Sorption and desorption of phosphorus as influenced by corn stalk residue, pH, and ionic strength in a gleysol from Québec, Canada
Bibliographic record
Abstract
The Pike River watershed has a history of phosphorus (P) pollution due to surface and subsurface leaching, and erosion of agricultural soil rich in P. It is therefore important to consider factors that may change the dynamics of P sorption and desorption behaviours and potentially increase the P concentration in the soil solution.This thesis investigates the effect of corn stalk residue presence and application rate on P sorption and desorption.This thesis also investigates the effect of varying solution pH and ionic strength on P release.Batch experiments were used to investigate P sorption followed by experiments to test the reversibility of the sorption process under different corn stalk residue applications (0.3,5.3,10.3,15.3, and 20.3%) and at different P concentrations (0, 12.9, 27.7, 42.2, 57.0, and 71.8 mg L -1 ).The quantity of P sorbed to soil was found to decrease significantly as residue application rates increased (p<0.0001).Phosphorus remaining in the soil after desorption decreased significantly as application of residues increased (p<0.0001).Varying the P concentration under a constant dosage of residue (5.3%) showed that the concentration of P sorbed increased with increases in P application; however sorption efficiency decreased with increasing P application.Sorption in the presence of residues was significantly lower (p<0.0001)than sorption in the absence of residues for P treatments higher than 42.2 mg L -1 .Percent sorbed P remaining after desorption was similar in the presence (85-91%) and absence (86-91%) of the 5.3% corn stalk residue treatment.A second study was performed to investigate the effect of varying ionic strength and pH on P release into solution and to identify which factor had a greater effect on P release.It was found that at low ionic strengths the pH effects on P release were more pronounced whereas at high ionic strengths the P concentrations were not significantly different regardless of pH level.Since residue incorporatio n increased the availability of P in this soil, then due to the P pollution history of the area it is suggested that a large scale study be conducted taking into account a temporal component
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".