Soil Microbial Response to Nitrogen Rate and Placement and Barley Seeding Rate under No Till
Bibliographic record
Abstract
Urea [(NH 2 ) 2 CO] applied in the seed row can damage seedlings and affect soil microorganisms. A field study was conducted in five site‐years to compare the effects of seed‐placed and side‐banded N applied to barley ( Hordeum vulgare L.) at 0 to120 kg ha −1 on rhizosphere and bulk‐soil microbial biomass carbon (MBC) and functional diversity (Hʹ), and to investigate if increasing barley seeding rate (200–400 seeds m −2 ) would modify the N effects. Nitrogen rate affected MBC in four and one site‐years in barley rhizosphere and bulk soil, respectively. Two of the four responses in the rhizosphere were quadratic, and the other two were a linear decrease and a cubic response. The response in bulk soil was a linear decrease. One of the two responses in the rhizosphere depended on N placement. Responses of Hʹ to N rate, which were mostly cubic and depended on N placement, were observed in three and four site‐years in the rhizosphere and bulk soil, respectively. Increasing barley seeding rate increased MBC in one and three site‐years in the rhizosphere and bulk soil, respectively, and increased Hʹ in one and two site‐years, respectively. In two of the three cases in bulk soil, seeding rate increased MBC only when N was banded. Banded N up to 60 kg ha −1 had minimal adverse effects on soil microorganisms, but only 30 kg N ha −1 or less of seed‐placed N was relatively harmless. Increasing seeding rate did not usually alleviate the negative effects of seed‐placed N applied at high rates.
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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 | 0.001 |
| 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 | 0.001 |
| 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".