Changes of soil test phosphorus and phosphorus fractions with single and blended soil chemical amendments
Bibliographic record
Abstract
Supplementing phosphorus (P) is essential for crop production, but excessive P becomes a pollutant through soil-to-waterway losses. Soil amendments can stabilize P and reduce dissolved P losses in runoff. While single-amendment applications have been extensively studied, the effectiveness of blended amendments in decreasing soil P loss remains largely unexplored. This study evaluated the effects of single and blended applications of alum (KAl(SO4)2·12H2O), ferric chloride (FeCl3), gypsum (CaSO4·2H2O), and magnesium sulfate (MgSO4) on soil P status and transformations in six agricultural soils from southern Manitoba. Fresh soils treated with 15 amendment treatments, including an unamended control, were incubated at 22 ± 1 °C and analyzed for water extractable P (WEP) and Olsen P concentrations at 0, 28, and 84 days of incubation. Samples taken on day 84 were used for sequential P fractionation to quantify changes in P concentrations in different fractions and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) to examine co-localization of P with other elements. All amendments significantly reduced WEP concentrations compared to the unamended control. The blended amendments showed a superior impact, especially gypsum or magnesium sulfate blended with ferric chloride than single amendments. The decrease in Olsen P concentrations with amendments, on average (9.5%), was much less than in WEP concentrations (53.0%). The sequential fractionation revealed that amendments significantly reduced readily and moderately soluble P fractions with a corresponding increase in recalcitrant-P, while SEM-EDX results indicated co-localization of P with Ca and Fe, suggesting P transformations contributing to more stable forms.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.001 | 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) | 0.001 | 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 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".