Determining wheat responses to copper in prairie soils
Bibliographic record
Abstract
Criteria for assessment of the Cu status of prairie soils were developed in the early 1980s and are currently in use with some modifications. Although there appears to be a reasonable agreement on the soil critical value of 0.4 mg kg -1 soil based on DTPA-extractable Cu, a marginal range that extends between 0.4 and 1.2 mg DTPA-Cu kg -1 soil is used to generate fertilizer recommendations. The objective of this study was to verify the existing soil critical value and identify the frequency of agronomic as well as economic response of spring wheat to Cu fertilization on soils with levels both below and above the critical value. We carried out a large number (52) of trials with spring wheat (Triticum aestivum L.) between 1991 and 2000 in all three Prairie Provinces and compiled a large number of spring wheat experiments conducted in western Canada (63) by a number of researchers. Fifty-nine trials carried out on soils containing marginal and sufficient Cu levels were evaluated and were compared to 56 experiments on soils containing deficient levels. A number of methods of placement and products were compared. Agronomic responses were obtained in 41 of the 115 experiments and only by broadcasting either 3 to 5.5 kg Cu ha -1 as CuSO 4 ·5H 2 O or 0.5 to 2 kg Cu ha -1 as Cu-sulphonate and incorporating the product or by foliar application of 0.22 kg Cu ha -1 . Calibration of the DTPA-extractable Cu test using a Mitscherlich type of function verified the soil critical value of 0.4 mg Cu kg -1 soil. Statistically significant grain yield responses were obtained in 87, 16 and 0% of trials carried out on soils containing <0.4, 0.4 to 0.8 and >0.8 mg DTPA-extractable Cu kg -1 soil. Economic responses, defined as those where Cu application yielded a 2:1 return on the cost of fertilizer in the year of application, varied depending on the price of wheat and ranged between 19 to 45% in deficient soils for a price range of $100 to $200 t -1 of wheat grain; economic responses on marginal and sufficient soils occurred in 6% and none of the cases, respectively. Hence, fertilization of soils with DTPA-extractable Cu levels >0.4 mg kg -1 is associated with very high risk. Key words: DTPA-extractable, calibration, soil critical value, deficient, marginal, agronomic, economic
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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 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".