Environmental Mehlich-III soil phosphorus saturation indices for Quebec acid to near neutral mineral soils varying in texture and genesis
Bibliographic record
Abstract
The Mehlich-III method (M-III) (Mehlich 1984) is a multinutrient agri-environmental routine soil-testing procedure used in many jurisdictions in North America, but one that is affected by soil texture. The PW determined by the Sissingh (1971) method is an index of surface water contamination and desorbed P that is not influenced by soil texture and that can be used to define specific M-III critical environmental indices by soil texture group. Our objective was to define critical environmental indices by relating (P/Al)M-III to PW. We analyzed 275 soil samples from surface, and 175 from subsurface layers, varying in genesis, texture, and pH. The relationship between PW and (P/Al)M-III was influenced by soil properties, particularly soil texture and genesis. Fine-textured (> 300 g clay kg -1 ) and gleyed soils tended to release more PW at a given (P/Al)M-III compared with coarse-textured (≤ 300 g clay kg -1 ) and podzolized soils. Using a critical value of 9.7 mg PW L -1 derived from the literature, critical environmental (P/Al)M-III ratios were found to be 0.131 for coarse-, and 0.076 for fine-textured soils. Subsurface PW increased significantly with (P/Al)M-III above 0.131 in the plough layer of coarse-textured soils, but was independent of (P/Al)M-III in fine-textured soils, indicating contrasting mechanisms of P accumulation in subsurface layers (matrix vs. preferential flow). After accounting for soil texture, (P/Al)M-III appeared to be a useful index of P accumulation in Quebec mineral soils. Key words: Soil phosphorus saturation, Mehlich-III soil extraction method, water-extractable phosphorus, soil environmental phosphorus threshold, soil texture
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| 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".