“biochar,” a bit of myth busting
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“Biochar,” a bit of myth busting Lukas Van Zwieten
Principal Research ScientistAdjunct Professor, Rural Climate Solutions
University of New England
and
Tony WalkerRichmond Landcare
What is biochar and how is it made?
Biochar and Terra Preta
Downie, AE., Van Zwieten, L., Smernik RJ., Morris, S., Munroe, PR (2011) Terra Preta Australis: Reassessing the carbon storage capacity of temperate soils. Agriculture Ecosystems Environment 140, 137-147.
Pyrolysis is an engineering term “energy and biochar can be produced”
Biosecurity Odour Concentration of C and nutrients Transport costs Beneficial agricultural reuse Renewable energy
Why pyrolyse biomass
Biochar is carbon that is going to last for hundreds of years
Biomass carbon100%
100 years
Bio-char carbon50%
Biomass carbon100%
Biomass carbon0%
Bio-char carbon>40%
Energy Production
A
Diagram source: Lehmann et al., 2006, Mitigation and Adaptation Strategies for Global Change
Agronomic trials
Over 350 plots being managed as part of the Richmond Landcare collaborative project
Key soil constraints on ferrosols Declining C Immobilisation of P Low pH High Al saturation Low CEC
Control corn (13t cob/ha)
1200mm
1900mm
Poultry litter biochar, 50t/Ha (35t cob/ha)
Biochar “can” significantly improve soil fertility and crop production
Long-term field sites testing biochar
Trials in a macadamia orchard
45 trees used testing poultry litter char and greenwaste char (@10t/ha- 40kg per tree)
2 years on
Trials in coffee
3.3kg per tree, 30 trees per block, 4 treatments, 4 replicates, testing poultry biochar and rice husk biochar
2 years on
control 1% biochar 5% biochar
Sections of x-ray computed tomography scans of a vertosol soil, packed into tubes of ~ 30 mm, at a resolution of 70 µm
P Quin (PhD student) and I Young
Summary of effects of some biochars in some soils
Nutrients Stable C content Liming effect Reactive surfaces and
redox CEC and AEC Porosity/ water holding
capacity and bulk density Porosity / microbial habitat Smoke chemicals?
• Increases in nutrient use efficiency allowing reduced fertiliser inputs
• Improved water use efficiency• Reduced leaching and gaseous losses
of fertiliser• Reduced denitrification• Lowered Al toxicity • Reduced heavy metal bioavailability• Increased P availability on P sorbing
soils• Improved mycorrhizae and biological N2
fixation • Long-term accumulation of soil C
Properties of biochar Soil and crop outcomes
Myth Busting
Not all biochars will be valuable Biochars may not be beneficial in all soil types Value of the crop will limit application of biochar- and
bottom line Biochar certification is coming
More myth busting
Understand biochar characteristics to ameliorate soil constraints
Farming system impacts the way biochar works: Possible C accumulation under permanent pasture, but tillage and biomass removal under cropping can still result in a decline in C
Biochar can particularly target chemical constraints in ferrosols including low pH, high Al availability and low P availability
Biochars with high mineral ash component are more effective at improving crop production
Biochars with high C content are more effective at accumulating additional C in soil
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