1. Google images 2011
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

2. Introduction
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.
There is a need more more local renewables practices that can enhance the local soils.

3. Research questions
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?

4. Picea marianna Biochar
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
This feedstacks undergo a chemical and chemical trasnformation that makes it resitant to biotic and abiotic degradability making a it a long lasting soil amendment. This biochar can be made from different sources or organic waste.

5. Black Spruce biochar chemical analysis
Biochar type
(Residence 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
The skeletal porous structure of biochar serves as a Refugio for soil organism, increase water and nutrient retention and increases exchange sites for essential nutrients. which in turn benefits plant yield and reduce fertilizer cost.

6. Nutrient analysis Mehlich III
Biochar
P (ppm) K
(ppm) Ca Mg Cu Zn Mn Fe 1
<1 44
100 4
198.6
166.6
5.8
214 2 40 62
128.6
113.0
2.6
178 3 38 64
168.0
160.8
10.8
1018 48 78 6
176.0
161.6
7.0
656 5
130
172
111 13
534.5
558.8
6.1
349

7. Freeze-thaw and charcoal effect on soil biota
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)

8. Biochar influence on microbial activity before and after freeze-thaw
Run
Retention time
Biochar amount (g) 1
16.2
6.25 2
0.95 3
10.8
2.5 4
21.6 5 6
23.84 7 10 8 9
8.56 11 12
11.25 13
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 .

9. Cultivated soil

10. Cultivated soils after freeze-thaw

11. Forest Soils

12. Forest soils after freeze -thaw

13. Remaining work
Google images
Amend soils with the optimal biochar and evaluate plant response.
Examine the physical change of biochar after freeze – thaw cycles.

14. Summary
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.

15. Thanks! smcastillo@alaska.edu
Questions
Thanks!