Effect of Biochar on Soil Microbial Communities, Nutrient Availability, and Greenhouse Gases in Short Rotation Coppice Systems of Central Alberta
Bibliographic record
Abstract
Short rotation coppice (SRC) systems using willow (Salix spp.) grown on marginal soil, amended with biochar may represent a promising source of renewable green energy for rural communities of Alberta. The Ohaton Wood Energy project, an agroforestry site located in Camrose County, is one of several ongoing SRC projects in Alberta. This project evaluated the effect of biochar on microbial communities, nutrient availability, and greenhouse gases (GHG) in Solonetzic soils dedicated to agroforestry purposes. The study used both lab incubation and field plots to examine the effect of biochar. In the lab incubation, straw and willow biochars were applied to low and high EC soils. The application rates of biochar were 0, 1, 2.5, 5, and 10% (w/w). Chloroform fumigation extraction and alkali trap methods were used to assess soil microbial biomass and activity. Microbial biomass carbon (MBC) and nitrogen (MBN) increased in the presence of biochar in low EC soil. In high EC soil, the metabolic quotient increased, while MBC was reduced. Nitrate (NO3-) availability was reduced with biochar addition. In the field study, willow and conifer biochars were applied at 1 and 2.5% (w/w) application rates, to high and low EC and waste water irrigated and non-irrigated zones. The metabolic quotient increased by 177% with addition of conifer biochar at 2.5% rate in irrigated soil. MBC and MBN didn’t change drastically in response to biochar additions. Phospholipid fatty-acid (PLFA) analysis and community level physiological profiling (CLPP) were used to examine soil microbial structure and function. Non-metric multidimensional scaling (NMS) was used to distinguish differences between these microbial profiles. Biochar didn’t alter PLFA structure in any of treated soils compared to control, but conifer 2.5% changed CLPP in both high and low EC soils. These results indicate that microbial function can change in a short period of time with addition of biochar, but microbial structure and biomass may need more time to shift. Plant root simulator probes were applied in-situ to measure soil nutrient bioavailability. NMS was also applied to compare nutrient profiles. The nutrient profiles of conifer 2.5% and willow 1% were significantly different from the control in non-irrigated high EC zone. Photoacoustic multi-gas analyzer was connected to static chambers to measure CO2 and N2O emissions from soil. Biochar decreased gas emissions from non-irrigated high EC plots in the first 3 weeks. Establishing a strong link between GHG emissions, soil microbial processes, and nutrient profiles as indicators of ecosystem functions needs further research.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".