Evaluation of hot KCl extraction as an index of mineralizable N: Ammonium and ultraviolet absorption measurements
Bibliographic record
Abstract
Hot KCl extraction was examined as a possible nitrogen (N) soil test. The focus of this study was the influence of the method for determining N in the extracted solution. The study was conducted on a diverse set of Fraser Valley soils of British Columbia, using aerobic incubation as a reference for potential N mineralization rate. The pattern of nitrate and ammonium accumulation over time differed, possibly reflecting differences in organic matter composition, and affecting the interpretation of the results . Results from anaerobic incubation, a simple, alternative method, differed sufficiently from aerobic incubation to warrant caution in using it to estimate mineralization. The MgO steam distillation method was subject to interference in hot KCl extracts; a flow injection system involving room temperature volatilization and diffusion was proposed as a better alternative. Some soils had significant ammonium present before hot KCl extraction, requiring correction. These adjustments, though increasing laboratory requirements, improved the correlation of hot KCl ammonium with aerobically mineralized N. Simple measurements (steam distillation with strong NaOH and ultraviolet absorbance) of organic N extracted by hot KCl were good alternatives for estimating potential N mineralization. Further examination of extraction conditions and measurement variables are required to optimize these methods. Key words: Mineralized soil N, incubation N, soil N test, MgO-steam-distillable N, sodium-hydroxide-distillable N, flow injection analysis, ultraviolet absorbance
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".