Discovering Terra Preta Australis: Rethinking temperate soils capacity to sequester carbon

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1 Discovering Terra Preta Australis: Rethinking temperate soils capacity to sequester carbon Adriana Downie, Lukas Van Zwieten, Ronald Smernik, Timothy Flannery, Derek Barnstable, and Paul Munroe

2 If civilisation is to avoid catastrophic climate change, the sequestration of atmospheric greenhouse gases into low risk sinks via inexpensive and sustainable means should be a priority.

3 The Proposition BioChar: a Low Risk Sink which can add value Addresses challenges of sequestration? Impermanence Urgency Costs Side-effects

4 Amazonian Dark Earth: Terra-Preta Case for investigating side effects Demonstrates carbon holding capacity years old Amazon - Extreme environment for fast organics turnover Evidence of long-term productivity benefits

5 Australian Context Geographical Differences: Climate Land Management Practices Soil Types What is the capacity of Australian soils to sequester carbon? The potential for soils to sequester carbon is often assumed to be to the capacity of native, pre-cultivation soils. (Lal et al. 2007; Paustian et al. 1997)

6 In search of Terra preta Australis..

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9 How? When?

10 Operation of an Australian Aboriginal Cooking Oven Source: Coutts PJF, Henderson P & Fullagar RLK (1979) A Preliminary Investigation of Aboriginal Mounds in North-Western Victoria. Records of the Victorian Archaeological Survey 9: 1-116

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15 Radiocarbon Dating Terra Preta Australis, 14 C measurement by accelerated mass spectrometry (AMS) : 650 ± 30 years BP high clay, agricultural grazing field site Australian oven mound sites surveyed in the 1970s, further northwest along the Murray river were radiocarbon dated to between 600 to 3500 years BP Coutts PJF & Witter DC (1977) New radiocarbon dates for Victorian Archaeological sites. Records of the Victorian Archaeological Survey 4: ± 34 years BP sandy site on the border of a heavily timbered area in close proximity to the river Contemporary with Terra Preta de Indio soils of the Amazon basin.

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19 Solid-state 13 C CP NMR spectra Contributed by Dr. Ron Smernik, University of Adelaide

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21 Biochar from Terra Preta Australis

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25 In comparison to their adjacent sites, the Terra Preta Australis sites had higher : ph, cation exchange capacity, organic and total carbon, total nitrogen, calcium, potassium and phosphorous.

26 Organic carbon in the top 30cm compared with adjacent soil, a range of results across the sites analysed: TPA1-3.2% increase TPA2-0.46% increase Increases in organic carbon of more than 4% were measured in soil profiles of several sites. The upper limit of beneficial biochar incorporation is therefore considered to be in excess of this value for the temperate climate soils examined.

27 Potential Applied to Australia s 42 million hectares of cropped soils (DEWHA, 2007), 4% in the top 30cm represents 7.5 Gt of solid C or 27 Gt of CO 2-e sequestered. Cropped Land already has the vast infrastructure for soil amendment management. Product transport etc.

28 Meeting Emissions Targets Australia s net greenhouse gas emissions across all sectors totaled 576 Mt CO 2-e in 2006 (DCC, 2008). 27 Gt represents 48 years of Australian emissions at this level. (co-production of bioenergy would extend this)

29 Therefore: Not limited by Australia's, old, temperate climate soils capacity to beneficially hold biochar Limited by sustainable biomass supply Limited by ability to roll out technology.

30 Acknowledgements Australian Research Council BEST Energies Australia Pty Ltd NSW Department of Primary Industry The Yorta Yorta people as the Aboriginal Traditional Owners of the areas studied.