Nitrogen mineralization and uptake by ryegrass in a clay loam soil amended with composts or liquid pig manure
Bibliographic record
Abstract
Although composted liquid pig manure is increasingly being applied to agricultural soils, little is known about its impacts on N dynamics (mineralization, denitrification, immobilization, and plant uptake) in the crop root zone compared to liquid pig manure (LPM) or other types of composts. A greenhouse pot experiment was conducted to determine N mineralization and plant uptake in a ryegrass-cropped clay loam soil that had been amended with either LPM, LPM + wheat straw compost (PMS), or yard waste compost (YWC). Over a 20-wk growth period, plant biomass was increased relative to the control by 164% for LPM, 64.3% for YWC, and 39.6% for PMS. However, the recovery of amendment N in the ryegrass was low and variable at 3.3% for PMS (12.7 mg N kg-1), 3.7% for YWC (21.5 mg N kg-1), and 15.3% for LPM (90.9 mg N kg-1). Although gains and losses of mineral N occurred primarily within the first 8 wk, assimilation of amendment N by the ryegrass appeared to continue throughout the entire growth period. High amounts of inorganic N present in the LP M treatment led to the greatest loss of N, as N2O, through denitrification and nitrification (39.1 mg N kg-1). This was 35 times greater than the YWC treatment (1.1 mg N kg-1), over 50 times greater than the N2O loss from the PMS treatment (0.7 mg N kg-1) and over 76 times greater than the N2O loss from the control (0.5 mg N kg-1). There was a net gain in mineral and plant assimilated N from mineralization with the control (6.4 mg N kg-1) and YWC treatments (8.8 mg N kg-1) over 20 wk. However, there was a small decrease in mineral and plant assimilated N with the PMS treatment (4.3 mg N kg-1) and a large decrease with the LPM treatment (90.1 mg N kg-1). From an environmental perspective, the large amount of N2O generated by the LPM treatment compromises the usefulness of LPM as a source of crop-available N. Key words: Compost, pig manure, ryegrass, swine, hog, nitrogen mineralization
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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) | 0.000 | 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".