Analysis of variation of spectral vegetation index measured in differently fertilized field barley
Bibliographic record
Abstract
Abstract Information on crop conditions obtained from spectral reflectance measurements may be used in site specific farming systems. This study investigates the response of spring barley as measured with a relative vegetation index (RVI) to different fertilization treatments, aiming to analyze the response at different growth stages. Ground-based spectral reflectance readings were obtained in a split-plot experiment with nitrogen (N) in ammonium nitrate (49, 98, and 147 kg N ha−1), potassium (K) in potassium chloride (0 and 136 kg K ha−1), and calcium (Ca) in calcium carbonate (0 and 400 kg Ca ha−1). RVI, defined as the ratio between reflectance in a near-infrared (740–820 nm) and a photosynthetically active (400–700 nm) band, responded similarly and consistently during two consecutive growing seasons. Responses of RVI to fertilization were significant (P<0.05) from Feekes growth stage 1 (one shoot, 1–3 leaves) to stage 11.1 (milky ripe) or 11.2 (mealy ripe). Between 58 and 90% of the daily RVI-variability observed at growth stages between initial stem elongation and heading could be attributed to N-effects. The slope of the forced linear increase of RVI with time obtained during the tillering period, st, correlated non-linearly with the amount of applied nitrogen (R2≥82%). A model is formulated using st to predict the crop nitrogen supply. Independently predicted nitrogen application levels differed with 11.3 kg N ha−1 from known values, on the average. It is concluded that there may be a potential for prediction of the site specific need of sidedress N, based on derivations of site specific st-values, including a st-value for a reference area with known N-supply chosen within the field. Acknowledgments
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.009 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".