Fertilizer response of barley silage in southern and central Alberta
Bibliographic record
Abstract
Barley (Hordeum vulgare L.) silage is the foundation for cattle production on the Canadian prairies, but few studies have evaluated fertilizer requirements for the range of cultivars, soil types and environmental conditions in which it is grown. The objectives of this study were (1) to determine optimum N fertilizer rates for a range of barley cultivars when used for silage in southern and central Alberta and (2) to determine the frequency and impact of P, K and S deficiencies. Thirty-two field experiments were conducted from 1994 to 1996; 20 in southern Alberta under irrigated (8) or dryland (12) conditions and 12 in central Alberta under dryland conditions. Two semi-dwarf (CDC Earl, Tukwa) and three conventional (AC Lacombe, Leduc and Seebe) cultivars were tested. Fertilizer treatments included six rates of N (0 to 200 kg ha-1) and one rate each of P (13 kg ha-1), K (50 kg ha-1) and S (20 or 30 kg ha-1), compared to an appropriate unfertilized control. Optimum rates of N fertilizer ranged from 0 to 172 kg N ha-1. Irrigated sites had the highest N demand but the lowest economic optimum rate of N fertilizer (NFopt) due to high fertilizer N efficiency and high soil N availability. Dryland sites in southern Alberta had a lower N demand than irrigated sites, but NFopt was higher due to lower soil N availability. Sites in central Alberta had the least demand for N, but NFopt was similar to irrigated sites due to low N fertilizer efficiency. Nitrogen fertilizer efficiency frequently exceeded 80% in southern Alberta, particularly under irrigation. Soil N uptake increased with optimum barley yield, indicating that factors that increased crop growth also increased net mineralization and/or efficiency of soil N uptake. A good fit of NFopt was obtained in southern Alberta based on spring soil NO3-N levels and optimum yield. The best estimate of NFopt in central Alberta was the mean due to the lack of a relationship between soil N uptake and spring soil NO3-N. Barley response to P fertilizer was greatest in central Alberta and least in southern Alberta under irrigation. Few responses to K or S fertilizer were observed due to the generally adequate levels of these nutrients in Alberta soils. Fiber concentrations were not strongly affected by fertilizer treatment, while protein concentrations varied with the availability of N relative to demand. Improvements in prediction of fertilizer response for barley silage require better predictors of N fertilizer efficiency and soil N uptake, particularly in central Alberta. Key words: Hordeum vulgare, nitrogen fertilizer use efficiency, protein, fiber
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".