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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The temperature and moisture distribution in an unsaturated soil column subjected to surface evaporation

Cordes, Edwin Henry, January 1965 (has links) (PDF)
Thesis (M.S.- Hydrology)--University of Arizona. / Includes bibliographical references (leaves 190-198).
2

A study of soil moisture and soil temperature in relation to tile drainage /

Palmer, Melville Louis. January 1955 (has links)
Thesis (M.S.)--Ohio State University, 1955. / Includes bibliographical references (leaves 41-42). Available online via OhioLINK's ETD Center
3

Temperature and evaporation characteristics of Arizona soils

Poland, John Robert. January 1984 (has links) (PDF)
Thesis (M.S. - Soil and Water Science)--University of Arizona, 1984. / Includes bibliographical references (leaves 63-66).
4

The effect of mulch on soil temperature, soil moisture, and evaporation /

Loupo, Marshall Wilson, January 1951 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute, 1951. / Vita. Includes bibliographical references (leaves 56-58). Also available via the Internet.
5

Freezing points of soils at the moisture equivalent

Pinckney, Reuben Marion, January 1900 (has links)
Thesis (Ph. D.)--University of Minnesota, 1924. / Biographical sketch. "Literature cited": leaves 85-88.
6

Freezing points of soils at the moisture equivalent

Pinckney, Reuben Marion, January 1900 (has links)
Thesis (Ph. D.)--University of Minnesota, 1924. / Biographical sketch. "Literature cited": leaves 85-88.
7

Effects of rhizosphere priming and microbial functions on soil carbon turnover

Lloyd, Davidson A. January 2015 (has links)
A major uncertainty in soil carbon studies is how inputs of fresh plant-derived carbon affect the turnover of existing soil organic matter (SOM) by so-called priming effects. Priming may occur directly as a result of nutrient mining by existing microbial communities, or indirectly via microbial population adjustments. Soil type and conditions may also influence the intensity and direction of priming effects. However the mechanisms are poorly understood. The objectives of this study were (1) to investigate how additions of labile C4 substrate affected SOM turnover in two contrasting unplanted C3 soils (clayey fertile from Temple Balsall, Warwickshire (TB) and sandy acid from Shuttleworth, Bedfordshire (SH) using13 C isotope shifts; (2) to investigate the influence of rhizodeposition from plant roots on SOM turnover in the same two soils planted with a C4 grass; (3) to assess an automated field system for measuring soil temperature, moisture and photosynthesis sensitivities of SOM turnover in the same two soils over diurnal to seasonal time scales. I used a combination of laboratory incubation, glasshouse and field experiments. In the soil incubation experiment, I made daily applications of either a maize root extract or sucrose to soil microcosms at rates simulating grassland rhizodeposition, and followed soil respiration (Rs) and its δ13 C over 19 days. I inferred the extent of priming from the δ13 C of Rs and the δ13 C of substrate and soil end-members. There were positive priming effects in both soils in response to the two substrates. In the SH soil there were no differences in priming effects between the substrates. However in the TB soil, sucrose produced greater priming effects than maize root extract, and priming effects with sucrose increased over time whereas with maize root extract declined after the first week. I explain these effects in terms of the greater fertility of the TB soil and resulting greater microbial nitrogen mineralization induced by priming. Because the maize root extract contained some nitrogen, over time microbial nitrogen requirements were satisfied without priming whereas with sucrose the nitrogen demand increased over time. In the glasshouse experiment, I planted C4 Kikuyu grass (Pennisetum clandestinum) in pots with the same two soils. The extent of rhizodeposition by the plants was altered by intermittently clipping the grass in half the pots (there were also unplanted controls) and priming effects were inferred from the δ13 C of Rs and the δ13 C of plant and soil end-members. Unclipped plants in both soils generated positive priming effects, while clipping reduced priming in TB soil and produced negligible PEs in SH soil. Microbial nutrient mining of SOM again explained the observed PEs in this experiment. Photosynthesis was a major driver of priming effects in the planted systems. In the third experiment, I found that the tested automated chamber system provided reliable measurements of Rs and net ecosystem exchange (NEE), and it was possible to draw relations for the dependency of Rs and NEE on key environmental drivers. Collectively, the results contribute to a better understanding of the mechanisms of priming effects and highlight possibilities for further research. The methods developed here will allow high temporal and spatial resolution measurements of Rs and NEE under field conditions, using stable isotope methods to separate fluxes into plant- and soil-derived components. Keywords: Soil respiration, soil moisture, soil temperature, Isotope ratio, maize root, flux chamber, climate change, organic matter, rhizodeposition.

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