Crop performance on soils receiving annual papermill biosolid amendments with and without supplementary nitrogen
Bibliographic record
Abstract
Nitrogen availability is often a limiting factor for optimum crop growth on agricultural soils amended with papermill biosolids (PB). The objective of our study was to evaluate the effect on corn (Zea mays L.) and soybean (Glycine max L.) production of adding supplementary nitrogen fertilizer to soils amended with increasing rates of PB. Papermill biosolids were applied annually on four agricultural soils in southern Ontario, Canada. Treatments included three rates of PB (50, 100, and 150 Mg ha-1), combined with four levels of nitrogen fertilizer [crop recommended [CR], [CR] + 0.5 kg N Mg-1 PB, [CR] + 1.0 kg N Mg-1 PB, and [CR] + 1.5 kg N Mg-1 PB]. In addition, non-amended plots were also established receiving either (a) zero PB and zero nitrogen fertilizer or (b) zero PB and [CR] nitrogen fertilizer only. All the plots received the same treatment combinations, i.e., PB × N, each year for the duration of the study. In corn, [CR] nitrogen fertilizer was insufficient to satisfy plant growth and PB decomposition requirements. Supplementary nitrogen fertilizer at a rate of 1.0 kg N Mg-1 PB was generally required to maintain or increase corn grain production relative to the control plots receiving the [CR] nitrogen fertilizer only. Corn grain yield increases ranged from 1000 to 6000 kg ha-1 relative to the control at some of the research sites. The optimum rate of supplementary nitrogen fertilizer varied by soil texture (location) and year. In contrast, production of soybean did not require high supplementary nitrogen fertilizer, or in some cases any, in order to maintain or increase yields at most locations. Our study shows that nitrogen fertility management had a greater impact on yields in production systems planted to corn than soybeans while receiving annual PB amendments. No residual effects on corn yield or corn grain protein content were observed after PB amendments were stopped.Key words: Papermill biosolids, carbon:nitrogen ratio, corn, soybean, nitrogen fertilizer
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 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".