Quantitative and qualitative responses of an established Kentucky bluegrass (<i>Poa pratensis</i> L.) turf to N, P, and K additions
Bibliographic record
Abstract
Kentucky bluegrass is a common turf species used on golf courses, sports fields, municipal parks, sod farms, road banks, as well as residential and school yards. Our objective was to determine the effects of N, P, K rates on turfgrass quantitative response (clipping yield and underground turf biomass) and qualitative response (shoot density and foliage colour) under a continuous clipping removal. A 3-yr field study was conducted on two sites, a sand that met the specifications of the United States Golf Association (USGA) and a loam. The factorial experiment was arranged in a randomized complete block design with four replicates and different levels of three nutrients, N (0 or 50 to 300 kg ha-1 yr-1), P (0 or 21.8 to 87.3 kg P ha-1 yr-1), and K (0 or 41.7 to 250 kg K ha-1 yr-1). The maximum clipping yield was produced at the rate of 200 kg N ha-1 yr-1 in the loam and 300 kg N ha-1 yr-1 in the sand. Increasing N rates linearly reduced underground turf biomass. Added P and K had no effect on clipping yield and underground turf biomass. Nitrogen significantly improved shoot density and foliage colour. However, equivalent shoot density and colour ratings required 40 to 80 kg more N ha-1 yr-1 in the sand compared to the loam. Phosphorus and K had no significant effect on shoot density and colour in the loam. Colour response to P and K depended on N rates in the sand. Fertilizer units needed to increase soil test P averaged 6 kg added P ha-1 mg-1 PM-III kg-1 across soil types. To replenish soil K, 7 kg K ha-1 per mg KM-III kg-1 were required in the sand, and 3 kg K ha-1 per mg KM-III kg-1 in the loam. Phosphorus and K fertilizer programmes should account for P and K removals to maintain low to medium fertility levels for P, and medium for K when conditions are similar to those in this research. Key words: Turfgrass clipping yield, underground turf biomass, turfgrass shoot density, turfgrass foliage colour, Kentucky bluegrass fertilization
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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 | 0.001 |
| 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".