Nitrogen Accumulation by Conifer Seedlings and Competitor Species From <sup>15</sup> Nitrogen‐labeled Controlled‐Release Fertilizer
Bibliographic record
Abstract
A major impediment to the establishment of outplanted conifer seedlings is competition for available soil N by early successional species. The objective of this field study was to determine the fate of controlled‐release fertilizer (CRF) N in soils with outplanted white spruce ( Picea glauca [Moench] Voss.) and jack pine ( Pinus banksiana Lamb.) seedlings, and the effect of weed control or vegetation management (VM) on fertilizer N accumulation. Nitrogen‐15 labeled CRF was placed next to the seedling root plug during planting at four boreal mixed wood sites. After one growing season in the control plots, fertilizer N recovery as a percentage of 15 N added was 4% in seedlings, 3% in competing vegetation, <1% leached, and 85% residual CRF. After two growing seasons, fertilizer N recovery was 15% in seedlings, 20% in competing vegetation, <1% leached, and 58% residual CRF. Overall, VM increased seedling fertilizer N uptake by almost 300% compared with conifer seedlings in control plots. In VM plots, fertilizer bags contained more N than in control plots after two growing seasons. In both treatments, >50% of the fertilizer N remained in the fertilizer bag, presumably remaining available in subsequent seasons. Calamagrostis ( Calamagrostis canadensis ) was the primary competitor for fertilizer N in both growing seasons, with minor competition from fireweed ( Epilobium angustifolium L.), and aspen ( Populus tremuloides Michx.). The use of a point source CRF delivery method resulted in high fertilizer use efficiency (FUE), and minimized losses to competing vegetation and leaching.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.003 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 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 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".