published_or_final_version / Civil Engineering / Master / Master of Philosophy

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A one year water table management field study was conducted on a Soulanges sandy loam soil in Soulanges county, Quebec. Two controlled water table levels, i.e. 0.5 m and 0.75 m from the soil surface, as well as free outlet conventional drainage treatments were established in monocropped corn (Zea mays L.) and corn intercropped with ryegrass (Lolium multiflorum Lam) plots. / Cropping system showed no significant effects on evapotranspiration, and on soil moisture distribution. It was observed that the 0.5 m and 0.75 m controlled water tables (CWT) provided the same soil moisture trends in both cropping systems. The soil moisture was always higher in controlled water table plots compared to freely drained plots. The water use efficiency of 0.75 m CWT in both cropping systems was high compared to 0.5 m CWT. / The soil moisture contents at three depths were only 2% to 10% less in intercropped plots compared to monocropped plots. The soil moisture was 12 to 13% higher in CWT plots compared to freely drained plots for both cropping systems. The soil moisture in 0.5 m CWT and 0.75 m CWT plots was not significantly different. The average water table levels in monocropped plots were not significantly different from intercropped plots.

The objective of this study was to determine the correlation between potentiometric surface and the depth to selected soil morphological indicators of wetness for the Glynwood (Aquic Hapludalf), Blount (Aeric Epiaqulaf), and Pewamo (Typic Argiaguoll) soils in Delaware County, Indiana. Four years of potentiometric surface measurements were averaged and compared to detailed soil descriptions performed by the Natural Resources Conservation Service. Significant correlations exist between the morphological indicators and the potentiometric surface for the Glynwood (moderately well drained) 2-m depth piezometers and 2-m depth slotted pipes, the Blount (somewhat poorly drained) top of the C horizon and 2-m depth piezometers, and the Pewamo (poorly drained) top of the B horizon piezometers. The relationships among the horizons in which potentiometric surface correlated to indicator depth may be a function of the increased persistence and shallowness of the potentiometric surface in mid-April. / Department of Natural Resources and Environmental Management

A field lysimeter experiment was conducted on a sandy loam soil during the growing seasons of 1989 and 1990. The experiment tested the effects of four water table treatments on soybean (Glycine max) yields. The water table depths were 40, 60, 80, and 100 cm in depth. / Yields were measured in terms of: total seed mass per plant, number of seeds per plant, number of pods per plant, number of seeds per pod, and speed protein content at harvest. / The water management simulation model DRAINMOD, was used to develop irrigation and drainage strategies for soybean production. Three water table management methods were tested with each of three water table depths. The methods were conventional drainage, controlled drainage, and subirrigation, and the water table depths were 40, 60, 80, and 100 cm. / It was shown that for the driest year highest yields are obtained with subsurface irrigation and a weir setting of 40 cm. For the average year, highest yields are obtained with subirrigation and a 60 cm weir setting. For the wet years, best results are found when controlled drainage is used with 80 cm weir setting. It was found that in all but the driest and wettest years controlled drainage improved yields by 10% or more.

Thesis (M.S.)--University of Nevada, Reno, 2004. / "December, 2004." Includes bibliographical references (leaves 79-83). Online version available on the World Wide Web.

Thesis(M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references.

Thesis (Ph.D.) --Murdoch University, 2004. / Thesis submitted to the Division of Science and Engineering. Includes bibliographical references (leaves R-1 - R-24). Also available via the World Wide Web at.