Effects of different sources and rates of sulphur on the growth and foliar nutrition of nitrogen-fertilized lodgepole pine
Bibliographic record
Abstract
The effects of nitrogen (N) fertilizer, alone and in combination with different sources and rates of sulphur (S), on foliar nutrients and tree growth are reported over 3 and 6 years, respectively. After 3 years, foliar S levels in the N+S treatments were significantly higher than those in N-only treatments at all six study locations. Temporal patterns of foliar S response varied significantly with S source. When applied as ammonium sulphate (AS), foliar levels increased sharply in year 1 and slowly declined over the next 2 years. Conversely, additions of elemental S (S0), in the form of S0 sodium bentonite fertilizer, usually did not increase foliar S concentration in year 1, but had increasingly positive effects on foliar S in years 2 and 3. An increase in the S application rate from 50 to 100 kg/ha resulted in only a modest improvement in foliar S concentration for both S sources. Differences in individual-tree basal area increment between N and N+S treatments were statistically significant in only two of six trials. Prefertilization levels of foliar N and sulphate S, and probable induced deficiencies of nonadded nutrients following N fertilization, largely explained basal area and height responses to N and N+S additions at the six study sites. Despite delayed oxidation, S0 was as effective as the more readily available AS in stimulating radial growth after 6 years. However, the relative effectiveness of S source varied with S application rate in two trials. In both cases, basal area increment was positively related to application rate when S was applied as AS. Conversely, the effect of application rate was distinctly negative when S0 was applied. Despite large differences in short-term availability of AS and S0, the results from this study support the conclusion that the two S sources are likely equally effective in alleviating S deficiencies and in promoting tree growth of S-deficient lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.).
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".