Google images 2011
Biochar Application to Subarctic Soils: Effect of biochar on microbial activity after freezethaw cycles and plant response at different application rates.
S. Castillo., A. Soria., C. Ping., G. Michaelson., M. Leigh
University of Alaska Fairbanks




High latitude soils are weakly
developed and are a
challenge to producers (1)
Alaska has some has harsh
climatic conditions that affect
agriculture (2)
The demand for locally
grown produce is
gradually increasing .
Abundance of black spruce
as feedstock.



What are the differences among black spruce
biochar created at different residence times?
What is the influence on microbial activity of
soils amended with different biochar types and
amounts before and after freeze-thaw?
What is the effect of black spruce biochar on
plant yield and nutrient retention at different
application rates?




Five different types of biochar
were created based on a
response surface model
conditions.
Black spruce biochar was
produced in a pilot scale, fixed
bed pyrolysis unit, with a
capacity of 1 kg/hr
Temperature was maintained at
550 °C
Chemical analysis of samples
Biochar
type
(Residenc
e time
seconds)
Biochar
unit RPM
pH
EC
mmho/cm
CEC
cmol/kg
C/N ratios
%
(1) 160.7
8.56
4.73
0.12
12.15
68.59 – 0.26
(2) 134.4
10.8
5.06
0.11
9.77
71.0 – 0.27
(3) 97.3
16.2
4.55
0.15
17.36
67.30 – 0.23
(4) 81.97
21.6
4.29
0.2
16.49
68.90 – 0.24
(5) 73.65
23.8
4.77
0.17
17.07
66.10 - 0.43
Biochar P
K
(ppm) (ppm)
Ca
(ppm)
Mg
(ppm)
Cu
(ppm)
Zn
(ppm)
Mn
(ppm)
Fe
(ppm)
1
<1
44
100
4
198.6
166.6
5.8
214
2
<1
40
62
<1
128.6
113.0
2.6
178
3
<1
38
64
4
168.0
160.8
10.8
1018
4
<1
48
78
6
176.0
161.6
7.0
656
5
130
172
111
13
534.5
558.8
6.1
349


Forest fire charcoal presence on boreal forest
has shown greater efficiency of nutrient
uptake.( Wardle, 1997)
Freeze and thawing destroys microbial tissue
(Haines, 1938)


Burst of CO2 during freeze and thaw (Ross,1972)
Soil goes through physical and chemical
changes (DeLuca, 1992)
Methods:




Treatments based on a
response surface model,
constructed using Design
Expert v7 software
Actively cropped soil and
forest soil were collected
from the Matanuska
Experiment Farm
Microbial activity was
measured with 8210-CO2 gas
analyzer Columbus
instruments 180 C.
Samples underwent 1 cycle
of freeze-thaw .
Run
Retention
time
Biochar
amount
(g)
1
16.2
6.25
2
16.2
0.95
3
10.8
2.5
4
21.6
2.5
5
16.2
6.25
6
23.84
6.25
7
21.6
10
8
16.2
6.25
9
8.56
6.25
10
10.8
10
11
16.2
6.25
12
16.2
11.25
13
16.2
6.25
Microbial Activity
Design points above predicted value
Design points below predicted value
673727
64475
X1 = A: RPM
X2 = B: Amount of biochar
M ic r o b ia l A c t iv it y
Design-Expert® Software
690000
532500
375000
217500
60000
10.00
21.60
8.13
18.90
6.25
B: Amount of biochar
16.20
4.38
13.50
2.50
10.80
A: RPM
Microbial Activity
Design points above predicted value
Design points below predicted value
304356
74443
X1 = A: RPM
X2 = B: Amount of biochar
M ic r o b ia l A c t iv it y
Design-Expert® Software
310000
255000
200000
145000
90000
10.00
21.60
8.13
18.90
6.25
B: Amount of biochar
16.20
4.38
13.50
2.50 10.80
A: RPM
Microbial Activity
Design points above predicted value
Design points below predicted value
1010.74
319.876
X1 = A: RPM
X2 = B: Amount of biochar
M ic r o b ia l A c t iv it y
Design-Expert® Software
1020
842.5
665
487.5
310
10.00
21.60
8.13
18.90
6.25
B: Amount of biochar
16.20
4.38
13.50
2.50 10.80
A: RPM
Microbial Activity
Design points above predicted value
Design points below predicted value
478.139
218.036
X1 = A: RPM
X2 = B: Amount of biochar
M ic r o b ia l A c t iv it y
Design-Expert® Software
480
412.5
345
277.5
210
10.00
21.60
8.13
18.90
6.25
B: Amount of biochar
16.20
4.38
13.50
2.50 10.80
A: RPM
Google images


Amend soils with the optimal biochar and
evaluate plant response.
Examine the physical change of biochar after
freeze – thaw cycles.



Residence time influenced the chemical characteristics
of black spruce biochar specially at the shortest
residence time.
Biochar treatments increased microbial activity
especially on cultivated soils before and after freeze
thaw. It stabilization after few days confirms that
biochar can be a long term carbon storage on soils.
The response surface model indicated significance in
all models except for forest soils before and after
freeze-thaw.
Thanks!
smcastillo@alaska.edu