Application of biochar in rice productivity and nitrogen run-off control

International Workshop on Production and Application of Biochar in China’s Agriculture
Application of biochar in rice productivity
and nitrogen run-off control
Weixiang Wu, Min Yang, Yuxue Liu, Da Dong, Qibo Feng, Minmin Zhou
College of Environment and Resource Science,
Zhejiang University
E-mail: weixiang@zju.edu.cn
Sept, 2011

Current situation of soil quality in China
Low organic matter content: average 1% in China
Large area of middle and low yield arable land
Lack of nutrients
Arable land of different yield in Zhejiang (2006)
Intensive cropping system is one of the most important reasons.

2400
5000
2200
2000
1800
1600
1400
1200
N-fertilizer
4800
Produ. rate
4600
4400
4200
4000
3800
3600
Year
(Zhu & Chen, 2004)
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
Nitrogen fertilizer (10 4 ton)
Production rate (kg/ha)
Increasing rate
1000
3400
Decade
1949– 1958
1959– 1968
1969– 1978
1979– 1988
1989– 1998
1949– 1998
Nitrogen fertilizer VS food production
200
180
160
140
120
100
80
60
40
20
0
(China Statistical Yearbook, 2008)
b Y=A+bX

Run-off nitrogen fertilizer & water eutrophication
Crop
Sown area
(×10 8 hm 2 )
Consumption of chemical
Fertilizer (kg/hm 2 )
Amount of N run-off
(×10 4 t/a)
Rice 3.06 300 77.69
Vegetable 1.8 720 57.60
Nitrogen run-off rate from paddy field: 30-70%

A new technology ?
Reduce nitrogen run-off pollution
Improve soil quality
Increase crop yield
Carbon sequestration

Biochar
Temperature
residence time
oxygen
feedstock
Great porosity
Large surface
area
High stability
High capability
of adsorption
…
Retain
nutrients
Reduce
fertilizer used
Improve soil
productivity
…

Equipment for rice straw biochar production (small scale)
Rice straw/bamboo
Biochar

Facility for producing biochar and biochar-based slow release
fertilizer
Carbonization
equipment
Grinder
Waste gas treatment
Control System
Waste/heat
recovery unit
Conveyor
Suction device
Cutting Machine
(Patent Application No: 201010514198.7)

70-100 kg/d of rice straw biochar
Rice straw production facilities in pilot scale

Rice straw biochar
600
500
Temperature ( ℃)
400
300
200
100
0
0 20 40 60 80
Time (h)

Facility for producing slow release fertilizer
Yield: 10-100 kg/h

Slow release fertilizers
1# 2# 3#
4# 5#
Raw materials
Common N fertilizers
Rice straw biochar
Bentonite
…
(Patent Application No: 201110110405.7.)

Release rate of slow release fertilizer
samples
24h(%)
7d(%)
10d(%)
14d(%)
28d(%)
1#
87.59
---
---
---
---
2#
51.38
63.58
63.86
---
---
3#
15.05
26.79
27.64
28.45
63.66
4#
51.10
67.88
68.31
---
---
5#
14.88
25.10
26.04
27.24
60.88
The 5# sample meets the China criterion that Release rate of slow release
fertilizer < 15% in 24hrs and

Physiochemical property of bamboo and rice straw charcoal
Packing density
(g·cm -3 )
pH
CEC
(cmol·kg -1 )
BET SA
(m 2·g-1 )
Pore Volume
(cm 3·g-1 )
Bamboo
char(BC)
0.568
9.81
15.3
182.6
0.171
Straw char(SC)
0.125
10.8
23.9
101.6
0.070
0.2
0.18
BC
SC
0.16
D iffe r e n tia l P o r e V o lu m e (c m 3 g - 1 )
0.14
0.12
0.1
0.08
0.06
a
b
0.04
0.02
0
2
5
2 0
Pore Width (nm)
5 0
2 0 0
3 0 0
c
d
Pore size distribution curves of biochar
SEM photos of biochar
(a、b: bamboo char; c、d: c
straw char )

Adsorption capacity of biochar
8
7
6
BC
SC
q e (mg/g)
5
4
3
2
1
0
0 200 400 600 800 1000
C e (mg/L)
Equilibrium adsorption isotherm of NH + 4 -N N on bamboo and rice straw char
Rice straw char exhibited a much higher adsorption capacity for
NH 4+
-N than bamboo char at 25℃.

Stability of rice straw biochar
Micrographs of biochar in ancient paddy soil

Evaluation of biochar amendment on nitrogen
retention and leaching characteristic
Bamboo charcoal: 0.5%
N fertilizer: 400 kg N ha -1

Effect of biochar amendment on NH 4+
-N concentration in the
leachate of soil columns at different depth
300
250
200
150
*
*
*
* *
*
1 0 cm 6 0
2 0 cm
C K
N
N B
5 0
4 0
3 0
*
* *
*
NH4 + -N (mg L -1 )
100
50
16
14
2 0
1 0
30 c m 1 8
4 0 cm
1 6
12
10
8
6
1 4
1 2
1 0
4
0 7 14 21 2 8 35 42 4 9 56 6 3 7 0
8
0 7 14 21 2 8 35 4 2 49 56 6 3 70
Tim e (d )
Addition of BC could significantly reduce NH 4+
-N concentration in leachate from 10 cm depth
within the first 7 days. However, it was in reverse from 7 to 28 days during the experiment.
No significant difference in leachate NH 4+
-N concentration was observed until day 49 at 20 cm
depth.

Effect of biochar amendment on cumulative losses of NH 4+
-N
from soil columns at different depths
100
80
CK
N
NB
20
10 cm 20 cm
15
*
*
NH 4
+ -N (mg column
-1 )
60
40
20
10
8
6
*
*
*
*
*
10
5
30 cm
10
40 cm
8
6
4
4
2
2
1 4 7 10 14 21 28 35 42 49 56 63 70
Time (d)
1 4 7 10 14 21 28 35 42 49 56 63 70
Application of BC can reduce cumulative losses of NH 4+
-N via leaching by 15.2% at 20 cm
within 70 days observation.
(Water Air Soil Pollut. 2010, 213:47–55.)

Influence of biochar (SC and BC) amendment on rice
productivity
Heading
Control
Rice straw biochar
1%
Maturity
CK: control; BC: bamboo char; SC: rice straw char;
CKU: urea; BCU: BC + urea; SCU: SC + urea;

CK
BC
SC
CKU
BCU
SCU
SRU
CK BC SC CKU BCU SCU SRU
Heitht (cm)
120
110
100
90
80
ab ab ab
ab a
bcc
c
c
c
cd
d
b
bc b
a
bc
ab
cd c
d
bc
a
ab
70
60
50
a a a a a a a
Seedling Booting Heading Maturing
Stages of rice development
Effect of rice straw biochar on rice height

10
8
c
c
b
CK BC SC CKU BCU SCU
a
ab
b ab
bc
c
a
abc abc
Yield(t/ha)
6
4
2
0
2009 2010
Time
Effect of biochar on rice yield over 2 years’ field experiment (experiment set in 2009)
CK: control; BC: bamboo char; SC: rice straw char;
CKU: urea; BCU: BC + urea; SCU: SC + urea;
Average increasing rate: SC 19.8-21.6%(Compared to CK); SCU 11.1-14.4%
(Compared to CKU).

Influence of rice straw biochar on nitrogen fertilizer
input reduction
SC
1%straw char + CK
CK
general amount of fertilizer
SCL
1%SC + 10% less of CK
Second field experiment set in 2010

Influence on concentration of NH 4 + -N, NO 3 - -N in surface water
NH4 + -N(mg/L)
40.00
35.00
30.00
25.00
20.00
15.00
10.00
5.00
0.00
* *
CK BC SC SCL RS SRF1 SRF2
Treatment
2010-7-27 2010-9-5
CK: general amount of fertilizer (180kg N/ha)
BC: bamboo char(1%) + CK (180kg N/ha)
SC: straw char (1%) + CK (180kg N/ha)
SCL: straw char(1%) +less CK(162kg N/ha)
RS: rice straw(1.3%) + CK (180kg N/ha)
SRF1: charcoal coated slow released fertilizer1 (180kg N/ha)
SRF2: charcoal coated slow released fertilizer2 (180kg N/ha)

13.5% 7.14% 15.1% 10.3%
Gloss fresh Yield(t/ha)
14.00
12.00
10.00
8.00
6.00
4.00
2.00
0.00
cd
ab bc cd
a d
ab
CK BC SC SCL RS SR1 SR2
Treatment
Effect of biochar and biochar-based based slow released fertilizer on rice
yield (experiment set in 2010)

Conclusions
Biochar might be used as an ideal amendment for
retarding vertical movement of NH 4+ -N and minimizing
the nitrogen loss through leaching.
Biochar amendment in paddy field is able to
significantly increase rice productivity and reduce N
fertilizer input. Thus, it may prevent N fertilizer run-off
from paddy field.
Rice straw biochar-based slow released fertilizer can
not only increase rice productivity, but also reduce N
fertilizer run-off from paddy field.
Rice straw biochar with proper properties might be and
ideal material for improving low fertility paddy field.

Perspectives
1
Optimizing biochar ???
Characteristics Function
Soil-biochar-crop interaction
70
1h 2h 3h 5h
CEC(cmol/kg)
60
50
40
30
20
10
0
300 400 500 600 700
Temperature(℃)
1.0
0.8
300 400 500 600 700
H/C
0.6
0.4
0.2
0.0
0.0 0.1 0.2 0.3 0.4 0.5
O /C

2
Mechanisms and technology development
for N run-off control in agriculture
Biochar??
http://www.google.com.hk/imgres
www.google.com.hk/imgres?

3
Risk Assessment?
a
b
Biochar concentration
Biochar concentration
c
d
Comet assay
Biochar concentration
Biochar concentration
Distributions and mean levels of DNA damage caused by biochar. (a) Tail
length; (b) Tail moment; (C) Oliver tail moment; (d) Tail DNA (*: p

Acknowledgments:
• National Natural Science Foundation of China (NSFC)
• Natural Science Foundation of Zhejiang Province
• National Critical Project for Science and Technology on
Water Pollution Prevention and Control
Thanks for your attention!