Key Factor #1: The Potential of Australian Soils

The Coalition contends that the potential contribution of soils to removing carbon from the atmosphere is so great that, rather than its proponents having to argue for its consideration, those who oppose its deployment should be required to give evidence against this potential. No such evidence has been produced to date.

The proponents, on the other hand, have produced evidence of the potential for Australian soils to sequester carbon. While no one research study has tested soil carbon sequestration under ideal conditions to reveal our soil’s full potential, several cases have recorded significant shifts that put the lie to commonly held misconceptions.

• Exhibit 1: The NSW DPI, DECC and CSIRO are currently evaluating an increase in soul carbon recorded on grazing and cropping land from 2% to 4% recorded on “Winona”, Gulgong, between 1995 and 2005.(2)

• Exhibit 2: There was a 0.46% carbon difference between a paddock managed by conservation farming techniques (stubble retained/no-tillage) and a paddock heavily grazed and conventionally tilled over 10 years at Greenethorpe, NSW translated into a difference of 185 tonnes of carbon per hectare (or 675 tonnes of CO2e.) (3)

• Exhibit 3: A CSIRO study (unpublished) in Albany WA found a significant difference in organic matter between two paddocks, one stubble-burned 3 years previous then no-tillage treatment for three years (3.35% OM), the other managed with no-tillage (5% OM).

• Exhibit 4: Dr K Yin Chan, Principal Research Scientist (Soils), NSW Department of Primary Industries, has a research project which has stretched over 20 years. In the soils studied, he found that there was on average 70 tonnes of soil carbon per hectare under undisturbed native vegetation. This fell dramatically to 40 T/ha under conventional tillage by the 1940s. It rose 5T/ha under Reduced Tillage, to 45T/ha. Dr Chan believes we can recover the (25T/ha) balance. He calls it the "Soil C Sequestration Potential". (4)

• Exhibit 5: “Permanent unimproved pastures in moister areas of NSW, SA, WA and Qld, after sowing to introduced grasses and legumes and fertilised with superphosphate have been shown to exhibit linear increases in soil C at a rate of about 0.4 t C ha-1 yr-1 over several decades. (Russell and Williams 1982, Gifford et al 1992). (5)

• Exhibit 6: Barrow (1969) reported a soil C gain of 440 kg/ha/yr in sandy soils under permanent pasture during a period of 30-40 years in Western Australia. The pasture outscored undisturbed native vegetation on soil C by 2.0% to 0.8%. (6)

• Exhibit 7: Senior CSIRO soil scientist Jeff Baldock says there is today no technical barriers to a fully-functioning market in soil carbon, and that such a market could make it ‘more economic to farm for carbon than to farm for yield.’ (7)

These case studies and other expert opinions indicate that Australia’s 450 million hectares of agricultural soils have the potential to make a powerful contribution to the national effort to mitigate Climate Change.


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FOOTNOTES:

(2) Colin Sies, “Combinations That Move The Carbon Needle: Grazing Management, Pasture Cropping, and Biological Farming”, Carbon Farming Expo & Conference, 16th-17th November, 2007, AREC, Mudgee. Ian is Catchment Coordinator, Lachlan CMA, PO Box 510, Cowra 2794.
(3) Ian Packer, “Quantifying the Obvious - Soil Management Impact on Soil Carbon Sequestration, Carbon Farming Expo & Conference, 16th-17th November, 2007, AREC, Mudgee. Ian is Catchment Coordinator, Lachlan CMA, PO Box 510, Cowra 2794.
(4) Presentation at DPI farmers’ gathering at Junee Reef, 21 June, 2007.
(5) Gifford RM, Cheney NP, Noble JC, Russell JS, Wellington AB and ZamitC (1992) Australian land use, primary production of vegetation and carbon pools in relation to atmospheric carbon dioxide concentration. pp151-187 in Australia’s Renewable Resources, Sustainability and Global Change. Roger M. Gifford and Michele M. Barson (Eds) Publ Bureau of Rural Resources and CSIRO Division of Plant Industry. Quoted in “Pasture improvement for potential additional C-sinks for inclusion under the Kyoto Protocol”, by Roger M. Gifford, Damian J. Barrett and Andrew Ash (with input from Miko Kirschbaum, John Donnelly, Richard Simpson and Mike Freer) for the Biosphere Working Group of the CSIRO Climate Change Research Program, 30 April, 1998
(6) Barrow, N. J. 1969. The accumulation of soil organic matter under pasture and its effect on soil properties. Australian Journal of Experimental Agriculture and Animal Husbandry 9:437-445.
(7) ABC Rural Radio, October 2007, Orange Field Days.