AGO) completes an annual audit of Australia’s total net greenhouse gas emissions, the National Greenhouse Gas Inventory, (NGGI). The latest audit (2004) attributes nearly 17% of Australia’s total emissions to agriculture. (Fig.1). This figure only represents emissions from biological processes on farm. Emissions from energy (fuel and electricity) are recorded in the transport and energy sectors.

Figure 1. Sectoral greenhouse gas emissions in Australia for 2004

Sectoral greenhouse gas emissions chart in Australia 2004

The main gases emitted from agriculture are methane and nitrous oxide. Both are powerful greenhouse gases with 21 and 310 time the global warming potential of carbon dioxide respectively. Agriculture is the dominant national source of both methane at 60% and nitrous oxide at 86%, (AGO 2006).

Emissions sources from agriculture include;
Rumen fermentation and manure management in livestock producing methane,
Agricultural soils - from the nitrogen cycle including fertiliser application, animal wastes and nitrogen fixing plants, producing nitrous oxide,
Prescribed burning of savannas: tropical savannas and grasslands,
Field burning of residues: crop stubble, and
Rice cultivation- anaerobic process when flooded.

Methane

Methane emissions from rumen fermentation in livestock account for over 60% of agriculture’s total emissions. The process is natural and essential for livestock maintenance. The methane is produced by microbes in the rumen (methanogens) who use surplus hydrogen in the rumen with the methane belched or breathed out. Only small amounts are emitted via the rear end flatulence contrary to many media reports.

Methane gas is a high-energy source, which as an emission represents a significant loss of energy from the production system. The challenge for reducing methane emissions is to provide another mechanism for reducing the hydrogen levels in a manner that does not disturb normal digestion but realises the energy savings as improved production.

Research by DPI Victoria’s Greenhouse in Agriculture (GIA) program is investigating this challenge for dairy cows. Initially the research is evaluating the impact of animal management, diet and dietary supplements on animal performance, comparing the improved production against the cost of feeding. If this evaluation results in a neutral or positive financial return, the option is then tested for its methane abatement potential, as this presents a possible win-win opportunity and a driver for practice adoption. The farmer wins though improved production and the environment wins though reduced methane emissions.

From the work conducted to date and the reviews of published literature, an abatement of over 20% of methane produced per animal is achievable. While it is too early to endorse specific practices until further research has proven their efficacy in the field, there are a number of promising and potentially cost-effective options including managing animal numbers, animal breeding and nutrition, dietary supplements, rumen modifiers and biological controls.

Nitrous oxide

Nitrous oxide is primarily lost from agricultural soils as a result of cultivation, legumes, nitrogen fertilisers and animal excreta when soil micro-organisms convert soil nitrogen into nitrous oxide via processes of nitrification and denitrification. Essentially any agricultural activity that inefficiently supplies nitrogen to the soil-plant system can lead to large losses of nitrogen through a number of loss processes, including nitrous oxide.

Loss of nitrous oxide from agricultural soils represents nearly 20% of agriculture’s emission profile. These emissions equate to a loss of a valuable soil nutrient and an economic loss to farmers as they represent inefficient use of nitrogen by the soil-plant system. Again, like with methane, opportunities exist to achieve win-win scenarios for farmers and the environment with nitrous oxide abatement.

Practices that increase nitrogen use efficiency via improved use of fertilisers, (including replacement of artificial fertilizer nitrogen by plant produced “natural” nitrogen), and soil and animal management will mean less nitrogen is available in the system to be lost as nitrous oxide. Significant abatement potential exists with nitrous oxide given its high global warming potential compared to carbon dioxide, ie 310 to 1, meaning small reductions in nitrous oxide emissions provide high value abatement benefits.

Focusing on the win-win theme of linking wins for greenhouse with wins for farmers, the GIA program has developed management practices that emphasise that practices for reducing nitrous oxide emissions align well with other goals farmers are trying to achieve in regard to production efficiency and nitrogen use. These include practices for source, rate, and timing of fertiliser applications, and improved soil, crop and pasture management.

The loss of methane and nitrous oxide from our farming systems does not only potentially contribute to our changing climate, but also presents an opportunity and different motivation for researching emission processes to identify efficiency gains for our farming systems in general.

A good message for the agriculture sector and government is that reductions in both methane and nitrous oxide can be achieved through the implementation of practices that are consistent with improving the overall efficiency of agricultural production. These practices represent a win-win opportunity for Australian agriculture and the environment on reducing greenhouse gas emissions.

Information

Visit - www.greenhouse.unimelbourne.edu.au
Contact Traci Griffin, DPI Victoria traci.griffin@dpi.vic.gov.au

Reference –
AGO (2006). National Greenhouse Gas Inventory 2004. Department of Environment and Heritage, Australian Greenhouse Office, Canberra. ISBN: 1 921120 53 www.greenhouse.gov.au/inventory.

Soils offer new hope as carbon sink:
www.dpi.nsw.gov.au/research/updates/issues/may-2007/soils-offer-new-hope

Carbon Coalition Against Global Warming PDF Documents

 

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