Nitrous oxide emissions from cultivated black soil: A case study in Northeast China and global estimates using empirical model
Bibliographic record
Abstract
Abstract Manure application is effective in promoting soil carbon sequestration, but its impact on N 2 O emission is not well understood. A field experiment was conducted in a maize‐cultivated black soil in Northeast China with six treatments: inorganic fertilizer (NPK), 75% inorganic fertilizer N plus 25% pig (PM1) or chicken (CM1) manure N, 50% inorganic fertilizer N plus 50% pig (PM2) or chicken (CM2) manure N, and no N fertilizer (CK). Annual N 2 O emission significantly increased from 0.34 kg N ha −1 for CK to 0.86 kg N ha −1 for NPK and further to 1.65, 1.02, 1.17, and 0.93 kg N ha −1 for PM1, CM1, PM2, and CM2, respectively. A 15 N tracing study showed that 71–79% of total N 2 O was related to nitrification at 30–70% water‐filled pore space (WFPS), and heterotrophic nitrification contributed 49% and 25% to total N 2 O at 30% and 70% WFPS, respectively. In an incubation, N 2 O emission was only stimulated when nitrate and glucose were applied together at 60% WFPS, indicating that denitrification was carbon limited. PM had a stronger effect on denitrification than CM due to higher decomposability, and the lower N 2 O emission at higher manure application rate was associated with decreased mineral N supply. After compiling a worldwide database and establishing an empirical model that related N 2 O emissions (kg N ha −1 ) to precipitation ( P r , m) and fertilizer N application rate ( N r , kg N ha −1 ) (N 2 O = 1.533 P r + 0.0238 P r N r ), annual N 2 O emission from global‐cultivated black soil applied with inorganic fertilizer N was estimated as 347 Gg N. Our results suggested that N 2 O emission from cultivated black soils in China was low primarily due to low precipitation and labile organic carbon availability, and would be stimulated by manure application; thus, increased N 2 O emission should be taken into consideration as applying manure increases soil organic carbon sequestration.
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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".