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Adriana Downie, Asia Pacific Biochar Conference 2009
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
Adriana Downie, Asia Pacific Biochar Conference 2009
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.
Adriana Downie, Asia Pacific Biochar Conference 2009
The Proposition
Addresses challenges of sequestration?
• Impermanence
• Urgency
• Costs
• Side-effects
BioChar: a Low Risk Sink which can
add value
Adriana Downie, Asia Pacific Biochar Conference 2009
Amazonian Dark Earth: Terra-Preta• Case for investigating
side effects
• Demonstrates carbon
holding capacity
• 500-2500 years old
• Amazon - Extreme environment for fast
organics turnover
• Evidence of long-term productivity benefits
Adriana Downie, Asia Pacific Biochar Conference 2009
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)
Adriana Downie, Asia Pacific Biochar Conference 2009
In search of Terra preta Australis…..
Adriana Downie, Asia Pacific Biochar Conference 2009
Adriana Downie, Asia Pacific Biochar Conference 2009
Adriana Downie, Asia Pacific Biochar Conference 2009
How?
When?
Adriana Downie, Asia Pacific Biochar Conference 2009
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
Adriana Downie, Asia Pacific Biochar Conference 2009
Adriana Downie, Asia Pacific Biochar Conference 2009
Adriana Downie, Asia Pacific Biochar Conference 2009
Adriana Downie, Asia Pacific Biochar Conference 2009
Adriana Downie, Asia Pacific Biochar Conference 2009
Radiocarbon Dating
Terra Preta Australis, 14C
measurement by accelerated
mass spectrometry (AMS) :
• 650 ± 30 years BP
high clay, agricultural grazing field
site
• 1609 ± 34 years BP
sandy site on the border of a
heavily timbered area in close
proximity to the river
Australian oven mound sites
surveyed in the 1970s, further north-
west 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: 59-73
Contemporary with Terra Preta de Indio soils of the Amazon basin.
Adriana Downie, Asia Pacific Biochar Conference 2009
Adriana Downie, Asia Pacific Biochar Conference 2009
Adriana Downie, Asia Pacific Biochar Conference 2009
Adriana Downie, Asia Pacific Biochar Conference 2009
Solid-state 13C CP NMR spectra
Contributed by Dr. Ron Smernik, University of Adelaide
Adriana Downie, Asia Pacific Biochar Conference 2009
Adriana Downie, Asia Pacific Biochar Conference 2009
Biochar from Terra Preta Australis
Adriana Downie, Asia Pacific Biochar Conference 2009
A B
Adriana Downie, Asia Pacific Biochar Conference 2009
Adriana Downie, Asia Pacific Biochar Conference 2009
Adriana Downie, Asia Pacific Biochar Conference 2009
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.
Adriana Downie, Asia Pacific Biochar Conference 2009
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.
Adriana Downie, Asia Pacific Biochar Conference 2009
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 CO2-e sequestered.
Cropped Land already has the vast infrastructure for soil amendment management. Product transport etc.
Adriana Downie, Asia Pacific Biochar Conference 2009
Meeting Emissions Targets
Australia’s net greenhouse gas emissions across all sectors totaled 576 Mt CO2-e in 2006 (DCC, 2008).
27 Gt represents 48 years of Australian emissions at this level.
(co-production of bioenergy would extend this)
Adriana Downie, Asia Pacific Biochar Conference 2009
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.
Adriana Downie, Asia Pacific Biochar Conference 2009
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.