Temperature‐Dependency of Phosphorus Sorption by Goethites and Tropical Soils Amended with Woodchip Biochar
Bibliographic record
Abstract
Core Ideas Freundlich and Langmuir isotherms described P sorption by oxides and soils, respectively. Biochar increased the extent and relative strength of P sorption by goethite at 15°C. Biochar reduced P sorption but increased P binding strength for sandy loam at 35°C. Phosphorus is a key nutrient in agriculture but also a common contaminant. Bioavailability and transport of P are controlled by, among other things, the presence of Fe and Al oxides in tropical soils. Biochar has been suggested for improving the bioavailability and reducing the off‐site transport of P. The objective of this study was, therefore, to evaluate the effect of biochar on P sorption by goethite, aluminum‐substituted goethite (Al‐goethite), and two tropical soils amended with 0, 20, and 40 g biochar kg −1 at 15, 25, and 35°C. Sorption by goethite and Al‐goethite was adequately described by the Freundlich isotherm although the Langmuir isotherm was a better fit for the two soils tested. At 15°C, biochar application increased P sorption by goethite from 9.5 to 11 g kg −1 /(mg L −1 ) 1/ n as indicated by the increase in the Freundlich constant, K f , and the increase in relative sorption strength represented by a reduction in the Freundlich exponent (1/ n ) from 1.2 to 0.8. At 35°C, biochar addition significantly reduced the Langmuir sorption maximum ( S max ) from 17.3 to 15.8 g kg −1 (mg L −1 ) −1 for the sandy loam soil, indicating a reduction in P sorption capacity in the presence of biochar. Biochar addition also significantly increased the Langmuir constant, ( K L ) for the sandy loam from 0.04 to 1.7 L mg −1 at 35°C, indicating greater P binding strength in the presence of biochar. The sorption data from this study provide insights into the effect of temperature on P sorption by Fe oxides and tropical soils in the presence of biochar.
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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 | 0.000 |
| 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 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".