Greenhouse gas exchange above potato and pea fields in the lower Fraser Valley in British Columbia, Canada
Bibliographic record
Abstract
The three main biogenic greenhouse gases (GHGs), nitrous oxide (N₂O), methane (CH₄) and carbon dioxide (CO₂), are associated with agricultural production and strongly affected by environmental factors, which makes mitigation of GHG emissions a more challenging task in intensive agricultural system in the context of global climate change. Quantification of GHG emissions is of great interest in agroecosystems to better understand flux exchange between agroecosystems and the atmosphere and to provide knowledge for climate change related policy making. However, in Canada, these studies are largely limited to Ontario and the Canadian Prairie provinces, and GHG emissions in the main cropping systems in British Columbia have scarcely been studied. Therefore, this study is aimed at making continuous measurements of N₂O, CO₂ and CH₄ from potato and pea crops in the lower Fraser Valley using the eddy covariance (EC) technique. Furthermore, to cope with the issue of slight spatial inhomogeneity at this study site, flux footprint analysis was used, coupled with EC and closed-chamber measurements. I found that flux footprint correction had the largest effect on N₂O flux compared with CO₂ flux because of more pronounced difference of N₂O flux between two different land surfaces (crop and edge areas). After flux footprint correction, the potato and pea crops were both weak CO₂ sinks with annual net ecosystem exchange values being -57 and -97 g C m⁻² yr⁻¹, respectively. After taking carbon (C) export via crop harvest into account, the potato crop shifted from being a C sink to a C source of 375 g C m⁻² yr⁻¹, while the pea crop became near neutral sequestering only 19 g C m⁻² yr⁻¹. Annual GHG budget was quantified by converting N₂O and CH₄ to CO₂ equivalents using global warming potential on a 100-year timescale, which is 298 for N₂O and 34 for CH₄. The annual GHG budgets were 481 and 200 g CO₂e m⁻² yr⁻¹ for the potato and pea crops respectively. For both potato and pea crops, N₂O contributed the largest proportion to annual total CO₂e and outweighed the CO₂ uptake from the atmosphere, making both crop fields net sources of GHGs.
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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 | 0.003 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".