Soil Tests as Risk Indicators for Leaching of Dissolved Phosphorus from Agricultural Soils in Ontario
Bibliographic record
Abstract
Phosphorus movement in subsurface flow from agricultural soils can be a significant pathway contributing to eutrophication of surface waters. Our study aimed to evaluate several environmental and agronomic soil P tests as indicators of dissolved reactive P (DRP) concentrations in soil‐column leachate from Ontario soils. Undisturbed soil columns were collected from six major soil series, with 10 sites of each to quantitatively cover a wide range of soil test P (STP) or degree of P saturation (DPS). Split‐line models described the relationships ( P < 0.001) between leachate DRP concentrations and the values of ln(STP) and ln(DPS), with a greater slope observed above the change points than below them. Among the tested soil P measures, water‐extractable P (WEP), Mehlich‐3 P/(Mehlich‐3 Al + Fe) (DPS M3 ‐1), and Mehlich‐3 P/Mehlich‐3 Al (DPS M3 ‐2) had the strongest overall relationships with leachate DRP concentration. Ontario soils were grouped into no‐risk, low‐risk, medium‐risk, and high‐risk categories based on the conditional probability of yielding leachate DRP > 0.1 mg P L −1 at a given STP as measured by WEP and Olsen P or a given DPS as measured by DPS M3 ‐1 and DPS M3 ‐2. While the Olsen P test is most commonly used for agronomic calibration in Ontario, DPS M3 ‐2 provided the best indicator of leachate DRP concentration from Ontario soils. Regardless of the test method used, these numeric criteria could be combined with site hydrology and P management practices for a more comprehensive soil P loss assessment.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 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".