The effect of water table management on water quality under sandy loam and clay loam soils at the farm scale
Bibliographic record
Abstract
The water table management systems on agricultural primary nutrients of NO3 -N, TP and K were investigated on three large field sites (a sandy loam site and two clay loam sites, one with no tillage and the other with conventional tillage) located in Southwestern Ontario. The investigation was conducted over a period from May 8, 1995 to July 14, 1998. The purpose of this investigation was to compare tile drainage volume, nutrient mean concentration and nutrient loss between water table control treatments (i.e. controlled drainage with subirrigation-CDS or controlled drainage only-CD) and the free drainage treatment (FD). The results of this study showed that both CDS and CD treatments produced less tile drainage volume compared with FD treatment. At the sandy loam site, the CDS treatment produced less tile drainage volume by 5.3% compared with FD treatment. At the clay loam sites of conventional tillage and no tillage respectively, the CD treatment produced less tile drainage volume by 12.2% and 2.9% compared with FD treatment. Both CDS and CD treatments promoted reduction of NO3 -N mean concentration, respectively by 38.6%, 13.1% and 12.8% at the sandy loam site and at the clay loam sites of conventional tillage and no tillage compared with FD treatment over the study period. Contrary, both CDS and CD treatments promoted increase in K mean concentration by 40.6%, 19.2% and 11.6 % respectively, at the sandy loam site and clay loam sites of conventional tillage and no tillage compared with FD treatment. The CD treatment reduced TP mean concentration marginally at conventional tillage site by 6.9% and at no tillage site by 1.3%, while at the sandy loam site the CDS treatment increased TP mean concentration by 21.9% compared with the FD treatment. Both CDS and CD treatments reduced NO3 -N and TP loss respectively, by 13.4% and 6.7% at the sandy loam site, by 13.2% and 7.1% at conventional tillage site and by 16.3% and 25% at no tillage site compared with FD treatment. In contrast, both CDS and CD treatments increased K loss at the sandy soil site and at the clay loam sites of conventional tillage and no tillage, respectively by 5.2%, 5.5% and 28.1% compared with FD treatment.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 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 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".