Analyses of biochar properties - International Biochar Initiative

Transcription

Demolition wood Leek Cabbage Potato Analyses of biochar properties
Report presented by
The Char Team
25th September 2015
Correspondence:
Suzanne Allaire
2480 Boulevard Hochelaga
Pavillon Envirotron
Université Laval
Québec, QC, Canada G1V 0A6
email: suzanne.allaire@fsaa.ulaval.ca
Photos: Agnès Lejeune
© 2015
Reference:
Allaire SE, Lange SF, Auclair IK, Quinche M, Greffard L (The Char Team) (2015) Report: Analyses of
biochar properties. CRMR-2015-SA-5. Centre de Recherche sur les Matériaux Renouvelables,
Université Laval, Québec, Canada, 59 p. DOI: 10.13140/RG.2.1.2789.4241
2 Table of contents
1. INTRODUCTION 5 2. OBJECTIVES 7 3. MATERIALS AND METHODS 13 3.1. RESIDUAL ORGANIC MATTER (ROM) AND PYROLYSIS METHODS 3.1.1. HARDWOOD 3.1.2. CONIFEROUS SOFTWOOD 3.1.3. NON-CONIFEROUS SOFTWOOD 3.1.4. NON-WOODY MATERIALS 3.2. BIOCHAR ANALYSIS METHODS 3.2.1. GENERAL PROPERTIES 3.2.2. PHYSICAL PROPERTIES 3.2.3. CHEMICAL PROPERTIES 3.2.4. BIOLOGICAL PROPERTIES 13 13 13 14 15 19 19 20 21 22 4. RESULTS AND DISCUSSION 28 4.1. GENERAL PROPERTIES 4.2. PHYSICAL PROPERTIES 4.3. CHEMICAL PROPERTIES 4.4. BIOLOGICAL PROPERTIES 28 28 38 47 5. CONCLUSION AND FUTURE WORK 47 6. REFERENCES 56 3 List of Tables
9 Table 1. Team members Table 2. Biochar producers or industries that provided access to their pyrolyzer 10 Table 3. Institutions that provided the feedstock to be pyrolyzed 11 Table 4. Institutions that contributed to the project through grants or supplemental student scholarships 12 Table 5. List of biochars with their feedstock and pyrolysis method 16 Table 6. Photos of some biochars 18 Table 7. Analysis methods for general properties of biochars 23 Table 8. Analysis methods for physical properties of biochars 24 Table 9. Analysis methods for chemical properties of biochars 25 Table 10. Analysis methods for biological properties of biochars 26 Table 11. Comparison between analyses in this report and those of IBI (2012) and EBC (2012) 27 Table 12. General properties of biochars 31 Table 13. General physical properties of biochars 33 Table 14. Physical properties related to water 34 Table 15. Physical properties related to particle-size distribution and abrasion resistance of biochars 36 Table 16. Chemical properties of biochars related to acidity 40 Table 17. Biochar contents in N, P, and S 41 Table 18. Biochar contents in exchangeable macro- and micronutrients (related to plants) 42 Table 19. Biochar contents in soluble macro- and micronutrients (related to transport of contaminants and plants) 43 Table 20. Biochar contents in other elements (related to the environment) (Part 1) 44 Table 21. Biochar content in other elements (related to the environment) (Part 2) 45 Table 22. Biochar contents in PAH (related to the environment) 46 Table 23. Percentage of earthworms that chose the mixture of garden soil with 10% biochar compared to garden soil alone,
or with 50% biochar compared to garden soil alone, and germination rate of lettuce after 3 and 6 days in the same
48 mixtures (related to biological toxicity) Table 24. Summary of general and physical properties of biochars 53 Table 25. Summary of chemical properties of biochars 54 Table 26. Summary of biological properties of biochars 55 List of figures
Figure 1. Relative content of C types in biochars (green: Corg, red: Cinorg, blue: Cgraph) 32 Figure 2. Capillary rise of different biochars under tensions of -0.05 m (very wet) to -1.5 m (humid) 35 Figure 3. Cumulative particle-size distribution of biochars 37 Figure 4. Preference of earthworms for garden soil alone (0% biochar) or a mixture of garden soil with 10% v/v biochar 49 Figure 5. Preference of earthworms for garden soil alone (0% biochar) or a mixture of garden soil with 50% v/v biochar 50 Figure 6. Germination rate of lettuce in garden soil amended with 10% biochar 51 Figure 7. Germination rate of lettuce in garden soil amended with 50% biochar 52 4 Analyses of biochar properties
1. Introduction
The province of Quebec produces millions of tonnes of residual organic matter (ROM) every year.
This ROM comes from municipal sources and from forest, agricultural, food, and demolition
industries. Cities alone produce 5.8 M tonnes of commercial and urban ROM. Although some ROM is
recycled in fields either directly or following composting, millions of tonnes cannot be used because of
biological risk, the possibility of recirculation of pathogens, or non-compostability. ROM from the
food industry is often too humid for composting, and most parts of the food industry do not have
suitable locations to spread their residues or would have to transport them to distant sites to do so,
which is costly. In most cases, the food industry must send its ROM to municipal facilities for
treatment; cities also lack sufficient land for spreading their ROM. Instead, they regularly send them to
landfills.
Municipalities, particularly the large ones, also generate millions of tonnes of ROM on their own,
much of which is contaminated. For example, green wastes such as those from lawn mowing and leaf
collection can be composted, but these wastes are often contaminated with plastic bags and other
impurities. Cities also produce large volumes of ROM from street, sewer, and septic tank cleaning.
Recycling bins and eco-centres provide ways to recycle and reuse ROM, but these facilities also
produce millions of tonnes of ROM.
To provide numbers, about 60% of the 5.8 M tons of urban ROM generated annually in Quebec is
not reused, and only 21% of putrescible residues were recycled in 2012 (Recyc-Québec, 2014). In order
to force the urban and industrial sectors to find solutions to this problem, the Quebec government has
developed an action plan for ROM management. The Ministère de l’Agriculture, des Pêcheries et de
l’Alimentation du Québec (MAPAQ) has mandated, by legislation, that 60% of ROM should be
diverted from landfill by 2015 and 100% by 2020. In response, the industrial sector has greatly
increased its efficiency in recycling materials. For example, the Quebec forest industry hopes to reuse
the entire 6.4 M tons of biomass generated by its forest activities (CEF, 2015). It has developed a
panoply of new products made from sawdust and wood chips, among other materials. Much work is
still required, however, to utilize all of the ROM produced by the industry, especially bark and
branches, which represent about 25% of the trees. Thus, millions of tonnes of ROM produced annually
by this industry remain unexploited.
All ROM could potentially be used to produce energy. However, existing subsidies render hydroelectricity very inexpensive in Quebec; energy from ROM is unable to compete with this low price.
Composting offers an alternative means of recycling such materials, but it is not suitable for many
types of ROM, and there is insufficient market demand for the quantities of compost that could be
produced. Composting also emits large quantities of greenhouse gases (GHG) that are usually not
captured, because doing so requires large installations. The majority of this ROM must therefore be
processed using another way.
Methanization of ROM can produce large quantities of biogases, but it also generates 50 to 90% of
its initial volume in ROM (Agrinova, 2013). The resulting digestates are subject to legislation from the
Ministère du Développement Durable, de l’Environnement, et de la lutte contre les changements
5 Climatiques (MDDELCC) regarding their use in the environment (Agrinova, 2013). Their use depends
upon the quality, innocuity, and nutrient content of the digestate, while their quality depends upon their
storage, the original type of ROM, and the transformation process (Agrinova, 2013). Because the ROM
that remain contain more than 70% of water, solids have to be separated from the liquid components.
Composting, dehydration, or pyrolysis can then treat these solid residues.
Incineration often offers the ultimate alternative for ROM treatment. However, while incineration
decreases the volume of ROM considerably, it is also costly. The energy produced by the process could
be used to heat industrial plants, but the low cost of energy in Quebec and the large variability in
demand between seasons renders this alternative complex and uneconomical. Also, the ash that remains
after incineration is not easily valorized.
Pyrolysis provides an interesting alternative to direct soil application, composting, methanization,
and incineration since the gases produced are usually captured and recycled within the pyrolysis
system, thus reducing GHG emissions; and the resulting material, known as biochar, is stabilized,
making it easy to handle, transport, and distribute. Biochar offers the possibility of reducing the cost of
transformation and storage of ROM, plastics, and other contaminants. In addition, biochar is sterile.
Pyrolysis carbonizes organic matter in the absence or in quasi absence of oxygen at temperatures
between 275°C and 1000°C. The organic matter is thermo-chemically transformed, producing gases,
oils, and solid residues, the solid is name biochar. The oils can be used to produce energy or new
products such as biopesticides. In Quebec, the gases produced are often recycled to dry the source
material before pyrolysis. Since biochar can be produced using a variety of feedstock and pyrolysis
technologies, the properties of the resulting products vary.
Also called "biocarbon" or "vegetal charcoal", biochar differs from standard coal and charcoal
because its source material is mostly fresh residual matter rather than fossilized or good quality hard
wood. The final result consists of black, carbon-rich, initially sterile fragments that are lightweight,
highly porous, and easy to transport.
The potential uses of biochar have excited growing interest among producers, processors, and
managers of ROM, retailers of agro-environmental products, farmers, environmental consulting firms,
and others - potentially everyone involved in agricultural production, environmental protection, or the
disposition of organic residues. Possible applications in agriculture and environmental protection
include carbon sequestration, interception of contaminants, and improvement of plant growth
(Verheijen et al., 2010; Montanarella, 2013). For example, biochar can be used to improve soil fertility,
water retention, and microbial activities, thus improving plant productivity (Allaire and Lange, 2013).
Therefore, the young biochar industry in Quebec has the potential to grow into a multi-milliondollar sector, but a number of steps are needed to clear the way for its development in Quebec.
However, the listed advantages vary, depending on the type of biochar used, the oil type, the climate
conditions, and the plant species involved. Although pyrolysis has existed for millennia, the methods
for manufacturing biochar with specific characteristics for specific applications have yet to be fully
mastered.
In order to make the best use of biochar, we must improve our understanding of its properties in
relation to both the feedstock and the pyrolysis method used to manufacture it. In addition, to ensure
that obstacles such as unnecessary regulation, subsidies for other methods of ROM transformation, and
lack of knowledge about biochar no longer limit the development of this sector, greater knowledge is
needed concerning the properties of biochar in relation to manufacturing processes and source
materials, including new feedstocks.
6 The main part of the report describes the analysis methods used, the properties of the biochars
examined, most of which were made in Quebec, and their manufacturing technologies. Several
analyses remained underway. Consequently, statistical analyses are not presented or discussed, nor are
correlations between manufacturing procedures and specific biochar properties. Values are simply
given without interpretation. Comparisons, relationships, correlations, and further discussion will come
in subsequent papers.
In this report, we also present our work team (Table 1), the institutions that manufactured them or
gave accesses to their pyrolyzer (Table 2), those that provided feedstock (Table 3), and financially
supported the project (Table 4). The team thanks all the individuals and institutions that have
contributed to this project.
2. Objectives
Our purpose in conducting a comparative analysis of the bio-physico-chemical properties of
biochar was to create a reference database that will be of use to generators and managers of ROM,
manufacturers of pyrolyzers and biochars, and biochar users. This information will help the industry
better understand how to obtain desired products with desired characteristics and predictable properties
for specific uses. The goal is to reduce the amount of trials and errors required, facilitating the
development and marketing of biochar for agricultural and environmental applications in Quebec.
Characterisation of the biochars is the first step towards this goal.
The team also set itself a sub-goal of defining a set of biochar analysis methods for Quebec
conditions. Biochar specifically designed to amend agricultural soils, rehabilitate contaminated or
degraded sites, or as supplement to potting soils began appearing on the market only recently, and thus
methods of biochar analysis have not yet been formalized in Quebec or Canada as a whole. Some of the
methods used in the literature are derived from standard analyses in the coal and energy industries,
while others come from fertilizer and agricultural amendment applications. Other analyses derived
from mandatory reporting requirements related to environmental protection, as in the case of heavy
metals. The International Biochar Initiative (IBI) has suggested a set of biochar analysis methods (IBI,
2012), but the list is incomplete for some uses, including those related to plant growth. The European
Biochar Foundation has suggested another set of methods for use with its European Biochar Certificate
(EBC, 2012) that are similar but not identical to those recommended by the IBI. Some of the methods
are applicable primarily to the coal and energy industries and have little relevance to agricultural and
environmental applications.
In Quebec, the Bureau de Normalisation du Québec (BNQ) is accredited by the Standards
Council of Canada (SCC) to develop norms and certifications using procedures and methods in
accordance with the rules of the International Organization for Standardization (ISO) and the World
Trade Organization (WTO). The use of ROM in agricultural fields, for food production, or for
application on environmentally degraded sites is subject to Canadian federal government and Quebec
provincial government legislation, but those rules differ from the standards of the IBI and EBC. For
now, Quebec and Canada do not have standards specific to biochar.
To fill this gap, the team has sought to compile a list of the most appropriate methods for the
analysis of biochar for agricultural contexts (effects on soil properties and plant growth, and
environmental factors), taking into consideration the norms and regulations of the Quebec government
for protecting the environment. We also wanted to assess a wide range of biochars using the standards
of the IBI, the EBC, and the Quebec government in order to better understand their potential for use in
Quebec and abroad. This classification will be discussed in another document.
7 The present report is only preliminary since it only provides data on a selection of available
biochars. Additional biochars have recently arrived at the laboratory, while others are in production in
order to expand the range of pyrolysis conditions and raw materials examined. Following analysis of
these biochars and application of multivariate statistical methods, we will map the properties of all of
these and new biochars according to method of pyrolysis and type of feedstock. Classification of the
biochars will be the subject of another paper, while their effects on plant growth (across various plants
and conditions) will be addressed in a number of different thesis and articles.
8 Table 1. Team members
Photo
Name
E-mail
Title and
institution
Degree
Responsibility in this
project
Speciality
Suzanne
E. Allaire
suzanne.allaire@fsaa.
ulaval.ca
Full professor,
Université
Laval
Ph.D.
Director of soil
physics lab
Soil physics
and porous
media
Sébastien
F. Lange
sebastien.lange@fsaa.
ulaval.ca
Researcher,
Université
Laval
Ph.D.
Lab management
Soil physics
Melissa
Quinche
Gonzalez
melissa.quinchegonzalez.1@ulaval.ca
Ph.D. student,
Université
Laval
M.Sc.
Some analyses
Agroenvironment
Isabelle K.
Auclair
isabelle.auclair@uqtr.
ca
Ph.D. student,
Université du
Québec à
Trois-Rivières
M.Sc.
Pyrolysis method,
recycled wood and
vegetables
Agroforestry
Laurence
Greffard
laurence.greffard.1@u
laval.ca
M.Sc. student, Biologist
Université
Laval
Some analyses
Biology
9 Table 2. Biochar producers or industries that provided access to their pyrolyzer
Company
Logo
Contact person
E-mail
Internet site
Abri-Tech
Peter Fransham,
Vice-President
pfransham@abritechinc.c
om
http://www.advbiorefineryi
nc.ca/
Airex Energy
Sylvain Bertrand,
CEO
sbertrand@airexenergy.c
om
http://www.airexenergy.com/fr/abr
Award
Rubber
Michel Kaine,
President
info@awardrubber.com
http://www.awardrubber.co
m/
Biopterre
Benoît Cayer,
CEO
benoit.cayer@biopterre.c
om
http://www.biopterre.com/
Basques
Hardwood
Charcoal
David Huard,
Director
davidhuard@globetrotter
.net
http://charbonbasques.com/
IRDA
Stéphane
Godbout,
Researcher
stephane.godbout@irda.q
c.ca
http://www.irda.qc.ca/fr/
Maple Leaf
Simon Langlois,
Director
simon.langlois@maplele
afcharcoal.com
http://mapleleafcharcoal.co
m/fr/
Pyrovac
Christian Roy,
Owner
croy@pyrovac.com
http://www.canbio.ca/event
s/quebec/presentations/roy
_f.pdf
Wood Ash
Industries Inc.
Brian Coghlan,
Owner
admin@woodash.net
http://www.woodash.net
10 Table 3. Institutions that provided the feedstock to be pyrolyzed
Institution
Contact
Internet site
Feedstock
Biopterre
info@biopterre.com
Forest residues,
phragmites
BRQ Fibre et
broyure
info@boisrecycle.com
http://www.brq.ca/
Recycled wood
Centre de Tri CoÉco
info@co-eco.org
http://co-eco.org/
Branches, bark
norvie30@hotmail.com
None
Potato residues
Ferme Massibec
louis@massibec.com
http://www.massibec.com/
Cabbage residues
Ferme du Domaine
2000
fermedudomaine@ferme
dudomaine.com
http://www.fermedudomain
e.com/
Leek residues
Ferme Norvie
Logo
None
11 Table 4. Institutions that contributed to the project through grants or supplemental student
scholarships
Acronym
Name
Internet site
Contribution
Airex
Airex Energy
http://www.airexenergy.com/fr/abr
1. MITACS scholarship, 2. Participation in a
CRIBIQ project
Biopterre
Biopterre
1. BMP scholarship, internship in industry
CJLP
Centre Jardin Lac Pelletier
http://www.cjlp.ca/
1. MITACS scholarship, 2. Participation in a
CRSNG-RDC project operated by the CTRI
CRIBIQ
Consortium de Recherche et
d’Innovations en Bioprocédés
Industriels au Québec
http://www.cribiq.qc.ca/fr/
Grant program
CRIEB
Industrial UQTR-foundation
research chair on environment
& biotechnology
http://www.uqtr.ca/CRIEB
They paid the cost of some analyses
CRSNG
Conseil de Recherche en
Sciences Naturelles et Génie du
Canada
http://www.nserccrsng.gc.ca/index_fra.asp
1. BMP scholarship, internship in the
industry, 2. Two Grant programs
CTRI
Centre de Traitement des
Résidus Industriels
http://www.ctri.qc.ca/
MITACS scholarship
FOGRN BC
Programme de formation en
gestion des ressources
naturelles du Bassin du Congo
http://www.projetfogrnbc.ulaval.ca/pefogrn_bc_ul
aval/
Ph.D. scholarship
FQRNT
Fonds Québécois de Recherche
Nature et Technologie
http://www.frqnt.gouv.qc.c
a/
MITACS and BMP scholarships
Innofibre
Centre d’innovation de produits
cellulosiques
http://innofibre.ca/
MITACS scholarship
MAPAQ
Ministère des pêcheries et de
l’alimentation du Québec
http://www.mapaq.gouv.qc
.ca/fr
Grant through Innov’Action program
MITACS
MITACS
https://www.mitacs.ca/fr
Scholarships
U. Laval
Soil physics lab
http://www.fsaa.ulaval.ca
Scholarships to undergrad students
Biochars were obtained from a number of different research projects, funded or not. Only parts of certain grants were used for
biochar analysis in each of these projects, all of which concerned agricultural, horticultural, or environmental issues related to
the use of biochar. Most biochars were donated by the industrial partners.
12 3. Materials and methods
3.1. Residual organic matter (ROM) and pyrolysis methods
This report examines the physical, chemical, and biological properties of a selection of
biochars. The biochars were grouped into five categories by feedstock: hardwood, coniferous softwood,
non-coniferous softwood, non-woody ROM, and other carbon-containing residues (e.g., pig manure)
(Table 5).
3.1.1. Hardwood
The hardwood biochars included residues from charcoal manufacturers such as Maple Leaf and
Basques Hardwood Charcoal (Table 5). These manufacturers burn large logs, principally maple (Acer
sp.) and birch (Betula alleghaniensis, also called yellow birch), for about two days (Table 5) without
oxygen in a batch furnace (Missouri-type kiln). The wood that enters the Maple Leaf pyrolyzer
contains between 30 and 52% moisture, depending on season and wood inventory. The Maple Leaf
pyrolyzer operates at about 350ºC at a set pressure and recycles its gases. The company's ovens can
produce about 15 tonnes of charcoal per day (Leaf-Maple-350). The Basques Hardwood Charcoal
pyrolyzer operates at a slightly higher temperature (500ºC) for two to three days (Table 5). Both
companies produce biochar as a by-product of their charcoal manufacturing. The residues are sieved
after pyrolysis. The three biochars from Basques Hardwood Charcoal examined in this report (BQMaple-500-1, 2, and 3) differ primarily in particle size and date of manufacture. The technology used
by these manufacturers produces mainly biochars rather than oils, although the ratio depends on the
speed of pyrolysis and the extent of desorption of water before carbonization. Bark is an integral part of
the biochars. We also examined two other biochars (Award-Maple-700 and Nuchar-1000) made from
hardwood residues from the forest industry. The Award-Maple-700 biochar is made from maple bark,
rather than logs, burned at 700ºC for just 20 minutes. The Nuchar-1000 (MeadWestVaco, MWV SN20) was purchased from Buyactivatedcharcoal.com. This biochar is activated at 1000°C after
production. No further information was given about the manufacturing process. Nuchar-1000 is the
only activated biochar made from hardwood discussed in this report. By examining a range of biochars,
we were able to compare the effects of different production temperatures on the properties of biochars
made from the same plant species (Table 5).
We also examined eucalyptus bark (B-Eu-300) processed in Cameroon in a small-batch vertical
pyrolyzer with a gas recycling system. The operating temperature of this pyrolyzer varies around
300ºC, and pyrolysis lasts from 4 to 6 hours. A small amount of air is allowed to enter the system. The
bark was collected at the soil surface, which resulted in the addition of soil impurities.
3.1.2. Coniferous softwood
Other biochars were made from softwood residues such as branches, bark, and sawdust from
spruce (Picea sp.), fir (Abies sp.), or other species. These biochars were made by three companies:
Biopterre, Airex Energy, and Pyrovac. Biopterre uses Abri-Tech technology, while Airex Energy and
Pyrovac use their own technology.
The Abri-Tech system processes batches of about 2000 kg per hour. It was designed primarily
to produce pyrolytic oils, with an output of about 65% oil and 20% biochar. The biochar is a byproduct and not the final goal, and may contain volatiles. The source biomass is converted thermally in
contact with steel balls heated to increase the gasification of the material. The size of the biomass
13 particles has to be very small (usually less than 2 mm; maximum 20 mm), so there is no need for
sieving after pyrolysis. Pyrolysis takes only a few minutes, at temperatures ranging between 425 and
550ºC depending on the product requested, without oxygen, at a pressure of about 1 cm. The two
softwood biochars produced using Abti-Tech technology discussed in this report (BP-Res-400 and BPRes-500) differed in terms of pyrolysis temperature (400 or 500ºC).
Airex Energy, the developer of the Carbon FX technology, is a spin-off from the company
Airex Industries, which specializes in industrial dust. The Airex Energy pyrolyzer is a cyclonic bed
reactor developed for fine particles such as sawdust. Biomass is pyrolyzed at about 427ºC over the
course of several seconds, at atmospheric pressure, using a fine air inlet and heat transfer via high
turbulence. The system can continuously produce about 250 kg of biochar per hour. Very little oil is
produced. The main differences between the Airex biochars discussed in this report relate to production
temperature in the case of the first two biochars (Airex-Res-427 and 454) and the type of ROM used
(recycled wood from BRQ) in the case of the second two (Airex-RW-315 and 426).
Pyrovac's pyrolyzer processes softwood with 10 to 15% moisture content. It can accommodate a
variety of products, accepting heterogeneous particles between 0.4 and 40 mm in size. Pyrolysis is
performed at a pressure of 20 kPa and a temperature of 475ºC in a slightly oxygenated environment for
15 minutes. The pyrolyzer can produce 3000 kg of biochar per hour. The two Pyrovac biochars
discussed in this report differed in terms of storage and sieving. The first (Pyr-Res-475) was stored for
about 2 years in a warehouse and a waterproof container. The second (Pyr-Res-475-aged) was sieved to
2 mm and stored outside in leaky super sacks (polypropylene bags).
We also tested recycled wood residues. These residues represent a large, unexploited resource,
but one that often contains toxic agents. For this report, we tested two biochars made from demolition
wood and/or construction residues composed roughly 90% of spruce and 10% of assorted hardwoods
(I-RW-300-24 and 48). The large volume of residues produced by the forest industry are stored
relatively homogeneously by species. It is therefore possible to obtain biochars made from specific
wood species from this source. By contrast, the residues of the construction–demolition industry offer
mostly mixtures of wood species, which are therefore less homogeneous. However, since the frames
and walls of Quebec buildings are mainly made from spruce, a large proportion of Quebec demolition
wood is composed of this species. The recycled-wood biochars that we examined were made in a batch
furnace with a small amount of air. As the wood was old, its initial water content was low (less than
10%). The wood was ground and screened to a particle size of 0-2 mm. Atmospheric pressure was
maintained in the furnace. The biomass remained in the oven for 24 to 48 hours at 300ºC. Neither gas
nor oil was recycled. Two recycled-wood biochars made with the Airex technology were also tested
(Airex-RW-315 or 426).
3.1.3. Non-coniferous softwood
Other biochars are made from non-coniferous softwood (Table 6) such as white birch (Betula
papyrifera) and willow (Salix sp.), using branches, bark, or the entire tree. Biopterre has produced a
variety of such biochars (BP-Willow-x, BP-Birch-x, x being the temperature) with the Abri-Tech
technology, using a range of raw materials (bark vs. branches vs. whole trees) and production
temperatures. We also examined activated charcoal made from coconut shell residues (Coco-1000) sold
by Buyactivatedcharcoal.com. The only activated biochar in the softwood category discussed in this
report, Coco-1000 is produced by slow pyrolysis at about 300ºC, with the temperature increasing by 5°
per minute for about 1 hr. It is then activated at 1000°C. Other manufacturing conditions were not
disclosed.
14 3.1.4. Non-woody materials
Phragmites (Phragmites australis sp.) is a highly invasive plant that causes many problems in
Quebec. To control it, we tend to mow it. Hay residues were used to test the potential of this material
for the manufacture of biochar. Mowing was carried out in spring on stems from the previous year that
had dried during winter. The residues were shredded to 8 mm but not dried, and then pyrolyzed with
the Abri-Tech technology at 400 or 500ºC to form two biochars (BP-Phragmite-400 and 500).
We also examined the potential to use residues from vegetable production that cannot easily be
recycled by composting or incorporation directly into the field. Downgraded potatoes, cabbage leaves,
and leeks are too wet to be easily composted, while direct field recycling can lead, in some cases, to
proliferation of diseases. We pyrolyzed these materials to study their potential as biochars (I-Potato300-24, I-Cabbage-300-48, I-Leek-300-48). The potatoes were manually julienned, while the cabbage
and leek residues were cut up with a forage harvester. Pyrolysis was performed at Innofibre and
Lignocellulosic Materials Research Centre (CRML) of the UQTR using ovens operating at atmospheric
pressure, with little air entry. The biomass remained in the oven for either 24 or 48 hours at 300ºC.
Neither gas nor oil was recycled. The potato biochars remained in the oven for just 24 hrs because
experiments showed they were consumed before 48 hours.
We also looked at corncobs (B-Corn-300) that had been pyrolyzed in Cameroon using the same
system as used for eucalyptus (a vertical pyrolyzer oven with gas recycling). The temperature of the
oven varied around 300ºC, and pyrolysis lasted from 4 to 6 hours.
3.1.5. Other materials
This category includes the use of non-standard biomass for biochar manufacturing.
Cogeneration activities by Kirkland Lake Power Corp. produce biochar that is sold by Ash Wood
Industries (Wood-Ash-1500). The materials used in the cogeneration come in a wide range of sizes
from a variety of wood wastes (softwood such as pine, birch, fir, and spruce) and often contain sand
and other impurities. They are burned using flame at temperatures between 1500 and 1800ºC for less
than one hour. Some residues are completely burnt, some are pyrolyzed into biochar, and others are
less transformed. The process generates a highly variable product that is mostly ash (less than 50%
biochar). Because of this variability, the features of the sample described in this report do not represent
the full range of its potential properties. Even though this product contains less than 50% biochar, we
included it in this report since the results could be of interest for other such industries.
Manure produced by the pork industry offers another potential source of biomass for biochar.
The Quebec pork industry, which produces 7.5 million pigs annually (Gariepy and Lacroix, 2013),
generates such a large amount of manure that the Quebec government has controlled pig production to
limit its environmental and social consequences. The industry and various research bodies have sought
improved technologies for processing pig manure slurry for many years. Recently, these efforts have
included some small biochar trials. For this report, manure was collected from a pig growing–finishing
farm where the liquid and solid fractions were separated under the slats of the barn. The collected solid
was subsequently dried using the SHOC™ process (details of the process can be found in Léveillée et
al.,
2011)
(http://www.irda.qc.ca/fr/publications/le-procede-shoc-une-solution-novatrice-pour-letraitement-et-la-valorisation-des-residus-organiques/). The dry solid fraction of the pig slurry was
converted into biochar (IRDA-Manure-500) using slow-batch pyrolysis at 500°C for 1.5 hours. A flow
rate of 2 L min-1 of nitrogen was established in the reactor at atmospheric pressure to maintain an inert
atmosphere and promote the evacuation of gases from the reactor. The material must enter with a
moisture content below 85%.
15 Table 5. List of biochars with their feedstock and pyrolysis method Name
Feedstock
Conditioning
Tem
p
(ºC)
Leaf-Maple-350
Charcoal plant residues,
maple and cherry
BQ-Maple-500-1
Award-Maple-700
>75% maple
>75% maple
>75% maple
Maple bark
B-Eu-300
Hardwood
Sieved to ≤ 1.9 mm after
pyrolysis + binding
matter
Sieved to medium-coarse
after pyrolysis
Sieved to fine after
pyrolysis
Sieved after pyrolysis
Time
(hrs)
Pyrolysis
Pressure
(KPa)
Technology
350
40
Yes
Missouri oven
type
500
Yes
Yes
Missouri oven
type
Missouri oven
type
Missouri oven
type
Award Rubber
None
700±100
4872
4872
4872
0.4
Eucalyptus bark
Ground
300
6
0
Custom oven
Nuchar-1000
Hardwood from undeclared
species
Activated at 1000ºC
300-1000
NA
NA
NA
BP-Res-400
50% fir branches, 50% spruce
branches
50% fir branches, 50% spruce
branches
Resinous softwood sawdust
400
0.08
0.1
Abri-Tech
500
0.08
0.1
Abri-Tech
427
<0.01 0
Airex
454
<0.01 0
Airex
475
0.25
20
Pyrovac
475
0.25
20
Pyrovac
315
0.01
0
Airex
426
0.01
0
Airex
300
24
0
Exp. oven
300
48
0
Exp. oven
400
0.08
0.1
Abri-Tech
450
0.08
0.1
Abri-Tech
450
0.08
0.1
Abri-Tech
500
0.08
0.1
Abri-Tech
550
0.08
0.1
Abri-Tech
400
0.08
0.1
Abri-Tech
BQ-Maple-500-2
BQ-Maple-500-3
BP-Res-500
Airex-Res-427
Airex-Res-454
Pyr-Res-475
Pyr-Res-475-aged
Airex-RW-315
Airex-RW-426
I-RW-300-24
I-RW-300-48
Coniferous softwood
Ground + dried before
pyrolysis
Ground + dried before
pyrolysis
Ground and sieved to ≤ 2
mm before pyrolysis
Spruce trunk sawdust
Ground and sieved to ≤ 2
mm before pyrolysis
Resinous softwood bark
Sieved to ≥ 0.5 mm
before pyrolysis
Resinous softwood bark, aged Sieved to ≥ 0.5 mm,
in super bags and sieved
dried to 8-15% moisture
Recycled demolition wood
Sieved to < 6.4 mm
before pyrolysis
Recycled demolition wood
Sieved to < 6,4 mm
before pyrolysis
100% demolition wood, 90%
Ground and sieved to 0spruce, 10% hardwood
3/4 inches before
pyrolysis
100% demolition wood, 90%
Ground and sieved to 0spruce, 10% hardwood
3/4 before pyrolysis
500
500
Yes
Yes
Non-coniferous softwood
BP-Willow-400
Whole willow
BP-Willow-450-2013
Whole willow
BP-Willow-450-2014
Whole willow
BP-Willow-500
Whole willow
BP-Willow-550
Whole willow
BP-Birch-400
>75% white birch branches
Ground and sieved before
pyrolysis
pyrolysis
pyrolysis
pyrolysis
pyrolysis
pyrolysis
16 BP-Birch-500
>75% white birch branches
Coco-1000
Coconut shell
BP-Phragmite-400
Phragmites
BP-Phragmite-500
Phragmites
I-Potato-300-24
pyrolysis
Activated at 1000ºC
500
0.08
0.1
Abri-Tech
300
1
NA
NA
400
0.08
0.1
Abri-Tech
500
0.08
0.1
Abri-Tech
Non-marketable potatoes
pyrolysis
pyrolysis
Cut into julienne potatoes
300
24
0
Exp. oven
Cabbage residues
Ground with fodder
300
48
0
Exp. oven
Leek residues
Ground with fodder
300
48
0
Exp. oven
Corn cobs
Ground with fodder
300
6
0
Custom
500±25
90
IRDA
15001800
<1
-27 to 55
Atm
Non-woody material
I-Cabbage-300-48
I-Leek-300-48
B-Corn-300
IRDA-Manure-500
Dehydrated pig manure
Wood-Ash-1500
Mixed softwood (pine,
spruce, birch, fir)
Others
Sieved to 1-3 mm, dried
to 15% moisture
None
Kirkland Lake
Power Corp.
17 Table 6. Photos of some biochars
Award-Maple-700 (67 x)
Leaf-Maple-350 (10 x)
BQ-Maple-500-2 (67 x)
I-RW-300-48 (10 x)
BP-Willow-450-2013 (6.7 x)
Pyr-Res-475 (4.7 x)
BP-Willow-550 (67 x)
I-Leek-300-48 (6.7 x)
Wood-Ash (13 x) I-Cabbage-300-48 (10 x)
I-Potato-300-24 (6.7 x)
I-RW-300-24 (10 x)
Airex-Res-427 (6.7 x)
18 3.2. Biochar analysis methods
The methods for analysing biochars recommended by the IBI and the EBC are primarily related
to energy industry requirements due to the resemblance between biochar and coal. Some analyses are
required to assess environmental risk or to respond to environmental regulations. The methods are
significantly less affected by the forest industry, which is the source of the materials most commonly
used to make biochars. There is also very little influenced by agriculture, although biochars are often
used as soil amendment or in potting soils. We attribute the current focus on energy industry
requirements mainly to the history of biochar.
Our team sought to meet the main IBI, EBC, and Quebec government requirements in terms of
analytical methods in order to (1) meet current standards, (2) enable later comparison with other
studies, and (3) assist industry to obtain environmental recognition. We used ASTM methods or
certified Quebec methods as often as possible. Since our goal was to study the potential of biochars for
agricultural, forest, or environmental applications, we did not focus on properties related to energy
(BTU, flash point, flammability, etc.). We focused instead on those properties, whether mandatory or
not, that can help predict the behaviour of biochars in porous media such as soil, potting soils, mine
tailings, and soil rehabilitation.
Biochar properties were divided into the following classes: general properties (Table 7),
physical properties (Table 8), chemical properties relevant to plant growth or environmental protection
(Table 9), and biological properties indicative of environmental risk (Table 10). For simplification, all
methods are briefly described in tables with their reference with little explanations in the text.
The general properties analyzed were those normally considered of relevance to energy industry
requirements. These properties affect the behaviour of biochar in soil and potting soil only slightly, and
provide little help in identifying risks to the environment. However, determining the type of carbon
does help to establish the potential for long-term C sequestration; graphitic carbon is probably the most
stable form. The physical properties of biochars (Table 8), e.g., bulk density, solid density, surface
area, water-related characteristics, and particle size distribution, greatly influence their behaviour in
porous media, in storage, and in transport. Chemical properties (Table 9) were considered because they
influence the effect of biochars on plant growth (solubility, exchangeability, total nutrients) or their
exchange capacity with the environment (pH), or because environmental regulations require
identification of their contents (heavy metals, PAHs). Dioxin and furan levels are not presented in this
report because of the high analysis cost (~800 $ CAN ea.). Finally, we examined the effect of biochars
on earthworms and lettuce (Table 10), two species sensitive to pollution and other environmental
factors, in order to identify potentially negative effects on biology.
3.2.1. General properties
Data was collected on the total ash, C, H, N, and S contents of the biochars (Table 7). In
addition to total carbon (Ctot) content, data is given on organic carbon (Corg), inorganic carbon (Cinorg),
and graphite (Cgraph) content to provide an indication of the likely transformation modes of the various
biochars in soil. Cinorg corresponds mainly to CaCO3 content. We expect that Cgraph would show the
highest stability in soil. The ratios H/Corg and O/C are simple calculations from the previous
measurements.
19 3.2.2. Physical properties
Hydraulic properties
The physical properties examined for this report include a number of properties related to water
(Table 8). The EBC and IBI both require declaration of the gravimetric water content (WC) of the
materials. The EBC differentiates between easy-to-extract water and hygroscopic water that is strongly
sorbed onto particles, whereas the IBI requires only the easy to extract be reported. For simplicity and
ease, we measured only easily extractable water for this report. WC has little effect on the behaviour of
biochars in porous media. It is used primarily for determining the heating value of the material and to
indicate to buyers the amount of water they are paying for. WC is, however, important in the case of
activated charcoal. WC was measured at temperatures of 70 or 105°C for 24 hrs, a method adapted
from the IBI and soil analysis.
Another parameter suggested, but not required, by the two organizations concerns the water
retention capability of the material. This property determines the behaviour of the biochar in porous
media and during storage when exposed to water. The method suggested by the EBC indicates only if
the biochar is capable of sorbing water when completely submerged. We did not use this method.
Instead, we measured the amount of water that can be extracted by the biochar both from the
atmosphere and from a porous medium by capillary rise. For the first, we exposed the biochar to a
relative humidity (RH) of 80% and measured how much water it could sorb from the air in 72 hrs. For
capillary rise (CR), the biochar was subjected to water retention forces (CRx) simulating both a very
wet (matric potential, or tension, near zero) and a somewhat drier but still very moist (more negative
matric potential) soil. We selected these properties because they best represent the behaviour of
biochars in the environment. Such data are likely to be especially useful because, although it is
frequently asserted in the literature that biochars increase soil water retention, such assertions are often
made without actual measurements in porous media.
Properties related to size and shape of particles, porosity, and electrical conductivity
These physical properties strongly affect the behaviour of biochar in soils and porous media.
Bulk density (BD) is the mass/volume of the material including intra- and inter-particle pores (Table 8).
This property is relevant to storage and transport, and it indicates the potential change in soil or potting
soil density when biochar is added. Information on this property is required by the EBC, but not the
IBI. Solid density (SD) is the mass/volume of the material excluding inter-particle voids. SD indicates
the behaviour of a particle in another medium, such as buoyancy in water. Total porosity, P, is
calculated according to P=1-BD/SD. External surface area (SSext) provides information on the
exchange and sorption capacity, and reactivity, of the biochar. SSext includes exchange sites at the
particle surface only. Electrical conductivity (EC) indicates the capacity to transport electricity. The IBI
and EBC both require this information, but they recommend different methods. EC depends on the salt
content of the biochar and thus could be used to calculate the salinity of the material. The ability of
plants to extract water from their environment depends not only on matric potential, but also on
osmotic potential, which is created by salinity.
A particle-size analysis was performed using two successive sieving procedures for each
sample: (1) the first with a column of sieves being 8-, 4-, 2-, 1-, 0.50-, 0.25-, and 0.125-mm mesh size,
and (2) the second with an ultrasonic sieve to separate particles smaller than 0.250 mm. The stack
included the following sieves: 0.250, 0.106, 0.053, and 0.025 mm. The IBI requires a particle-size
20 analysis, although not as complete, while the EBC does not require one. From these sieving procedures,
several parameters were calculated. Mean weight diameter (MWD) indicates the average particle size.
This information is important to determine the type of machinery necessary to apply the biochar in the
environment and to predict its behaviour once applied. The MWD influences, for example, water
retention and potential mixture with other ingredients such as fertilizers.
From the particle-size distribution curve, we can calculate parameters such as the diameter
representing the finest 10% of particles (D10). These parameters are used to calculate the particle-size
uniformity index (UI) of the material. A low uniformity index (D95/D10) value means that the particles
are uniform in size. A highly heterogeneous distribution of particle sizes may provide some benefit
over the homogeneous mixes often obtained by screening, since different particle sizes may play
different roles in water retention, protection against soil erosion, and soil decompaction. In some cases,
however, one might select a biochar with a very homogeneous particle-size distribution for a specific
behaviour such as often found in horticultural potting soils. When working with mixtures of
amendments, the UI of the material will indicate whether or not it might separate from the other
components of the mixture during transportation, handling, spreading, or plant growth.
The biochars were also subjected to abrasion tests using steel balls. Abrasion-resistance
measurements (AR) show the resistance offered by a material to the action of different forces during its
movement. This information can help determine the effects of transport, storage, spreading, and
handling of the biochar on the integrity of its particles. Particle size after the abrasion was measured
using the sieving method described above. The variation in mean weight diameter (DMWD),
uniformity index (DUI), and specific particle size (DDx) following the abrasion were also calculated.
This information is not required by any of the standards, but it is inexpensive to produce and useful for
determining bagging, transportation, and handling needs.
3.2.3. Chemical properties
Properties related to acidity
Measured chemical properties included pH value and buffer capacity (BC) (Table 9). The IBI
and EBC both require provision of the pH value, but each specifies a different method. These methods
yield slightly different results, but considering the large variation in pH between biochars, the results
are close enough for comparative purposes, as in the case of this report. We used a method similar to
the IBI's, measurement in water, in this report. BC is required by IBI, but is also useful for determining
biochar behaviour in a medium with a different pH. This information is valuable in agriculture.
Biochars, which are often basic, can be incorporated into much more acidic environments, such as peat,
podzols, or mine tailings, for example. The pH value of the material alone does not indicate whether
the biochar has sufficient buffer capacity to maintain its pH. BC was measured until either pH 7
(BCpH7) or pH 4 (BCpH4) was reached.
Exchangeable elements
Measurements of the content of exchangeable elements (Table 9) are used to check the
availability of elements to plants and their nutritional balance relative to plant needs. The sum of the
exchangeable elements N, P, K, Ca, and Mg is normally used to calculate the cation exchange capacity
(CEC) of the soil. Since soils are subject to rain year after year, it is their ability to retain these
elements over time that indicates their CEC. Fresh biochar has not been subjected to such leaching, and
thus the exchangeable element data only indicate total content of these elements on exit from the
21 factory, regardless of whether they can be exchanged or not. In this report, we therefore use the term
"sum of exchangeable elements" rather than CEC.
Soluble element content indicates not only the availability of nutrients when water is present,
but also the risk of their movement into and potential contamination of the environment. Soluble
elements (K, Ca, Mg, Na, Mn, Fe, Al, Cu, Zn) were extracted with water.
Properties related to environmental protection
The IBI and EBC both require declaration of heavy metal content (Tables 9 and 11). These
values are used to determine approved and prohibited uses for environmental protection purposes. The
list of metals covered, methods of analysis, and maximum permitted values vary between the
organizations. The accepted maxima of the EBC and IBI generally correspond to European or US
government regulations. We measured most of the metals and several other elements (Al, As, Cd, Co,
Cr, Cu, Fe, Hg, Mo, Ni, Pb, Se, and Zn) using the methods prescribed by the IBI. The results will be
compared to Quebec regulations, and those listed by the IBI and EBC, in another paper. We also
measured the presence of polycyclic aromatic hydrocarbons (PAHs) (Table 9) using the standard
methods of the Centre d’Expertise en Analyse Environnementale du Québec (CEAEQ). PAH
measurements are required by both the IBI and the EBC. The range of properties analyzed was greater
than that requested by these organisations.
3.2.4. Biological properties
The final group of properties corresponding to IBI information requirements was related to
biological toxicity (Table 10), which we investigated by examining the preferences of earthworms and
the germination of lettuce in mixtures of garden soil and biochar. For these tests, the biochar content in
the soil mixtures, the earthworm species and the variety of lettuce were not dictated by the IBI, but
simply suggested.
Eisenia fetida sp., an earthworm species often used in vermicompost, was used to measure the
reaction of earthworms to the biochar. The worms were deposited on the soil surface in the middle of
containers vertically separated into two equal parts, after which they were able to move freely from one
side to the other for 48 hrs. On one side we put garden soil and on the other we put a mixture of this
soil containing either 10% or 50% biochar. The subsequent distribution of the earthworms indicated
their preference for either the mixture or the soil alone. This preference depends on factors such as
toxicity, pH, abrasion on their skin, etc.
The lettuce (Lactuca sativa var. Buttercrunch) germination experiments suggested by the IBI
were also performed. Seeds were sown in dishes containing the same concentrations of biochar as in
the earthworm avoidance tests (0, 10, and 50%) in the same soil for 10 days. The germination rate of 20
seeds was monitored over time and reported as a percentage of the number of sown seeds. This
information indicates whether the mixture can support plant growth, as lettuce is sensitive to
environmental factors such as pH, nutritional imbalances, and the presence of contaminants. Under
these conditions, the test only examines the effects of chemical properties of the medium, not its
physical properties (e.g., humidity, density, gas movement, abrasion).
Briefly, the methods selected were those that we believe are the most appropriate for
agricultural and environmental uses as well as for meeting the requirements of the Quebec government
and international organizations.
22 Table 7. Analysis methods for general properties of biochars
Symb.
Name
Units
Method
Apparatus
Reference
Ash
Ash content
%
Loss to ignition
Oven
Ctot
Total carbon content
%
LECO Truspect
Cinorg
Inorganic carbon content
%
Total dry
combustion,
elementary analysis
Quick determination
of carbonate in soil
Corg
Organic carbon content
%
Corg=Ctot-Cinorg
---
Cgraph
Graphitic carbon content
%
Combustion
IR spectroscopy
H
H content
%
LECO Truspect
O
Oxygen content
%
H/Corg
Molar ratio of H/Corg
---
Total dry
combustion,
elementary analysis
Total dry
combustion,
elementary analysis
H/Corg=H/Corg
Adapted from l’ASTMD1762-84 and from CAEAQ
MA.1010-PAF 1.0
Adapted from Meng et al.
(2014) and Brewer (2012),
LECO (2009)
ASTM D4373-14 and
CEAEQ (2009, 2013) and
ISO 9686 (2006)
ASTM D4373-14 and
CEAEQ (2009, 2013) and
ISO 9686 (2006)
ASTM D4373-14 and
CEAEQ (2009, 2013) and
ISO 9686 (2006)
(2014) and Brewer (2012)
O/C
Molar ratio of O/C
---
N
Nitrogen content
%
S
Sulfur content
%
Several analysis
methods
LECO Truspect
(2014) and Brewer (2012)
---
---
---
---
---
Total dry
combustion,
elementary analysis
Total dry
combustion,
elementary analysis
LECO Truspect
(2014) and Brewer (2012)
LECO Truspect
(2014) and Brewer (2012)
% = percent on a mass basis (g g-1 x 100).
23 Table 8. Analysis methods for physical properties of biochars
Symb.
Name
Units
BD
Bulk density
g cm-3
SD
Solid density
g cm-3
3
-3
Method
Apparatus
Density and porosity
Tapped density after
Cylinder
3 drops of 0.15 m
Gas pycnometer
AccuPyc 1330
Micromeritics
TP=1-BD/SD
---
TP
Total porosity
m m
SSext
External specific
surface area
m2 g-1
EC
Electrical
conductivity
dS m-1
WC
Gravimetric water
content
%
CRx
Regression
parameters of the
water sorption rate
by capillary rise at
a tension of x
Total water
sorption over 72
hrs under different
tensions
g g-1 h-1
MWD
Mean weighted
diameter
um
Dx
Diameter of the
x% of finer
particles
um
UI
Uniformity index
---
D95/D10
---
AR
Abrasion
resistance
um
Abrasion with
rotating steel balls
RX-29 Ro-Tap
(W.S. Tyler,
Mentor, Ohio,
USA)
---
CR72
DDx
%
BET multi-points
Surface area
analyzer
Hydraulic properties
In water
Radiometer,
Copenhagen
Reference
Adapted from ISO 5311
(1992)
ASTM B923-10
Flint and Flint (2002)
ASTM D6556-10
Rajkovich et al. (2011),
TMECC 4.11 (2001), IBI
(2012)
Adapted from ASTM D176284
Dried in oven at
105ºC (24h) or 70ºC
(72h)
-0.05, -0.25, -0.50, 0.75, -1.00, and -1.40
m tension
Oven
Tension table,
non-linear
regression
Adapted from Allaire and
Parent (2004b)
-0.05, -0.25, -0.50, 0.75, -1.00, and -1.40
m tension
Tension table,
non-linear
regression
Adapted from Allaire and
Parent (2004b)
Particle size and resistance
Particle-size
RX-29 Ro-Tap
distribution with
sieve shaker
standard sieve series
(W.S. Tyler) and
ultrasonic sieve
Particle-size
--distribution
Adapted from Gee and Or
(2002) for sieving, Nimmo
and Perkins (2002) for MWD
Adapted from Gee and Or
(2002), and Nimmo and
Perkins (2002) for sieving,
adapted from ASTM D286210 and from
Allaire and Parent (2003,
2004a), for Dx
CFI (2001)
Paré et al. (2009), adapted
from Kiekens et al. (1999),
Kemper and Roseneau (1986)
Change in Dx after um
DDx=Dxbefore-Dxafter
--abrasion
abrasion
DUI,
Changes after
---, and
DMWD
abrasion
m
% = g g-1 x 100. For CRx, capillary rise curves were calculated using three replicates and the equation y = m ln(x) + b, where
y = water sorption g g-1 h-1, x = tension (-m), and b = asymptote g g-1 h-1.
24 Table 9. Analysis methods for chemical properties of biochars
Symb.
Name
Units
Method
Related to acidity
pH in water
Apparatus
pHH2O
pH in water
---
PTpH4
Buffer capacity at
pH 4
meq HCl
Extraction HCl 1
N
PTpH7
Buffer capacity at
pH 7
meq HCl
Extraction HCl 1
N
Pex
Exchangeable
phosphorus
Nutrients and Elements
cmol (+)
Formic acid 2%
kg-1
Kex, Caex, Mgex,
Naex
Exchangeable
elements
cmol (+)
kg-1
Extraction CaBl2NH4Cl
Extot
Sum of
exchangeable
elements
Content in soluble
phosphorus
cmol (+)
kg-1
Equation
ICP Optima
4300DV PerkinElmer
---
mg L-1
Water extraction
ICP-AES
Soluble elements
mg L-1
Water extraction
ICP Optima
4300DV PerkinElmer
Psol
Ksol, Casol, Mgsol,
Nasol, Mnsol,
Fesol, Alsol, Cusol,
Znsol
pH-meter (VWR
SB20)
Potentiometric
electrode with pHmeter (VWR SB20)
Potentiometric
electrode with pHmeter (VWR SB20)
Spectrophotometer
Reference
Rajkovich et al.
(2011), AGDEX
(1989)
Rajkovich et al.
(2011), AGDEX
(1989)
Rajkovich et al.
(2011), AGDEX
(1989)
Wang et al. (2012),
Rajan et al. (1992),
AOAC (2005)
Amacher et al.
(1990)
---
Enders and
Lehmann (2012),
IBI (2012)
AGDEX 533
(1989)
Related to the environment
P, Cu, Zn, As,
Cd, Co, Cr, Hg,
Mo, Ni, Pb, Se
Total content in
elements
PAH content:
Acenaphtene, acenaphtylene,
anthracène, benzo(a)anthacene,
benzo(a)pyrene, benzo(b)pyrene,
benzo(b+j+k)fluoranthene,
benzo(c)phenanthrene,
benzo(g,h,i)perylene, chrysene,
dibenzo(a,h)anthracene,
dibenzo(a,i)pyrene,
dibenzo(a,h)pyrene,
dibenzo(a,l)pyrene, diméthyl7,12benzo(a) anthacene, fluoranthene,
fluorene, indenol(1,2,3-cd)pyrene,
methyl-3 cholanthrene, naphtalene,
phenanthrene, pyrene, methyl1naphtalene, methyl-2 napthalene,
dimethyl-1,3 naphtalene, trimethyl2,3,5 naphtalene
% = percent g g-1 x 100.
mg kg-1
Modified ash
methods
ICP-AES
mg kg-1
Extraction with
dichloromethane
GC/MS-SIM
Enders and
Lehmann (2012),
IBI (2012)
CAEAQ MA.400HAP.1.1., ISO
17025 and G34
25 Table 10. Analysis methods for biological properties of biochars
Symb.
Name
Units
Method
Apparatus
Reference
Wormsx
Percent of earthworms
(Eisenia fetida sp.) that
chose the mixture with x%
of biochar
%
Trays with garden soil on
one side and garden
soil+biochar at x% on
the other side at 20°C
Small containers
IBI (2012), ISO
17512-1 (2008),
Major (2009)
Lettuceyj-x
Germination rate of lettuce
(Lactuca sativa var.
Buttercrunch) after 10 days
in a mixture of garden soil
and x% of biochar
%
Petri dishes in
environment-controlled
chamber at 22°C:16 hrs
daytime /15°C: 8 hrs
nighttime
Environmentcontrolled
chamber
IBI (2012),
OECD (1984),
ISO 17126
(2005), Van
Zwieten et al.
(2010)
26 Table 11. Comparison between analyses in this report and those of IBI (2012) and EBC (2012)
Parameter
Ash
C
H/Corg
O/C
BD
SD, TP
SS
EC
WCg
CRx
Particle-size distribution
AR
pHH2O
PT
Exchangeable elements
Soluble elements
Heavy metals and
metalloids
PAH
BCP
PCDD/PCDF
Allaire et al.
IBI
General properties
Given
Required
Ctot, Corg, Cinorg and
Ctot required
Cgraph
Given
Required
Given
Required
Physical properties
Given
Required
Given
Not required
Given
Required
Given
Required
Given
Required
Given
Optional
Several parameters
Not required
Given
Not required
Chemical properties
pHH2O
Required,
pHCaCl2
Given
Not required
Given
Not required
Given
Given
Not required
Required
EBC
Required
Corg required
Required
Not required
Not required
Not required
Optional
Required
Required
Not required
Required
Not required
Required,
pHH2O
Not required
CEC
suggested
Not required
Required
Given
Required
Required
Not measured
Required
Required
Not measured
Required
Required
Biological properties
Earthworms
Given
Not required
Suggested
Lettuce
Given
Not required
Required
IBI: International Biochar Initiative. EBC: European Biochar Certificate. PCDD: Dioxin
and furans. N.B. Most of the analyses required by the IBI and EBC do not use the same
methods. Properties measured by our team that are not listed in this table were neither
required nor suggested by either IBI or EBC.
27 4. Results and discussion
4.1. General properties
In the energy industry, ashes are useless and undesirable. A biochar containing more ash is
generally less energy-efficient. However, for plant growth, ash can be considered a desirable mineral
amendment as long as its heavy metal content does not exceed environmental standards. Agricultural
applications of ashes are sometimes made. For the purposes of soil carbon sequestration or organic
amendment, however, biochars should contain less ash and as much carbon as possible.
The percentage of ash in the biochars examined here varied between 1 and 54% of dry weight
(Table 12). The biochars containing the least ash were two of the biochars manufactured with softwood
(Airex-Res-427 and 454) and Coco-1000, which contains activated carbon, whereas the biochar that
contained the most ash was made by Wood Ash Industries (Wood-Ash-1500). The latter result was no
surprise, as this company uses a cogeneration plant that burns a wide range of materials, often
containing contaminants such as sand, at high temperature. These ashes are sold as such. The biochars
made with phragmites, cabbage, and pig slurry contained more than 18% ash. The biochars with the
greatest ash content were not the same of those that showed the greatest variation in content. The
biochars showing the greatest variability were BQ-Maple-500-3 and those manufactured by Airex with
softwood sawdust. BQ-Maple-500-3 is made from anything that falls from timbers during and after
pyrolysis into charcoal, including coal particles, bark, and sand.
Most of the biochars met the standards of the EBC, e.g., they contained more than 50% Ctot, the
exceptions being one that was 30% C, manufactured using a cogeneration power plant (Table 12) and
those manufactured with the Airex technology (Airex-Res-427 and 454) and recycled wood (AirexRW-315 and 426). Only the activated-carbon biochar made with coconut (Coco-1000) contained more
than 90% C, although BQ-Maple-500-1 contained about 80% C. The coefficients of variation (CV) of
Ctot were very low. Relative to Ctot, Cgraph content was generally higher with hardwood, followed by
non-coniferous softwood and coniferous softwood (Figure 1). The activated biochars (Nuchar-1000 and
Coco-1000) contained the highest levels of Cgraph since the proportion of graphitic carbon generally
increases with pyrolysis temperature. BQ-Maple-500-1 also contained more than 70% Cgraph (Table
12). Cinorg was present in much smaller proportions than Cgraph, but because it corresponds mainly to
CaCO3. It could be useful for liming when present. Biochars made from recycled wood contained up to
9% Cinorg (Airex-RW-315), while those made from phragmites contained very little. Corg ranged
between 1.5% for the BP-Willow-450-2014 and 45% for the BP-Birch-400. Relative to Ctot, the
variation between biochars was lower among those made of hardwood. BP-Willow-450-2014 stood out
with the highest H/Corg ratio because of its low Corg content. Maple wood biochars tended to provide
relatively high values of H/Corg, as did biochars made at 500ºC. Biochars made of maple wood tended
to give lower O/Ctot (Table 12), while non-woody materials tended to give somewhat higher values.
However, the highest values were obtained with Airex-RW-315 and Airex-RW-426, followed by
Wood-Ash-1500. These trends will be evaluated statistically in a future publication.
4.2. Physical properties
The bulk density (BD) of the biochars was very low (Max. 0.42 g cm-3), close to the values for
peat and soil organic matter (Table 13). Those made from eucalyptus wood (B-Eu-300) and phragmites
(BP-Phragmite-500) showed the highest BD values, while the biochars produced in the experimental
laboratory (I-...) tended to give the lowest values. Low BD values are excellent for use in potting soils
28 or to loosen soils, but they increase transportation and bagging costs. Particle-size distribution
influenced these BD values. SD density was similar between biochar except for Coco-1000 and Woodash that were higher. Only two biochars stood out, Wood-Ash-1500, since it contains a lot of ash, and
Coco-1000. Based on BD and SD, TP values also tended toward somewhat higher values than those of
peat. None of the values suggest potential problems for application to soil for vegetable, horticultural,
or nursery production or for water filtration. Those produced in the laboratory tended to have greater
porosity because of their very coarse grain size. Electrical conductivity (EC) varied little between the
biochars, except for those manufactured in the laboratory using vegetable residues (I-Potato-300-24, ICabbage-300-48, I-Leek-300-48). Biochars manufactured by Pyrovac and Airex with softwood
sawdust tended to have lower EC. Species and pyrolysis temperature appeared to influence the EC
value. No biochars had a salinity level that could cause problems to plants when mixed with soil, unless
used for greenhouse crops, where salinity can rapidly increase because of fertilization.
Hydraulic properties varied greatly between biochars (Table 14). These properties are much
influenced by particle size, internal and external porosity, and surface tension, which can make the
biochar either hydrophilic or hydrophobic under different conditions. Initial water content depends
mainly on the method of pyrolysis and method of storage. Therefore, these values are of little use for
soil applications, being relevant primarily to handling and energy efficiency. Wood-Ash-1500
contained the highest water content, partly because it contained more ash (highly sorbent), but also
because it had been exposed to air. Capillary rise leads some biochars to quickly sorb liquid water
available around them (Fig. 2). For example, Nuchar-1000 and Wood-Ash-1500 sorbed water as soon
as they came into contact with a wet, porous medium, whereas Pyr-Res-475 and I-Cabbage-300-48
were capable of sorbing a lot of water, but did so especially when the porous medium was soak but
required more time; they sorbed much less when the soil was only moist. Other biochars, such as BQMaple-500-1 and Airex-Res-427, remained relatively dry even in very wet conditions. After 72 hrs,
Wood-Ash-1500 sorbed up to 150 and 420% of its weight in water under soil tensions of -1.4 m (wet)
and -0.05 m (soggy), respectively. Nuchar-1000 also sorbed a lot of water (275% at -0.05 m), as did
BP-Willow-450-2014 (137%); comparativelyAirex-Res-427 sorbed only 12%.
Since it takes greater force to extract water from a drier environment, sorption rates under
higher tension are not as high as those under lower tension (-1.4 m vs. -0.05 m). The biochars also vary
in their relative sorption abilities at different tensions. For example, BP-Willow-450-2014, which was
among those that sorbed the most in wet conditions, was among the least sorbent in humid conditions
(a little drier). Its behaviour resembled that of peat. As a result, not all biochars are able to sorb as
much as water as the literature tends to say. Some are hydrophobic, much like peat, under drier
conditions.
The sorption of water vapour from the air differs from that of liquid water from the ground.
Particle size is important for sorbing liquid water, but it is much less so for water vapour, where surface
properties and salt are more important. Nuchar-1000 sorbed more than 100% of its weight from water
vapour over 72 hrs, while I-potato-300-24 sorbed about 15% and the two biochars made by Pyrovac
about 12 and 13%. This property will need to be considered for storage and bagging requirements. We
must also be careful when applying them to the field under humid conditions to make sure that they do
not clog the machinery.
Nuchar-1000 contained the largest proportion of fine particles, followed by the biochars
manufactured by Biopterre using Abri-Tech technology (Table 15). Biochars with very fine particles
tend to produce a lot of dust, which is potentially harmful to workers and can also be very messy. Fine
biochars cannot be mixed directly with compound fertilizers unless they are part of fertilizer granules,
29 Fines reduce the speed of drainage or clog drains. By contrast, the biochars made from vegetable
residues (potato, cabbage, leek) and BQ-Maple-500-1 were too coarse to be mixed with fertilizers or
incorporated into the soil. Other biochars were a good size for use in potting soil. The uniformity of the
particle sizes varied greatly from one biochar to another (Fig. 3), depending on both the raw material
and sieving before or after pyrolysis. The particle-size distribution curve shown in Figure 3 is spread,
with great heterogeneity in particle size in some biochars (e.g., Award-Maple- 700 and Leaf-Maple350). BQ-Maple-500-1, on the other hand, had a highly uniform particle size. Depending on intended
use, a uniform particle size may be desirable, while in other cases heterogeneous granulometry may be
required. It is generally desirable that the particle size remains the same during transport, handling, and
time of use. The biochars with the finest particles and those pre-sieved were generally more resistant to
break down (DMWD, Table 15), but this was not always true. Also, large particles tend to break more
often (e.g., Leaf-Maple-350 and BQ-Maple 500-1), but this was not true for the biochars made from
vegetable residues, which had very large and quit resistant particles.
30 Table 12. General properties of biochars
Biochar
Ash
%
Ctot
CV
%
CV
Cgraph Cinorg
%
%
Corg
%
H
O
%
CV
%
CV
H/Corg O/CTot
-----
Hardwood
Leaf-Maple-350
BQ-Maple-500-1
BQ-Maple-500-2
BQ-Maple-500-3
Award-Maple-700
B-Eu-300
Nuchar-1000
11.9
5.10
12.5
12.2
14.2
10.0
5.40
8.4
19.3
2.5
38.5
2.7
3.1
3.1
68.0
79.5
68.2
69.4
65.4
56.2
77.4
1.6
57.8
1.71
8.5
0.4
71.7
1.17
6.7
0.9
53.5
2.50 12.2
0.5
48.4
0.74 20.2
1.5
51.7
2.00 11.7
0.4
24.9
3.46 27.8
0.7
66.8
0.49 10.2
Coniferous softwood
2.35
2.57
2.41
2.68
1.89
3.26
0.97
3.5
0.4
3.2
1.8
5.6
2.6
1.3
9.6
10.0
13.1
10.0
10.2
27.4
11.0
2.6
4.1
3.5
3.7
0.4
1.2
0.8
0.28
0.39
0.20
0.13
0.16
0.12
0.10
0.14
0.13
0.19
0.14
0.16
0.49
0.14
BP-Res-400
BP-Res-500
Airex-Res-427
Airex-Res-454
Pyr-Res-475
Pyr-Res-475-aged
Airex-RW-315
Airex-RW-426
I-RW-300-24
I-RW-300-48
I-RW-300-48-2nd
13.8
10.7
1.38
1.56
8.13
9.91
NA
NA
2.2
9.0
19.0
23.3
8.5
18.6
NA
NA
19.2
10.7
NA
NA
25.7
8.6
66.3
72.0
69.8
74.9
61.4
60.2
43.5
45.2
60.5
52.4
54.7
3.63
2.70
3.41
2.98
2.82
2.45
4.99
3.35
3.18
1.86
2.69
2.1
2.1
1.9
0.8
1.8
5.3
2.7
0.6
1.1
0.2
0.9
16.2
11.0
17.4
10.8
20.8
21.0
33.1
23.3
22.1
20.5
22.3
12.9
1.5
5.1
3.7
0.5
2.1
1.6
2.9
0.5
0.3
11.8
0.16
0.25
0.09
0.21
0.15
0.13
0.21
0.13
0.09
0.13
0.09
0.24
0.15
0.25
0.14
0.34
0.35
0.76
0.52
0.37
0.39
0.41
BP-Willow-400
BP-Willow-450-2013
BP-Willow-4502014
BP-Willow-500
BP-Willow-550
BP-Birch-400
BP-Birch-500
Coco-1000
11.1
9.80
1.1
1.1
67.4
NA
0.3
42.2
1.73 22.3
0.4 60.0
1.09 10.9
0.2
29.8
2.08 37.9
0.2
60.3
NA
14.5
0.4
42.1
1.07 18.3
1.4
40.2
1.14 18.9
2.8
10.7
9.17 23.7
0.5
16.0
3.47 25.7
0.7
25.5
1.35 33.6
0.2
36.9
1.49 14.0
0.9
22.8
2.64 29.2
1.4
23.7
5.31 38.4
1.6
NA
NA
NA
3.58
2.77
2.2
1.2
16.2
16.0
1.5
1.0
0.09
NA
0.24
NA
11.6
0.2
70.2
1.4
1.5
2.51
9.5
14.5
2.4
1.72
0.21
12.2
9.56
7.26
10.5
1.11
4.57
9.14
0.89
3.05
9.84
71.5
NA
71.8
69.6
91.5
0.2
61.6
0.96
8.9
1.3
NA
NA
NA
1.5
24.6
2.54 44.7
0.5
59.9
0.42
9.2
0.2
84.8
0.85
5.8
Non-woody material
2.62
2.41
4.03
2.62
0.10
1.1
1.5
3.3
1.2
0.0
13.7
10.5
17.0
11.9
3.2
0.9
1.1
0.5
1.1
0.4
0.29
NA
0.09
0.28
0.02
0.19
NA
0.24
0.17
0.04
BP-Phragmite-400
BP-Phragmite-500
I-Potato-300-24
26.3
28.6
9.88
20.0
18.1
5.28
2.19
3.55
4.69
2.49
1.66
1.22
57.0
56.3
62.8
55.4
54.7
68.8
0.4
1.7
1.8
0.2
0.1
0.7
3.04
2.45
4.28
4.16
4.30
3.83
2.3
5.3
3.4
2.1
0.2
2.1
14.1
14.7
20.6
20.8
18.8
14.7
0.5
12.4
1.8
1.2
1.4
0.2
0.09
0.19
0.12
0.14
0.10
0.13
0.25
0.26
0.33
0.38
0.34
0.21
Wood-Ash-1500
54.9 5.26 30.0
3.0
25.0
1.79
3.2
0.21 45.3 15.2 15.2 0.06
IRDA-Manure-500
21.7 8.49 52.4
0.4
23.5
3.88 25.1 3.06
0.1
19.3
1.1
0.12
CV = coefficient of variation (%). The properties that are not associated with CV have not been repeated. NA: Not
Available
0.51
0.37
I-Cabbage-300-48
I-Leek-300-48
B-Corn-300
67.5
1.28
21.2
0.89
43.2
0.48
24.8
1.32
21.8
3.21
10.1
3.21
37.7
1.32
Others
35.0
12.6
36.8
30.4
41.5
29.7
31 d-
0#
50
-1
50
0#
e-
ur
As
h
an
-M
DA
IR
W
oo
8#
-4
048
B#
Co
rn
-3
00
#
30
k-
ee
I-L
#
Hardwood&
00
0%#
24
0%#
-3
20%#
0-
20%#
ge
40%#
ba
40%#
ab
60%#
#
60%#
00
80%#
30
80%#
I-C
100%#
-5
100%#
o-
40%#
at
40%#
ite
60%#
ot
BP
00
#
-R
es
50
re
0#
xRe
s-4
Ai
re
27
x#
Re
s
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4#
rPy
r-R Res
47
es
5#
-4
75
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ag
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ed
xRW #
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re
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xRW #
-4
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26
W
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00
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00
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-3
-4
00
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-4
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d#
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#
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-4
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-R
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-4
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ag
BP
#
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-3
00
#
Nu
ch
ar
-1
00
0#
100%#
hr
-P
ite
m
ag
Non7coniferous&so5wood&
hr
#
#
#
Content&rela*ve&to&total&carbon&
0%#
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Cinorg#
-P
-3
-2
00
00
00
e7
e5
e5
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00
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e5
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l
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l
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ar
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ap
l
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ap
l
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af
-M
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BP
-W
illo
w
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-4
00
-W
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w
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-W
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-5
00
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-B
irc
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-B
irc
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0#
Content&rela*ve&to&total&carbon&
100%#
Coniferous&so5wood&
20%#
0%#
Cgraph#
Non7woody&materials&
Figure 1. Relative content of C types in biochars (green: Corg, red: Cinorg, blue: Cgraph)
32 Table 13. General physical properties of biochars
Biochar
BD
g cm-3
CV
SD
g cm-3
CV
TP
EC
m3 m-3
CV
dS m-1
CV
Hardwood
Leaf-Maple-350
BQ-Maple-500-1
BQ-Maple-500-2
BQ-Maple-500-3
Award-Maple-700
B-Eu-300
Nuchar-1000
0.39
0.26
0.33
0.29
0.35
0.46
0.28
2.36
1.60
2.27
2.80
3.44
1.26
0.29
1.68
0.54
0.77
1.53
1.06
0.83
1.66
0.33
0.80
1.54
0.31
0.81
1.77
1.57
0.80
1.63
0.77
0.72
1.78
0.44
0.85
Coniferous softwood
0.73
0.39
0.65
0.61
0.49
0.19
0.05
0.33
0.44
1.43
0.38
0.48
0.68
0.65
27.7
20.9
38.7
0.85
34.2
0.97
54.2
BP-Res-400
BP-Res-500
Airex-Res-427
Airex-Res-454
Pyr-Res-475
Pyr-Res-475-aged
Airex-RW-315
Airex-RW-426
I-RW-300-24
I-RW-300-48
I-RW-300-48-2nd
0.39
0.42
0.21
0.19
0.30
0.31
0.28
0.26
0.18
0.18
0.18
0.44
1.45
0.41
0.73
1.22
1.52
0.32
0.72
1.51
1.48
0.75
0.86
2.44
1.48
0.44
0.87
2.14
1.55
0.28
0.80
3.23
1.54
0.60
0.80
1.12
1.48
0.59
0.81
10.7
1.52
1.83
0.83
1.93
1.66
2.58
0.89
3.03
1.63
2.87
0.89
3.24
1.62
1.19
0.89
0.31
0.40
0.29
0.39
0.47
0.77
0.40
1.89
0.34
0.74
0.54
0.40
0.62
0.10
0.11
0.13
0.15
0.72
0.88
1.41
1.57
0.74
1.64
1.06
13.2
3.01
23.3
0.01
2.28
3.72
2.21
4.64
12.7
BP-Willow-400
BP-Willow-450-2013
BP-Willow-450-2014
BP-Willow-500
BP-Willow-550
BP-Birch-400
BP-Birch-500
Coco-1000
0.34
0.31
0.36
0.32
0.31
0.39
0.40
0.32
1.97
2.28
3.37
0.75
6.07
0.96
1.29
1.71
0.55
0.64
1.11
0.64
1.41
0.27
0.71
0.27
0.37
1.20
0.73
0.50
2.09
0.28
0.44
0.34
33.6
32.5
36.4
0.66
12.1
5.40
1.30
9.61
BP-Phragmite-400
BP-Phragmite-500
I-Potato-300-24
0.39
0.42
0.13
0.18
0.17
0.33
0.91
1.08
12.1
3.26
0.77
1.91
1.54
1.59
1.25
1.39
1.38
1.62
0.20
0.31
0.46
0.32
1.07
1.15
Others
0.75
0.74
0.90
0.87
0.88
0.79
0.33
0.49
1.43
0.49
0.28
0.21
0.32
0.33
3.61
4.81
3.10
0.25
1.01
1.99
32.6
12.6
40.6
2.27
0.31
0.33
CV = coefficient of variation (%).
6.46
1.51
2.74
1.59
28.42
0.73
0.88
0.79
3.32
0.47
0.86
1.53
35.5
29.0
I-Cabbage-300-48
I-Leek-300-48
B-Corn-300
Wood-Ash-1500
IRDA-Manure-500
1.46
0.29
0.77
1.57
0.88
0.80
1.51
0.21
0.76
1.51
1.71
0.79
1.61
1.40
0.81
1.41
0.28
0.72
1.53
0.69
0.74
2.11
0.15
0.85
Non-woody materials
33 Table 14. Physical properties related to water
Biochar
WC
%
CV
Leaf-Maple-350
BQ-Maple-500-1
BQ-Maple-500-2
BQ-Maple-500-3
Award-Maple-700
B-Eu-300
Nuchar-1000
2.42
2.04
1.04
4.19
2.42
5.19
6.44
0.46
0.60
0.33
3.2
0.25
10.3
2.24
BP-Res-400
BP-Res-500
Airex-Res-427
Airex-Res-454
Pyr-Res-475
Pyr-Res-475-aged
Airex-RW-315
Airex-RW-426
I-RW-300-24
I-RW-300-48
I-RW-300-48-2nd
0.0
0.16
5.64
3.41
5.98
7.86
0.76
0.77
3.19
5.94
2.23
NA
200
0.06
5.5
2.0
21
18
100
5.4
32
20
BP-Willow-400
BP-Willow-4502013
BP-Willow-4502014
BP-Willow-500
BP-Willow-550
BP-Birch-400
BP-Birch-500
Coco-1000
1.17
0.73
9.4
NA
0.56
8.51
Capillary rise
Regression curve
CR
m
b
R2
CR-1.4 m
g g-1 h-1 g g-1 h-1
--%
CV
Hardwood
-0.0006 0.005
0.92
15.5
8.3
-0.0004 0.004
0.90
13.8
18.0
-0.0056 0.029
0.86
23.3
32.3
NA
NA
NA
NA
NA
-0.0005 0.005
0.94
14.9
15.9
NA
NA
NA
NA
NA
-0.0072 0.055
0.61
86.3
8.3
Coniferous softwood
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
-0.0004 0.003
0.97
7.7
0.4
NA
NA
NA
NA
NA
-0.0098 0.047
0.94
6.8
51.5
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
-0.0012 0.007
0.97
10.0
9.4
-0.0061 0.029
0.89
5.7
9.4
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
-0.0059
0.033
0.78
20.0
55.8
RH
RH80
CR-0.05 m
%
CV
%
CV
23.5
21.3
43.8
NA
23.0
NA
275
18.3
12.1
17.0
NA
16.2
NA
0.6
5.90
5.98
6.14
5.24
5.93
6.14
102.8
1.9
6.2
0.4
1.9
3.3
6.4
1.7
NA
NA
12.3
NA
121
NA
NA
NA
21.1
14.5
NA
NA
NA
10.4
NA
32.4
NA
NA
NA
11.6
10.0
NA
5.67
6.04
6.11
6.79
12.44
13.17
9.90
5.94
8.42
8.65
7.04
1.8
3.4
5.4
2.1
1.2
0.5
6.4
1.5
6.1
1.8
11.4
NA
NA
6.72
1.6
40
4.3
NA
NA
0.048
0.88
6.5
66.1
137
20.4
5.62
7.7
NA
NA
NA
NA
NA
NA
7.62
8.0
0.032
0.88
15.9
41.6
124
7.0
NA
NA
NA
NA
NA
NA
NA
NA
5.29
0.5
NA
NA
NA
NA
NA
NA
6.58
2.4
0.031
0.62
43.5
58.9
149
1.2
NA
NA
Non-woody material
BP-Phragmite-400
0.0
100
NA
NA
NA
NA
NA
NA
NA
5.71
1.6
BP-Phragmite-500
0.0
100
NA
NA
NA
NA
NA
NA
NA
6.20
2.6
I-Potato-300-24
1.00
8.40 -0.0028 0.018
0.97
24.4
5.8
64.2
3.8
14.58
11.3
I-Cabbage-300-48
0.80
16.4 -0.0069 0.039
0.98
39.8
9.4
106
10.0
11.12
2.2
I-Leek-300-48
1.36
9.16 -0.0013 0.020
0.95
28.7
14.8
64.7
30.1
12.75
4.0
B-Corn-300
5.07
3.3
NA
NA
NA
NA
NA
NA
NA
6.17
0.7
Others
Wood-Ash-1500
16.8
6.64 -0.0224 0.127
0.92
150.7
130.4
420
93.8
5.89
6.7
IRDA-Manure-500
2.48
1.1
-0.0011 0.009
0.88
19.4
16.8
41.8
16.7
9.25
12.1
CV = coefficient of variation (%). The capillary rise curves were completed with replicates using the equation y = m ln(x)+b,
where y = sorption of water g g-1 h-1, x = tension (-m), and b = asymptote g g-1 h-1. Therefore, there is no CV for m and b.
Capillary rise (CR-1.4 or CR-0.05) indicates the mass of water sorbed per biochar mass during 72 hrs under different tensions
(-1.4 m = humid, -0.05 m = wet). Sorption of relative humidity (RH80) is the mass of water sorbed in vapour form per biochar
mass during 72 hrs under a RH of 80% at 22°C. NA: Not Available
0.4
0.70
0.01
0.22
2.95
82
NA
150
173
1.70
-0.0098
NA
-0.0059
NA
NA
-0.0039
34 Sorp%on'rate'(g''g-1'h-1)'
0.04#
0.04#
Leaf(Maple(350#
0.03#
Airex(Res(427#
0.03#
BQ(Maple(500(1#
Pyr(Res(475#
BQ(Maple(500(2#
I(RW(300(24#
Award(Maple(700#
0.02#
I(RW(300(48#
0.02#
Nuchar(1000#
0.01#
0.01#
0.00#
(1.50#
0.04#
Sorp%on'rate'(g''g-1'h-1)'
Coniferous'so9wood'
Hardwood'
(1.25#
(1.00#
(0.75#
(0.50#
(0.25#
0.00#
0.04#
Non-coniferous'so9wood'
0.03#
0.00#
(1.50#
BP(Willow(450(2013#
(0.75#
(0.50#
(0.25#
0.00#
(0.25#
0.00#
I(Potato(300(24#
I(Cabbage(300(48#
BP(Willow(550#
0.02#
(1.00#
Non-woody'materials'
0.03#
BP(Willow(450(2014#
(1.25#
I(Leek(300(48#
Coco(1000#
0.02#
Wood(Ash(1500#
IRDA(Manure(500#
0.01#
0.00#
(1.50#
0.01#
(1.25#
(1.00#
(0.75#
Tension'(m)'
(0.50#
(0.25#
0.00#
0.00#
(1.50#
(1.25#
(1.00#
(0.75#
(0.50#
Tension'(m)'
Figure 2. Capillary rise of different biochars under tensions of -0.05 m (very wet) to -1.4 m
(humid)
35 Table 15. Physical properties related to particle-size distribution and abrasion resistance of
biochars
Biochar
Before
UI (D60/D10)
MWD
µm
CV
--
CV
UI (D95/D10)
--
CV
After abrasion
DMWD
DUI
(D60/D10)
µm
CV
--
Hardwood
Leaf-Maple-350
BQ-Maple-500-1
BQ-Maple-500-2
BQ-Maple-500-3
Award-Maple-700
B-Eu-300
Nuchar-1000
1397
6107
287
2191
1242
138
171
9
0.6
5
3
12
5
14
BP-Res-400
BP-Res-500
Airex-Res-427
Airex-Res-454
Pyr-Res-475
Pyr-Res-475-aged
Airex-RW-315
Airex-RW-426
I-RW-300-24
I-RW-300-48
I-RW-300-48-2nd
189
204
961
884
1302
1543
901
1210
1837
1814
1592
2
3
7
5
5
4
2
4
7
4
2
BP-Willow-400
BP-Willow-450-2013
BP-Willow-450-2014
BP-Willow-500
BP-Willow-550
BP-Birch-400
BP-Birch-500
Coco-1000
194
192
202
194
202
226
236
197
2
0.5
3
1
2
7
3
0.2
BP-Phragmite-400
BP-Phragmite-500
I-Potato-300-24
I-Cabbage-300-48
I-Leek-300-48
B-Corn-300
198
203
6017
2102
2594
253
5
3
2
4
16
1
6.34
10
19.22
1.60
0.5
2.33
2.20
14
2.95
2.06
0.7
3.37
6.42
10
21.93
8.30
71
22.93
1.89
9
2.86
Coniferous softwood
2.74
3
5.39
2.20
14
3.18
3.91
5
19.66
4.09
3
10.42
5.45
2
21.27
6.93
5
22.47
4.82
1
10.66
14.91
2
47.44
4.98
8
11.13
5.47
70
12.13
4.88
6
11.75
2.23
8
3.03
1.71
0.8
2.20
1.75
8
2.53
2.06
3
2.74
1.72
0.7
2.22
2.69
5
6.10
1.78
0.8
3.67
1.65
0.2
2.11
Non-woody materials
2.27
10
3.12
1.80
9
2.34
49.42
6
58.95
3.63
0.7
9.26
3.62
7
9.38
2.47
8
6.70
18
0.1
15
4
9
60
27
-280
-655
-14.8
NA
-93.7
NA
-3.50
46
24
180
NA
190
NA
645
25.7
7.46
2.32
NA
23.6
NA
3.47
4
16
6
8
3
3
0.9
8
13
7
8
NA
NA
-62.0
NA
-96.8
NA
NA
NA
-71.7
-150
NA
NA
NA
332
NA
144
NA
NA
NA
6
18
NA
NA
NA
19.2
NA
24.8
NA
NA
NA
13.2
17.2
NA
9
1
9
4
0.9
10
2.
0.3
NA
NA
NA
NA
-3.83
NA
NA
NA
NA
16
112
NA
126
NA
NA
398
NA
2.10
2.31
NA
2.10
NA
NA
2.10
13
10
6
2
12
8
NA
NA
-1062
-402
-853
NA
NA
NA
5
12
36
NA
NA
NA
109.6
15.5
21.8
NA
31
36
-60.7
-123
23
24
68.3
24.3
Others
Wood-Ash-1500
1214
IRDA-Manure-500
1014
0.4
30
12.33
3.64
30
10
88.39
18.94
36 100"
100"
Par$cles)ﬁner)than)(%))
Hardwood)
Coniferous)so9wood)
Leaf,Maple,350"
80"
80"
BQ,Maple,500,1"
BP,Res,400"
BP,Res,500"
Airex,Res,427"
Airex,Res,454"
Pyr,Res,475"
Pyr,Res,475,aged"
Airex,RW,315"
Airex,RW,426"
I,RW,300,24"
I,RW,300,48"
I,RW,300,48,2nd"
BQ,Maple,500,2"
60"
60"
BQ,Maple,500,3"
Award,Maple,700"
B,Eu,300"
40"
40"
Nuchar,1000"
20"
20"
0"
0"
1"
10"
100"
1000"
1"
10000"
100"
1000"
10000"
100"
1000"
10000"
100"
100"
Non;coniferous)so9wood)
Par$cles)ﬁner)than)(%))
10"
80"
Non;woody)materials)
80"
BP,Willow,400"
BP,Willow,450,2013"
BP,Willow,450,2014"
BP,Willow,500"
BP,Willow,550"
BP,Birch,400"
BP,Birch,500"
Coco,1000"
60"
40"
BP,Phragmite,400"
BP,Phragmite,500"
60"
I,Potato,300,24"
I,Cabbage,300,48"
I,Leek,300,48"
40"
B,Corn,300"
20"
20"
0"
0"
1"
10"
100"
Particle size (µm)
1000"
10000"
1"
10"
Par$le)size)(µm))
Figure 3. Cumulative particle-size distribution of biochars
37 4.3. Chemical properties
The pH values of the biochars ranged from 4.8 for Nuchar-1000 to 10.4 for Wood-Ash-1500,
i.e., from relatively acid to very strongly basic (Table 16). However, neither of these biochars was
typical, the first being activated and the second containing much ash. The latter one is used as a liming
agent. The hardwood biochars tended to be rather basic, with pH values between 7.5 and 8.5, while
those made of softwood tended to be a bit more neutral or even slightly acid. The biochars made of
non-coniferous wood and other soft materials also tended to be basic, with pH values above 7.5,
especially those made of vegetable residues, which had pH values above 9.
The biochars with the highest buffer capacity (PTpH4) were Wood-Ash-1500, BQ-Maple-500-2,
and BP-Res-500, followed by I-Cabbage-300-48, which had a large CV. Essentially, the same biochars
also had the highest PTpH7 values. Despite the frequent claim that biochars have excellent buffer
capacity, some of the biochars we examined, such as Airex-Res-454, Airex-Res-427, and Nuchar-1000,
did not. In fact, although the pH of most of the biochars was basic, most had little buffer capacity and
would quickly change their pH in contact with more acidic substances such as peat or decaying organic
matter.
As nitrogen (N) is generally volatilized during pyrolysis, most biochars have very low N
concentrations and thus cannot be regarded as nitrogen fertilizer. However, those made from vegetables
(I-Potato-300-24, I-Cabbage-300-48, I-Leek-300-48) were composed 2 to 5.7% of N (Table 17), while
the pig manure biochar (IRDA-Manure-500) contained about 4.5%. The large particle size of the
feedstock and low temperature during pyrolysis of the vegetable residues promote greater nitrogen
retention. By contrast, several of the biochars contained a significant amount of total P. The IRDAManure-500 biochar had the highest P content, which was unsurprising as Quebec hog manure contains
a lot of P. Nuchar-1000 followed closely with 18 682 mg kg-1, while the Coco-1000 and I-RW-300-48
contained very little. Some biochars can therefore be used as a P amendment for plants, while others
may be preferred when redistribution of P in the environment must be avoided. Sulphur content (S) was
low in almost all biochars, but may be high enough to serve as a micronutrient for plants. I-RW-300-48
contained slightly more S, at 5.8%. The N and S contents of the biochars in this study were therefore
insufficient to cause detrimental effects on plants or the environment.
The exchangeable micro- and macro- nutrient contents of the biochars are given in Table 18.
The contents greatly varied from one biochar to another, but in general the biochars contained all or
most nutrients without exceeding most standards, and thus could be considered suitable as soil
amendments in respect to the environment. The biochars made of vegetable residues had the highest
potassium content (K), while biochars made of recycled wood (Airex-RW-315 and Airex-RW-426) had
the lowest levels. The Ca content also greatly varied between biochars, with those made of recycled
wood tending to contain slightly more. There was no obvious trend in Mg content among biochar types.
The biochars made of recycled wood, Wood-Ash-1500, and IRDA-Manure-500 contained
comparatively high levels of sodium (Na), while Nuchar-1000 and I-Cabbage-300-48 stood out for
their very high Na content, which could cause problems when applied in high concentrations, as in
potting soils. However, Na is easily soluble and does not remain in the biochar if large amounts of
water are applied, as in greenhouse and nursery potting soils. The sum of exchangeable elements varied
from 6.43 cmol + kg-1 for Airex-Res-427 to more than 120 cmol + kg-1 for biochars made of vegetable
residues, which offers an interesting range for plant growth and environmental applications.
The total content in heavy metal and other elements (Table 19) varied as much as that of soluble
and exchangeable elements. Mercury (Hg) was not detected in any biochar and thus is not listed in
38 Tables 20 and 21. Only 6 biochars contained arsenic (As). Airex-RW-315 contained the highest
proportion because it was made of recycled wood and thus probably contained As associated with old
paint or wood treatments. Cadmium (Cd) was detected in 10 of 34 biochars, but in small quantities.
Cobalt (Co) was present in the majority of biochars in relatively small amounts. Only BP-Phragmite400 and IRDA-Slurry-500 contained more than 15 mg kg-1. Chromium (Cr) was detected in nearly all
biochars. BP-Willow-450-2013 contained the most, followed by Airex-BR-277. The others contained
little. Cupper (Cu) was detected throughout the samples. The biochar made from pig manure contained
as much as 556 mg kg-1 (pigs receive both Cu and zinc (Zn) in their diet, and more than 99% is
excreted in their feces). Molybdenum (Mo) was found in only 3 biochars, and in small quantities. By
contrast, only 4 biochars did not contain nickel (Ni). The biochar made from phragmites and the BPWillow-450-2013 contained the most. More than half of the biochars had no lead (Pb). Among those
that did contain Pb, all of the biochars made from recycled wood (Airex-RW-315 and -426 and I-RW300-24 and -300-48) contained more than 45 mg kg-1, probably because of old paint and other wood
treatments. Only 8 biochars showed a detectable selenium (Se) content. Airex-RW-426 contained the
highest level, followed by BP-Phragmite-500. Zn was found in all biochars. Those made of willow
tended to contain significantly more than the others, as did the biochar made of pig manure. The
biochars made from non-woody materials or coniferous softwood contained only a little Zn.
Data on PAH contents were available for only six of the biochars at the time this report was
written (Table 22). Among those biochars, only BP-Willow-450 exceeded the level permitted by
regulations and thus cannot be used for applications in the field. Three others, BQ-Maple-500-1,
Wood-Ash-1500, and I-Leek-300-48, would receive the ‘B’ classification according to the MDDELCC
criterion (1998).
The chemical properties of the biochars will be compared and classified with respect to Quebec
regulations and the IBI and EBC criteria in a future paper. The implications for plant growth of the
macro- and micronutrient contents of the biochars will be discussed in another paper.
39 Table 16. Chemical properties of biochars related to acidity
Biochar
pHH2O
PTpH4
---
CV
Meq
HCl
Leaf-Maple-350
BQ-Maple-500-1
BQ-Maple-500-2
BQ-Maple-500-3
Award-Maple-700
B-Eu-300
Nuchar-1000
8.58
7.56
8.89
7.78
8.39
8.08
4.80
Hardwood
0.88
0.59
0.67
0.21
0.58
1.57
0.61
0.26
7.38
0.95
0.66
0.19
0.49
0.06
BP-Res-400
BP-Res-500
Airex-Res-427
Airex-Res-454
Pyr-Res-475
Pyr-Res-475-aged
Airex-RW-315
Airex-RW-426
I-RW-300-24
I-RW-300-48
I-RW-300-48-2nd
8.56
0.06
0.27
9.75
0.10
1.54
5.50
0.45
0.02
7.21
0.43
0.06
5.97
1.81
0.21
6.37
2.07
0.27
6.86
0.07
0.26
7.71
0.12
0.60
6.09
0.67
0.19
5.64
1.06
0.13
6.11
1.23
0.29
8.10
0.17
0.32
NA
NA
NA
9.56
1.13
0.63
8.99
1.20
0.96
NA
NA
NA
7.64
0.31
0.12
8.78
2.15
1.03
8.91
0.06
0.22
PTpH7
CV
Meq
HCl
CV
13.06
4.42
3.01
2.41
8.59
7.64
6.80
0.03
0.01
0.10
0.05
0.05
0.04
ND
0.01
0.01
20.41
4.42
0.01
6.15
NA
0.88
0.76
20.41
8.08
17.82
5.24
1.84
0.00
1.61
31.70
12.56
0.08
0.74
NA
0.01
ND
ND
ND
0.08
ND
ND
ND
3.01
1.59
NA
0.01
NA
NA
NA
0.01
NA
NA
NA
0.00
NA
3.72
1.77
NA
2.02
2.28
7.78
0.07
NA
0.12
0.34
NA
0.01
0.31
0.06
0.01
NA
9.39
5.31
NA
0.01
5.69
4.16
Coniferous softwood
BP-Willow-400
BP-Willow-450-2013
BP-Willow-450-2014
BP-Willow -500
BP-Willow -550
BP-Birch-400
BP-Birch-500
Coco-1000
Non-woody material
BP-Phragmite-400
BP-Phragmite-500
I-Potato-300-24
I-Cabbage-300-48
I-Leek-300-48
B-Corn-300
0.06
0.21
1.14
0.04
0.01
0.42
0.15
4.88
0.03
4.04
0.18
0.78
6.02
0.20
0.01
2.31
1.38
9.09
0.37
4.11
0.05
1.05
0.00
0.24
4.88
0.40
0.64
0.37
0.10
2.28
Others
Wood-Ash-1500
10.42
0.90
2.20
6.43
0.23
36.42
IRDA-Manure-500
9.69
0.51
1.17
17.61
0.11
10.88
CV = coefficient of variation (%). Nd: Not Determined a siniitla pH > 7. Na: Not Available
7.55
7.72
9.29
9.94
9.45
7.69
40 Table 17. Biochar contents in N, P, and S
Biochar
Ntotal
%
Leaf-Maple-350
BQ-Maple-500-1
BQ-Maple-500-2
BQ-Maple-500-3
Award-Maple-700
B-Eu-300
Nuchar-1000
BP-Res-400
BP-Res-500
Airex-Res-427
Airex-Res-454
Pyr-Res-475
Pyr-Res-475-aged
Airex-RW-315
Airex-RW-426
I-RW-300-24
I-RW-300-48
I-RW-300-48-2nd
CV
Ptotal
mg kg-1
CV
Hardwood
0.63
3.50
1043
0.55
0.35
550
0.57
3.16
1453
0.77
1.75
NA
0.58
5.57
806
0.47
2.56
1659
0.33
1.30
18682
Coniferous softwood
1.23
2.14
1110
1.28
2.11
NA
0.31
1.88
221
0.21
0.84
NA
0.48
1.76
755
0.49
5.28
NA
0.47
2.66
NA
0.46
0.60
NA
0.71
1.11
241
0.93
0.22
72
0.89
0.86
NA
Stotal
%
0.7
5.0
3.2
NA
22.3
3.0
6.2
3.35
0.00
3.64
0.00
1.51
0.00
3.58
27.4
NA
45.3
NA
24.3
NA
NA
NA
NA
63.4
36.6
0.00
0.00
3.90
0.00
3.73
0.00
0.00
0.00
3.99
5.83
0.00
8.0
65.8
9.2
NA
11.7
4.0
NA
4.3
0.00
3.14
2.88
NA
3.28
0.00
NA
2.56
7.7
NA
5.1
7.1
0.3
2.0
0.00
NA
3.54
5.72
1.41
0.00
14.5
2.9
2.69
3.91
BP-Willow-400
BP-Willow-450-2013
BP-Willow-450-2014
BP-Willow-500
BP-Willow-550
BP-Birch-400
BP-Birch-500
Coco-1000
BP-Phragmite-400
BP-Phragmite-500
I-Potato-300-24
I-Cabbage-300-48
I-Leek-300-48
B-Corn-300
Wood-Ash-1500
IRDA-Manure-500
1.00
2.17
756
1.08
1.21
1699
0.95
9.45
1033
1.06
1.09
NA
1.16
1.45
1620
0.94
3.30
1415
0.98
1.18
NA
0.27
0.00
169
Non-woody materials
1.19
2.26
1383
1.15
5.28
NA
2.92
3.43
10544
3.73
2.14
9348
5.71
0.24
7029
0.88
2.14
1780
Others
0.32
45.3
4.49
0.07
2676
22796
NA = Not available.
41 Table 18. Biochar contents in exchangeable macro- and micronutrients (related to plants)
Biochar
cmol+
kg-1
K
CV
Ca
cmol+
kg-1
7.30
2.75
18.42
6.27
8.10
7.54
0.40
7.84
19.83
0.66
5.68
4.07
32.77
3.46
9.04
4.63
23.35
11.08
13.90
14.73
1.44
CV
Mg
cmol+
kg-1
CV
Na
cmol+
kg-1
CV
Total
cmol+
kg-1
2.17
0.45
11.14
1.30
2.23
1.02
0.18
7.79
15.33
0.75
4.08
8.32
34.45
0.65
2.10
0.44
2.15
0.16
2.04
0.96
33.52
5.69
10.14
2.31
6.54
2.18
31.26
28.81
20.61
8.27
55.06
18.81
26.27
24.24
35.54
2.45
16.97
15.81
7.89
97.40
2.28
2.31
9.19
5.90
25.25
3.19
0.79
0.71
0.50
0.20
1.62
0.57
2.33
2.93
4.86
5.43
3.43
2.98
18.14
7.68
4.07
7.35
2.15
2.11
10.29
2.80
7.33
2.46
27.46
24.25
6.43
7.85
82.63
62.12
27.96
27.09
34.22
33.96
21.79
2.37
0.52
4.23
29.76
Hardwood
Leaf-Maple-350
BQ-Maple-500-1
BQ-Maple-500-2
BQ-Maple-500-3
Award-Maple-700
B-Eu-300
Nuchar-1000
5.98
50.35
0.69
3.38
9.41
16.16
1.30
Coniferous softwood
9.91
1.97
1.48
8.93
15.08
1.25
1.31
4.04
0.03
3.45
7.48
0.64
63.47
92.27
6.62
47.16
3.81
4.12
21.21
6.04
1.57
19.89
10.76
0.82
25.56
2.47
0.94
23.53
38.05
1.01
15.43
5.79
0.53
17.17
1.93
1.22
BP-Res-400
BP-Res-500
Airex-Res-427
Airex-Res-454
Pyr-Res-475
Pyr-Res-475-aged
Airex-RW-315
Airex-RW-426
I-RW-300-24
I-RW-300-48
I-RW-300-48-2nd
15.27
13.36
4.59
3.56
10.93
10.27
2.84
3.45
2.87
3.98
2.41
1.60
21.54
1.19
4.60
95.70
14.67
0.47
9.26
1.58
7.51
3.15
BP-Willow-400
BP-Willow-4502013
BP-Willow-4502014
BP-Willow-500
BP-Willow-550
BP-Birch-400
BP-Birch-500
Coco-1000
10.85
4.24
31.99
9.72
17.44
7.42
2.61
9.95
4.33
2.06
56.36
24.39
27.31
28.48
4.80
16.49
7.84
2.63
1.06
8.62
2.32
2.89
0.48
10.76
21.37
6.07
8.93
17.88
2.18
0.31
3.60
10.08
1.08
1.53
2.36
1.28
1.66
1.15
0.96
1.19
1.14
2.06
3.03
12.02
0.56
1.71
1.46
0.49
0.52
3.50
0.26
0.56
0.90
1.72
3.02
5.46
4.12
2.87
0.33
36.92
50.86
39.20
14.95
36.13
12.05
BP-Phragmite-400
BP-Phragmite-500
I-Potato-300-24
I-Cabbage-300-48
I-Leek-300-48
B-Corn-300
10.83
12.00
117.38
138.51
137.41
26.47
3.41
1.42
2.57
1.14
1.10
6.79
13.54
5.98
0.39
21.47
14.40
0.81
Wood-Ash-1500
IRDA-Manure500
28.40
10.59
30.87
7.09
Non-woody materials
0.99
0.62
1.71
6.17
6.96
0.78
1.99
0.69
1.33
3.04
3.34
4.75
1.36
1.52
0.43
18.63
1.22
0.50
2.17
1.12
1.53
1.46
1.30
6.50
26.72
20.11
119.90
184.77
159.98
28.55
62.83
0.93
0.86
1.35
0.97
4.08
2.29
Others
4.05
2.24
9.46
4.60
7.71
98.07
8.16
7.14
4.72
11.99
6.49
8.94
50.24
42 Table 19. Biochar contents in soluble macro- and micronutrients (related to transport of
contaminants and plants)
Biochar
K
Ca
mg kg-1 CV mg kg-1
X 103
X 102
Mg
Na
CV
mg kg-1
X 102
CV
mg kg-1
X 102
0.34
0.11
0.32
0.28
0.26
1.8
55
Mn
CV mg kg-1 CV
Fe
Al
Cu
Zn
mg kg-1
CV
mg kg-1
CV
mg kg-1 CV
mg kg-1
2.7
0.89
0.22
0.60
0.94
2.7
41
24
41
26
11
12
29
1.0
6.4
5.6
6.6
0.5
14
1.4
27
21
7.9
2.4
14
5.8
11
0.92
0.24
0.16
0.14
0.25
0.13
0.34
0.34
58
14
30
14
39
22
41
0.08
0.03
0.05
0.09
0.01
0.07
0.31
45
43
15
19
62
29
21
1.1
0.62
1.9
0.48
1.7
1.8
1.2
3.7
0.43
14
0.54
5.3
2.1
2.5
34
17
33
8.4
6.2
2.4
12
137
0.7
4.3
1.8
0.29
6.2
0.43
0.93
2.1
0.19
11
0.69
24
7.3
3.4
35.4
13.2
24.9
20
6.1
13
31
119
0.20
0.10
0.25
0.11
0.11
0.26
0.62
0.68
0.76
0.57
0.84
76
18
44
17
17
30
60
16
13
34
51
0.06
0.07
0.13
0.05
0.03
0.15
0.10
0.55
1.46
2.75
0.83
0.00
11
29
44
55
32
17
6
8
39
78
1.0
0.67
0.41
0.64
0.26
0.72
0.45
0.20
8.2
6.0
9.0
5.2
19
7.0
15
2.9
0.31
2.6
8.7
0.20
5.9
0.16
0.20
0.19
40
1.2
29
28
2.5
7.0
13
4.0
0.39
0.14
0.17
0.30
0.15
0.32
0.23
0.11
28
5.18
19
74
19
31
47
8
0.21
0.03
0.19
0.13
0.04
0.18
0.31
0.18
14
12
13
4.23
11
19
18
37
CV
Hardwood
Leaf-Maple-350
BQ-Maple-500-1
BQ-Maple-500-2
BQ-Maple-500-3
Award-Maple-700
B-Eu-300
Nuchar-1000
2.1
1.6
4.3
2.0
1.9
0.9
0.04
14
43
2.0
2.1
3.6
2.0
8.9
3.0
5.2
9.6
7.4
3.8
4.0
1.6
6.4
90
1.5
2.5
12
4.5
68
0.69
1.5
5.2
1.6
0.07
1.9
NA
13
104
1.8
0.8
7.6
1.6
NA
BP-Res-400
BP-Res-500
Airex-Res-427
Airex-Res-454
Pyr-Res-475
Pyr-Res-475-aged
Airex-RW-315
Airex-RW-426
I-RW-300-24
I-RW-300-48
I-RW-300-48-2nd
2.6
5.2
0.2
0.4
0.9
0.6
0.7
0.8
0.1
0.4
0.08
1.9
0.4
1.1
0.6
128
2.9
5.1
0.9
1.1
11
49
3.0
2.3
0.09
1.8
1.9
2.4
33
24
74
46
3.0
2.3
4.8
52
1.8
128
2.4
1.1
5.0
7.0
25
18
1.5
0.7
0.02
0.42
0.33
0.47
1.3
1.8
1.2
1.4
0.54
1.3
5.5
64
1.1
125
2.9
3.2
4.4
4.9
4.3
1.1
BP-Willow-400
BP-Willow-450-2013
BP-Willow-450-2014
BP-Willow-500
BP-Willow-550
BP-Birch-400
BP-Birch-500
Coco-1000
2.3
3.4
4.4
3.7
5.6
1.2
3.3
1.8
1.4
13
2.6
0.3
1.5
9.7
3.4
0.7
1.1
3.8
3.1
8.4
0.6
0.5
0.6
0.1
1.3
6.6
1.1
1.5
3.9
7.6
5.8
14
1.7
0.61
1.2
1.4
0.42
1.2
1.0
0.02
1.9
9.7
3.8
1.4
2.3
9.3
7.9
7.5
BP-Phragmite-400
BP-Phragmite-500
I-Potato-300-24
I-Cabbage-300-48
I-Leek-300-48
B-Corn-300
1.4
1.7
20
42
38
5.5
0.3
2.0
2.0
1.3
3.1
2.1
5.0
3.0
0.03
5.2
2.7
0.2
1.3
2.7
10
6.4
3.6
47
1.1
0.57
0.45
1.6
1.3
0.32
0.7
0.9
2.5
8.1
2.4
11
2.0
2.3
0.37
35
2.1
0.94
Wood-Ash-1500
IRDA-Manure-500
5.5
9.8
13
4.7
3.5
0.06
9.2
0.44
0.12
5.7
30
1.1
8.8
18
9.3
78
1.6
15
1.4
1.0
1.5
1.2
6.8
5.6
29
0.2
12
0.1
14
63
6.0
1.9
12
7.7
55
Coniferous softwood
1.4
1.4
0.04
0.23
0.1
0.7
71
59
38
16
2.3
1.3
1.4
9.6
7.9
51
9.9
3.0
1.2
1.4
8.0
95
0.9
0.3
0.3
3.2
3.8
4.4
7.5
21
11
17
8.6
2.9
57
14.0
29
108
43
5.1
2.1
4.9
17
35
1.1
0.35
0.85
0.66
0.47
0.58
0.99
1.9
0.7
14
2.6
3.9
0.4
8.0
8.7
1.0
2.9
0.2
0.4
0.6
0.04
2.0
0.2
NA
11
95
17
6.2
17
10
12
NA
Non-woody materials
2.0
2.4
3.3
0.6
2.0
0.8
4.0
6.7
0.4
0.3
1.3
0.6
1.7
1.9
10
113
4.0
35
0.71
1.1
7.1
9.4
29
7.8
18
9
15
5.4
3.5
6.1
0.15
0.06
15
60
60
5.0
36
127
1.5
6.1
1.6
13
0.20
0.29
4.18
1.08
1.51
0.60
63
72
2
17
19
27
0.07
0.18
1.23
0.61
1.64
0.52
28
37
19
5
7
12
1.7
1.1
28
31
5.6
4.0
25
6.2
252
0.08
3.6
80
0.48
1.18
24
29
0.45
0.51
17
6
Others
0.02
6.7
CV = coefficient of variation (%). NA: Not Available
43 Table 20. Biochar total contents in other elements (related to the environment) (Part 1)
Biochar
As
mg kg-1
CV
Cd
Co
mg kg-1 CV
mg kg-1
Hardwood
5.33
9
ND
0.67
141
ND
2.99
1
1.33
ND
0
0.26
5.33
18
0.67
ND
0
3.52
ND
0
ND
Coniferous softwood
ND
0
3.35
ND
0
ND
ND
0
ND
ND
0
ND
ND
0
ND
ND
0
ND
ND
0
1.70
ND
0
2.69
0.16
141
5.53
ND
0
1.66
ND
0
ND
1.17
3
7.08
Leaf-Maple-350
BQ-Maple-500-1
BQ-Maple-500-2
BQ-Maple-500-3
Award-Maple-700
B-Eu-300
Nuchar-1000
ND
ND
ND
ND
ND
ND
ND
0
0
0
0
0
0
0
BP-Res-400
BP-Res-500
Airex-Res-427
Airex-Res-454
Pyr-Res-475
Pyr-Res-475-aged
Airex-RW-315
Airex-RW-426
I-RW-300-24
I-RW-300-48
I-RW-300-48-2nd
ND
ND
ND
ND
ND
ND
2.5
72.1
60.8
40.6
27.0
0
0
0
0
0
0
141
84
9
40
84
BP-Willow-400
BP-Willow-4502013
BP-Willow-4502014
BP-Willow-500
BP-Willow-550
BP-Birch-400
BP-Birch-500
Coco-1000
18.9
21
ND
0
3.24
17
0
0.43
4
CV
Cr
mg kg-1
CV
Cu
mg kg-1 CV
0
0
71
141
141
5
0
3.42
5.21
3.48
0.65
3.48
1.19
3.36
29
50
18
0
7
4
5
19.7
10.3
21.7
6.1
21.3
9.5
4.2
13
40
8
20
19
7
29
14
0
0
0
0
0
54
17
34
39
0
6.35
6.21
3.72
0.00
6.39
ND
3.81
22.6
14.5
4.89
1.30
27
6
39
0
16
0
46
61
13
71
62
17.0
13.5
12.7
3.4
15.3
9.4
10.5
54.9
70.7
24.1
41.3
5
6
10
20
11
30
13
49
29
46
111
6
17.7
14
86.4
1
2.33
20
33.0
49
72.0
12
4.34
4
6.91
18
27.8
2
ND
0
ND
0
5.88
16
1.78
32
1.00
141
23.1
28
ND
0
1.70
4
4.10
8
ND
0
0.26
141
5.14
5
ND
0
0.82
19
1.50
1
Non-woody materials
BP-Phragmite-400
ND
0
ND
0
12.99
6
20.8
7
BP-Phragmite-500
ND
0
ND
0
1.61
5
22.3
6
I-Potato-300-24
ND
0
ND
0
ND
0
ND
0
I-Cabbage-300-48
ND
0
ND
0
1.33
7
ND
0
I-Leek-300-48
ND
0
ND
0
1.07
11
0.42
9
B-Corn-300
ND
0
ND
0
1.38
8
0.22
6
Others
Wood-Ash-1500
ND
0
0.40
35
9.84
7
3.57
11
IRDA-Manure-500
ND
0
ND
0
15.89
1
1.37
12
Hg was not detected. CV = coefficient of variation (%). ND = Not detected (< limit of detection)
20.0
74.7
11.1
26.8
15.0
3
25
1
24
6
27.7
23.5
29.8
6.0
12.9
6.1
7
11
25
6
6
5
57.8
556
26
2
ND
ND
ND
ND
ND
ND
0
0
0
0
0
44 Table 21. Biochar content in other elements (related to the environment) (Part 2)
Biochar
Pb
Se
mg kg-1 CV
mg kg-1
Hardwood
Leaf-Maple-350
ND
0
7.00
12
1.97
141
ND
BQ-Maple-500-1
ND
0
4.67
36
1.56
141
ND
BQ-Maple-500-2
ND
0
9.33
22
4.90
141
ND
BQ-Maple-500-3
ND
0
2.66
24
ND
0
16.0
Award-Maple-700
ND
0
6.33
7
7.12
50
ND
B-Eu-300
ND
0
0.00
0
ND
0
ND
Nuchar-1000
2.74
9
2.67
29
ND
0
ND
Coniferous softwood
BP-Res-400
ND
0
34.9
12
ND
0
ND
BP-Res-500
ND
0
23.0
5
ND
0
14.0
Airex-Res-427
ND
0
4.67
20
ND
0
ND
Airex-Res-454
ND
0
1.51
141
ND
0
ND
Pyr-Res-475
ND
0
8.33
34
4.37
71
ND
Pyr-Res-475-aged
ND
0
4.50
35
ND
0
19.9
Airex-RW-315
ND
0
6.70
38
66.6
35
9.1
Airex-RW-426
ND
0
23.6
12
184
13
27.5
I-RW-300-24
ND
0
22.4
123
180
82
ND
I-RW-300-48
ND
0
2.03
34
51.0
76
ND
I-RW-300-48-2nd
ND
0
1.96
40
45.1
40
ND
BP-Willow-400
ND
0
40.2
7
207
2
ND
BP-Willow-450-2013
ND
0
63.3
3
1.71
141
ND
BP-Willow-450-2014
ND
0
38.7
3
ND
0
ND
BP-Willow-500
ND
0
22.0
3
1.54
141
11.5
BP-Willow-550
ND
0
43.0
17
ND
0
ND
BP-Birch-400
ND
0
12.5
4
ND
0
ND
BP-Birch-500
ND
0
35.1
3
ND
0
13.0
Coco-1000
ND
0
4.39
5
ND
0
ND
Non-woody materials
BP-Phragmite-400
1.19
12
51.6
2
4.58
4
ND
BP-Phragmite-500
ND
0
67.8
1
5.75
8
25.7
I-Potato-300-24
ND
0
1.95
48
15.4
4
ND
I-Cabbage-300-48
ND
0
1.90
10
ND
0
ND
I-Leek-300-48
ND
0
0.42
141
ND
0
ND
B-Corn-300
ND
0
ND
0
ND
0
ND
Others
Wood-Ash-1500
ND
0
ND
0
6.68
14
ND
IRDA-Manure-500
3.28
2
ND
0
ND
0
ND
CV = coefficient of variation (%). ND= not detected (< Limit of detection).
Mo
mg kg-1
CV
Ni
mg kg-1
CV
CV
Zn
mg kg-1 CV
0
0
0
23
0
0
0
289
29.3
185
26.5
301
18.0
ND
0
15
6
29
21
8
0
0
5
0
0
0
27
10
45
0
0
0
54.2
73.9
27.0
13.1
195
63.3
40.0
130
149
151
20.4
2
4
18
11
12
31
45
15
96
116
10
0
0
0
2
0
0
2
0
290
379
151
136
455
55.3
87.5
ND
1
10
4
5
8
5
7
0
0
4
0
0
0
0
42.2
93.2
30.7
6.6
47.7
139
14
2
5
21
5
4
0
0
81.9
326
23
5
45 Table 22. Biochar contents in PAH (related to the environment)
Pyr-Res-500
BP-Willow-450-2014
Nuchar-1000
Wood-Ash-1500
I-RW-300-48
I-Poireau-300-48
Acenaphtene
0.1 10
Acenaphtylene
0.1 10
Anthracene
0.1 10
Benzo(a)anthracene
0.1 1
Benzo(a)pyrene
0.1 1
Benzo(e)pyrene
----Benzo(b+j+k)fluoranthene
0.1 1
Benzo(c)phenanthrene
0.1 1
Benzo(g,h,i)perylene
0.1 1
Chrysene
0.1 1
Dibenzo(a,h)anthracene
0.1 1
Dibenzo(a,i)pyrene
0.1 1
Dibenzo(a,h)pyrene
0.1 1
Dibenzo(a,l)pyrene
0.1 1
Dimethyl-7,12 benzo(a)anthracene 0.1 1
Fluoranthene
0.1 10
Fluorene
0.1 10
Indeno(1,2,3-cd)pyrene
0.1 1
Methyl-3 cholanthrene
0.1 1
Naphtalene
0.1 5
Phenanthrene
0.1 5
Pyrene
0.1 10
Methyl-1 naphtalene
0.1 1
Methyl-2 naphtalene
0.1 1
Dimethyl-1,3 naphtalene
0.1 1
Trimethyl-2,3,5 naphtalene
0.1 1
Yellow: Downgraded to B; Red: Downgraded to C
Biochars
BQ-Maple-500-1
MDDELCC (B)
Criteria
MDDELCC (A)
PAH
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
0.1
<0.1
<0.1
<0.1
1.5
0.3
0.1
0.5
0.6
0.3
0.2
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
2.0
0.2
<0.1
0.7
1.0
0.4
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
0.5
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
3.5
<0.1
<0.1
0.2
0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
0.4
<0.1
<0.1
0.1
<0.1
<0.1
<0.1
46 4.4. Biological properties
Only two biological properties were measured (Table 23, Figs. 4-7). Earthworms did not want
to live in soil containing activated biochars (Nuchar-1000 and Coco-1000) regardless of concentration.
Among all biochars, they preferred those made of non-woody materials, especially when the mixture
contained only 10% biochar, which they preferred to garden soil alone (Fig. 4). When the soil
contained 50% biochar, they preferred garden soil without biochar except in the case of hardwood
biochars.
The lettuce germination tests had not all been completed by the time we wrote this report.
Among those that were completed, germination was found to occur in all biochars. However, the speed
and germination rate varied. In mixtures of soil containing 10% biochar, IRDA-Manure-500 and two of
the biochars made of vegetables showed a slight delay in germination, but in all cases germination in
the biochars was completed within 10 days. In mixtures of soil containing 50% biochar, the speed and
rate of germination in biochars made from non-woody material was delayed, except in the case of the
Wood-Ash-1500. Little difference was observed in the germination of lettuce in mixtures containing
50% of the other biochars, except for BQ-Maple-500.
These tests demonstrate that the biochars we examined are not toxic for earthworms (excepted
activated ones) and lettuce, two sensitive species. The tests also show, however, that biochars can cause
problems in extremely high concentrations, as in mixtures containing 50% biochar. Interpretation of
these results will be completed later.
5. Conclusion and future work
The average, minima, and maxima values found for most properties are given in Tables 24
to 26.
The list of biochar analysis methods outlined in this report will be of value to all individuals and
organizations interested in the potential uses of biochar. The wide variety of physico-chemical
properties of the biochars found in Quebec, also documented here, will also be of great interest. This
report also serves to identify the biochar companies in Quebec and to compare the properties of their
biochars with those of some of the others found around the world. One can, from these data, assess how
a single method of pyrolysis can produce different biochars with different materials (e.g., Airex
biochars and BP biochars), how the same material makes very different biochars when subjected to
different pyrolysis methods (e.g., all maple biochars, BP biochars made of willow), and the potential of
unusual materials for pyrolysis (e.g., manure, phragmites).
Interpretation of these results, and classification of the biochars and their potential uses in
agriculture and the environment, will be the subject of later papers by our team. Team members are
also conducting specific studies of the leaching of elements from biochars and of the structure and
carbon composition of biochars in relation to pyrolysis methods. The correlations between methods of
pyrolysis and biochar properties are now the subject of statistical analysis. Finally, the effect of
biochars on the growth of a variety of plants under a range of conditions (field, greenhouse, nursery,
mines, buffer strips) is also under study by our team. Publications will follow. Several documents will
become available in 2015, while others will be published in 2016.
47 Table 23. Percentage of earthworms that chose the mixture of garden soil with 10% biochar
compared to soil alone, or with 50% biochar compared to soil alone, and germination rate of
lettuce after 3 and 6 days in the same mixtures (related to biological toxicity)
Biochar
Earthworm
Lettuce
10% biochar
50% biochar
10% biochar
50% biochar
%
CV
%
CV
3 days
6 days
3 days 6 days
Hardwood
Leaf-Maple-350
63.3
20
60.0
14
78.3
95.0
61.7
86.7
BQ-Maple-500-1
76.7
25
79.6
10
83.3
90.0
26.7
73.3
BQ-Maple-500-2
46.7
20
56.7
22
70.0
93.3
3.3
75.0
BQ-Maple-500-3
63.3
27
NA
NA
NA
NA
NA
NA
Award-Maple-700
50.0
43
56.3
24
68.3
88.3
66.7
93.3
B-Eu-300
56.7
8
NA
NA
NA
NA
NA
NA
Nuchar-1000
0.0
0
0.0
0
81.7
91.7
73.3
90.0
Coniferous softwood
BP-Res-400
36.7
56
NA
NA
NA
NA
NA
NA
BP-Res-500
43.3
29
NA
NA
NA
NA
NA
NA
Airex-Res-427
40.0
20
33.3
28
73.3
88.3
85.0
93.3
Airex-Res-454
53.3
23
NA
NA
NA
NA
NA
NA
Pyr-Res-475
NA
NA
33.3
14
80.0
91.7
51.7
93.3
Pyr-Res-475-aged
30.0
27
NA
NA
NA
NA
NA
NA
Airex-RW-315
70.0
12
NA
NA
NA
NA
NA
NA
Airex-RW-426
76.7
6
NA
NA
NA
NA
NA
NA
I-RW-300-24
56.7
8
40.0
NA
78.3
95.0
58.3
93.3
I-RW-300-48
26.7
47
26.7
0
85.0
90.0
51.7
93.3
I-RW-300-48-2nd
66.7
14
NA
18
NA
NA
NA
NA
BP-Willow-400
40.0
0.0
NA
NA
NA
NA
NA
NA
BP-Willow-450-2013
NA
NA
NA
NA
NA
NA
NA
NA
BP-Willow-450-2014
33.3
51
60.0
0
83.3
95.0
70.0
91.7
BP-Willow-500
56.7
30
NA
NA
NA
NA
NA
NA
BP-Willow-550
NA
NA
NA
NA
NA
NA
NA
NA
BP-Birch-400
36.7
46
NA
NA
NA
NA
NA
NA
BP-Birch-500
66.7
26
NA
NA
NA
NA
NA
NA
Coco-1000
NA
NA
0.0
0
86.7
93.3
33.3
90.0
Non-woody materials
BP-Phragmite-400
30.0
0
NA
NA
NA
NA
NA
NA
BP-Phragmite-500
13.3
94
NA
NA
NA
NA
NA
NA
I-Potato-300-24
72.3
18
70.0
11.7
73.3
95.0
0.0
25.0
I-Cabbage-300-48
90.0
0
0.0
0
45.0
90.0
0.0
0.0
I-Leek-300-48
73.3
10
38.2
30
66.7
88.3
0.0
16.7
B-Corn-300
46.7
10
NA
NA
NA
NA
NA
NA
Others
Wood-Ash-1500
NA
NA
3.3
141
88.3
98.3
48.3
88.3
IRDA-Manure-500
80.0
10
13.3
94
61.7
95.0
0.0
45.0
CV = coefficient of variation. NA: Not Available
48 "
48
0"
50
,3
00
"
e,
ur
an
,M
DA
IR
B,
Co
rn
8"
,4
0,
30
k,
ee
00
0"
I,L
0"
"
20"
,3
20"
24
40"
ge
40"
0,
60"
ba
60"
ab
Hardwood+
I,C
80"
"
Non;coniferous+so9wood+
30
0%+
o,
80"
00
20"
at
20"
,5
40"
ot
40"
ite
60"
I,P
"
60"
m
00
80"
ag
80"
hr
es
,4
00
"
,R
es
,5
Ai
00
re
x,
"
Re
s,4
Ai
27
re
x,
"
Py
eé
r,R
s,4
es
54
,4
"
75
,a
Ai
g
re
ed
x,
RW "
Ai
,3
re
15
x,
RW "
,4
I,R
26
W
"
,3
00
,2
I,R
4"
W
I,R
,3
0
W
0,
,3
48
00
"
,4
8,
2n
d"
0"
BP
,R
100"
,P
,4
ite
BP
Distribu(on+of+worms+(%)+
100"
BP
m
ag
hr
,P
100"
BP
ap
le
,3
50
"
ap
le
,5
00
BQ
,1
,M
"
ap
le
,5
00
BQ
,2
,M
"
ap
le
,5
Aw
00
,3
ar
"
d,
M
ap
le
,7
00
"
B,
Eu
,3
00
"
Nu
ch
ar
,1
00
0"
af
,M
Le
BQ
,M
10%+
BP
,B
irc
h,
50
0"
BP
,B
irc
h,
40
0"
BP
,W
illo
w
,4
00
BP
"
,W
illo
w
,4
50
,2
01
4"
BP
,W
illo
w
,5
00
"
Coniferous+so9wood+
0"
Non;woody+materials+
100"
Figure 4. Preference of earthworms for garden soil alone (0% biochar) or a mixture of garden
soil with 10% v/v biochar
49 Distribu(on+of+worms+(%)+
Coniferous+so9wood+
Hardwood+
100"
100"
80"
80"
60"
60"
40"
40"
20"
20"
0"
"
0
,35
le
ap
f,M
Lea
"
0,1
"
0,2
0
a
,M
BQ
,5
ple
50
le,
ap
,M
BQ
"
0
,70
M
rd,
a
Aw
le
ap
1
r,
cha
0"
"
0
00
Air
Pyr
80"
80"
60"
60"
40"
40"
20"
20"
100"
i
,W
BP
Co
10
co,
8"
0,4
30
W,
I,R
I,R
Non;woody+materials+
Non;coniferous+so9wood+
4"
01
0,2
5
,4
llow
4"
0,2
30
W,
0%+
100"
0"
5"
47
s,
,Re
ex
Nu
50%+
7"
42
s,
,Re
00
0"
"
ot
I,P
"
,24
00
,3
ato
b
ab
I,C
"
,48
00
,3
age
I,L
"
,48
00
,3
eek
o
Wo
sh,
d,A
"
00
15
A,M
IRD
0"
50
re,
u
an
Figure 5. Preference of earthworms for garden soil alone (0% biochar) or a mixture of garden
soil with 50% v/v biochar
50 Hardwood*
Germina(on*(%)*
100"
Coniferous*so5wood*
100"
80"
80"
60"
60"
Leaf,Maple,350"
40"
Airex,Res,427"
40"
BQ,Maple,500,1"
Pyr,Res,475"
BQ,Maple,500,2"
20"
I,RW,300,24"
20"
Award,Maple,700"
I,RW,300,48"
Nuchar,1000"
0"
0"
2"
4"
6"
8"
10"
0"
0"
2"
6"
8"
10"
Non9woody*materials*
Non9coniferous*so5wood*
Germina(on*(%)*
4"
100"
100"
80"
80"
60"
60"
40"
40"
I,Potato,300,24"
I,Leek,300,48"
BP,Willow,450,2014"
20"
I,Cabbage,300,48"
20"
Wood,Ash,1500"
Coco,1000"
IRDA,Manure,500"
0"
0"
0"
2"
4"
6"
Time*(days)*
8"
10"
0"
2"
4"
6"
8"
10"
Time*(days)*
Figure 6. Germination rate of lettuce in garden soil amended with 10% biochar
51 Hardwood*
Germina(on*(%)*
100"
Coniferous*so5wood*
100"
80"
80"
60"
60"
Leaf,Maple,350"
40"
40"
BQ,Maple,500,1"
Airex,Res,427"
BQ,Maple,500,2"
Pyr,Res,475"
20"
Award,Maple,700"
20"
I,RW,300,24"
Nuchar,1000"
I,RW,300,48"
0"
0"
0"
2"
4"
6"
8"
0"
10"
2"
Non9coniferous*so5wood*
4"
6"
8"
10"
Non9woody*materials*
100"
100"
I,Potato,300,24"
Germina(on*(%)*
80"
I,Cabbage,300,48"
80"
I,Leek,300,48"
Wood,Ash,1500"
60"
60"
40"
40"
20"
BP,Willow,450,2014"
IRDA,Manure,500"
20"
Coco,1000"
0"
0"
2"
4"
6"
Time*(days)*
8"
10"
12"
0"
0"
2"
4"
6"
8"
10"
Time*(days)*
Figure 7. Germination rate of lettuce in garden soil amended with 50% biochar
52 Table 24. Summary of general and physical properties of biochars
Property
Ash
Ctot
Cgraph
Cinorg
Corg
H
O
H/Corg
O/Ctot
BD
SD
TP
EC
WC
CRm
CRb
CR1.4
CR-0.05
RH90
MWD
UI (D95/D10)
DMWD
Units
Min
General properties
%
1.11
%
23
%
10.1
%
0.4
%
1.5
%
0.1
%
3.2
--0.02
--0.04
Physical properties
m3 m-3
0.13
m3 m-3
1.25
m3 m-3
0.72
dS m-1
0.1
% (mass)
0
g g-1 h-1
-0.0224
g g-1 h-1
0.003
% (mass)
5.7
% (mass)
12.3
% (mass)
5.24
µm
138
-2.1
µm
-1062
Max
Mean
54.9
91.5
84.8
9.2
44.5
5
33.1
1.7
0.76
13.1
63.3
40.3
2.1
20.9
2.8
16.2
0.2
0.28
0.46
2.74
0.9
4.81
9.3
-0.0004
0.127
130
419
102
6106
109.6
5.62
0.3
1.6
0.81
0.94
2.4
-0.0051
0.03
30.8
100
10.7
1153
21.4
-218
53 Table 25. Summary of chemical properties of biochars
Property
pHH2O
PTpH4
PTpH7
NTotal
Ptotal
Stotal
K
Ca
Mg
Na
Echg. tot
K
Ca
Mg
Na
Mn
Fe
Al
Cu
Zn
As
Cd
Co
Cr
Cu
Mo
Ni
Pb
Se
Zn
Units
Min
Max
Properties relative to acidity
--4.8
10.4
meq
0.02
2.2
meq
0.01
0.74
Basic elements
%
0.2
5.1
-1
mg kg
4.58
207
%
0
5.8
Exchangeable nutrients
cmol+ kg-1
0.4
138
cmol+ kg-1
0.39
63.5
cmol+ kg-1
0.03
11.1
cmol+ kg-1
0.16
33.5
cmol+ kg-1
6.43
185
Soluble nutrients
mg kg-1
34
42 508
mg kg-1
2.95
9938
mg kg-1
1.16
579
mg kg-1
3.3
5 589
mg kg-1
0.03
31
mg kg-1
0.16
41.6
mg kg-1
ND
264
mg kg-1
0.04
4.25
mg kg-1
0.006
5.76
Other elements
mg kg-1
ND
72.1
mg kg-1
ND
5.33
mg kg-1
ND
15.9
mg kg-1
ND
33
mg kg-1
3.42
556
mg kg-1
ND
3.28
mg kg-1
ND
67.8
-1
mg kg
ND
207
mg kg-1
ND
27.5
mg kg-1
ND
455
Mean
7.79
0.58
0.14
1.2
42.5
3.3
22.9
16.1
2.14
3.25
44.4
51 112
926
119
508
4.7
4.26
14.7
0.51
0.40
6.53
0.63
2.42
6.96
41.7
0.21
16.2
23.2
4.02
120
ND: Not Detected (< Limit of detection)
54 Table 26. Summary of biological properties of biochars
Percentage
biochar
Time
(days)
Min
Max
Mean
Earthworms
0.0
90
51.6
0.0
79
36
Lettuce
10%
3
45
88
75
6
88
98
92
50%
3
0.0
85
39
6
0.0
9
72
N.B. The values do not add up, they are only min, max and mean of all observations. 10%
50%
10
10
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