Controlled drainage – Effects on nutrient attenuation and water quality – A field study in Eastern Ontario, Canada
Bibliographic record
Abstract
Controlled drainage (CD) is a promising practice for mitigating the adverse effects of tile drainage on downstream waterbodies by reducing pollutants while maintaining agro-economic benefits. In cold-climate regions, like Eastern Ontario, Canada, previous CD studies have typically focused on growing season based on operational recommendations. However, the fate of retained water and nutrients after stoplog removal (flush) and any CD residual effects during non-frozen, post-harvest period remain unclear. The central objective of this three-year study was to assess CD versus free drainage from planting to freeze-up (May to November) by analyzing Growing, Flush and Post-Harvest Periods (GP, FP, PHP). Greatest reductions in flow (68 %) and nutrient loads (nitrate by 51 %, soluble reactive phosphorus (SRP) by 76 %) occurred in GP under CD. During FP, flow and nutrient losses at CD increased significantly before returning to background levels. CD plots showed 35 % significantly greater relative abundance of nitrate-reducing bacteria in soil, suggesting enhanced denitrification. However, any positive effects of denitrification and crop uptake on nitrate reductions in dry GP subperiods were outweighed by increased leaching losses in the wet subperiods (19 %). CD significantly reduced total suspended solids and total phosphorus migration in GP+FP likely due to stoplog damming reducing macropore flow. While SRP concentrations at CD were 35–85 % significantly lower during GPs, they increased three to seven times during FP, indicating possible desorption under stagnant conditions. Overall, CD implemented in GP reduced total flow (37 %), nitrate (21 %), and SRP (57 %) loads from planting to freeze-up, highlighting its potential for cold-climate cropping systems.
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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) | 0.000 | 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".