Thesis (Ph. D. - Arid Lands Resource Sciences)--University of Arizona, 1986. / Includes bibliographical references (leaves 301-331).

Thesis (Ph. D.)--University of Adelaide, Dept. of Agronomy and Farming Systems, 1998. / Includes bibliographical references (p. 283-313).

Thesis (M.Inst.Agrar.(Agicultural Economics, Extension and Rural Development)) -- University of Pretoria, 2000. / Abstract in English. Includes bibliographical references.

Thesis (Ph. D., Natural Resources)--University of Idaho, December 2008. / Major professor: Paul E. Gessler. Includes bibliographical references. Also available online (PDF file) by subscription or by purchasing the individual file.

Dissertation (M. Appl. Sc.) -- Lincoln University, 2009. / Also available via the World Wide Web.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project. / Assisted by C. R. Fillerup and L. L. Bates / Edited and Revised by H. C. Heard

In order to understand the ecological characteristics of three dry farming systems in the semiarid San Luis Potosi Plateau, Mexico, a one year study was conducted. The systems studied were a purely rainfed field, a field on an alluvial fan irrigated with runoff water, and a field in a bottomland irrigated with water diverted from an ephemeral stream. Three treatments, farmed, edge and unfarmed, were established in a Randomized Block design, with three replications, for each system. The major conclusions of this research were the following. During the summer, climate is resposible for a concentration of the communities's production and reproduction. Climate is also of paramount importance to agriculture. Rainy periods, on the other hand, decreased the activity of animals. None of the farming systems had detrimental effect on soil fertility. Only slight modifications of soil temperature and air temperature and humidity resulted from farming. A general overview of all the results did not provide evidence that all farming systems decrease biotic richness and diversity. The effects depended on the type of system, its isolation, and the natural vegetation adjacent to it. Herbs were enhanced by farming only when the natural system was relatively free of them. Farming did not have important effects on invertebrates. Birds were negativelly affected by farming, whenever the unfarmed areas included an arboreal stratum. Also, insectivorous birds responded differently than non-insectivores. Rodents were affected negatively by farming in two of the systems, and this could be linked to habitat simplicity. In one case, dense herb cover was associated with very high rodent populations. In general the data adjusted to the hypothesis that structurally more heterogeneous agroecosystems hold more diverse biotas. The concepts of "farmland biota" and "edge effect" were not supported by this study. Edges were ocasionally superior, and only when they included more complex plant communities than either side. A mosaic of heterogeneous farmlands and natural vegetation attracts certain rodents and birds, increasing environmental diversity.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Thesis (M. Agr. Sc.) -- Lincoln University, 2009. / Also available via the World Wide Web.

Call number: LD2668 .T4 1949 B51 / Master of Science