Nitrous oxide fluxes related to soil freeze and thaw periods identified using heat pulse probes
Bibliographic record
Abstract
Surface N 2 O fluxes have not been unequivocally linked to soil profile conditions, in particular the timing of water phase change. The heated needle probe is a sensor that has the potential to monitor in situ apparent volumetric heat capacity (C a ), which considers latent heat transfer, during freezing and thawing. The objective of this study was to relate the timing of N 2 O flux to the occurrence of soil water phase change between liquid and ice as determined by C a in no-tillage (NT) and conventional tillage (CT) plots monitored from fall to spring. Half-hourly micrometeorological N 2 O fluxes were measured using a tunable diode laser trace gas analyzer. Apparent heat capacity was measured at 5-cm depth using three 4-cm-long parallel needles, two equipped with thermistors and one with a heater. Two N 2 O flux events were observed for CT in January, followed by the main emission event in early March. For NT, only one emission event occurred, with lower magnitude than the CT event, and a later starting and ending date. The apparent heat capacity measured in situ with HPP showed a different temporal pattern between NT and CT, with CT presenting more phase change events. Two out of the three N 2 O emission events in CT that occurred during winter and early spring occurred immediately after phase change from ice to liquid water at 5-cm depth. The N 2 O flux associated with the phase change during the main thaw event in CT was an exponential function of the soil surface temperature increasing sharply when T > 0°C, but with smaller fluxes once T was > 5°C. The temperature response observed is consistent with the suggestion of a breakdown in the N 2 O reduction process in the 0 to 5°C range, while the N 2 O production enzymes are less affected by low temperature.Key words: Nitrous oxide flux, freeze-thaw cycles, heat pulse probes, no-tillage, conventional tillage
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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 | 0.001 | 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 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| 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".