1. “Biochar,” a bit of myth busting
Lukas Van Zwieten
Principal Research Scientist
Adjunct Professor, Rural Climate Solutions
University of New England
and
Tony Walker
Richmond Landcare

2. What is biochar and how is it made?

3. 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,

4. Pyrolysis is an engineering term “energy and biochar can be produced”
High efficiencies are gained through the recyclying of heat and all emissions. Biomass goes into the drier before the pyrolysis kiln. Typically the kiln will operate at 550 degrees cencius, and the biomass residence time is up to an hour- it is a full continual process. Syn gas which is made up primarily of hydrogen, methane and carbon monoxide is collected and purified, before it is used to heat the kiln, with surplus gas going to the electrical generator.

5. Why pyrolyse biomass Biosecurity Odour
Concentration of C and nutrients
Transport costs
Beneficial agricultural reuse
Renewable energy

6. Biochar is carbon that is going to last for hundreds of years
Diagram source: Lehmann et al., 2006, Mitigation and Adaptation Strategies for Global Change

7. 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

8. Biochar “can” significantly improve soil fertility and crop production
1900mm
1200mm
Control corn (13t cob/ha)
Poultry litter biochar, 50t/Ha (35t cob/ha)

9. Long-term field sites testing biochar

10. Trials in a macadamia orchard
45 trees used testing poultry litter char and greenwaste char 40kg per tree)
2 years on

11. Trials in coffee 2 years on
3.3kg per tree, 30 trees per block, 4 treatments, 4 replicates, testing poultry biochar and rice husk biochar

12. Sections of x-ray computed tomography scans of a vertosol soil, packed into tubes of ~ 30 mm, at a resolution of 70 µm
3D imaging and calculation of pore space and connectivity currently being undertaken.
control
1% biochar
5% biochar
P Quin (PhD student) and I Young

13. Summary of effects of some biochars in some soils
Properties of biochar
Soil and crop outcomes
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

14. 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

15. 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