Annette Cowie, Bhupinderpal Singh Lukas Van Zwieten

The Case for Biochar

Amazonian Terra preta

Source: www.biochar-international.org

Terra preta (dark earth) soils High plant productivity High organic carbon – stable char (black carbon)

Recreate Terra preta?

Pyrolysed biomass as a soil amendment

Source: Adriana Downie Pacific Pyrolysis

Adriana Downie – June 2012

EEA Continuous Flow System - scrap tyres

Splainex – Waste Pyrolysis

Dynamotive - fast-pyrolysis

Pacific Pyrolysis

Recalcitrant

National Biochar Initiative: E Krull CSIRO

Source: L. Van Zwieten

Recalcitrant Source: S. Joseph UNSW

Source: E Krull CSIRO

Terrestrial Carbon Cycle

Substrate C litter & roots

Microbial Biomass C

Humified Organic carbon

Humification

-

Assimilation

Death

Fire

Charcoal

Photosynthesis

Particulate carbon

Labile carbon: Microbial biomass, Soluble C

Humification

Fire

Charcoal

After J. Skjemstad, CRC Greenhouse Accounting

Humified carbon

Atmosphere

Respiration

CO2 Mineral- isation

Cumulative per cent of biochar-C decomposed

0 20 40 60 260 520 780 1040 1300 1560 1820

Cum

ulat

ive

% o

f add

ed b

ioch

ar-C

min

eral

ized

0.0

0.5

1.0

1.5

2.0

2.5

3.0

4.0

6.0

8.0

10.0

Duration of incubation (days)0 20 40 60 260 520 780 1040 1300 1560 1820

Cum

ulat

ive

% o

f add

ed b

ioch

ar-C

min

eral

ized

0.0

0.5

1.0

1.5

2.0

2.5

3.0

4.0

6.0

8.0

10.0

Poultry litter

Low-temperature (400 oC) biochars High-temperature (550 oC) biochars

Cow manure

Eucalyptus leaf

Eucalyptus wood

Papermill sludge

Poultry litter

Cow manure

Eucalyptus leaf

Eucalyptus wood

0.5% to 8.9% of biochar C mineralized over 5 years.

BP Singh et al. 2012 (EST)

Biochar stability - a function of feedstock and pyrolysis conditions

Least stable(~100 years)

Most stable(~2000 years)

Fuse

d ar

omat

ic ri

ngs

Mineral nutrient content

Pyrolysis temperature

550°C wood (A or NA)

400°C manures (poultry, cow) (NA)

400°C wood (A or NA)

550°C leaf (A)

550°C paper sludge (A)??

Car

bon

cont

ent

400°C leaf (A)

550°C poultry (A)550°C cow (A)

Synthesis: “after E. Krull”

BP Singh et al. 2012 (EST)

Biochar can reduce soil N2O emissions

0

5000

10000

15000

20000

25000

30000

35000

4-Aug 9-Aug 14-Aug 19-Aug 24-Aug 29-Aug

The day of gas sampling

0

2000

4000

6000

8000

10000

12000

4-Aug 9-Aug 14-Aug 19-Aug 24-Aug 29-Aug

The day of gas sampling

Alfisol Vertisol Control

Poultry manure_400

Poultry manure_550

Wood_400

Wood_550

14-73% reduction in N2O 23-52% reduction in N2O

Cum

ulat

ive

N2O

em

issi

ons

µg /m

2

BP Singh et al. 2010 (JEQ)

Nitrous oxide measurement

N2O emissions

09 Dec 23 Dec 06 Jan 20 Jan 03 Feb

0.000

0.002

0.004

0.006

0.008

0.010

N 2O(k

g.ha

1.h

r1)

Biochar+Urea

Urea

Poultry

0

50

100

Rai

n (m

m)

010203040

Tem

pC

standard error = 1.0 least significant difference (5% critical value) = 2.5

Van Zwieten et al (2013) Science of the Total Environment.

N2O-N (kg.ha-1)

Calculated Emission

Factor

Biochar+ Urea 1.5 1.3

Urea 1.2 1.0

Poultry litter 4.9 8.4

Biochar impact on soil porosity

National Biochar Initiative: Peter Quin et al UNE/NSW DPI

0 40 80 120 260 520 780 1040130015601820

Cum

ulat

ive

prim

ed s

oil C

O2-

C (m

g g-

1 so

il C

)

-10

0

10

20

30

40

Wood550Leaf550APL550ACM550AYWood450_2%LOMYWood550_4%LOM

Duration of incubation (days)

0 40 80 120 260 520 780 1040130015601820

Cum

ulat

ive

prim

ed s

oil C

O2-

C (m

g g-

1 so

il C

)

-10

0

10

20

30

40

Wood400Leaf400APL400CM400YWood450_2%LOMYWood450_4%LOM

(c) (d)

Cumulative priming of soil C by biochar 400 °C biochars 550 °C biochars

Singh & Cowie (Unpublished)

Biochar initially enhanced mineralisation of native soil C Native soil C was stabilised as biochar aged

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

Transport

Soil amendment

Pyrolysis to biochar and

syngas

Distribution of biochar

Distribution of energy carrier

Energy service (heat, electricity)

Biomass residue

Biochar system

Transport

Biomass residue

Fossil energy/carbon

source

Extraction

Conversion to energy carrier

Distribution of energy carrier

Energy service (heat, electricity)

Soil amendment

Fertiliser manufacture

Transport

Composting

Reference system

Distribution of compost

Distribution of fertiliser

Life cycle GHG emissions

Maize Wheat

Greenwaste biochar applied to canola

Poultry litter biochar applied to broccoli

Factors contributing to mitigation

Potential mitigation through biochar - global

Woolf et al 2010 Total mitigation predicted: 6 Gt CO2-e pa =12% current emissions

Interactions between herbicide and biochar

National Biochar Initiative, Rai Kookana CSIRO

Contamination risk?

National Biochar Initiative, Mark Farrell, CSIRO

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

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

Sustainability issues for biochar – direct (2)

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

Sustainability issues for biochar – indirect

How can we encourage sustainability?

Sustainability framework approach:

Institutional systems: Regulation Incentives Standards

Guidelines Certification

Monitoring, assessment and reporting Criteria and Indicators

Adaptive management

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

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

annette.cowie@une.edu.au

More information:

International Biochar Initiative http://www.biochar-international.org/