Phosphorus-Sorption Characteristics of Calcareous Soils in Arid and Semi Arid Regions
Bibliographic record
Abstract
Understanding of phosphorus (P) sorption and desorption by soils is important for water quality. The objectives of this study are to: (1) estimate P-sorption parameters of calcareous soils; and (2) determine the factors affecting P sorption and the relation between equilibrium P concentration at zero-net P sorption (EPCo) and soil parameters. In this study selected samples of calcareous soils (CaCO3 % 34-60) were collected from the Al-Hashemiya area. Phosphorus sorption isotherms covering a wide concentration range of phosphate (0-500 mg/L phosphate) were determined at room temperature by batch experiments. The results indicate that as the P concentration in solution increased, the slope of the sorption isotherm changed abruptly. The abrupt change in slope of the sorption isotherms suggests that P precipitation at the carbonate surface began to dominate the process as concentrations increased beyond that of the point of inflection. Sorption isotherm results showed that these soils best fit Freundlich isotherm. Both Pearson correlation matrix and stepwise regression models indicated that Fe-oxide and soil cation exchange capacity (CEC) are the most significant effective (P<0.05) predictors on P availability and occurrence in calcareous soils, while carbonate content, soil pH, EC, and OM content were insignificant on P availability
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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 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".