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Annette COWIE, Bhupinderpal SINGH, Lukas VAN ZWIETEN "The value of soil organic carbon: the case for biochar"
 

Annette COWIE, Bhupinderpal SINGH, Lukas VAN ZWIETEN "The value of soil organic carbon: the case for biochar"

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UNCCD 2nd Scientific Conference

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    Annette COWIE, Bhupinderpal SINGH, Lukas VAN ZWIETEN "The value of soil organic carbon: the case for biochar" Annette COWIE, Bhupinderpal SINGH, Lukas VAN ZWIETEN "The value of soil organic carbon: the case for biochar" Presentation Transcript

    • The Case for BiocharAnnette Cowie, Bhupinderpal Singh Lukas Van Zwieten
    • Amazonian Terra preta Terra preta (dark earth) soils High plant productivity High organic carbon – stable char (black carbon)Source: www.biochar-international.org
    • Recreate Terra preta? Pyrolysed biomass as a soil amendmentSource: Adriana Downie Pacific Pyrolysis
    • Dynamotive - fast-pyrolysis Splainex – Waste Pyrolysis EEA Continuous Flow System - scrap tyresPacific Pyrolysis Adriana Downie – June 2012
    • Recalcitrant National Biochar Initiative: E Krull CSIRO
    • Source: L. Van Zwieten
    • Recalcitrant Source: S. Joseph UNSW Source: E Krull CSIRO
    • 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 HumificationAfter J. Skjemstad, CRC Greenhouse Accounting
    • 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.
    • 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”
    • Biochar can reduce soil N2O emissions 35000 Alfisol Control 12000 Vertisol 30000 Poultry manure_400 10000Cumulative 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)
    • Nitrous oxidemeasurement
    • 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.
    • Biochar impact on soil porosityNational Biochar Initiative: Peter Quin et al UNE/NSW DPI
    • 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
    • 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
    • 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 ofDistribution of Distribution of compost energy carrier biochar energy carrier Fertiliser manufacture Distribution of fertiliser Soil Energy service Soil Energy serviceamendment (heat, electricity) amendment (heat, electricity)
    • Life cycle GHG emissionsMaize Wheat
    • Factors contributing to mitigationGreenwaste biochar applied to canola Poultry litter biochar applied to broccoli
    • Potential mitigation through biochar - globalWoolf et al 2010 Total mitigation predicted: 6 Gt CO2-e pa =12% current emissions
    • Interactions between herbicide and biocharNational 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
    • 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
    • Sustainability issues for biochar – indirectIndirect 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
    • How can weencouragesustainability?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 soilsBUT 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 Initiativehttp://www.biochar-international.org/