Nitrous oxide emissions from denitrification and the partitioning of gaseous losses as affected by nitrate and carbon addition and soil aeration
Bibliographic record
Abstract
National inventories of N2O emissions from agricultural situations are being developed; however, the factors controlling such emissions may vary with soil and environmental conditions and management practices. This study determined the relative importance of soil aeration, as measured by water-filled pore space (WFPS), NO3− addition, C addition and C source on the amount and partitioning of gaseous N losses from denitrification from an arable soil in Atlantic Canada. Denitrification (N2O + N2) and N2O emissions were measured on repacked soil cores using acetylene inhibition.The N2O:(N2O + N2) ratio was frequently 0.7 or higher, indicating that most emissions occurred as N2O. N2O emissions and denitrification were negligible at a WFPS of 0.45 m3 m-3, and high at WFPS of 0.75 m3 m-3, regardless of NO3−or C addition treatments. At a WFPS of 0.60 m3 m-3, N2O emissions and denitrification were low and were increased by both NO3− and C addition treatments. Carbon source was investigated by amendment with glucose, red clover or barley straw. Based on the quantity of soil respiration per unit of C added in the amendment, C in the red clover and barley straw was estimated to be 48 and 28% as available as glucose C. When corrected for C availability, cumulative N2O emissions averaged 0.010, 0.011 and 0.002 mg N kg-1 soil, and cumulative denitrification averaged 0.014, 0.014 and 0.003 mg N kg-1 soil, for each 1.0 mg C kg-1 soil of available C added as glucose, red clover or barley straw, respectively. NO3− addition had no effect on denitrification, but increased N2O emissions, especially where C availability was high. The amount of denitrification was controlled primarily by soil O2 supply, as controlled by WFPS and C availability. The N2O:(N2O + N2) ratio was generally high in cases where the supply of O2 or NO3− was sufficient to meet the demand for terminal electron acceptors. Key words: Denitrification, nitrous oxide, glucose, red clover, barley straw, carbon availability, terminal electron acceptor, aeration
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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 | 0.000 |
| 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 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".