Nitrous oxide, carbon dioxide and methane emissions from irrigated cropping systems as influenced by legumes, manure and fertilizer
Bibliographic record
Abstract
Irrigated land in southern Alberta is intensively managed, producing high yields but also requiring higher inputs, notably of nitrogen (N), than adjacent rainfed lands. The higher N inputs, combined with enhanced soil moisture, might stimulate nitrous oxide (N 2 O) emissions, but the influence of management on these emissions has not been widely studied. Our objective was to assess soil N 2 O emissions, along with those of carbon dioxide (CO 2 ) and of methane (CH 4 ), from irrigated cropping systems as influenced by source of N. We used a chamber technique to measure year-round emissions for 3 yr in long-term irrigated crop rotations receiving N as legume crop residues, non-legume crop residues, livestock manure or ammonium nitrate fertilizer. Unlike CO 2 fluxes, which peaked during the growing season, those of N 2 O showed no consistent seasonal trends; emissions occurred sporadically in bursts throughout the year. Depending on management practices, 0.4 to 4.0 kg N 2 O-N ha -1 yr -1 was emitted to the atmosphere. The amount of N 2 O emitted from the alfalfa system, averaged over all manure and fertilizer N amendments, was more than twofold that emitted from the corn system. The proportions of fertilizer-N released as N 2 O were 0.95% for the alfalfa system and 1.30% for the corn system. After livestock manure or legume residues were incorporated, soil CO 2 and N 2 O emissions appeared to be intertwined, but during the early spring N 2 O emissions were decoupled from CO 2 . Furthermore, N 2 O emissions were highly variable in space; at three of 54 chambers, N 2 O fluxes were consistently 12 to 55 times greater than those for other chambers in the same treatment. Such complexity conceals the underlying processes of net N 2 O production and transport to the soil surface. Key words: Greenhouse gas, fluxes, carbon dioxide, methane, flux chamber, alfalfa, silage corn, fababean, manure, fertilizer, N inputs, N 2 O leakage, legumes
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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 teacher head, 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".