Wheat yield and grain protein variation within an undulating soil landscape
Bibliographic record
Abstract
The objective of this study was to compare landform element complexes (LEC) and soil series as discrete management units for variable rate N fertilizer application. Crop response attributes including grain yield, and grain protein concentration were studied in ten intensively sampled transects in an undulating glacial till soil-landscape near Miniota, Manitoba. In 1997, a year with growing season precipitation 37% below average, median grain yield tended to increase with both N fertilizer and with convergent character in the landscape (upper < mid < lower). Varcoe soils, located predominantly within the lower LEC, were generally more productive than Newdale soils. Grain protein concentration increased with N fertilizer, but tended to decrease with convergent character in the landscape (upper > mid > lower), and was lowest in the Varcoe series. In 1998, growing season precipitation was 62% above average. Grain yield responses to N fertilizer were greater, due in part to declining N fertility in the check and 45 kg ha–1 treatments. Trends among LEC were opposite to those in 1997, as median grain yield estimates tended to decrease with convergent character in the landscape (upper > mid > lower). Grain yield was modeled as a function of estimated plant-available N supply within each LEC and soil series. Modeled 1997 grain yield maxima were 2077, 2261 and 2485 kg ha–1 in the upper, mid and lower LEC. Estimated plant-available N supply at the yield maxima were 89, 130 and 130 kg N ha–1, respectively. In 1998, the relative order of modeled maxima among LEC was reversed. Grain yield of 2501, 2355 and 2227 kg ha–1 were predicted in the upper, mid and lower LEC. Estimated plant-available N supply at the yield maxima were 146, 142 and 154 kg N ha–1, correspondingly. In 1997, plateau yields were 2379, 2495 and 2325 kg ha–1 for Newdale, Varcoe and Angusville series, respectively, where the Varcoe series responded most strongly to estimated plant-available N supply. The corresponding estimated plant-available N supply values at the modeled maxima were 195, 139 and 110 kg ha–1. In 1998, plateau yields were 2343, 2253 and 2285 kg ha–1 for Newdale, Varcoe and Angusville series, respectively. The corresponding estimated plant-available N supply values at the modeled maxima were 136, 148 and 155 kg ha–1. Successful variable-rate fertilization by LEC or soil series will require long-term empirical study to establish risk-based grain yield-N relationships, and to determine if an economic advantage over conventional fertilization practices exists. Key words: Variable-rate fertilization, nitrogen, wheat yield, grain protein concentration, soil-landscape
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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 | 0.001 |
| 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".