Impacts of Biochar Additions on Agronomic Yields
Kurt Spokas
USDA-ARS, Soil and Water Management Unit, St. Paul, MN
Adjunct Professor University of Minnesota – Department of Soil, Water and Climate
Illinois Biochar Group Meeting
ISTC
June 9, 2011
Biochar: Soil Application
• The assumed target for biochar has been soil
application
• Focus has been on “creating” Terra Preta soils
Observations of increased soil fertility and productivity.
Postulated from ‘slash and burn’ historic charcoal additions
Biochar: Soil Application
However, on the other side:
• Wood distillation plants [1800-1950’s]
• Wood pyrolysis – source of chemicals and energy prior to
petroleum (fossil fuel)
• Multiple large plants existed (10 cords [14 tons] per day)
• Some plants on US-EPA Superfund site list
• Other charcoal sites
• Not always productive
• Reduced seed germination
• Reduced plant growth
(BEGLINGER AND LOCKE, 1957)
Soil Application… Long History
Applications date back to the beginning
of modern science [1800’s]:
(LeFroy, 1883)
Biochar Soil Application
Does biochar improve
agronomic yields?
Biochar Soil Application
Recent compilation of historical and recent biochar (black
carbon) applications:
• 50% positive,
• 30% no effect, and
• 20% negative impacts on growth and/or yield
(Spokas et al., 2011)
• However, should not be used as a basis for
forecasting outcomes  Publication bias
(Møller and Jennions, 2001)
Further Observations from Existing Studies
Wood Feedstock –
Majority of observed positive yield
improvements have used wood
feedstock with traditional soil kiln/fire pit
methods (not pyrolysis units)
Other feedstocks:
negative to no impact…
Exception: Poultry manure (higher N-content)
Significant Hurdles
1. Lack of adequate documentation of biochar
properties and conditions in existing studies
2. Existing feeling that biochar = biochar
3. Once produced – Biochar is reactive
• Surface chemistry is not only a function of production
and feedstock, but also of post-production conditions
and storage (i.e. cooling method, activation)
• Biochars with equivalent production conditions still can
be chemically and structurally different
Sorbed Organics on Oak Biochar
Slow pyrolysis
Slow pyrolysis
Equivalent
production
conditions
Fast pyrolysis
Gasifier pyrolysis
Soil kiln mound (traditional)
Active Biochar Research
MN Corn Growers Association
> Examining the potential use of microwave assisted pyrolysis in
the conversion of distillers grain into value added products
(energy, bio-oil and biochar)
MN Dept. of Agriculture (Specialty Crop Block Grant)
> Impacts of biochar on specialty crop production
- Soil and yield impacts
- Potential bioaccumulation of other organic compounds on
biochar
USDA-ARS
> Rosemount, MN Field Plots – 8 different biochars & biomass
> Laboratory assessments of GHG and VOC impacts
Conclusions

Despite the long research history –

No absolute “biochar” consistent trends

Highly variable material
– Production & post-production handling

Different responses to biochar


Importance of fully documenting methods of creation,
handling, and properties



Function of soil ecosystem (microbial linkage) & position on black
carbon continuum
– Allow future elucidation of factors
Several inter-related mechanisms
Biochar does act as a carbon sequestration agent

As long as biochar has low oxygen to carbon (O:C) molar ratio
Looking Forward
•
Economics caused the shift from biomass to fossil fuels in the early
1920’s:
We at the cusp where environmental stewardship is returning the
pendulum back to biomass as the source for human’s energy,
chemical and agronomic needs
Research is needed to optimize both:
1. Advanced pyrolysis system development for
combined energy, chemical, and biochar
production
2. Subsequent utilization of biochar in a
sustainable and environmentally responsible
manner [not limited solely to soil application]
American Society of Agronomy
Biochar Community
Acknowledgements
I would like to acknowledge the cooperation:
National Council for Air and Stream Improvement (NCASI)
Universität Bonn (Germany)
IRNASE-CSIC (Spain)
Università di Bologna (Italy)
Penn State; University of Minnesota
Illinois Sustainable Technology Center (ISTC) [Univ. of Illinois]
US-EPA and other USDA-ARS locations
Dynamotive Energy Systems
NC Farm Center for Innovation and Sustainability
Best Energies
Northern Tilth
Minnesota Biomass Exchange
Biochar Brokers
Chip Energy
AECOM
Avello Bioenergy
ICM, Inc.
Freedom Field Energy
Partial Funding:
• Minnesota Corn Growers Association/Minnesota Corn Research Production Council
• Minnesota Department of Agriculture Specialty Crop Block Grant Program
Technical Support : Martin duSaire
Students: Tia Phan, Lindsey Watson, Lianne Endo, Kia Yang, Eric Nooker, Ed Colosky and Amanda Bidwell
USDA-ARS Biochar and Pyrolysis Initiative
Multi-location USDA-ARS research efforts:
GRACEnet Project (30 locations): Greenhouse Gas Reduction and Carbon Enhancement Network
REAP Project (24 locations): Renewable Energy Assessment Project
Biochar and Pyrolysis Initiative (15 locations)
Ongoing field plot trial (6 locations)