Estimation of N<sub>2</sub>O emissions from agricultural soils in Canada. II. 1990–2005 inventory
Bibliographic record
Abstract
International initiatives such as the United Nations Framework Convention on Climate Change and the Kyoto Protocol require that countries conduct national inventories of their greenhouse gas emissions. The primary objective of the present study was to apply a country-specific (Tier II) methodology at the regional (≈150 000 ha) scale to estimate direct N2O emissions from agricultural soils in Canada for the period 1990–2005. Other N2O sources such as manure management and indirect emissions were estimated using the Tier I Intergovernmental Panel on Climate Change (IPCC) methodology and were included to provide a complete assessment of agricultural N2O emissions. Total N2O emissions from agricultural sources averaged 58.1 Gg N2O-N yr-1 between 1990 and 2005 (from 48.9 in 1990 to 71.6 Gg N2O-N yr-1 in 2004). Of these mean emissions, 39.3 Gg N2O-N yr-1 or 68% were direct emissions from soils, 8.7 Gg N2O-N yr-1 or 15% were direct emissions from animal waste management systems and 10.1 Gg N2O-N yr-1 or 17% were from indirect emissions. Application of synthetic N fertilizers was the largest direct source of soil N2O with average emissions during the inventory period of 13.7 Gg N2O-N yr-1 or 35% of direct emissions. Crop residues (9.3 Gg N2O-N yr-1; 24%), grazing animals (6.8 Gg N2O-N yr-1; 17%) and manure applied to soils (4.1 Gg N2O-N yr-1; 10%) were the other major direct soil N2O sources. New non-IPCC N2O sources/offsets included in the Tier II methodology accounted for 10% of total direct soil emissions. Emissions occurring during summerfallow (2.2 Gg N2O-N yr-1; 6%), in lower portions of the landscape (2.2 Gg N2O-N yr-1; 6%), and following irrigation (0.7 Gg N2O-N yr-1; 2%) were partially offset by changes in tillage practices (-1.2 Gg N2O-N yr-1; -3%) and in coarse-textured soils (-0.2 Gg N2O-N yr-1; -1%). Differences in N2O estimates between Tier I and Tier II approaches mainly arise from the use of lower fertilizer-induced emission factors in the dry Prairie region and the addition of several new N2O sources/offsets in the Tier II methodology. Key words: Nitrous oxide, soils, greenhouse gases, inventory
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.003 | 0.003 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".