Direct and Indirect Effects of Soil Properties on Phosphorus Retention Capacity
Bibliographic record
Abstract
Phosphorus retention ability of soil has been predicted from different combinations of soil properties as a result of significant correlations between these variables. However, a significant correlation between P retention capacity and a soil property does not necessarily imply a significant direct effect of the soil property on P retention. The objective of this study was, therefore, to evaluate the direct and indirect influence of soil properties on P retention capacity of neutral to calcareous soils of Manitoba (Canada). One hundred fifteen archived surface soil samples representing major soils of Manitoba were used for the study. The P retention index (PRI) of these soils was determined by the single‐point adsorption method. The relationships between P retention and soil properties were evaluated by correlation analyses while the direct and indirect influences of these soil properties on P retention were evaluated using the path analysis procedures. Significant correlations (p = 0.05) were observed between PRI and pH; CO 3 2− ; organic C; sand content; silt content; clay content; exchangeable Ca (Ca Ex ); exchangeable Mg (Mg Ex ); cation exchange capaciaty (CEC); Mehlich‐3 extractable Ca (Ca M3 ); Mehlich‐3 extractable Mg (Mg M3 ); and oxalate extractable Al (Al Ox ). However, path analysis showed that only Ca M3 D = 0.62), Mg M3 ( D = 0.26), and Al Ox ( D = 0.21) had significant direct effects ( p = 0.05) on PRI. The significant effect of sand (soil texture) was due to the indirect influence of Ca M3 Our results show that the PRI for the neutral to calcareous soils of Manitoba is best predicted from Ca M3 , Mg M3 , and Al Ox Similar analysis conducted to relate the classical Langmuir adsorption maximum with the properties of a subset of soils also showed Ca M3 , Mg M3 , and Al M3 as the soil variables that had significant direct effects on soil's P retention.
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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 | 0.001 | 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 | 0.003 |
| 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".