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The soil carbon sequestration is the long-term storage of carbon in soil which could well be accomplished by the application of biochar as a soil amendment. Biochar (BC) is a fine grained, highly carbonaceous, pyrolysed (low temperature) product of biomass. The pyrolysis temperature strongly influences the stability of biochar in soil; the higher the pyrolysis temperature higher would be the stability. Biochar being highly stable in soil due to its aromaticity, presence of amorphous structure and turbostatic crystallites, rounded structures and reduced accessibility to decomposers has lot of potential for long-term carbon sequestration. The higher stability of biochar in soil is also due to strong interactions with mineral surfaces. Biochar interacts with native soil organic matter (SOM) in a complex way; sometimes biochar showed positive priming effect or negative priming effect or no effect on native SOM. This depends upon the feedstock type, pyrolysis temperature and organic matter level of soil. The soils richer in organic matter status provide positive priming effect of native SOM due to biochar addition and vice-versa. Biochar has high carbon sequestration potential and long-term influence on native SOM. Biochar has huge potential for reduction of greenhouse gas emission form paddy field soils. Therefore, optimisation of feedstock, pyrolysis temperature for preparation biochar and its application in a specific soil is extremely essential for stability of biochar and protection of native SOM and greenhouse gas reduction for long-term carbon sequestration. Thus biochar carbon sequestration is not a myth rather it would be a reality in near future.
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Biochar Carbon Sequestraon in Soil - A myth or Reality?
T. J. Purakayastha1*, Savita Kumari1, Subodh Sasmal1 and H. Pathak2
1Division of Soil Science and Agricultural Chemistry, Indian Agricultural Research Institute, New Delhi (110 012), India
2Center for Environmental Science and Climate Resilient Agriculture, Indian Agricultural Research Institute,
New Delhi (110 012), India
International Journal of Bio-resource and Stress Management 2015, 6(5):623-630
Abstract
Article History
Correspondence to
Keywords
Manuscript No. AR1153
Received in 3rd December, 2014
Received in revised form 5th September, 2015
Accepted in nal form 6th October, 2015
The soil carbon sequestration is the long-term storage of carbon in soil which could
well be accomplished by the application of biochar as a soil amendment. Biochar
(BC) is a ne grained, highly carbonaceous, pyrolysed (low temperature) product of
biomass. The pyrolysis temperature strongly inuences the stability of biochar in soil;
the higher the pyrolysis temperature higher would be the stability. Biochar being highly
stable in soil due to its aromaticity, presence of amorphous structure and turbostatic
crystallites, rounded structures and reduced accessibility to decomposers has lot of
potential for long-term carbon sequestration. The higher stability of biochar in soil is
also due to strong interactions with mineral surfaces. Biochar interacts with native soil
organic matter (SOM) in a complex way; sometimes biochar showed positive priming
eect or negative priming eect or no eect on native SOM. This depends upon the
feedstock type, pyrolysis temperature and organic matter level of soil. The soils richer
in organic matter status provide positive priming eect of native SOM due to biochar
addition and vice-versa. Biochar has high carbon sequestration potential and long-term
inuence on native SOM. Biochar has huge potential for reduction of greenhouse
gas emission form paddy eld soils. Therefore, optimisation of feedstock, pyrolysis
temperature for preparation biochar and its application in a specic soil is extremely
essential for stability of biochar and protection of native SOM and greenhouse gas
reduction for long-term carbon sequestration. Thus biochar carbon sequestration is
not a myth rather it would be a reality in near future.
*E-mail: tpurakayastha@gmail.com
z CO2, properties of biochar, pyrolysis, soil
carbon sequestration
DOI: 10.5958/0976-4038.2015.00097.4
1. Introduction
Over the twenty rst century average temperature of the
earth surface is likely to increase 1.8-4 °C (IPCC, 2007).
Among the major greenhouse gases, at present the carbon
dioxide (CO2) has the higher concentration in the atmosphere
which already touched to almost 400 ppm as compared to its
concentration of 275-285 ppm in pre-industrial era leading
to warming of climate with an increasing rate at about 1.4
ppm year-1 (IPCC, 2007).The presence of black carbon in
“Tera Preta’ soils in central Amazon in Brazil created lot of
interests among scientic community towards its use for long
term carbon sequestration. Carbon (C) sequestration is the
capture and secure storage of carbon that would, otherwise, be
emitted or remain in the atmosphere. Carbon sequestrations in
agricultural soils is of signicant importance, as it can mitigate
atmospheric carbon dioxide (CO2) emission and enhance
soil fertility (Glaser et al., 2002; Lehmann, 2007). Biochar is
produced by pyrolysis and is dominantly composed of aromatic
compounds that are largely resistant to biological degradation
(Baldock and Smernik, 2002). Biochar is a highly carbonized
material in which the carbon content varies depending on the
feedstock and production conditions. It was reported that the
total C content was highest in maize biochar (66%) followed
by pearl millet biochar (64%), wheat biochar (64%) and rice
biochar (60%) (Purakayastha et al., 2015). Due to its relative
inertness, biochar application contributes to the soil refractory
organic C pool (Glaser et al., 2001; Marris, 2006). Therefore,
biochar application is a promising alternative to sequester more
C compared to more traditional agricultural practices involving
direct incorporation of biomass, which results in immediate and
rapid mineralization, and CO2 release (Bruun et al., 2011).
Biochar interacts with native soil organic matter (SOM) in a
complex way showing positive as well as negative priming
eect. Optimisation of feedstock for preparation of biochar
and its application in a specic soil (low organic matter or high
organic matter) is extremely essential for stability of biochar and
Review Article
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Purakayastha et al., 2015
protection of native SOM for long-term carbon sequestration.
The major problem which cropped up recently with rice-wheat
cropping system is how to dispose o large quantities of crop
residues with special reference to rice residues left over in
the eld due to the use of mechanised combined harvester
(Purakayastha et al., 2015). In order to clear the land ready for
the next crop, the easiest option available to the farmers is to
burn the residues in the eld which cause losses of essential
plant nutrients and environmental pollution by releasing
suspended particulate matter, smoke and greenhouse gases.
It is a matter of concern that in Indian state of Punjab alone,
some 70 to 80 mt of rice and wheat straw are burned annually
releasing approximately 140 mt of CO2 to the atmosphere, in
addition to methane, nitrous oxide and air pollutants (Punia
et al., 2008). In this scenario, biochar, a pyrolysed product of
biomass oers a signicant, multidimensional opportunity
to transform large scale agricultural waste streams from a
nancial and environmental liability to valuable assets.
2. Biochar and its Properties
2.1. What is biochar?
Biochar is a fine-grained, carbon-rich, porous product
remaining after plant biomass, such as wood, manure or leaves
have been subjected to thermo-chemical conversion process
(pyrolysis) at a temperature between 350 to 600 °C in an
environment with little or no oxygen (Amonette and Joseph,
2009) Biochar is not a pure carbon, but rather mix of carbon
(C), hydrogen (H), oxygen (O), nitrogen (N), sulphur (S) and
ash in dierent proportions (Raveendran et al., 1995; Skodras
et al., 2006; Bourke et al., 2007). Slow pyrolysis temperature
≤500 °C and hydrothermal carbonization are two ecient
methods to produce biochar in high amount (Malghani et al.,
2013).
2.1.1. Aromaticity
Biochar is commonly considered to be highly aromatic and
containing random stacks of graphitic layers (Schmidt and
Noack, 2000). Specically, H, C and O, C ratios present are
used to measure the degree of aromaticity and maturation. In
general, C and O, C ratios in experimentally produced biochars
decrease with increasing temperature (Shindo, 1991; Baldock
and Smernik, 2002) and increased time of heating (Almendros
et al., 2003). It was discussed and claried the possibility of
utilizing H/C ratios of organic materials to infer information
about the bonding arrangements (Knicker et al., 2005). It was
further concluded that H and C ratio between 0.4 and 0.6 of the
aromatic portion of chars indicates that every second to third
carbon is connected to a proton. Fourier transform infra-red
spectroscopy (FTIR) analysis of biochar exhibited that the
band between 3417 and 3434 cm-1 was ascribed to the mixed
stretching vibration absorption of amino and hydroxyl groups
and maize stover biochar showed the maximum and wheat
straw biochar showed the lowest absorption and the other two
biochars were in between the above two in terms of energy
absorption (Purakayastha et al., 2015).
2.2. Presence of amorphous structures and turbostatic
crystallites
Biochar is mainly characterized by amorphous structures
and turbostratic crystallites (unordered graphene layers) that
may contain defect structures in the graphene sheets with
oxygen groups and free radicals (Bourke et al., 2007). Ordered
graphene sheets were found to increase only at a carbonization
temperature above 600°C (Kercher and Nagle, 2003). Because
of their unordered structure, amorphous and turbostratic
crystallites have a high stability (Paris et al., 2005), which could
be one reason for the stability of biochar produced at relatively
low temperatures of less than 600 °C. In comparison, layers of
graphene in graphite are held together by comparatively weak
van der Waals forces.
2.3. Presence of rounded structures
Rounded structures may be even more stable than turbostratic
structures in biochar (Cohen-Ofri et al., 2007). The round
structures are actually fullerenes, molecular scale spherical
structures that include both hexagonal and pentagonal rings
that have great stability (Harris, 2005). Simulations of the
development of fused aromatic ring structures during charring
show the appearance of heptagons and, with increasing
temperature, heptagons in conjunction with folding of the
grapheme sheets (Acharya et al., 1999; Kumar et al., 2005).
Rounded features were also reported in biochars from German
Chernozems with ages of 1160 to 5040 years using high-
resolution transmission electron microscopy (Schmidt et al.,
2002). The particulate form may have an important role in
decreasing decomposition rates of biochar. The pore structure
of biochar seen under scanning electron microscopy (SEM)
provided physical refuge, resulting in increased abundances of
benecial microorganisms (Purakayastha et al., 2013).
3. Interaction of Biochar With Soil
3.1. Interactions with clay minerals
Biochar is reported to be found in the organo-mineral fraction
of soil, suggesting that biochar interacts with minerals
(Brodowski et al., 2006; Laird et al., 2008; Liang et al., 2008).
Large particles of biochar observed under spectroscope to
be embedded within the mineral matrix (Glaser et al., 2000;
Brodowski et al., 2005), but can also be present as very ne,
yet distinguishably particulate, material within aggregates.
Rapid association of biochar surfaces with aluminium (Al)
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and silicon (Si) and, to a lesser extent, with iron (Fe) was
found during the rst decade after addition of biochar to
soil, which increased more slowly within biochar structures
(Nguyen et al., 2008). Coating of biochar particles with mineral
domains is frequently visible in soils (Lehmann, 2007), and
suggests interactions between negatively charged biochar
surfaces and either positive charge of variable-charge oxides
by ligand exchange and anion exchange, or positive charges
of phyllosilicates by cation bridging. Likewise calcium (Ca)
can increase the biochar stability, most likely by enhancing
interactions with mineral surfaces (Czimczik and Masiello,
2007). Large amounts of ionic iron (Fe) and aluminium (Al)
were also found in biochar type humic fractions (Nakamura
et al., 2007), which may indicate that complexion between
biochar surfaces and polyvalent metal ions could increase
biochar stability. The energy dispersive X-ray spectroscopy
(EDS) analysis indicated that pearl millet stalk biochar and rice
straw biochar particles consisted of high calcium agglomerates
(Purakayastha et al., 2015).
3.2. Biochar stability
The stability of biochar is of prime requisite for long-term
sequestration of C in soil. The mechanisms of biochar stability
is mainly due to the composition changes through a complete
destruction of cellulose and lignin, thus changes the appearance
of aromatic structures (Paris et al., 2005) with furan-like
compounds (Baldock and Smernik, 2002). These changes in the
composition of organic bonds by pyrolysis have a signicant
eect on the stability of biochar. The conversion of organic
matter to biochar by pyrolysis signicantly increases the
recalcitrance of C in the biomass. The principal mechanisms
operating in soils through which biochar entering the soil is
stabilized and signicantly increase its residence time in soil
are intrinsic recalcitrance, spatial separation of decomposers
and substrate, and formation of interactions between mineral
surfaces (Sollins et al., 1996). Among the four dierent biochar
used for CO2 eux study, the maize biochar was found to be
the most stable showing reduced C mineralization to protect the
native soil organic C (Purakayastha et al., 2015). The reduced
C mineralization was also observed in the case of pearl millet
and wheat biochar. Contrarily, rice biochar exhibited higher
C mineralization.
3.3. Eect of pyrolysis temperature on biochar stability
Increase in pyrolysis temperature from 400 °C to 600 °C
decreased the volatile and nitrogen component of biochar,
while it increased ash and xed carbon content (Purakayastha
et al., 2016). Thus biochar prepared at 600 °C had wider
carbon and nitrogen ratio making it more stable in soil. It was
reported that thermal alteration decreases bioavailability of
wood (Baldock and Smernick, 2002). Crombie and Masek
(2015) reported that after 120 days incubation 20% of the
added organic carbon from unaltered wood (heated at 70 °C)
was mineralized, but this value was less than 2% for samples
heated at temperatures ≥200 °C indicating much higher stability
of thermally altered woods. Higher temperature pyrolysis not
only shifted energy contribution from biochar in favour of gas
and co products but also led to increased stable carbon yields.
The C mineralization from sugarcane bagasse applied in silty-
clay loam soil from Rothamsted was substantially decreased
when pyrolysis temperature increased from 350 °C to 450 °C
than from 450 °C to 550 °C (Figure 1) (Cross and Sohi, 2011).
In contrast to this, Zimmerman et al. (2011) reported that C
mineralization from biochar prepared from Eastern gamma
grass (Tripsacum dactyloides L.) (250 and 400 °C) was greater
than expected as compared to the biochar prepared from hard
wood at hogher pyrolysis temperature (525 and 650 °C). The
biochar prepared from Eucalyptus saligna at 550 °C resulted
in greater stabilisation of the native SOC in clay-rich soils than
the 450 °C biochar (Fang et al., 2015).
3.4. Reduced accessibility to decomposers
The principal mechanisms operating in soils through which
biochar entering the soil is stabilized and signicantly increase
its residence time in soil are intrinsic recalcitrance, spatial
separation of decomposers and substrate, and formation of
interactions between mineral surfaces (Sollins et al., 1996).
Biochar has been preferentially found in fractions of SOM
that reside in aggregates rather than as free organic matter
(Brodowski et al., 2006; Liang et al., 2008), which is considered
to reduce its accessibility to decomposers. It was reported that
no dierence in mineralization between biochar rich soils with
27, 10 and 0.3% clay, suggesting that greater aggregation in the
ner-textured soils had no inuence on biochar mineralization
(Liang et al., 2008). Moreover, microorganisms can be spatially
associated with biochar in soils as porous structure of biochar
invites microbial colonization.
4. Biochar and Soil Carbon Sequestration
4.1. Inuence of biochar on native soil organic carbon
Due to relative inertness, biochar application contributes to
the soil refractory organic C pool (Glaser et al., 2001; Marris,
2006). Therefore, biochar application is a promising alternative
to sequester more C compared to more traditional agricultural
practices involving direct incorporation of biomass, which
results in immediate and rapid mineralization, and CO2
release (Bruun et al., 2011). However, both suppression and
stimulation of native SOC decomposition by biochar have
been reported by previous studies (Liang et al., 2010; Cross
and Sohi, 2011; Luo et al., 2011), the inconsistent results were
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International Journal of Bio-resource and Stress Management 2015, 6(5):623-630
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probably due to dierences in the nature of biochar and soil,
and incubation conditions used in dierent studies (Jones et
al., 2011). Measured mineralization rates greater than predicted
indicate positive priming of a specic C source, whereas
measurements of mineralized C lower than that predicted
indicate negative priming. In general, low temperature (250
and 400 °C) biochar-C mineralization was positively primed
during early incubation (Zimmerman et al., 2011). On the
contrary, grass 650 biochar-C mineralization was reduced by its
interaction with soil during both early and late incubation stages
as was Grass 400 biochar-C during late stages. During the early
incubation stage, the presence of Grass 250 biochar strongly
reduced SOC mineralization in both soils, whereas other grass
biochars had little eect on SOC respiration. During the late
incubation stage, however, SOC mineralization was reduced
(by 12-90%) due to its interaction with biochar in all cases
except that of Grass 400 biochar in SF922 soil (Table 1). Field
experiments, with addition of biochar (derived from Eucalyptus
saligna wood) or freshly picked Tithonia diversifolia leaves as
green manure along with control showed that in carbon poor
soils, CO2 evolution was 29% less with biochar addition than
control indicating lesser mineralization of pre-existing SOC
due to biochar (Kimetu and Lehmann, 2010). This could be
due to the reduced accessibility of carbon in microbes and
their enzymes caused by sorption of labile carbon to the added
biochar. The priming eect of biochar is greatly inuenced by
Table 1: Comparison of measured (includes priming) and predicted (neglects priming) C mineralization (C min.) rates (in mg C
g-1 y-1) attributable to biochar and soil organic carbon (OC) in incubations of biochar+soil, Source (Zimmerman et al., 2011)
Incubation type Early incubation Late incubation
(soil+biochar) Soil OC min. Biochar C min. Soil OC min.
Meas.aPred.bMeas.aPred.bMeas.a Pred.bMeas.aPred.b
SF33+Grass 250 3.6 0.7 0.1 1.3 0.7 0.5 0.1 1.3
SF33+Grass 400 4.0 2.8 1.6 1.3 0.4 0.9 0.5 1.3
SF33+Grass 650 1.2 1.3 1.4 1.3 0.0 0.7 0.2 1.3
SF922+Grass 250 8.6 0.7 1.8 10.1 1.1 0.5 1.2 2.8
SF922+Grass 400 5.3 2.8 9.0 10.1 0.8 0.9 4.7 2.8
SF922+Grass 650 0.2 1.3 8.0 10.1 0.3 0.7 2.5 2.8
SF33: Alsol; SF922: Mollisol
Co2-C (mg C g-1 soil)
Biochar production parameters:
1.00
1 2 3 4 5 67 8 9 10
20
350 °C
Fallow GrasslandArable
450 °C 550 °C
Activated Trash
biochar
10-20 min
heating
rate
2040 40 40 40 40 4080 80
Final
temp:
residence
time
(mins)
0.90
0.80
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
Control
Sample number
Figure 1: Mineralised CO2 carbon over 2 weeks for control (soil only) and biochar amended soils, as determined using the
soda lime method (expressed on a soil wet weight basis). Production characteristics for each biochar are also shown. Error
bars are one standard error of the mean (n=2), Source (Cross and Sohi, 2011)
Purakayastha et al., 2015
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biochar type, pyrolysis temperature and most importantly soil
type. In general, the priming eect was more negative (in the
Entisol, Oxisol and Vertisol) or less positive (in the Inceptisol)
from the 550 °C biochar than the 450 °C biochar prepared
from Eucalyptus saligna (Fang et al., 2015). In a recent study
Purakayastha et al. (2016) reported that wheat straw biochar
preated at 600 °C showed positive priming in Alsol, while
the same biochar showed negative priming in Mollisol. The
corn stover biochar showed negative priming in Mollisol but
sugarcane bagasse biochar prepared at 400 °C and 600 °C did
not show any priming eect.
4.2. Carbon sequestration and greenhouse gas emission
Biochar is carbon negative and thus resulting in long-term
removal of carbon from the atmosphere. Mitigation of carbon
emissions is obtained not only from biochar soil application,
but also from substitution of fossil fuel by the produced bio-oil.
As discussed, the stability biochar could be increased by raising
the pyrolysis temperature, but this will be at the expense of
the quantity produced. This inverse relation makes it possible
to determine the pyrolysis temperature that gives the highest
carbon sequestration. Interestingly, the highest biochar carbon
sequestration is achieved at 500 °C, despite the fact that biochar
made at higher temperatures is relatively more recalcitrant than
low temperature biochars.
Biochar is highly stable against microbial decomposition
and applying this to farmland has the potential to mitigate
greenhouse gases emissions. Feng et al. (2014) reported that
paddy CH4 emissions significantly decreased under corn
stalk biochar amendments, which, interestingly, didn’t result
from the inhibition of methanogenic archaeal growth. qPCR
further revealed that biochar amendments (1) increased
methanotrophic proteobacterial abundances signicantly, and
(2) decreased the ratios of methanogenic to methanotrophic
abundances greatly. Case et al. (2015) reported that adding
biochar to agricultural soil with mineral fertilisers can suppress
N2O emissions without suppressing the activity of soil biota
involved in N transformation processes such as mineralisation
or nitrication. Biochar application decreased both cumulative
N2O (52-84%) and NO (47-67%) emissions compared to a
corresponding treatment without biochar after urea and nitrate
fertilizer application, and only NO emissions after ammonium
application (Nelissen et al., 2014). N2O emissions were more
decreased at high compared to low pyrolysis temperature.
Recently Woolf et al. (2010) estimated the maximum
sustainable technology potential of biochar in the world is
2.27 Pg C year-1. They also indicated that among the benecial
feedbacks, the largest is due to avoided CH4 emissions from
biomass decomposition (14-17 Pg CO2-Ce), predominantly
arising from the diversion of rice straw from paddy elds.
The next largest positive feedbacks, in order of decreasing
magnitude, arise from biochar-enhanced NPP on cropland,
which contributes 9-16 Pg CO2-Ce to the net avoided emissions
(if these increased crop residues are converted to biochar),
followed by reductions in soil N2O emissions (4.0-6.2 Pg CO2-
Ce), avoided N2O emissions during biomass decomposition
(1.8-3.3 Pg CO2-Ce) and enhanced CH4 oxidation by dry
soils (0.44-0.8 Pg CO2-Ce ). The two most important factors
contributing to the avoided emissions from biochar are carbon
stored as biochar in soil (43-94 Pg CO2-Ce) and fossil-fuel
osets from coproduction of energy (18-39 Pg CO2-Ce).
Biochar when applied to soil, it remains in soil for centuries
and securely store C for long-term C sequestration. The total
soil C (TSC) at the end of one year of C mineralization in an
incubation study showed that the TSC increased in the range
of 41 to 65% in biochar treated Inceptisol of Delhi (Figure 2)
(Purakayastha et al., 2015). The TSC was highest in maize
stover and wheat straw biochars treated soils, while it was
observed lowest in the case of rice straw biochar treatment.
International biochar initiative (IBI) has developed a simple
model to predict the carbon removing power of sustainable
biochar systems. Counting only the impacts of biochar burial in
soil, and without considering the displacement of energy from
fossil fuels, we can conservatively oset one quarter of a Pg
of C annually by 2030. Optimistically, it is possible to achieve
one Pg of osets annually before 2050. In the “Optimistic
Plus” scenario, reductions in nitrous oxide emissions and the
feedback eect of increased biochar production that may arise
Control Maize-Biochar
Pearl millet -Biochar Rice-Biochar
Wheat-Biochar
Biochar feedstock
Total soil C (g kg-1
12
10
8
6
4
2
0
Figure 2: Eect of dierent biochar on total soil carbon at the
end of one year of carbon mineralization, the bars with dierent
lower case letters are signicant according to Duncan’s multiple
range test at p=0.05, Source (Purakayastha et al., 2015)
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International Journal of Bio-resource and Stress Management 2015, 6(5):623-630
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from increased plant growth in soils enhanced with biochar
have been taken into account. Keeping in view the entire
discussion, it would be better to consider biochar-carbon
sequestration as a reality rather than a myth.
It has been projected that in India about 309 million tons
of biochar (eqv. to 154 mt of biochar C) could be produced
annually, the application of which might oset about 50%
of C emission (292 Tg C yr-1 ) from fossil fuel (Lal, 2005).
Additionally both heat and gases can be captured during
production of biochar by pyrolysis to produce energy carriers
such as electricity, bio-oil, or hydrogen and certain other
valuable co-products.
The potential of biochar application for soil organic carbon
(SOC) sequestration may be 1 Pg C yr-1 (Sohi et al., 2010)
or more (Lehmann et al., 2006). Biochar can have ≥60-80%
carbon composition that is equivalent to ≥2.20-2.94 t carbon
dioxide sequestered ton-1 biochar (Verma et al., 2014).
5. Conclusion
Stability of biochar carbon increases with pyrolysis temperature
making it suitable for the purpose of carbon sequestration in
soil. To derive the maximum possible benefit of carbon
sequestration by soil application, both yield and stability of
the biochar should be optimized. Carbon sequestration by
biochar is likely to be less in soils relatively higher in carbon
than in soils lower in carbon. The knowledge on mechanism of
biochar induced reduction in greenhouse gas emission can be
applied to develop a more eective greenhouse gas mitigation
process for paddy elds. The potential of biochar application
for soil organic carbon (SOC) sequestration may be 1 billion
t carbon year-1 or more.
6. Acknowledgement
The authors are extremely grateful to the Indian Council of
Agricultural Research for providing necessary fund in the
form of National Initiative on Climate Resilient Agriculture
(NICRA) project to carry out part of work and develop this
manuscript.
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... Biochar has carbon sequestration potential and a long-term effect on soil organic matter [43]. Here, the scenarios for the use of subsidies at the levels of USD 10, USD 20 and USD 30 [44,45] are presented. ...
... Biochar may improve soil physical properties such as water regulation and respiration, porosity, texture, aggregate stability and bulk density as well as soil chemical properties [55]. Furthermore, biochar has considerable carbon sequestration potential and a long-term effect on soil organic matter [43]. Moreover, the production of biochar may contribute to diminishing CO 2 emissions, as the raw materials used to produce biochar would normally be landfilled or combusted in a conventional manner, consequently increasing CO 2 emissions to the atmosphere [56]. ...
... When added to soil, biochar can persist in soil for decades, which efficiently enables C to store for long term sequestration . Incubation analysis at the end of a year of C mineralization revealed that total soil C increased from 410 to 650 g kg −1 in biochar-amended Inceptisol soils in India (Purakayastha et al., 2015). The ability of biochar application for sequestration of soil organic C may reach 1 Pg C year −1 (annual mean of C budget) or even higher Sohi et al., 2010). ...
... Biochar is obtained by pyrolysis of feedstock at high temperature for the burning of organic content such as lignin and cellulose (Paris et al., 2005;Purakayastha et al., 2015). As the major proportion (70%-80%) of biochar is C, it can potentially provide the soil with more C compared with plant residue (approximately 40%) of comparable density (Matovic, 2011;Smith, 2016). ...
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... Biochar has carbon sequestration potential and a long-term effect on soil organic matter [43]. Here, the scenarios for the use of subsidies at the levels of USD 10, USD 20 and USD 30 [44,45] are presented. ...
... Biochar may improve soil physical properties such as water regulation and respiration, porosity, texture, aggregate stability and bulk density as well as soil chemical properties [55]. Furthermore, biochar has considerable carbon sequestration potential and a long-term effect on soil organic matter [43]. Moreover, the production of biochar may contribute to diminishing CO 2 emissions, as the raw materials used to produce biochar would normally be landfilled or combusted in a conventional manner, consequently increasing CO 2 emissions to the atmosphere [56]. ...
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... The association between the surface of biochar and Al can take place during the first decade after the addition of biochar to the soil [9]. Biochar also has P which can survive in the soil [10]. Organic C content increased by 1.12% from the effect residue of 2% bamboo biochar, compared to the control, while the increase in total N from the residue of 2% bamboo biochar was 0.13%, compared to Table 1A], while biochar can also improve and increase the N of soil by supplying and holding nutrients in the soil [10]. ...
... Biochar also has P which can survive in the soil [10]. Organic C content increased by 1.12% from the effect residue of 2% bamboo biochar, compared to the control, while the increase in total N from the residue of 2% bamboo biochar was 0.13%, compared to Table 1A], while biochar can also improve and increase the N of soil by supplying and holding nutrients in the soil [10]. Biochar has a high content of carbon with an aromatic carbon structure that is recalcitrant and potentially reduces greenhouse gas emissions [11]. ...
... Charcoal is one of the most stable carbon compounds, which means that it takes a long time for it to degrade [13]. This contrasts with regular compost, which is quickly consumed by soil microorganisms and converted into carbon dioxide and methane [31]. This makes biochar a long-term method of sequestering carbon into the soil-the carbon that would otherwise be quickly lost as greenhouse gases into the atmosphere. ...
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... Biochar can be used as a means of increasing the efficiency of the carbon sequestration process in rice paddies. Approximately 1 billion pounds of OC may be contained in biochar spread on land, or that the potential for soil organic carbon (SOC) [19]. ...
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... Biochar is a stable, carbon (C)-rich residue obtained from the pyrolysis of organic biomass in the absence or limited supply of oxygen (Lehmann & Joseph, 2009). In recent years, significant interest has been placed on using biochar as a soil amendment to sequester C while providing simultaneous benefits for soil health (Fidel et al., 2017;Purakayastha et al., 2015;Smith, 2016). Although biochar is typically not considered a source of nutrient to plants, it often improves soil physicochemical (i.e., soil bulk density, porosity, water holding capacity, cation exchange capacity, pH) and biological properties (soil microbial composition and activity) (Hardie et al., 2015;Hseu et al., 2014;Nielsen et al., 2014). ...
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Nanoporous carbons (NPCs) are useful in adsorptive separations and calalysis, owing to their ability to discriminate between molecules on the basis of size and shape. This property arises from their narrow pore size: distribution, which is typically centred at a size corresponding to 0.5 nm. Despite this level of nanoregularity, there is no long-range order within these materials. Structural coherence dissipates to extinction at distances longer than 1-1.2 nm. For this reason, these nanoporous materials are complex solids and offer an intriguing problem in structural simulation and modelling. We show: that modelling the spatial complexity of NPCs carl be overcome by their chemical simplicity. Recognizing that the structures are comprised of trigonal sp(2) carbon and imposing chemical and physical constraints on the possible outcomes of the simulation provide a means to surmounting the modelling problem presented by the intrinsic disorder. By this approach, models of the solid can be arrived at that match the density, hydrogen to carbon ratio and neutron diffraction patterns of actual NPCs guile well. Thus, by using chemical logic and experimentally grounded constraints, good three-dimensional structures for NPC can be obtained by simulation.
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Due to its recalcitrance against microbial degradation, biochar is very stable in soil compared to other organic matter additions, making its application to soils a suitable approach for the build-up of soil organic carbon (SOC). The net effects of such biochar addition also depend on its interactions with existing organic matter in soils. A study was established to investigate how the status of pre-existing soil organic matter influences biochar stabilisation in soil in comparison to labile organic additions. Carbon loss was greater in the C-rich sites (C content 58.0 g C/kg) than C-poor soils (C content 21.0-24.0 g C/kg), regardless of the quality of the applied organic resource. Biochar-applied, C-rich soil showed greater C losses, by >0.5 kg/m(2). year, than biochar-applied C-poor soil, whereas the difference was only 0.1 kg/m(2). year with Tithonia diversifolia green manure. Biochar application reduced the rate of CO(2)-C loss by 27%, and T. diversifolia increased CO(2)-C losses by 22% in the C-poor soils. With biochar application, a greater proportion of C (6.8 times) was found in the intra-aggregate fraction per unit C respired than with green manure, indicating a more efficient stabilisation in addition to the chemical recalcitrance of biochar. In SOC-poor soils, biochar application enriched aromatic-C, carboxyl-C, and traces of ketones and esters mainly in unprotected organic matter and within aggregates, as determined by Fourier-transform infrared spectroscopy. In contrast, additions of T. diversifolia biomass enriched conjugated carbonyl-C such as ketones and quinones, as well as CH deformations of aliphatic-C mainly in the intra-aggregate fraction. The data indicate that not only the stability but also the stabilisation of biochar exceeds that of a labile organic matter addition such as green manure.