Soil Phosphorus in Farmed Potholes: Assessing Concentrations and Testing Export Mitigation with Steel Media
Bibliographic record
Abstract
Highlights Phosphorus concentrations were higher near the bottom of farmed potholes compared to soils outside of the potholes. Benchtop flow-through experiments demonstrated that steel shavings effectively adsorbed dissolved reactive phosphorus. A blind inlet amended with steel shavings reduced phosphorus export from a surface-drained pothole. Abstract. The Prairie Pothole Region, which extends from north-central Iowa northward into Canada and westward to Montana, is typified by closed depressions that formed over 10,000 years ago during the most recent glacial retreat. Today, many of these potholes contain artificial drainage to lower the water table, allowing for agricultural production of the land. Even when drained, farmed potholes can become inundated with phosphorus (P) enriched surface waters after large rain events. The goal of this study was to characterize the spatial distribution of soil P in farmed potholes and evaluate a steel media-modified blind inlet as a tool to reduce P export from farmed potholes. Results from the soil sampling indicated that Bray-1 soil test P concentrations are nine times higher near the bottom of the pothole compared to locations outside of the farmed pothole. Steel shavings were evaluated for P sorption in a laboratory flow-through cell evaluation where they removed between 60 and 70% (discrete P), even when cumulative P loading was over 6000 mg kg -1 . In a field investigation, a modified blind inlet containing a mixture of steel shavings and pea gravel replaced a Hickenbottom surface intake. The modified blind inlet retained an average of 83% of the influent dissolved reactive P and 62% of the influent total P based on five paired samples. The results from this study demonstrate that farmed potholes contain a significant amount of legacy soil P and that blind inlets containing steel shavings can replace surface intakes and reduce P export from farmed potholes. This research could inform future design and implementation of these P removal structures. Keywords: Drainage, Farmed wetland, French drain, Iron filings, Iron shavings, Iron tailings, Prairie pothole, Surface intake, Tile.
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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 | 0.000 |
| 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 | 0.001 | 0.000 |
| Open science | 0.001 | 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".