Availability of nitrogen from municipal biosolids for dryland forage grass
Bibliographic record
Abstract
A 3-yr study, initiated in 1996, evaluated the availability of N from applied biosolids for dryland forage grass production under the cool, continental climatic conditions in central British Columbia. Treatments included 600 (LB), 1200 (MB) and 1800 (HB) kg total N ha −1 applied as municipal biosolids, a single application of 150 kg N ha −1 as urea in the first year of the experiment (SF), a multiple application of 150, 60 and 30 kg N ha −1 as urea in the first, second, and third years of the experiment (MF), and a control that received no biosolids or urea. All treatments were roto-tilled to 15-cm depth and seeded to a mixture of four grasses. The LB treatment was predicted to supply a similar quantity of plant-available N as the MF treatment, assuming 25, 10, and 5% of biosolids N is available in the first, second, and third year, respectively. Soil N fertility was poor as indicated by the very low forage yield and N uptake in the control, and minimal apparent net soil N mineralisation. Recovery of urea N in the crop over 3 yr averaged only 27%, likely reflecting net immobilisation in this recently broken site and accumulation of N in non-harvested portions of the crop. Cumulative recovery of N from biosolids in the harvested forage averaged only 11%. However, the fertiliser N equivalency of the biosolids N (ratio of recovery of biosolids N to urea N) was estimated at 41%, close to the predicted value of 40%. Forage yield and N uptake were similar for the LB and MF treatments, suggesting that actual biosolids N availability was similar to that predicted. Limited forage yield increase for the HB compared with the MB treatment early in the experiment, and high forage nitrate content for the HB treatment in the first year, suggest that the HB treatment initially supplied an excessive quantity of N. Both urea and biosolids applications increased cumulative uptake of other macro- and micro-nutrients, with forage Cu concentrations reaching values in the establishment year that may be of concern for some animal species. Monitoring of forage NO 3 and Cu concentrations is advisable where biosolids are applied. Key words: Phleum pratense L., Dactylis glomerata, Bromus inermis, Bromus biebersteinii, soil N mineralisation, NO 3 toxicity
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.001 | 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 teacher head, 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".