Rice husk biochar improves
productivity of sandy soils in
Central Coastal Vietnam
Peter Slavich, Tran Tien Dung, Brad Keen and Hoang Minh Tam
NSW Department of Primary Industries, Wollongbar
Centre for Coastal Agricultural Landscapes, Southern Cross University
Agricultural Science Institute for Southern Central Coastal Vietnam
Australian Centre for International Agricultural Research
Biochar activities in Vietnam and Aceh
• What are the effects on crop productivity
and soil properties?
• How does biochar affect plant nutrient
availability and water use efficiency?
Monthly rainfall
600.0
500.0
400.0
300.0
200.0
100.0
0.0
t hang 1
t hang 2
t hang 3
t hang 4
t hang 5
t hang 6
t hang 7
thang 8
t hang 9 t hang 10 t hang 11 t hang 12
-100.0
ða Nang
Qui Nhon
Binh Dinh
Ninh Thuan
Nha Trang
Poly.
ða
Nang)
(
Poly. (Qui Nhon)
Poly. (Nha Trang)
Peanuts intercropped with tree crops on sandy soil in Binh Dinh
Irrigation of field crops using hand held hose in Binh Dinh
Cow manure is widely used as soil amendment
Rice husk biochar
From Philippines
Rice husk stoves used
in Vietnam, Phang Rang.
Phang Rang rice husk biochar
from stove, biochar is doused with
water after being raked from stove
- Biochar samples B and C in slide 17
Rice husk stoves are smoke free
Rice husk biochar
used by local nurseries
for plant propagation
Rice husk stove used in Hanoi – biochar samples D&E in slide 17, D was not
doused with water to prevent further burning
Treatments
•
•
•
•
Control (nil NPK and manure)
Manure
NPK
NPK+ manure
Each with and without biochar; ie 8 treatments
NPK (30 N:60 P2O5 :90 K2O); cow manure 5 t/ha
Rice husk biochar 20 t/ha
3 reps, random block design, farmer practice field trial.
Biochar trial with peanuts on sandy soil
in Binh Dinh, Vietnam
Rice husk biochar sample
A
EC (1:5) dS/m
B
C
D
E
0.95
1.5
1.5
0.77
pH (CaCl2)
9.1
7.4
8.1
8.2
Total Carbon (Dumas) %
35
34
46
11
42
0.72
0.83
1
0.44
1.1
0.076
0.22
0.11
0.15
0.12
27
16
27
Total Nitrogen %
Total P %
CEC cmol(+)/kg
17
Saturated water content
g/g
2.2
A =Philippines biochar; B &C from rice husk stoves in Phang Rang;
D&E residue fromHanoi cooking stove
Above ground biomass of peanut
Nil RH biochar
-1
Dry matter biomass (Mg ha )
2.5
RH biochar
LSD=0.23
LSD=0.23
2
1.5
1
0.5
0
Control
NPK
Biomass greater when NPK applied
Biochar increases biomass production
No significant response to manure
Manure
Manure + NPK
Rice husk biochar on groundnut pod yield (2009)
2.5
Nil RH biochar
-1
pod yield (Mg ha )
2
LSD=0.3
LSD=0.3
RH Biochar
1.5
1
0.5
0
Control
NPK
Manure
NPK and manure increase yield
Biochar enhances pod yield response to NPK but not manure
Peanut yields also increased with biochar application alone
Manure + NPK
Potassium uptake
40
-1
K uptake (kg ha )
35
Nil RH biochar
LSD=10.8
RH biochar
30
25
20
15
10
5
0
Control
NPK
Manure
NPK enhances potassium uptake
Biochar enhances fertiliser potassium uptake
Manure + NPK
Phosphorous uptake
16
-1
P uptake (kg ha )
14
Nil RH biochar
LSD=4.1
RH biochar
12
10
8
6
4
2
0
Control
NPK
NPK enhances P uptake
Biochar enhances fertiliser P uptake
Manure
Manure + NPK
Nitrogen uptake
-1
N uptake (kg ha )
30
Nil RH biochar
LSD=7.7
RH biochar
25
20
15
10
5
0
Control
NPK
Manure
Manure + NPK
N uptake not enhanced by NPK or manure – legume effect
Biochar enhances N uptake when manure + NPK applied
Field water content
Average field water content mm (0-0.2m)
16
15
14
Nil Biochar
13
Biochar
12
LSD=2.2
11
10
Nil Manure +nil NPK
Nil Manure + NPK
Manure +nil NPK
Assessed in field using portable capacitance probe
Manure + NPK
-1
Saturated water content (g g dry soil)
Field capacity water content
0.25
LSD=0.04
Nil RH biochar
RH biochar
0.20
0.15
0.10
0.05
0.00
Control
NPK
Manure
Assessed in laboratory in Vietnam using field samples
Manure + NPK
saturated water content (g g
-1
)
Increase in soil water holding
capacity
0.20
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
0
20
30
40
60
Application rate (Mg ha-1 mixed to 20cm depth)
Pilot laboratory assessment conducted in NSW
80
Soil moisture after irrigation mm (0-0.3
m)
Field capacity water content vs soil organic matter
28
26
NPK+M
24
M
C
NPK
Nil Biochar
M
Biochar
C
22
20
0.00
NPK+M
NPK
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
Soil organic matter % (0-0.2 m)
C – control, NPK- fertiliser, M - manure
Field water content higher due to organic matter accumulation which is
enhanced in biochar treatments
Conclusions
• Rice husk biochar has
– improved uptake of P and K from sandy soils
– increased water holding capacity
– Increased yields of peanuts
• Trials are continuing

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