A field study comparing soil profile N2O concentration with surface flux under different farming practices
Bibliographic record
Abstract
Existing research has consistently demonstrated a significant increase in N2O emissions during the spring thaw period. However, understanding the precise influence of farming practices such as cover crops and enhanced efficiency nitrogen fertilizers (EENFs) on N2O dynamics—production, diffusion, consumption in the soil profile, and surface emissions—remains limited, particularly in clay soil in Manitoba. A two-year field study was conducted in 2022 and 2023 on clay soil at the TGAS-MAN research station in Manitoba to investigate the impact of different farming practices [cover crop and enhanced efficient nitrogen fertilizers (EENFs)] on soil profile N2O concentrations at 5, 15, 30 and 60 cm of soil profile in relation to surface flux. The research site was divided into four 4-hectare fields, each measuring 200 meters by 200 meters. Six modified silicone diffusive equilibrium samplers were installed in each field to collect soil profile gas samples from different depths. The micrometeorological method was used to measure N2O surface flux rates. The results indicated that growing winter rye as a cover crop significantly (p<0.01) decreased soil profile N2O concentrations across all depths from September to December. Compared to non-cover crop, the cover crop treatment decreased the median N2O concentrations at 5, 15, 30, and 60 cm. With the increasing temperature and soil moisture at spring–thaw, profile N2O concentrations at all depths increased significantly. In contrast, no significant difference was observed between the non-cover and cover crop treatments during spring–thaw. While different fertilizer sources did not significantly affect N2O concentrations, EENF demonstrated a capacity to reduce N2O concentration in the 5 cm depth but did not have a discernible effect at deeper depths during the growing season 2023. The lowest N2O concentrations were consistently observed at shallow depths (5 cm) throughout the study period, while peak N2O concentrations were observed at deeper soil depths (30-60 cm). The peak N2O concentration during spring–thaw 2022 and 2023 occurred at 30 cm of soil profile likely due to higher microbial activity, confirming that de novo production is the main mechanism driving N2O peak emission during spring–thaw.
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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 | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".