Kinetics and mechanisms of monoammonium phosphate-induced potassium release from selected potassium-bearing minerals
Bibliographic record
Abstract
A high concentration of phosphate in the immediate vicinity of the phosphate fertilizer zone of soil could induce K release from K-bearing minerals to soil solution. In this study, the kinetics of K release by monoammonium phosphate (NH 4 H 2 PO 4 ) from biotite, muscovite, and microcline were investigated. The results indicate that K release from all of these minerals was promoted by 1 M NH 4 H 2 PO 4 (pH 4.0). The release of K from these minerals can be described by the zero-order rate equation. The rate coefficients of K released from the minerals (2–5 µm) in 1 M NH 4 H 2 PO 4 solution ranged from 0.20 to 2.09 mg kg -1 h -1 at 25°C and from 1.22 to 9.00 mg kg -1 h -1 at 45°C, respectively. The amount of K release from the same mineral samples in 1 M NH 4 Cl solution (pH 4.0) at 25°C was not detectable and was too low to be determined accurately at 45°C. The dfferences in the rate of NH 4 H 2 PO 4 -induced K release from the different minerals were explained by the chemical composition, crystal structure, and the crystallization sequence of the minerals. The activation energies of the phosphate-induced K release from these minerals ranged from 37 to 72 kJ mol -1 and the pre-exponential factor values (Arrhenius equation) ranged from 1.2 × 106 to 7.2 × 1011 mg kg -1 h -1 . The examination of the phosphate-reacted minerals shows the formation of crystalline NH 4 -taranakite in the muscovite and microcline systems and noncrystalline products in the biotite system. The absence of the formation of crystalline NH 4 -taranakite in the biotite system is attributed to the Fe perturbation. These data indicate that the major mechanism of NH 4 H 2 PO 4 -induced K release from the K-bearing minerals was the combined effect of phosphate and protons on the alteration of minerals. Therefore, the K-supplying rate of soils in the immediate vicinity of fertilizer zones may be enhanced through phosphate fertilization. Key words: Potassium release, kinetics and mechanisms, phosphates, potassium-bearing primary minerals
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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 | 0.001 |
| 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".