Corn (Zea mays L.) production under monoculture and conventional tillage systems may land to soil degradation and nitrate (NO$ sb3 sp-$) pollution of surface and groundwater. This study evaluated the impact of no-till and conventional tillage, monoculture corn and soybean, corn-soybean rotations and corn-soybean-alfalfa rotations, and three fertilizer N rates applied to monoculture corn or soybean, and corn in rotation, on soil NO$ sb3$-N and NH$ sb4$-N levels. Experimental sites were a Ste-Rosalie clay (Humic Gleysol) and an Ormstown silty clay loam (Humic Gleysol). Results obtained from fall 1992 to spring 1995 showed that tillage had no effect on soil N levels under corn. Soil N levels under corn showed a linear response to added N, specially in the fall. Soil N levels under corn did not change considerably during the non-growing season. Higher spring NO$ sb3$-N levels, particularly in plots under conventional tillage and alfalfa or soybean, compared to fall values indicated greater nitrification and/or mineralization than denitrification, immobilization or leaching. Low NH$ sb4$-N levels indicated that nitrification processes were active. No consistent estimation could be made of fertilizer N credits for corn from either soybean or alfalfa based on NO$ sb3$-N levels in soil.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.27319 |
| Date | January 1996 |
| Creators | Galiano, Norma Graciela. |
| Contributors | MacKenzie, A. F. (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 Natural Resource Sciences.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001576694, proquestno: MQ29694, Theses scanned by UMI/ProQuest. |
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