Foliar uptake of volatilized ammonia from surface‐applied urea by spring wheat
Bibliographic record
Abstract
Large volatile losses of NH3 can occur from surface‐applied urea in semi‐arid areas. Our objective was to determine possible absorption of this volatilized N by the crop canopy under field conditions. At two different times during crop growth, 15N‐enriched urea was surface‐applied at rates equivalent to 100 kg N ha‐1 to soil contained in trays placed between two rows of spring wheat. Seven days after application, the soil in the trays was removed from the field and analyzed for 15N content. Addition of HC1 during soil air drying was necessary to prevent volatile losses of 15N. Of applied urea‐N, 13% was volatilized over seven days at both application times. Of the urea‐N that was volatilized, 15% was absorbed by wheat at the first application time and 7% was absorbed by wheat at the second application time. Plant absorption of urea N (Y, mg) declined with distance from the source (x, cm) following the equation Y=10.95*10(‐0.0142x). About 90% of absorbed N was within the first three wheat rows. Our findings suggest that a significant portion of ammonia volatilized from top‐dressed urea might be captured by plant foliage.
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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) | 0.001 | 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".