Availability of nitrogen in solid manure amendments with different C:N ratios
Bibliographic record
Abstract
Manures behave differently as sources of available N due to differences in the amounts and forms of N in the manure. The C:N ratio is an important factor affecting the rate of mineralization and release of available N from manures in which the majority of N is contained in organic forms. In order to ascertain the effect of manure C:N ratio on N mineralization in manure-amended soils, 13 solid manures with a large range in C:N ratio were applied to two Saskatchewan soils (Haverhill sandy loam and Blaine Lake clay loam) at 100 mg N kg-1 along with control (no manure) treatments. A growth chamber experiment was conducted to evaluate the relationship between manure C:N ratio and canola yield and N uptake, and a laboratory incubation was conducted to measure how the addition of manures with different C:N ratios affected the pattern of N release in the soils as measured by supply rates to anion exchange membrane (PRSTM) probes placed directly in the soil. Canola (Brassica napus var. Sprint) was grown under the same environmental conditions to maturity, and yield and nutrient contents were determined. A significant increase in canola yield and N uptake was observed over the control in both soils only when amended with poultry manure (C:N 7.6) or a pelletized form of hog manure that was supplemented with fertilizer N (C:N 6.6). A significant negative correlation was found between cattle manure organic C:N ratio and N mineralization. Overall, the manures showed limited release of available N over the short-term (67 d) when the organic C:N ratio was in the range of 13–15 and tended to decrease N availability in the short-term if the organic C:N ratio was over 15. The C:N ratio appears to be a useful parameter to measure when attempting to predict the effects of solid manure amendments on short-term N availability. Key words: Nitrogen availability, mineralization, manure, C:N ratio, anion exchange membrane
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 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".