Post on 26-Mar-2015
Biochar Application to Subarctic Soils: Effect of biochar on microbial activity after freeze-thaw cycles and plant response at different application rates.
S. Castillo., A. Soria., C. Ping., G. Michaelson., M. Leigh University of Alaska Fairbanks
Google images 2011
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(Residence time seconds)
Biochar unit RPM
pH ECmmho/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 (ppm)
K(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)
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
Methods:
Design-Expert® Software
Microbial ActivityDesign points above predicted valueDesign points below predicted value673727
64475
X1 = A: RPMX2 = B: Amount of biochar
10.80
13.50
16.20
18.90
21.60
2.50
4.38
6.25
8.13
10.00
60000
217500
375000
532500
690000
M
icro
bia
l A
cti
vit
y
A: RPM B: Amount of biochar
Design-Expert® Software
Microbial ActivityDesign points above predicted valueDesign points below predicted value304356
74443
X1 = A: RPMX2 = B: Amount of biochar
10.80
13.50
16.20
18.90
21.60
2.50
4.38
6.25
8.13
10.00
90000
145000
200000
255000
310000
M
icro
bia
l A
cti
vit
y
A: RPM B: Amount of biochar
Design-Expert® Software
Microbial ActivityDesign points above predicted valueDesign points below predicted value1010.74
319.876
X1 = A: RPMX2 = B: Amount of biochar
10.80
13.50
16.20
18.90
21.60
2.50
4.38
6.25
8.13
10.00
310
487.5
665
842.5
1020
Mic
rob
ial
Ac
tiv
ity
A: RPM B: Amount of biochar
Design-Expert® Software
Microbial ActivityDesign points above predicted valueDesign points below predicted value478.139
218.036
X1 = A: RPMX2 = B: Amount of biochar
10.80
13.50
16.20
18.90
21.60
2.50
4.38
6.25
8.13
10.00
210
277.5
345
412.5
480
M
icro
bia
l A
cti
vit
y
A: RPM B: Amount of biochar
Amend soils with the optimal biochar and evaluate plant response.
Examine the physical change of biochar after freeze – thaw cycles.
Google images
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