Phosphorus Release from Unamended and Gypsum‐ or Biochar‐Amended Soils under Simulated Snowmelt and Summer Flooding Conditions
Bibliographic record
Abstract
Prolonged flooding changes the oxidation–reduction status of soils, often enhancing P release to overlying floodwater. We studied P release from unamended, gypsum‐amended, and biochar‐amended soils under simulated snowmelt flooding (previously frozen, cold flooding at +4°C) and summer flooding (unfrozen, warm flooding at +22°C) using two soils, Fyala clay (FYL‐Cl) and Neuenberg sandy loam (NBG‐SL), from Manitoba, Canada. Amended and unamended soils were packed into vessels and flooded under cold and warm temperatures in the laboratory. Pore water and floodwater samples were taken weekly for 6 wk after flooding (WAF) and thereafter biweekly for 10 WAF and analyzed for dissolved reactive P (DRP), pH, and cation concentrations. The NBG‐SL showed a significantly higher DRP concentration in pore water and floodwater despite its low Olsen P content. Redox potential (Eh) decreased slowly under cold versus warm flooding; hence, redox‐induced P release was substantially lower under cold flooding. Gypsum amendment significantly decreased the floodwater DRP concentrations in NBG‐SL by 38 and 35% under cold and warm flooding, respectively, but had no significant effect in FYL‐Cl, which had low DRP concentrations (<1.2 mg L −1 ) throughout the flooding period. Biochar amendment significantly increased floodwater DRP concentrations by 27 to 68% in FYL‐Cl under cold and warm flooding, respectively, but had no significant effect in NBG‐SL. The results indicate substantially less P release under cold than under warm flooding. Gypsum was effective in reducing floodwater DRP concentrations only at high DRP concentrations; thus, the effectiveness was greater under warm than under cold flooding conditions. Core Ideas Floodwater DRP concentration increased with time of flooding in amended and unamended soils. Increase in floodwater DRP concentration was less under simulated snowmelt than summer flooding. Rate of P diffusion from pore water to floodwater was less under simulated snowmelt flooding. Gypsum reduced floodwater DRP in one soil with DRP concentrations >1 mg L −1 , but not in the other. Woodchip biochar was ineffective in reducing P release from soils to overlying floodwater.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".