Two field investigations were undertaken to study the role of water table management in reducing herbicide pollution of ground water. One of the three-year studies (1992-1995) was conducted in a sandy field near Joliette (Laurin farm), (Quebec) to monitor the herbicide metribuzin where potatoes were grown. Two water table management systems were evaluated, namely subsurface drainage and subirrigation. Soil and ground water samples were taken at two week intervals, once before and six times after the herbicide application. / The amount of rainfall received in the first few weeks following herbicide application is crucial in assessing the extent of ground water contamination. In 1992, fewer rainfall events occurred after the application as compared to 1993, so metribuzin leached slowly. In 1992, it appears that subirrigation reduced ground water contamination by a factor of 10 through enhanced degradation and the greater effect of dilution. However, the role of subirrigation in reducing the metribuzin contamination of ground water was negligible in 1993 due to considerable leaching soon after the application. / The second project was conducted in an organic soil in St-Patrice-de-Sherrington (Van Winden farm) where the herbicide prometryn was studied. Surface irrigation with a controlled water table was also used as a water table management system. One experimental unit was used for each of the three treatments (subirrigation, surface irrigation and subsurface drainage). / The herbicide application rate was greater at the Van Winden farm than in the Laurin farm (5.5 kg/ha versus 1.0 kg/ha). However, a higher adsorption coefficient of the organic soil minimized the leaching process. Ground water contamination was less extensive in the organic deposit. The effect of subirrigation in reducing ground water contamination was significant when the water table was shallow. Prometryn degradation was relatively slow during the summer. Moreover, significant amounts of prometryn carried-over into the soil after the winter season, so it appears to be a quite persistent herbicide in our climate.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.55410 |
| Date | January 1994 |
| Creators | Aubin, Eric |
| Contributors | Yong, R. N. (advisor), Prasher, S. O. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Civil Engineering and Applied Mechanics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001447993, proquestno: AAIMM05514, Theses scanned by UMI/ProQuest. |
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