UNCCD 2nd Scientific Conference

1. The Case for Biochar
Annette Cowie, Bhupinderpal Singh
Lukas Van Zwieten

2. Amazonian Terra preta
Terra preta (dark earth) soils
High plant productivity
High organic carbon
– stable char (black carbon)
Source: www.biochar-international.org

3. Recreate Terra preta?
Pyrolysed biomass as a soil amendment
Source: Adriana Downie Pacific Pyrolysis

5. Dynamotive -
fast-pyrolysis
Splainex – Waste Pyrolysis
EEA Continuous Flow System - scrap tyres
Pacific Pyrolysis
Adriana Downie – June 2012

6. Recalcitrant
National Biochar Initiative: E Krull CSIRO

7. Source: L. Van Zwieten

8. Recalcitrant Source: S. Joseph UNSW
Source: E Krull CSIRO

9. Terrestrial Carbon Cycle
Atmosphere
Photosynthesis Respiration
Fire
CO2 -
Mineral-
isation
Assimilation Labile carbon:
Substrate C Microbial
Microbial
Particulate Death
litter & roots biomass, C
Biomass
carbon Soluble C Charcoal
Charcoal
Humified
Organic carbon
carbon
Humification
After J. Skjemstad, CRC Greenhouse Accounting

10. Cumulative per cent of biochar-C decomposed
BP Singh et al. 2012 (EST)
Low-temperature (400 oC) biochars High-temperature (550 oC) biochars
10.0 10.0
8.0 Poultry litter Papermill sludge 8.0
Cumulative % of added biochar-C mineralized
Cumulative % of added biochar-C mineralized
6.0 6.0
4.0 4.0
Cow manure
3.0 3.0
Eucalyptus leaf
2.5 2.5
Cow manure
2.0 2.0
1.5 1.5
1.0 Poultry litter 1.0
Eucalyptus wood
Eucalyptus leaf
0.5 0.5
Eucalyptus wood
0.0 0.0
0 20 40 60 260 520 780 1040 1300 1560 1820 0 20 40 60 260 520 780 1040 1300 1560 1820
Duration of incubation (days)
0.5% to 8.9% of biochar C mineralized
over 5 years.

11. Biochar stability -
a function of feedstock and pyrolysis conditions
BP Singh et al. 2012 (EST)
Most stable
(~2000 years)
Pyrolysis temperature
550°C wood (A or NA)
Carbon content
Fused aromatic rings
550°C leaf (A)
550°C poultry (A)
550°C cow (A)
400°C wood (A or NA)
400°C leaf (A)
550°C paper sludge (A)??
400°C manures (poultry, cow) (NA)
Least stable Mineral nutrient content
(~100 years) Synthesis: “after E. Krull”

12. Biochar can reduce soil N2O emissions
35000 Alfisol Control
12000 Vertisol
30000
Poultry manure_400 10000
Cumulative N2O emissions µg /m2
25000
8000
20000 Wood_550
6000
15000 Poultry manure_550
4000
10000 Wood_400
2000
5000
14-73% reduction in N2O 23-52% reduction in N2O
0 0
4-Aug 9-Aug 14-Aug 19-Aug 24-Aug 29-Aug 4-Aug 9-Aug 14-Aug 19-Aug 24-Aug 29-Aug
The day of gas sampling The day of gas sampling
BP Singh et al. 2010 (JEQ)

13. Nitrous oxide
measurement

14. N2O emissions Calculated
Poultry
N2O-N Emission
(kg.ha-1) Factor
0.010
Biochar+
Urea 1.5 1.3
0.008
Urea 1.2 1.0
N2O(kg.ha .hr )
1
0.006 Poultry litter 4.9 8.4
1
0.004 standard error = 1.0
Biochar+Urea least significant difference (5%
critical value) = 2.5
Urea
0.002
0.000
100
40
Rain (mm)
TempC
30
50 20
10
0 0
09 Dec 23 Dec 06 Jan 20 Jan 03 Feb
Van Zwieten et al (2013) Science of the Total Environment.

15. Biochar impact on soil porosity
National Biochar Initiative: Peter Quin et al UNE/NSW DPI

16. Cumulative priming of soil C by biochar
Singh & Cowie (Unpublished)
400 C biochars 550 C biochars
(c) (d)
40 40
Cumulative primed soil CO2-C (mg g-1 soil C)
Cumulative primed soil CO2-C (mg g-1 soil C)
30 30
20 20
10 10
0 0
Wood400 Wood550
Leaf400A Leaf550A
PL400 PL550A
-10 CM400 CM550A -10
YWood450_2%LOM YWood450_2%LOM
YWood450_4%LOM YWood550_4%LOM
0 40 80 120 260 520 780 1040 1300 1560 1820 0 40 80 120 260 520 780 1040 1300 1560 1820
Duration of incubation (days)
Biochar initially enhanced mineralisation of native soil C
Native soil C was stabilised as biochar aged

17. GHG mitigation benefits of biochar
 Delayed decomposition of biomass
 Reduced nitrous oxide emissions from soil
 Increased soil organic matter
 Avoided fossil fuel emissions due to use of syngas as
renewable energy
 Increased plant growth, plant health
 Avoided emissions from N fertiliser manufacture
 Reduced fuel use in cultivation, irrigation
 Avoided methane and nitrous oxide emissions due to
avoided decay of residues

18. Biochar system Reference system
Fossil
Biomass Biomass
energy/carbon
residue residue source
Extraction
Transport
Transport Transport
Pyrolysis to
biochar and
syngas Conversion to
Composting
energy carrier
Distribution of Distribution of
Distribution of Distribution of compost energy carrier
biochar energy carrier
Fertiliser
manufacture
Distribution of
fertiliser
Soil Energy service Soil Energy service
amendment (heat, electricity) amendment (heat, electricity)

19. Life cycle GHG emissions
Maize Wheat

20. Factors contributing to mitigation
Greenwaste biochar applied to canola
Poultry litter biochar applied to broccoli

21. Potential mitigation through biochar -
global
Woolf et al 2010 Total mitigation predicted: 6 Gt CO2-e pa =12% current emissions

22. Interactions between herbicide and biochar
National Biochar Initiative, Rai Kookana CSIRO

23. Contamination risk?
National Biochar Initiative, Mark Farrell, CSIRO

24. Sustainability issues for
biochar – direct (1)
 Biomass procurement
 Residues:
Soil erosion
Soil compaction
Nutrient depletion
Soil carbon loss (GHG, productivity
impact)
 Purpose grown:
Water use
Biomass and/or soil carbon decline
GHG balance - N2O emissions

27. Sustainability issues for biochar – direct
(2)
 Biochar production
 GHG emissions
 particulate emissions
 Biochar application
 dust
 contamination (if feedstock contaminated)
 Whole system:
 net mitigation benefit (incl transport, plant
construction)
 Compared with reference use

28. Sustainability issues for biochar –
indirect
Indirect land use change – Deforestation
 GHG emissions: loss of biomass carbon, soil carbon
 Biodiversity
 Air pollution
 Water quality
 Social – community displacement, food security
 Economic – competing uses of biomass

29. How can we
encourage
sustainability?
Sustainability framework
approach:
 Institutional systems:
 Regulation
 Incentives
 Standards
 Guidelines
 Certification
 Monitoring, assessment
and reporting
 Criteria and Indicators
 Adaptive management

30. What do we know about biochar?
 Biochar can increase plant yield
 But not all plants / all soils
 Biochar is resistant to decomposition
 But some biochars are more resistant than others
 Biochar can reduce nitrous oxide emissions
 But not from nitrification
 Biochar can deliver net greenhouse gas mitigation
 Other options may give greater mitigation; each situation must be
assessed separately
 Biochar could contaminate soil
 But only if made from contaminated feedstock
 Some unintended consequences
 Biochar can reduce efficacy of herbicides

31. Biochar can…
 Contribute significantly to climate change mitigation
 Enhance agricultural productivity
 Restore degraded soils
BUT ONLY IF
 produced in a facility that controls emissions and harnesses
heat for efficient beneficial use
 applied with care, to responsive soil type / crop
 made from sustainably harvested and renewable biomass
resources

32. annette.cowie@une.edu.au
More information:
International Biochar Initiative
http://www.biochar-international.org/