Distribution of fertilizer phosphate in a coarse sandy soil profile after different long-term liming strategies
Bibliographic record
Abstract
We studied the distribution of P in the profile of an arable coarse sandy soil at Jyndevad Experimental Station, Denmark, using plots treated with mineral fertilizer P and different rates of lime. Since 1942, lime has been added at three rates while P has been added at an annual rate of 15.6 kg P/ha since 1944. Reference treatments were no lime and no P additions since 1942/44. Soil cores (0-100 cm) were retrieved in autumn 2016 shortly after barley harvest. We hypothesized that long-term liming, and the resulting differences in soil solution pH and cation composition, affects P mobility and sorption properties in the soil profile, and that long-term liming and annual P addition increases soil C content in response to improved crop growth. Soil chemical properties (pH, total P, total inorganic (Pi) and organic P (Po), Olsen P, water extractable P (Pw), soil C, and oxalate-extractable P, Fe and Al) were determined in five depths. The P sorption index (PSI), based on addition of 50-mmol P kg-1 soil, and was used to evaluate soil sorption capacity. Soil pH significantly increased with increased liming addition to at least 70 cm depth. For P fertilized soil, total P, Pi, Olsen P, Pw and oxalate P were significantly higher in 0-30 cm than in soil depth below, indicating that P had not migrated down the soil profile. Liming significantly increased soil C in 0-30 cm. There were strong relations between oxalate-extractable Al and PSI, while the relations between oxalate-extractable Fe and PSI were weak. In conclusion, long-term mineral fertilizer P application only affected the distribution of P to 30 cm depth. P sorption capacity increased substantially with depth until 50 cm, and it was only moderately affected by liming and P additions until 30 cm depth. Furthermore, P sorption capacity was related to the presence of amorphous Al oxides, while the role of amorphous Fe oxides was inferior.
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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 | 0.000 | 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 | 0.000 | 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".