Growing season N<sub>2</sub>O emissions from two-year potato rotations in a humid environment in New Brunswick, Canada
Bibliographic record
Abstract
Snowdon, E., Zebarth, B. J., Burton, D. L., Goyer, C. and Rochette, P. 2013. Growing season N2O emissions from two-year potato rotations in a humid environment in New Brunswick, Canada. Can. J. Soil Sci. 93: 279–294. Few studies have examined the effects of crop rotation on N2O emissions. This study quantified N2O emissions from seven 2-yr potato rotations over a 3-yr period, 2008–2010, where the potato phase was present in 2008 and 2010. In addition, the potential to predict variation in cumulative growing season N2O emissions was examined using indices of nitrate availability [nitrate exposure (NE), a time integrated measure of soil nitrate concentrations in the surface soil], carbon availability (cumulative growing season CO2emissions) and aeration [time-weighted average water-filled pore space (WFPS)]. In the potato phase of the rotations, even for treatments receiving the same fertilizer N rate (193 kg N ha−1), a wide range in cumulative growing season N2O emissions was measured in both 2008 and 2010 (0.39–1.49 and 0.81–2.03 kg N ha−1, respectively). The NE explained 52 and 70% of the variation in growing season N2O emissions under potato production in 2008 and 2010, respectively. Carbon availability also had a significant effect on N2O emissions, as indicated by increased N2O emissions in rotations where residues of the preceding crop resulted in increased CO2emissions early in the growing season. A large proportion (67%) of the variation in cumulative N2O emissions among rotation crops was also explained by NE. Choice of rotation crop resulted in an almost twofold difference (0.9–1.7 kg N ha−1) in N2O emissions over the 2-yr rotation cycle. Greater N2O emissions over the 2-yr rotation cycle were measured for rotation crops of soybean, Italian ryegrass, red clover and potato than for rotation crops of corn, canola and barley. However, the fertilizer N management in both the potato and rotation crop phases may be as or more important than the choice of rotation crop in influencing the risk of N2O emissions.
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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 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".