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Effects of biochar amendment in two soils on greenhouse gas emissions and crop production

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Abstract

Background Worldwide, there is an increasing interest in using biochar in agriculture to help mitigate global warming and improve crop productivity. Methods The effects of biochar on greenhouse gas (GHG) emissions and rice and wheat yields were assessed using outdoor pot experiments in two different soils (upland soil vs. paddy soil) and an aerobic incubation experiment in the paddy soil. Results Biochar addition to the upland soil increased methane (CH 4) emissions by 37 % during the rice season, while it had no effect on CH 4 emissions during the wheat season. Biochar amendment decreased ni-trous oxide (N 2 O) emissions up to 54 % and 53 % during the rice and wheat seasons, respectively, but had no effect on the ecosystem respiration in either crop season. In the aerobic incubation experiment, biochar addition significantly decreased N 2 O emissions and increased carbon dioxide (CO 2) emissions from the paddy soil (P<0.01) without urea nitrogen. Biochar addition increased grain yield and biomass if applied with nitrogen fertilizer. Averaged over the two soils, biochar amendments increased the production of rice and wheat by 12 % and 17 %, respectively, and these increases can be partly attributed to the increases in soil nitrate retention. Conclusions Our results demonstrated that although biochar increased the global warming potential at high nitrogen fertilizer application, biochar incorporation significantly decreased N 2 O emissions while promoting crop production.
REGULAR ARTICLE
Effects of biochar amendment in two soils on greenhouse gas
emissions and crop production
Jinyang Wang &Xiaojian Pan &Yinglie Liu &
Xiaolin Zhang &Zhengqin Xiong
Received: 4 December 2011 / Accepted: 3 April 2012
#Springer Science+Business Media B.V. 2012
Abstract
Background Worldwide, there is an increasing interest
in using biochar in agriculture to help mitigate global
warming and improve crop productivity.
Methods The effects of biochar on greenhouse gas
(GHG) emissions and rice and wheat yields were
assessed using outdoor pot experiments in two differ-
ent soils (upland soil vs. paddy soil) and an aerobic
incubation experiment in the paddy soil.
Results Biochar addition to the upland soil increased
methane (CH
4
) emissions by 37 % during the rice
season, while it had no effect on CH
4
emissions during
the wheat season. Biochar amendment decreased ni-
trous oxide (N
2
O) emissions up to 54 % and 53 %
during the rice and wheat seasons, respectively, but
had no effect on the ecosystem respiration in either
crop season. In the aerobic incubation experiment,
biochar addition significantly decreased N
2
Oemis-
sions and increased carbon dioxide (CO
2
) emissions
from the paddy soil (P<0.01) without urea nitrogen.
Biochar addition increased grain yield and biomass if
applied with nitrogen fertilizer. Averaged over the two
soils, biochar amendments increased the production of
rice and wheat by 12 % and 17 %, respectively, and
these increases can be partly attributed to the increases
in soil nitrate retention.
Conclusions Our results demonstrated that although
biochar increased the global warming potential at high
nitrogen fertilizer application, biochar incorporation
significantly decreased N
2
O emissions while promot-
ing crop production.
Keywords Biochar .Greenhouse gas emissions .Crop
yield .Rice and wheat rotation .Paddy soil
Introduction
Worldwide, there is increasing concern over climate
change and sustainable agricultural production (Lal
2004). Agriculture is a major contributor of green-
house gases (GHG) to the environment, and these
agricultural emissions (60 % of N
2
O and 50 %
of CH
4
)are1012 % of the total global anthro-
pogenic emissions in 2005 (Smith et al. 2007).
Moreover, the global human population is
expected to increase to 9.2 billion by 2050, which
willinevitablyresultinanincreasingdemandfor
food and fiber supplies from a decreasing supply
of arable land (U.N. Population Division 2008).
Therefore, it is urgent to establish effective agri-
cultural management practices that can mitigate
GHG emissions while increase crop production.
Plant Soil
DOI 10.1007/s11104-012-1250-3
Responsible Editor: Johannes Lehmann.
J. Wang :X. Pan :Y. Liu :X. Zhang :Z. Xiong (*)
Jiangsu Key Laboratory of Low Carbon Agriculture
and GHG Mitigation, College of Resources
and Environmental Sciences,
Nanjing Agricultural University,
Nanjing 210095, China
e-mail: zqxiong@njau.edu.cn
The application of biochar to agriculture has been
proposed as an appealing approach for mitigating
GHG emissions and improving crop productivity
(Lehmann et al. 2006,2011). Biochar, which is pro-
duced by artificial pyrolysis (under a limited O
2
sup-
ply), is not only the byproduct of a renewable energy
source but can also be used for carbon sequestration
(Lehmann et al. 2006). Moreover, biochar can be used
to improve soil fertility and increase the crop produc-
tivity (Chan et al. 2008; Glaser et al. 2002; Lehmann
et al. 2003; Major et al. 2010; Zhang et al. 2011).
Woolf et al. (2010) have estimated that annual net
emissions of CO
2
,N
2
O and CH
4
could be reduced
by 12 % of current anthropogenic CO
2
C equivalent
emissions due to sustainable global implementation of
biochar without endangering food security, habitat or
soil conservation.
In agricultural experiments, however, the effects of
biochar on GHG emissions and crop productivities
have yet been inconsistent. The responses of CH
4
emissions from paddy soils to biochar amendments
were inconsistent, and the underlying mechanisms
are still unclear (Knoblauch et al. 2011; Liu et al.
2011; Zhang et al. 2010). For example, CH
4
emissions
from soils after biochar additions were 33 % greater
than those without biochar additions in a paddy field
(Zhang et al. 2010). For paddy soils amended with rice
residue biochar, however, Knoblauch et al. (2011)
found that there was no significant difference in CH
4
emissions between the biochar plot and the control
plot during the following year. On the other hand,
CH
4
uptake increased in various studies after biochar
additions (Karhu et al. 2011; Scheer et al. 2011; Zhang
et al. 2011). In addition, the use of biochar significant-
ly reduced the N
2
O emissions from various studied
soils (Singh et al. 2010; Taghizadeh-Toosi et al. 2011;
Wang et al. 2011a; Zhang et al. 2010,2011). For
example, the incorporation of biochar into pasture soil
that contained ruminant urine reduced N
2
O emissions
by up to 70 % (Taghizadeh-Toosi et al. 2011). Zhang
et al. (2010,2011) also reported that biochar additions
significantly lowered the N
2
O emissions from both
paddy and upland soils. However, Singh et al. (2010)
observed that N
2
O emissions following the addition of
biochar were dependent on the nitrogen (N) content of
the biochar feedstock (poultry manure versus wood).
Similarly, Spokas and Reicosky (2009) and Clough et
al. (2010) observed these specific effects of biochar.
Moreover, biochar additions had no significant effect
on seasonal total N
2
O emissions from an intensive
subtropical pasture soil (Scheer et al. 2011)anda
Mediterranean wheat crop soil (Castaldi et al. 2011).
Biochar amendment affects carbon cycling and
CO
2
emissions by changing the characteristics of the
soil and of the microbial community. Moreover, bio-
char itself can be decomposed by microbes to some
extent in soils (Czimczik and Masiello 2007). The
widely varying effects of biochar on CO
2
emissions
(Karhu et al. 2011; Scheer et al. 2010; Wang et al.
2011a; Zhang et al. 2011) underscore the necessity for
elucidating the underlying causative mechanisms. Us-
ing a meta-analysis, Jeffery et al. (2011) found that the
incorporation of biochar into soils improved the crop
productivity by approximately 10 %, however, the
results varied with the soil properties, land manage-
ment practices, experimental crops and biochar feed-
stock. Therefore, determining the specific responses of
crops and soils to the addition of biochar requires a
series of experiments using various biochars and soils.
The annual rotation of rice and wheat is the domi-
nant cropping system in China, whose agricultural
sector is responsible for feeding one of the worlds
most populous countries. In this study, we conducted
two outdoor pot experiments with different soils
(upland soil vs. paddy soil) and an aerobic incubation
with paddy soil to simulate the dominant rice-wheat
cropping system in Southern China. The objectives of
this study were to investigate the effects of biochar on
CH
4
,N
2
O and CO
2
emissions from two different soils
as well as to determine the agronomic values of bio-
char in terms of crop production and soil properties.
Materials and methods
Experimental soils and biochar
Two soils from areas with different land uses (i.e.,
upland soil vs. paddy soil) in Nanjing, China were
selected for this study. Samples of the two soils were
manually collected from the cultivated surface layer
(020 cm) and their physico-chemical characteristics
were analyzed. The upland soil was classified as
Orthic Anthrosols (RGCST 2001); it had the texture
of clay loam, a bulk density of 1.16 gcm
3
, an initial
pH (1:2.5, H
2
O) of 7.8, an organic C content of 4.8 g
kg
1
, a total N content of 0.42 gkg
1
and a mineral N
content of 18.5 mg N kg
1
. The paddy soil was
Plant Soil
classified as Stagnic Anthrosols (RGCST 2001); it had
the texture of silt loam, a bulk density of 1.28 gcm
3
,
an initial pH (1:2.5, H
2
O) of 6.6, an organic C content
of 14.7 gkg
1
, a total N content of 1.32 g kg
1
and a
mineral N content of 31.4 mg N kg
1
.
The biochar was produced from rice husks at a
temperature of approximately 450°C by a local
pyrolysis plant. The biochar had a total C content
of 465.4 gkg
1
, a total N content of 6.2 gkg
1
,a
pH of 9.1 (1:1.25 H
2
O), a mineral N content of
38.9 mg N kg
1
and cation exchange capacity of
17.9 cmol kg
1
.
Pot experiments
Outdoor pot experiments were carried out in both the
upland and the paddy soils; in these experiments, the
annual rice-wheat cropping rotations were followed.
Three (0, 25 and 50 tha
1
for the upland soil) or four
(0, 10, 25 and 50 tha
1
for the paddy soil) biochar
application rates and two nitrogen fertilizer application
rates (Nil N, 0; N, 200 kg N ha
1
) were included in a
factorial randomized block design; each experiment
was replicated three times.
The outdoor pot experiments in the upland soil
were performed at the greenhouse experimental station
of Nanjing Agriculture University, China. A specially
designed PVC pot (with a diameter of 45 cm and a
height of 50 cm) was used to measure the greenhouse
gas emissions. The top was covered with a water-filled
trough that allowed a chamber to sit on the pot and
prevented gas exchange during the gas sampling peri-
ods. The bottom of the pot had a hole (diameter of
1 cm) for rainfall percolation and for drainage during
the rice-growing season. For the outdoor paddy soil
experiment, the pots were buried in situ in a paddy
field located at Moling town, Nanjing, China; each pot
was 15 cm in diameter, had a height of 30 cm without
top or bottom.
A similar procedure was followed for two soils.
Soil samples were manually collected from the culti-
vated surface layer (020 cm) after the wheat harvest.
The samples were air-dried and passed through a 5-cm
stainless steel mesh sieve. Any visible roots or organic
residues were removed manually and then mixed thor-
oughly before being packed into the pots. All of the
pots were packed with the necessary amount of soil
to achieve the field bulk density of 1.25 gcm
3
.For
the biochar amendment plots, biochar was mixed
thoroughly within the top 020 cm layer. Then, irri-
gation water was added into the pots to maintain
40 % of the water holding capacity (WHC) for seven
days before rice season.
Four hills (each with 3 seedlings) for the upland
soil and 2 hills (each with 2 seedlings) for the paddy
soil were transplanted during the rice season; the seeds
were evenly sown during the wheat season for two
soils. For both the rice and wheat seasons, urea was
used as a N fertilizer, and it was applied at a split ratio
of 4:3:3. For each crop, calcium superphosphate was
used as a phosphate fertilizer and was applied at a rate
of 120 kg P
2
O
5
ha
1
, and potassium chloride was used
as a potassium fertilizer and was applied at a rate
of 60 kg K
2
Oha
1
. In accordance with the local
agricultural practice, the water regime of flooding-
midseason drainagereflooding-final drainage was
adopted for the rice season; during the wheat
season, the water was drained and irrigation was
provided by precipitation.
Aerobic incubation
For the paddy pot experiment, no gas samples were
collected during the rice and wheat growing seasons.
Alternatively, an aerobic incubation experiment was
conducted to mimic the wheat growing season. The
soil samples that were used for the incubation were
similarly prepared with the pot experiment. Four treat-
ments were performed with four replications: soil con-
trol (ck), soil plus biochar (B), soil plus urea N (N),
and soil plus urea N plus biochar (BN). The aerobic
incubation was performed according to the procedure
describedbyWangetal.(2011a). A 7-day pre-
incubation in the dark under 40 % WHC at 25±1°C
was adopted for stabilization. During the subsequent
60-day aerobic incubation (25±1°C, 60 % WHC by
adding distilled water every 2 or 3 days), urea was
applied at a rate of 200 mg N kg
1
soil and biochar
was applied at a rate of 26.67 gkg
1
soil, which is
equivalent to a field application rate of 50 t ha
1
.
Another set was simultaneously prepared and in-
cubated for determining the changes in soil miner-
al N content at day 1, 3, 7, 10, 17, 30, 41 and 60.
The N mineralization of the paddy soil was
expressed as the difference in soil inorganic N
(NO
3
-N plus NH
4
+
-N) changes over the whole
incubation period.
Plant Soil
Gas sampling and analysis
Gas samples were collected from the upland soil pot
experiment during the rice and wheat growing season
using the static opaque chamber method (Wang et al.
2011b) and from the paddy soil during the aerobic
incubation (Wang et al. 2011a). Methane, N
2
O and
CO
2
were analyzed for the upland soil samples while
N
2
O and CO
2
were analyzed for the paddy soil sam-
ples. The chambers were 50×50× 60/130 cm in height
and they were adapted to crop growth. The chamber
was equipped with a circulating fan to ensure com-
plete gas mixing and wrapped with sponge and alumi-
num foil to minimize temperature changes inside the
chamber during gas sampling. The gas fluxes were
usually measured once a week and more frequently
after the application of fertilizer and during drainage
periods. For each measurement, four gas samples were
withdrawn from the chamber through a three-way
stopcock using a 25-ml air-tight syringe at 10 min
intervals (0, 10, 20 and 30 min after closure). The
temperature in the chamber was manually measured
during the period of gas sampling.
For the paddy soil incubation experiment, after 7-
days pre-incubation, the headspace air was sampled
after 1, 2, 3, 4, 5, 6, 7, 10, 11, 15, 17, 18, 20, 23, 25,
30, 35, 40, 45, 50, 55 and 60 days of incubation. For
each measurement, an ambient air gas sample was
included as the initial concentration for calculating
the emission rate during the 2-hour enclosure. The
headspace air in the flasks was thoroughly flushed with
ambient air for 15 min at a rate of 200 ml min
1
.The
flasks were then capped immediately with silicone
(NQ-704 silicone adhesive sealant) rubber stoppers that
were fitted with butyl rubber septum and allowed to sit
for 2 h. These stoppers provided an airtight seal. After
the gas sampling, the flask was flushed with ambient air
and left open.
The gas samples were analyzed using a gas chro-
matograph (Agilent 7890A, USA) that was equipped
with two detectors. Methane and CO
2
were detected
using a hydrogen flame ionization detector (FID) and
N
2
O was detected using an electron capture detector
(ECD). Carbon dioxide was reduced to CH
4
by hy-
drogen; this reduction occurred in a Nickel catalytic
converter at 375°C. Argon-methane (5 %) and N
2
were used as the carrier gas at a flow rate of
40 ml min
1
for N
2
O and CH
4
analysis, respectively.
The temperatures of the column and the ECD were
maintained at 40°C and 300°C, respectively. The oven
and the FID were operated at temperatures of 50°C
and 300°C, respectively. The CH
4
,N
2
OandCO
2
concentrations were quantified by comparing their
peak areas with those of reference gases (Nanjing
special gas factory). The fluxes were determined from
the change in the slope of the mixing ratio of the
collected samples after the chamber or flask was
closed. The seasonal or cumulative greenhouse gas
emissions were sequentially cumulated from two ad-
jacent measurements (Wang et al. 2011b).
Plant and soil sampling and analysis
The same pot was used for the rice and the wheat
crops. After ripening, the whole plants were harvested
by removing them from the pots. The plants were
washed with distilled water and oven-dried at 85°C
to a constant weight; they were then weighed to deter-
mine the dry biomass production, which included the
grain yield and the total biomass.
After one annual rotation of rice and wheat crops,
three to five soil cores were collected after the wheat
harvest from the surface layer (020 cm) of each pot
and were mixed thoroughly for soil analysis. Accord-
ing to Lu (2000), soil texture was measured by the
pipette analysis; total soil organic C was analyzed by
wet-digestion with H
2
SO
4
K
2
Cr
2
O
7
and total N was
determined by semi-micro Kjeldahl digestion and
Nesslers colorimetric method. The soil NO
3
-N and
NH
4
+
-N were extracted with 2 M KCl solution at a
soil/water ratio of 1:5 at 25°C and measured following
the two wavelength ultraviolet spectrometry and indo-
phenol blue method, respectively, using the ultraviolet
spectrophotometer (HITACHI, U-2900, Japan). The
soil pH values were measured in a volume ratio of
1:2.5 by PHS-3 C mv/pH detector (Shanghai, China).
Data and statistical analyses
The statistical analyses were carried out using JMP
statistical software, Version 7.0 (SAS Institute, Cary,
NC, USA). A two-way factorial analysis of variance
(ANOVA) was used to determine whether the seasonal
(or cumulative) CH
4
,N
2
OorCO
2
emissions were
affected by biochar (B), N fertilizer (N) or their inter-
action in two soils. We also performed two-way
ANOVA to determine whether the crop production,
the soil mineral N content or the pH were influenced
Plant Soil
by B, N or their interaction. Multiple comparisons
among the different treatments were performed using
Studentst-test. The statistical level of significance
was chosen at P00.05 for all statistical analyses.
Results
The effect of biochar on the CH
4
,N
2
O and CO
2
emissions
In the upland soil experiment, the temporal dynamics
of the CH
4
,N
2
O and CO
2
emission rates during the
rice- and wheat-growing seasons followed similar
trends, however, the amplitudes of the fluxes of the
greenhouse gas varied among the different treatments
(data not shown). During the rice-growing season, the
incorporation of biochar substantially increased the
CH
4
emissions and decreased the N
2
O emissions
(P<0.05), while had no significant effect on the
ecosystem respiration (Table 1). Compared with the
control, biochar amendment (indicated by the average
of the B1 and B2 biochar application rates in this
study) increased the seasonal CH
4
emissions by 41 %
and 33 % for the treatments with and without N fertil-
izer, respectively (Table 2). Biochar amendment re-
duced the seasonal N
2
O emissions, on average, by
38 % and 70 % for the treatments with and without N
fertilizer, respectively (Table 2). During the wheat-
growing season, biochar amendment significantly re-
duced the N
2
O emissions (P<0.05) but had no effect
on the CH
4
emissions or the ecosystem respiration
(Table 1). Compared with the control, biochar reduced
the seasonal N
2
O emissions, on average, by 44 % and
61 % for the treatments with and without N fertilizer,
respectively (Table 2). No significant differences were
detected for all the measured parameters between dif-
ferent biochar rates when no N fertilizer was added,
while obvious differences were detected in the N
2
O
emissions during the rice season and in ecosystem
respirations during the wheat season when N fertil-
izer was added. Over the whole rice-wheat rotation,
biochar amendment tended to increase the global
warming potentials of CH
4
and N
2
O on a 100-
year horizon, especially when high N fertilizer
was applied (Table 2).
In the aerobic incubation experiment with paddy
soil, the cumulative amounts of N
2
O and CO
2
emis-
sions are shown in Fig. 1a and b, respectively. The
analysis of variance (ANOVA) indicated that the N
2
O
emission was significantly reduced due to biochar
addition (Table 1, Fig. 1a). The addition of biochar,
on average, increased the CO
2
emission from the soil
(Table 1,Fig.1b). Significant interactions between
biochar addition and N fertilization occurred for both
the N
2
OandCO
2
emissions (Table 1, Fig. 1), thus the
N
2
O reduced effect was significant when no urea N
was added, while insignificant when urea N was added
(Fig. 1a). Similarly, the stimulatory effect of biochar
addition on the CO
2
emissions was significant when
no urea N was added, while insignificant when urea N
was added (Fig. 1b). Since no obvious effect was
observed for N fertilizer on the CO
2
emissions, there
was no obvious difference between the treatments B
and BN (Table 1, Fig. 1b).
The effect of biochar on crop production
Nitrogen fertilization significantly increased the rice
grain yield and the total biomass (Table 3, Fig. 2a and
b). The effects of biochar amendment on the rice grain
yield and the total biomass were dependent on N
fertilization. Generally, biochar addition increased rice
Table 1 Analysis of variance (ANOVA) Fvalues for the effects
of biochar (B), nitrogen fertilizer (N) and their interaction on
greenhouse gas emissions from the upland soil during the rice-
and wheat-growing seasons and from the paddy soil under
aerobic incubation
df CH
4
N
2
OCO
2
Upland soil
Rice B 2 6.01*
a
5.18* 1.33ns
N 1 5.80* 25.80*** 192.64***
B×N 2 0.23ns 1.80ns 0.06ns
R
2
0.6 0.77 0.94
Wheat B 2 0.02ns 5.74* 3.05ns
N 1 0.01ns 28.31*** 266.02***
B×N 2 0.06ns 0.65ns 1.25ns
R
2
0.01 0.77 0.96
Paddy soil
B111.93** 11.81**
N1250.54*** 0.01ns
B×N 1 6.10* 11.80**
R
2
0.96 0.66
a
*P<0.05, ** P< 0.01, *** P< 0.001, ns not significant
Plant Soil
grain yield and biomass if applied with N fertilizer. In
the Nil N treatments, however, it had no effect on rice
grain yield and biomass or even a negative one. Aver-
aged over N treatments, biochar addition increased
both the rice grain yield and the total biomass by
13 % and 13 % in the upland soil, respectively, and
by 9 % and 14 % in the paddy soil, respectively, as
compared with the control (Fig. 2a and b). The inter-
action between biochar addition and N fertilization
occurred on the rice grain yield and the total biomass
in the paddy soil (Table 3).
Similarly, N fertilization significantly increased the
wheat grain yield and the total biomass (Table 3,
Fig. 2c and d). The effects of biochar amendment on
the wheat grain yield and the total biomass were also
dependent on N fertilization. Generally, biochar addi-
tion increased wheat grain yield and biomass if ap-
plied with N fertilizer. In the Nil N treatments,
however, it had no effect on wheat grain yield and
biomass (Fig. 2c and d). Averaged over N treatments,
biochar addition increased the wheat grain yield and
the total biomass by 10 % and 9 % in the upland
soil, respectively, and by 20 % and 26 % in the
paddy soil, respectively, as compared with the con-
trol (Fig. 2c and d). The interaction between bio-
char addition and N fertilization occurred on the
wheat grain yield and the total biomass for both
the studied soils (Table 3).
The effects of biochar on the soil mineral N content
and the pH
For the paddy soil incubation experiment, the net
amounts of N mineralization for the ck, B, N, and BN
treatments were 26.6, 31.0, 63.6 and 25.3 mg N kg
1
soil, respectively; and the corresponding net amounts of
nitrification were 31.8, 16.0, 67.9 and 41.4 mg N
kg
1
. As shown in Fig. 3, biochar addition thus
obviously inhibited the apparent soil mineralization
and nitrification.
For the pot experiments, both biochar and N fertil-
izer significantly increased the nitrate content in the
two soils, while had no significant effect on the soil
ammonium-N content after one annual crop rotation
(Tables 3and 4). Compared with the control and
averaged over N treatments, biochar amendment
increased the nitrate content by 28 % in the upland
soil and by 13 % in the paddy soil (Table 4). There
was an obvious interaction between biochar addition
and N fertilization on soil nitrate contents. When N
was added, the nitrate retention due to biochar addition
was enhanced with significant difference among bio-
char rates in the paddy soil (Tables 3and 4).
The addition of biochar increased the values of the
soil pH by 0.09 and 0.22 units for the upland and
paddy soils, respectively (P<0.010.001, Table 4).
When N fertilizer was applied, the pH increase effect
Table 2 Effects of biochar (B) and N fertilizer (N) on the seasonal emissions of CH
4
,NO
2
and CO
2
from the upland soil during the
rice- or wheat-growing seasons
Treatment Rice season Wheat season GWP (CH
4
+N
2
O)
c
CH
4
(kg Cha
1
)
N
2
O
(kg Nha
1
)
CO
2
(kg Cha
1
)
CH
4
(kg Cha
1
)
N
2
O
(kg Nha
1
)
CO
2
(kg Cha
1
)
Nil N
a
B0 16.7± 4.24c
b
0.05± 0.01b 1850.9 ±178.8b 0.16± 3.67a 0.09 ±0.01bc 436.8± 7.6c 454.5± 193.6b
B1 21.7± 1.10abc 0.01 ±0.0b 1540.8±198.1b 1.27± 1.46a 0.04±0.02c 397.7± 31.8c 586.1 ±12.7ab
B2 22.8± 1.28abc 0.02 ±0.0b 1458.8±386.6b 0.05± 0.21a 0.03±0.01c 491.5± 53.4c 595.8 ±69.9ab
N B0 19.6±0.57bc 0.12± 0.0a 4262.2 ±87.3a 0.34 ± 1.30a 0.27± 0.04a 1263.4± 104.1ab 614.5 ±23.1ab
B1 26.6± 2.80ab 0.10 ±0.04a 3978.1 ±229.9a 0.22 ±5.89a 0.16± 0.06b 1181.7± 107.0b 737.8± 62.1a
B2 28.7± 1.82a 0.05±0.01b 4017.7± 62.3a 0.78± 0.83a 0.14 ±0.03b 1441.1± 121.6a 791.9± 46.8a
a
B0, B1 and B2 refers to the biochar application rates at 0, 25, 50 tha
1
, respectively; two nitrogen fertilizer application rates at 0 for
Nil N and 200 kg N ha
1
) for N treatments.
b
Mean values ± standard error. Different letters within the same column indicate significant differences in parameters among treatments
using Studentst-test (P00.05).
c
The global warming potential (GWP) was calculated by CH
4
and N
2
O over the whole rice-wheat rotation; the IPCC GWPs factors
(mass basis) for CH
4
and N
2
O are 25 and 298, respectively in the time horizon of 100 years (IPCC 2007).
Plant Soil
of biochar was reduced; in the Nil N treatments, bio-
char addition accounted for 38 % and 42 % of the pH
increase in the upland and paddy soils, respectively
(Tables 3and 4).
Discussion
CH
4
emissions
In the pot experiment, averaged over N treatments, the
addition of biochar increased CH
4
emissions by an
average of 37 % during the rice season, while it had
no significant effect during the following wheat-
growing season when negligible amounts of CH
4
were
emitted (Tables 1and 2). The former result is in good
agreement with previous studies that biochar addition
promoted CH
4
emissions from rice fields (Knoblauch
et al. 2008,2011; Zhang et al. 2010). In a short-term
laboratory incubation experiment, however, Liu et al.
(2011) found that CH
4
emissions from paddy soil were
significantly reduced after the addition of biochar.
Other studies have reported that biochar amendment
reduces CH
4
emissions or has no significant effect on
CH
4
emissions as compared with their controls (Castaldi
et al. 2011; Karhu et al. 2011; Rondon et al. 2005;
Scheer et al. 2011; Zhang et al. 2011). The effects of
biochar addition on CH
4
emissions were thus inconsis-
tent and the underlying mechanisms may vary with the
soil type, the agricultural management technique and the
origin of the biochar (Lehmann et al. 2011).
On the one hand, the addition of biochar to flooded
rice paddies increases the substrate supply and creates
a favorable environment for methanogenic activity
(Kögel-Knabner et al. 2010; Lehmann et al. 2011).
The labile components of biochar can be decomposed
and become the predominant source of methanogenic
substrates, particularly in the early stages of rice grow-
ing season (Knoblauch et al. 2008). The biochar addi-
tion increased the rice biomass in this study (Fig. 2a
and b), which may partly be responsible for the in-
creased CH
4
emissions (Lehmann et al. 2011). On the
other hand, biochar addition may increase the soil
aeration resulting in the oxidation of CH
4
and the high
porosity and large surface area of aerated soil may
enhance CH
4
adsorption (Karhu et al. 2011; Rondon
et al. 2006; Yanai et al. 2007; Zhang et al. 2011), both
leading to reductions of CH
4
emissions from soils.
These may probably contribute to the negligible CH
4
emissions during the wheat season in our study. CH
4
emissions have been demonstrated to variy widely
with water regime (Cai et al. 1997), the type of soil
(Xiong et al. 2007) and the feedstock source and
chemical properties of biochar (Van Zwieten et al.
2010); these results highlighted that more studies are
needed to elucidate the mechanisms of CH
4
emissions
in biochar-amended soils.
N
2
O emissions
Nitrogen fertilization significantly increased N
2
O
emissions in our study, which was highly consistent
with numerous previous studies (Cai et al. 1997; Wang
0
10
20
30
40
50
0 102030405060
Cumulative amount of N2O-N
(mg kg-1 soil)
ck
NBN
B
a
Student's t-test:
ck (b), B(c), N(a), BN(a)
0
100
200
300
400
500
0 102030405060
Cumulative amount of CO2-C
(mg kg-1 soil)
Incubation time (da
y
)
bStudent's t-test:
ck(c), B(a), N(b), BN(ab)
Fig. 1 Cumulative amounts of N
2
O(a) and CO
2
(b) emissions
from the aerobic incubated paddy soil. The vertical bars repre-
sent the standard errors for each treatment, which were calcu-
lated from four replicate samples. Significant differences
between the means are indicated by different letters within the
same parameter (Studentst-test)
Plant Soil
et al. 2011a,b; Xiong et al. 2007). Nitrous oxide emis-
sions from the soil amended with biochar have often
depended on the inherent characteristics of biochar,
the addition of exogenous nitrogen and soil properties
(Clough et al. 2010; Spokas and Reicosky 2009;
Scheer et al. 2011; Zhang et al. 2010). The addition
of biochar significantly reduced N
2
O emissions during
both cropping seasons and also from the aerobic
Table 3 ANOVA Fvalues for the effects of biochar (B), N fertilizer (N) and their interaction on the grain yield and total biomass of rice
and wheat as well as on the NO
3
-N and NH
4
+
-N content and the pH of the two different soils after the wheat harvest
df Rice Wheat NO
3
-N NH
4
+
-N pH
Grain yield Total biomass Grain yield Total biomass
Upland soil
B 2 5.02*
a
5.54* 13.22** 8.21** 7.02** 0.75ns 10.06**
N 1 184.88*** 314.80*** 4183.06*** 1834.03*** 9.49** 0.02ns 55.95***
B×N 2 0.70ns 0.97ns 5.31* 4.23* 4.01* 0.64ns 1.10ns
R
2
0.94 0.96 1.00 0.99 0.55 0.09 0.87
Paddy soil
B 3 4.36* 14.78*** 8.10** 9.19*** 12.74*** 0.14ns 19.92***
N 1 353.89*** 553.26*** 82.62*** 85.99*** 139.35*** 0.22ns 7.93*
B×N 3 18.54*** 15.78*** 5.80** 4.42* 6.38** 0.49ns 3.64*
R
2
0.96 0.98 0.89 0.89 0.92 0.12 0.83
a
*P<0.05, **P< 0.01, ***P< 0.001, ns not significant
0
30
60
90
120
150
180
B0 B1 B2 B0 B1 B2
Wheat biomass (g pot-1)
NNliN
A
B
C
DD
D
a
b
c
d
dd
c
0
100
200
300
400
500
600
Rice biomass (g pot-1)
Grain yield
Total biomass
A
BB
CCC
a
ab
b
ccc
a
upland
0
15
30
45
60
75
90
B0 B1 B2 B3 B0 B1 B2 B3
Wheat biomass (g pot-1)
NNliN
A
BB
B
C
C
CC
a
b
b
bc
cd
d
dd
d
0
50
100
150
200
250
300
Rice biomass (g pot-1)
BAB A
C
DDE EE
aa
b
c
d
ddd
b
paddy
Fig. 2 Effects of biochar (B) and N fertilizer (N) on the grain
yields and the total biomass of rice and wheat crops that were
grown in the upland (a,c) and paddy (b,d) soils. The bars
indicate the standard errors of the means (±SE) for each
treatment, which were calculated from four replications. Signif-
icant differences between the treatments are indicated by differ-
ent letters within the same parameter (Studentst-test)
Plant Soil
incubation treatments when no urea N was added
(Tables 1and 2, Fig. 1a). These results are in good
agreement with previous studies (Clough et al. 2010;
Rondon et al. 2005,2006; Zhang et al. 2010). Biochar
may suppress N
2
O emissions by increasing the pH as
found in this study (Tables 3and 4). Increased soil
aeration by adding biochar may also be responsible for
reducing N
2
O emissions (Cavigelli and Robertson
2001; Zhang et al. 2011). Promoted microbial immo-
bilization of the available N in the soils by biochar
have also been proposed as underlying mechanisms in
N
2
O emission reduction (Rondon et al. 2005; Singh et
al. 2010; Wang et al. 2011a). Therefore, the depressed
net N mineralization of paddy soil following biochar
addition without urea N may also contribute to the
decreased N
2
O emissions (Table 1, Figs. 1a and 3).
Clough et al. (2010) found no significant difference
between biochar plus urine and urea alone in terms of
cumulative N
2
O emissions in silt loam pasture soil since
biochar additions did not reduce the inorganic-N pool,
which can also explain the results for the paddy soil
incubation experiment that the N
2
O reduction effect was
significant when no urea N was added while insignifi-
cant when urea N was added (Table 1,Figs.1a and 3).
0
20
40
60
80
100
0
40
80
120
160
0 102030405060
NO3--N content (mg kg-1 soil)
NH4+-N content (mg kg-1 soil)
Incubation time (da
y
)
Fig. 3 Dynamics of soil
NH
4
+
-N and NO
3
-N con-
tents in the aerobic incubat-
ed paddy soil. The vertical
bars represent the standard
deviation for each treatment.
ck, the control; B, soil plus
biochar; N, soil plus urea N;
BN, soil plus urea N plus
biochar
Table 4 Effects of biochar (B) and N fertilizer (N) on the NO
3
-N and NH
4
+
-N content and the pH of the two different soils after the
wheat harvest
Treatment Upland soil Paddy soil
NO
3
-N (mg Nkg
1
)NH
4
+
-N (mg Nkg
1
)pH NO
3
-N (mg Nkg
1
)NH
4
+
-N (mg Nkg
1
)pH
Nil N B0
a
2.00± 0.30c
b
0.38± 0.08a 7.85± 0.02b 15.09 ±1.15d 1.66 ±0.11a 6.57 ± 0.05b
B1 1.83± 0.23c 0.30 ±0.17a 7.98± 0.03a 15.42±1.92d 2.00± 0.39a 6.62± 0.02b
B2 2.31± 0.24bc 0.28 ± 0.05a 7.93±0.01a 16.61± 1.50d 1.81± 0.20a 6.94±0.03a
B3 13.58± 2.08d 2.13 ±0.27a 7.00 ± 0.02a
N B0 1.88 ± 0.11c 0.45± 0.14a 7.74 ±0.03c 23.22± 1.10c 2.04 ± 0.45a 6.56±0.01b
B1 2.68± 0.08ab 0.30 ± 0.07a 7.80±0.01bc 28.22 ± 1.50b 2.12± 0.54a 6.65±0.02b
B2 3.02± 0.09a 0.31 ±0.07a 7.81± 0.02b 36.43± 1.26a 2.08 ± 0.15a 6.66± 0.07b
B3 22.58± 1.06c 1.79 ±0.20a 6.86 ± 0.11a
a
B0, B1 and B2 refers to the biochar application rates at 0, 25, 50 tha
1
, respectively, for the upland soil; B0, B1, B2 and B3 refers to
the biochar application rates at 0, 10, 25, 50 tha
1
, respectively, for the paddy soil.
b
Mean values ± standard error. Different letters within the same column indicate significant differences in parameters among the
treatments using Studentst-test (P00.05).
Plant Soil
CO
2
emissions
Nitrogen fertilization increased the respiration of the
soil-plant ecosystem by increasing the accumulation
of biomass and improving the bioavailability of C to
soil microbes (Table 1), which is in good agreement
with previous results (Raich and Schlesinger 1992).
The addition of biochar did not increase the ecosystem
respiration during either crop season in the upland soil
(Tables 1and 2), which is in accordance with Knoblauch
et al. (2008) who found that charred rice residues had no
effect on the carbon mineralization or CO
2
emissions of
paddy soil over about two years of oxic incubation. The
addition of biochar and N fertilizer even suppressed the
microbial respiration by other studies (Iqbal et al. 2009;
Zhang et al. 2011). However, some studies reported that
biochar addition stimulated the evolution of soil CO
2
(Kuzyakov et al. 2009; Smith et al. 2010;Wangetal.
2011a), which was also confirmed by our study of the
short-term paddy soil incubation when no urea N was
added (Fig. 1b). After the addition of biochar, either the
organic C in the soil, the added labile organic matter
(Zimmerman et al. 2011) or the biochar C could be lost
simultaneously (Lehmann and Sohi 2008; Luo et al.
2011) for a short time (Nguyen et al. 2010). The initial
CO
2
emission increase could be attributed to the biochar
mineralization reported by Smith et al. (2010)withthe
δ
13
CCO
2
signature. Usually, the biochar decomposi-
tion rate was initially high due to the water-soluble
carbon (Nguyen and Lehmann 2009)andde-
creased to approximately 1 % of the initial decom-
position rate and remained constant during the
second and third years of laboratory incubation
(Kuzyakov et al. 2009). Therefore, though biochar
addition tended to initially increase CO
2
evolution
for a relatively short-term, it could be served as
long-term C sequestration acting as a recalcitrant C
in soil (Lehmann et al. 2011).
Effect of biochar on the crop production
In this study biochar addition increased grain yield and
biomass if applied with N fertilizer. Without N fertil-
izer, it had no effect on grain yield and biomass or
even a negative one (Fig. 2). Biochar addition follow-
ing N fertilization increased rice and wheat grain
yields and the total biomass (Tables 3and 4), which
is in good agreement with other paddy field results
(Asaietal.2009; Zhang et al. 2010). By a meta-
analysis, Jeffery et al. (2011) found that the incorpo-
ration of biochar into soils improved the crop produc-
tivity by 10 %. Both pot and field experiments have also
demonstrated that the addition of biochar increases the
crop biomass and grain yields, and often show much
higher increase rates (Lehmann et al. 2003;Lehmann
et al. 2006; Steiner et al. 2007; Van Zwieten et al. 2010).
In these experiments, biochar application rates varied
from less than 1 to over 100 tha
1
, and the increase in
crop biomass ranged from less than 10 % to over 200 %
relative to the controls (Chan et al. 2008; Jeffery et al.
2011; Lehmann et al. 2003; Major et al. 2010). These
wide variations were strongly depended on the types of
soils, crops and biochars that were used (Jeffery et al.
2011; Van Zwieten et al. 2010). To our knowledge,
biochar addition increased crop biomass by increas-
ing the amount of microelements, increasing the soil
pH and water holding capacity, and reducing the
amount of exchangeable Al in the soil (Asai et al.
2009; Chan et al. 2008; Major et al. 2010;Van
Zwieten et al. 2010).
Biochar amendment at rates of 10 and 25 t ha
1
,
together with N fertilization, increased the soil nitrate
content and thus improved N availability for crop
growth (Fig. 2), which was confirmed by previous
studies (Asai et al. 2009; Chan et al. 2008; Lehmann
et al. 2003). The increased soil nitrate retention due to
biochar addition would be thus responsible for the
improved crop production with N fertilization in this
study (Fig. 2). However, Van Zwieten et al. (2010)
attributed the different responses of crop biomass to
biochar addition between the calcarosol and ferrosol
soils to the difference in soil pH. When no N fertilizer
was added, both rice and wheat production were not
promoted or even inhibited by biochar addition
(Fig. 2), which was in accordance with results from
tropical regions that have relatively poor soils (Asai et
al. 2009; Steiner et al. 2007). Moreover, without
exogenous N addition, biochar amendment clearly
lowered paddy soil nitrate content (Fig. 3), which is
opposite to the nitrate response when planted with
crops (Table 4). Future research should therefore inves-
tigate the effect of biochar amendment on crop produc-
tion under different types of soils and crops (Van
Zwieten et al. 2010). Additional targeted field experi-
ments are needed to determine where, how and when
biochar can have a positive effect on the soil biota and to
establish other agricultural best management practices
(e.g., fertilization and land use changes).
Plant Soil
Conclusions
Results suggested that incorporating biochar into both
the upland and paddy soils caused a substantial de-
crease in the N
2
O emissions during the flooded rice
and drained wheat seasons, although increased the
CH
4
emissions during the flooded rice season and
the total global warming potential when high N fertil-
izer applied. Moreover, biochar addition increased
both rice and wheat grain yield and biomass if applied
with N fertilizer for both the upland and paddy soils.
Therefore, future field studies should make an attempt
to elucidate the long-term responses of CH
4
and N
2
O
to biochar amendments and the underlying mecha-
nisms for increased crop production.
Acknowledgments We sincerely appreciate the editor Dr.
Johannes Lehmann and two anonymous reviewers for their
critical and valuable comments to help improve this manuscript.
This work was jointly supported by the National Science Foun-
dation of China (41171238 and 40971139), the National Basic
Research Program of China (2009CB118603), the Nonprofit
Research Foundation for Agriculture (200903003), the Program
for New Century Excellent Talent in Universities (NCET-10-
0475), the Doctoral Program of Higher Education of China
(20110097110001), the Fundamental Research Funds for the
Central Universities (KYZ201110) and the PAPD.
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biochar-amended soils. Soil Biol Biochem 43:11691179
Plant Soil
... A previous study revealed that the application of peanut shell-based biochar in red soil in sub-tropical regions effectively amended soil properties compared to other types of soil in temperate and sub-tropical regions . Furthermore, biochar application in paddy fields increased CH 4 emissions by an average of 37%, but an insignificant improvement was observed in dryland (Wang et al. 2012). Maucieri et al. reported that 50% soil water holding capacity (WHC) induced significant changes in soil redox conditions, which reduced soil CH 4 emissions compared to 75% WHC soil (Maucieri et al. 2017). ...
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Biochar has been extensively utilized to amend soil and mitigate greenhouse gas (GHG) emissions from croplands. However, the effectiveness of biochar application in reducing cropland GHG emissions remains uncertain due to variations in soil properties and environmental conditions across regions. In this study, the impact of biochar surface functional groups on soil GHG emissions was investigated using molecular model calculation. Machine learning (ML) technology was applied to predict the responses of soil GHG emissions and crop yields under different biochar feedstocks and application rates, aiming to determine the optimum biochar application strategies based on specific soil properties and environmental conditions on a global scale. The findings suggest that the functional groups play an essential role in determining biochar surface activity and the soil’s capacity for adsorbing GHGs. ML was an effective method in predicting the changes in soil GHG emissions and crop yield following biochar application. Moreover, poor-fertility soils exhibited greater changes in GHG emissions compared to fertile soil. Implementing an optimized global strategy for biochar application may result in a substantial reduction of 684.25 Tg year−1 CO2 equivalent (equivalent to 7.87% of global cropland GHG emissions) while simultaneously improving crop yields. This study improves our understanding of the interaction between biochar surface properties and soil GHG, confirming the potential of global biochar application strategies in mitigating cropland GHG emissions and addressing global climate degradation. Further research efforts are required to optimize such strategies.
... Also, the high NPK uptake may be attributed to the greater solubilization impact of plant nutrients by the biochar application that slowly released more nutrients, ensuring sustainable nutrient availability. These outcomes concur with the findings published by Wang et al. (2012), who indicated that the biochar incorporation in ryegrass significantly improved NPK uptake. In addition, according to Nigussie et al. (2012), the maximum nutrient uptake in soils treated with biochar may also be attributed to an increase in microbial activity brought on by the application of biochar. ...
... Essas vantagens incluem: i) melhoria da fertilidade do solo; ii) aumento da capacidade de retenção de água; iii) melhora na estrutura do solo e aumento da produtividade nos agroecossistemas; iv) redução na disponibilidade de metais pesados no solo e redução das emissões de gases de efeito estufa. (Park et al., 2011;Petter et al., 2012;Wang et al., 2012;Basso et al., 2013). Sendo assim, ele é destinado principalmente à incorporação no solo para aprimorar suas propriedades físicas, químicas e biológicas. ...
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Este protocolo de revisão de escopo tem como objetivo mapear e resumir a literatura existente sobre a obtenção de biocarvão magnético a partir das cascas do maracujá amarelo. O biocarvão magnético (BCM) surge como uma solução promissora para a remediação ambiental, especialmente na purificação de água, devido à sua capacidade de adsorver poluentes e ser facilmente separável após o uso. O processo de magnetização envolve a incorporação de metais de transição, como ferro (Fe), que modifica as propriedades do biocarvão, tornando-o mais eficaz na remoção de contaminantes como metais pesados, ânions inorgânicos, pesticidas e outros poluentes orgânicos. A revisão seguirá as diretrizes do PRISMA-ScR, abrangendo estudos publicados nos últimos dez anos. A metodologia inclui a seleção de estudos, extração de dados e síntese dos resultados, que serão apresentados em tabelas e gráficos, alinhados com as questões norteadoras definidas no protocolo. O foco será identificar as principais técnicas de magnetização, os tipos de carvão utilizados e a eficácia dessas metodologias na adsorção de contaminantes. Este estudo visa fornecer uma visão abrangente e organizada da pesquisa atual sobre BCM, destacando as lacunas na literatura e sugerindo direções para futuras investigações.
... Moreover, biochar-amended compost has demonstrated superior performance as a soil amendment, enhancing soil fertility, water retention, and crop productivity compared to traditional compost [100]. Greenhouse Gas Emissions (%) 100 50-70 [104] Several studies have explored the potential benefits of biochar-amended composting. For instance, Zhang et al. [105] found that the addition of 10% biochar to a compost mixture of chicken manure and sawdust increased the nitrogen content of the compost by 20% and reduced the emission of ammonia and nitrous oxide by 50% and 60%, respectively. ...
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Biochar, a carbon-rich material produced through the pyrolysis of biomass, has gained significant attention due to its versatile applications across various sectors. This article provides a comprehensive overview of biochar's potential in agriculture, environmental remediation, energy production, and more. By exploring the physicochemical properties, production methods, and diverse uses of biochar, we highlight its role in addressing critical challenges such as soil fertility, carbon sequestration, water purification, and sustainable energy. The article also discusses the current state of biochar research, commercial adoption, and future prospects. With its multifaceted benefits, biochar emerges as a promising solution for sustainable development and environmental stewardship.
... The high P uptake could be attributed to the more solubilization effect of plant nutrients by the biochar addition that slowly released more nutrients insuring sustainable nutrients availability. These results are in agreement with those reported by Wang et al., (2012) whom indicated that the biochar incorporation in ryegrass significantly improved P uptake. The increase microbial activity due to application of biochar could also be the other reason for the highest nutrient uptake in biochar treated soils (Nigussie et al., 2012). ...
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Soil fertility and improvement of its properties depend on the fertilization process, which in turn affects nutrients release, especially phosphorus (P). The plant limitation to obtain an insufficient concentration of P is due to its fixation in primary and secondary minerals and/or its absorption on the organic materials surface. Finding an ideal formula or model is necessary to provide cross-validation between the experimental results and the empirical formula. In order to obtain the appropriate P availability, a suitable natural alternative must be found that uses the available resources. This study aims to investigate the impact of acidified biochar at two levels with 5 incubated times on phosphorus and carbon mineralization kinetic, as well as some soil chemical properties. Six equations (Zero-order, first-order, second-order, Elovich, power function, and parabolic diffusion model) was used to describe variations of released phosphorus and carbon mineralization with time. The results demonstrated that using acidified biochar decreased soil pH, increase organic matter and cumulative P release by time progress for all treatments. The acidified biochar caused a decline in the cumulative CO 2 emissions. Also, the addition of biochar had an encouraging impact on the development and vegetative growth of fennel plants. The best treatment that increased fresh weight, dry weight, and NPK uptake by fennel plants was BC 2. The Zero-order kinetic and parabolic diffusion models give better results with higher R 2 value. So, in order to create strategies for managing nutrients and soil carbon dioxide fluxes that contribute to climate change, it is crucial to consider the release kinetics and parameters associated with nutrient release and carbon mineralization from biochar.
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L'incorporation de biochars dans les sols est communément considérée comme une solution pratique pour améliorer la fertilité des sols et, par conséquent, la biomasse et la production alimentaire de manière durable. Notre étude a réexaminé la robustesse des données sous-jacentes et a révélé que sur plus de 12 000 publications sur les biochars et l'agriculture utilisées dans les méta-études, seuls 109 articles ISI (soit 0,9 %) fournissent des données expérimentales relatives à l'impact sur le rendement des cultures et/ou la production de biomasse. Notre analyse a révélé qu'aucune (0%) de ces études n'a comparé un traitement aux biochars à un traitement ajoutant au sol la même quantité de nutriments facilement accessibles trouvés dans les biochars, 0,9% ont évalué la toxicité des biochars, et 5,5% ont considéré au moins deux cycles de culture après l'application de biochars, ce qui, dans tous les cas, constitue des lacunes majeures. Enfin, lorsque les calculs sont effectués uniquement pour les sols agricoles (n=65), le gain moyen de biomasse ou de rendement en grains, qui était de 16,1 % (médiane à 7,1 %) pour toutes les expériences disponibles, a diminué à-0,64 % (médiane à 5,2 %). Par conséquent, la base de données sous-jacente pour soutenir l'application de biochars dans les sols agricoles afin d'améliorer la production de biomasse et le rendement céréalier est jusqu'à présent limitée.
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Biochar is stable in soil and can have long-term effects on its physicochemical properties. Hence, a pot experiment was conducted with medium-fertility (MF) and low-fertility (LF) soils after 1 year of rice husk biochar and organic fertilizer application to determine biochar’s residual effects on soil chemical properties, grain yield, and greenhouse gas emissions. In previous years, biochar alone (at application rates of 5 and 10 t ha−1) and biochar combined with chicken manure (CHM) or cow manure (at application rate of 5 t ha−1) were applied to the soil. In the present year, the soils were fertilized with only chemical fertilizers. Results indicated that application of 10 t ha−1 biochar combined with 5 t ha−1 CHM (B10:CHM) produced the highest grain yield and total global warming potential (GWPtotal) in both soils. Regarding grain yield, non-significant results were detected for B10:CHM, B5:CHM, and B10. This study revealed that biochar retains nutrients without annual reapplication and has long-term effects. Although biochar application can suppress N2O emissions effectively, the combined application of biochar 10 t ha−1 and organic manure significantly increased CH4 emissions. Overall, B5:CHM can be recommended for rice cultivation since it improves grain yield without increasing GWPtotal.
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Studies are being conducted to develop strategies to reduce the adverse effects of salinity stress. In the present study, it was aimed to determine the interactive effects of salinity stress with biochar on plant growth—the physiological and biochemical attributes of forage peas (Pisum sativum ssp. arvense L.). Salt applications were carried out with irrigation water at concentrations of 0, 25, 50, 75, and 100 mM NaCl. The experiment was conducted using a randomized complete block design with three applications [control: 0 (B0), 2.5% biochar (B1), and 5% biochar (B2)], five salt doses [0 (S0), 25 (S1), 50 (S2), 75 (S3), and 100 (S4) mM NaCl], and three replications, arranged in a 3 × 5 factorial arrangement. In the salt-stressed environment, the highest plant height (18.75 cm) and stem diameter (1.71 mm) in forage pea seedlings were obtained with the application of B1. The root fresh (0.59 g/plant) and dry weight (0.36 g/plant) were determined to be the highest in the B1 application, both in non-saline and saline environments. A decrease in plant chlorophyll content in forage pea plants was observed parallel to the increasing salt levels. Specifically, lower H2O2, MDA, and proline content were determined at all salt levels with biochar applications, while in the B0 application these values were recorded at the highest levels. Furthermore, in the study, it was observed that the CAT, POD, and SOD enzyme activities were at their lowest levels at all salt levels with the biochar application, while in the B0 application, these values were determined to be at the highest levels. There was a significant decrease in plant mineral content, excluding Cl and Na, parallel to the increasing salt levels. The findings of the study indicate that biochar amendment can enhance forage peas’ growth by modulating the plant physiology and biochemistry under salt stress. Considering the plant growth parameters, no significant difference was detected between 2.5% and 5% biochar application. Therefore, application of 2.5 biochar may be recommended.
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ABSTRACT We review measured rates of soil respiration from terrestrial and wetland ecosystems to define the annual global CO 2 flux from soils , to identify uncertainties in the global flux estimate, and to investigate the influences of temperature, precipitation, and ...
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Purpose A potential means to diminish increasing levels of CO2 in the atmosphere is the use of pyrolysis to convert biomass into biochar, which stabilizes the carbon (C) that is then applied to soil. Before biochar can be used on a large scale, especially in agricultural soils, its effects on the soil system need to be assessed. This is especially important in rice paddy soils that release large amounts of greenhouse gases to the atmosphere. Materials and methods In this study, the effects of biochar on CH4 and CO2 emissions from paddy soil with and without rice straw added as an additional C source were investigated. The biochars tested were prepared from bamboo chips or rice straw which yielded bamboo char (BC) and straw char (SC), respectively. BC and SC were applied to paddy soil to achieve low, medium, and high rates, based on C contents of the biochars. The biochar-amended soils were incubated under waterlogged conditions in the laboratory. Results and discussion Adding rice straw significantly increased CH4 and CO2 emissions from the paddy soil. However, when soils were amended with biochar, CH4 emissions were reduced. CH4 emissions from the paddy soil amended with BC and SC at high rate were reduced by 51.1% and 91.2%, respectively, compared with those without biochar. Methanogenic activity in the paddy soil decreased with increasing rates of biochar, whereas no differences in denaturing gradient gel electrophoresis patterns were observed. CO2 emission from the waterlogged paddy soil was also reduced in the biochar treatments. Conclusions Our results showed that SC was more effective than BC in reducing CH4 and CO2 emissions from paddy soils. The reduction of CH4 emissions from paddy soil with biochar amendment may result from the inhibition of methanogenic activity or a stimulation of methylotrophic activity during the incubation period.
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The objective of this study was to investigate the effect of biochar application (CA) on soil physical properties and grain yields of upland rice (Oryza sativa L.) in northern Laos. During the 2007 wet season, three different experiments were conducted under upland conditions at 10 sites, combining variations in CA amounts (0–16 t ha−1), fertilizer application rates (N and P) and rice cultivars (improved and traditional) in northern Laos.CA improved the saturated hydraulic conductivity of the top soil and the xylem sap flow of the rice plant. CA resulted in higher grain yields at sites with low P availability and improved the response to N and NP chemical fertilizer treatments. However, CA reduced leaf SPAD values, possibly through a reduction of the availability of soil nitrogen, indicating that CA without additional N fertilizer application could reduce grain yields in soils with a low indigenous N supply. These results suggest that CA has the potential to improve soil productivity of upland rice production in Laos, but that the effect of CA application is highly dependent on soil fertility and fertilizer management.