Rates and intensity of freeze–thaw cycles affect nitrous oxide and carbon dioxide emissions from agricultural soils
Bibliographic record
Abstract
In cool temperate regions, large emissions of nitrous oxide (N 2 O), an important greenhouse and ozone-depleting gas, have been observed during freeze–thaw (FT) cycles. However, it is unclear how freezing and thawing rates, freezing intensity, and freezing duration influence N 2 O emissions. We used a laboratory incubation to measure N 2 O emissions from two soils (sandy loam, silty clay) undergoing a single FT cycle of various freezing and thawing rates [rapid (0.5 °C h −1 ) vs. slow (0.017 °C h −1 )], freezing intensity (−1 vs. −3 °C), and freezing duration (24 vs. 48 freezing degree-days). In general, soil carbon dioxide fluxes during freezing were highest when soils were frozen slowly at −1 °C, whereas fluxes after thawing were highest from the soils frozen and thawed rapidly at −3 °C. Soil N 2 O emissions during both the freezing and thawing periods were greatest in the soils exposed to rapid freezing to −3 °C, intermediate under rapid freezing to −1 °C and slow freezing to −3 °C, and smallest under slow freezing to −1 °C and the control treatment (constant +1 °C). The similar N 2 O emissions between the unfrozen control and the slowly frozen −1 °C treatment was unexpected as previous field studies with similar freezing rates and temperatures still experienced high N 2 O emissions during thaw. This suggests that the physical disruptions caused by freezing and thawing of the surface soil are not the primary driver of FT-induced N 2 O emissions under field conditions.
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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 | 0.000 |
| Science and technology studies | 0.000 | 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) | 0.000 | 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".