Doctor of Philosophy / Department of Agronomy / Mary Beth Kirkham / In Kansas, winter cover crops have a new interest with the development of summer crops for biofuel. When a crop is harvested for bioenergy, the residue is removed leaving the soil prone to erosion during the winter. It is possible that the use of winter cover crops may allow for more residue to remain in a field while keeping the soil from blowing. Therefore, the objective of this research was to determine the effect of two winter cover crops on the growth of two biofuel crops, corn (Zea mays L.) and forage sorghum [Sorghum bicolor (L.) Moench] in a corn-forage sorghum rotation. The two cover crops were a legume, Austrian winter pea (Pisum sativum var. arvense Poir.) and winter wheat (Triticum aestivum L.). Control plots were fallowed. The experiment was done for two years (2010 and 2011) at two locations: under rain-fed conditions in Manhattan in the northeastern part of Kansas, where the soil was a Belvue silt loam (coarse-silty, mixed superactive non-acid, mesic Typic Udifluvents) and under irrigated conditions in Tribune in the western part of Kansas, where the soil was a Richfield silt loam (fine, smectitic, mesic Aridic Argiustolls). Two levels of nitrogen were added to the soil: 0 and 101 kg ha[superscript]-1 N. Grain and stover yields of the corn and forage sorghum were determined at harvest of the crops in the fall, and dry matter production of the cover crops was determined at their termination in the springs of 2011 and 2012. Additional nitrogen fertilizer increased grain and stover yields in both growing seasons at both locations, except for Manhattan in 2010. During the second winter of the study, Austrian winter pea did not emerge in Manhattan, probably due to a combination of cold temperatures and drought. Austrian winter pea survived both winters at Tribune. Corn yielded more grain than did the forage sorghum in Manhattan in 2011 and in Tribune in 2011. This suggests that, under both rain-fed and irrigated conditions in Kansas, corn would potentially be more productive for bioenergy production than forage sorghum. The results of the study also showed that winter wheat for both Manhattan, Kansas, and Tribune, Kansas, should be the cover crop chosen, because of its ability to grow well during the off-season of the bioenergy crops and to provide soil cover during winter.

This research explores multiple geo-visualisations to enhance the comprehension of changing reality. It establishes a cognitive visualisation model as a framework and a multiple visualisation approach for implementation. Multiple visualisations of land cover changes including 2D and 3D, abstract and realistic simulations with static and dynamic components are created and tested through a formal user survey. It is concluded that although the real world cannot be perfectly represented, comprehension and interpretation can be improved and enhanced by providing effective multiple visualisations in accordance with users’ specific needs and tasks.

The City of Regina Fleet Street landfill, north-east of Regina, Saskatchewan, is approaching its maximum capacity after a 47-year operating life and plans are now being made for its closure. As part of closure planning work, four test plots encompassing two different cover designs (a capillary break cover and a store-and-release cover) were constructed on the landfill in the summer of 2004. One cover of each design was constructed on both the north facing and the south facing slopes.<p> The overall objective of this thesis is to evaluate the preliminary performance of the four test plots on the City of Regina landfill with regards to net percolation, gas flux, water balance and vegetation. To meet this overall objective three specific objectives were developed as follows:<p> Evaluate the performance and integrity of the monitoring scheme. <p> Characterize the properties of the soil covers on the four test plots. <p> Develop a preliminary water balance using the monitoring field data. <p> A field instrumentation program was carried out which included detailed monitoring of gas composition, volumetric water content, matric suction and temperature within the cover profile as well as measurements of interflow, runoff and site-specific meteorology. Generally, the instrumentation performed well with the exception of the tipping bucket which did not accurately measure precipitation.<p> Evaluation of the covers revealed that the slope aspect exerts greater influence over the water balance than that exerted by cover design itself. The south test plots were drier than the north, experienced more net radiation, and generally had more abundant vegetation. A water balance was conducted for each test plot at the upper, mid and lower slope. It is clear that a capillary break was not maintained on the north slope for the entire monitoring period and the percolation from the store-and-release cover was less than that of the capillary break cover. The south test plots were very dry and net percolation was nearly the same for both test plots. Therefore, it is believed that the store-and-release covers are performing better than the capillary break covers.

The City of Regina Fleet Street landfill, north-east of Regina, Saskatchewan, is approaching its maximum capacity after a 47-year operating life and plans are now being made for its closure. As part of closure planning work, four test plots encompassing two different cover designs (a capillary break cover and a store-and-release cover) were constructed on the landfill in the summer of 2004. One cover of each design was constructed on both the north facing and the south facing slopes.<p> The overall objective of this thesis is to evaluate the preliminary performance of the four test plots on the City of Regina landfill with regards to net percolation, gas flux, water balance and vegetation. To meet this overall objective three specific objectives were developed as follows:<p> Evaluate the performance and integrity of the monitoring scheme. <p> Characterize the properties of the soil covers on the four test plots. <p> Develop a preliminary water balance using the monitoring field data. <p> A field instrumentation program was carried out which included detailed monitoring of gas composition, volumetric water content, matric suction and temperature within the cover profile as well as measurements of interflow, runoff and site-specific meteorology. Generally, the instrumentation performed well with the exception of the tipping bucket which did not accurately measure precipitation.<p> Evaluation of the covers revealed that the slope aspect exerts greater influence over the water balance than that exerted by cover design itself. The south test plots were drier than the north, experienced more net radiation, and generally had more abundant vegetation. A water balance was conducted for each test plot at the upper, mid and lower slope. It is clear that a capillary break was not maintained on the north slope for the entire monitoring period and the percolation from the store-and-release cover was less than that of the capillary break cover. The south test plots were very dry and net percolation was nearly the same for both test plots. Therefore, it is believed that the store-and-release covers are performing better than the capillary break covers.

Rapid population growth in Arizona is leading to increasing demand and decreasing availability of water, requiring a detailed quantification of hydrological processes. The integration of detailed spatial water fluxes information from remote sensing platforms, and hydrological models is one of the steps towards this goal. One example step is the use of MODIS Snow Cover Area (SCA) information to update the snow component of a land surface model (LSM). Because cloud cover obscures the images, this project explores a rule-based method to remove the clouds. The rules include: combination of SCA maps from two satellites; time interpolation method; spatial interpolation method; and the probability of snow occurrence in a pixel based on topographic variables. The application in sequence of these rules over the Upper Salt River Basin for WY 2005 resulted in a reduction of cloud obscuration by 93.7878% and the resulting images' accuracy is similar to the accuracy of the original SCA maps. The results of this research will be used on a LSM to improve the management of reservoirs on the Salt River. This research seeks to improve SCA data for further use in a LSM to increase the knowledge base used to manage water resources. It will be relevant for regions were snow is the primary source of water supply.

This research explores multiple geo-visualisations to enhance the comprehension of changing reality. It establishes a cognitive visualisation model as a framework and a multiple visualisation approach for implementation. Multiple visualisations of land cover changes including 2D and 3D, abstract and realistic simulations with static and dynamic components are created and tested through a formal user survey. It is concluded that although the real world cannot be perfectly represented, comprehension and interpretation can be improved and enhanced by providing effective multiple visualisations in accordance with users’ specific needs and tasks.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references. Also available via the Internet.

Thesis (M.S.)--Oregon State University, 1999. / Typescript (photocopy). Includes bibliographical references. Also available online.

Thesis (Ph.D.)--Bowling Green State University, 2006. / Document formatted into pages; contains vii, 184 p. Includes bibliographical references.

Dissertation (PhD(Agric))--University of Stellenbosch, 2007. / Bibliography.