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Filtering by: Advisor Evans, D. D. Remove constraint Advisor: Evans, D. D. Committee Member Kleber, Markus Remove constraint Committee Member: Kleber, Markus

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  • Soil Health and the Response of the Soil Microbial Community to Disturbances across Western North America

    Creator:
    Kersey, Jordan H.
    Abstract:
    Temperate coniferous forests, such as those that cover vast areas of the western US and Canada, have evolved to depend on cycles of disturbance for succession of species and overall ecosystem maintenance. Many of these forest systems are managed, often for timber production, where disturbances are of anthropogenic origin and...
    Resource Type:
    Masters Thesis
    Full Text:
    Abstract approved: ______________________________________________________ David D. Myrold

  • Diversity and Activity of Microbial Extracellular Peptidases in Soil

    Creator:
    Nguyen, Trang T. H.
    Abstract:
    Soil nitrogen exists largely as organic matter, including plant liter, dead animal matter, and microbial necromass. About 90% of soil organic nitrogen is proteinaceous material that is too large for plants and microorganisms to assimilate directly. Protein depolymerization therefore plays a critical role in mobilizing this organic source of nitrogen,...
    Resource Type:
    Dissertation
    Full Text:
    : _____________________________________________________ David D. Myrold Soil nitrogen exists largely as organic matter, including plant liter

  • Using Algal Biomass as a Fertilizer

    Creator:
    Cappellazzi, Shannon B.
    Abstract:
    Algae can be used in a variety of wastewater systems to capture nutrients while fixing carbon dioxide from the atmosphere. I conducted field trials at three locations in Oregon with both corn and potato crops to assess the agronomic value and environmental impact of using the resulting algal biomass as...
    Resource Type:
    Dissertation
    Full Text:
    : ______________________________________________________ David D. Myrold Algae can be used in a variety of wastewater systems to capture

  • Long-term Impacts of Nitrogen Fertilizer, Tillage and Crop Residue on Soil and Plant Nutrients in Winter Wheat Cropping Systems Under Dryland Conditions

    Creator:
    Shiwakoti, Santosh
    Abstract:
    Agricultural practices influence the nutrient dynamics of soil and plants, which may take more than a decade to be expressed in the drylands. The nutrient supplying capacity of soil is a crucial component of sustainable agriculture, and hence, this study can play an important role in policy making for the...
    Resource Type:
    Dissertation
    Full Text:
    : ______________________________________________________ Valtcho D. Jeliazkov Agricultural practices influence the nutrient dynamics of soil

  • Contributions of ammonia-oxidizing bacteria and archaea to nitrification in forest soils

    Creator:
    Lu, Xinda
    Abstract:
    Prior to 2005, ammonia oxidation, the first step of nitrification, was thought mediated mainly by ammonia-oxidizing bacteria (AOB). However, the discovery of Thaumarchaeota carrying the genes coding for the ammonia monooxygenase (AMO) enzyme led to the discovery that ammonia-oxidizing archaea (AOA) also contribute to nitrification. Despite the uptick in studies...
    Resource Type:
    Masters Thesis
    Full Text:
    : _____________________________________________________________________ David D. Myrold Prior to 2005, ammonia oxidation, the first step of nitrification, was

  • Response of soil microbial communities and nitrogen cycling processes to changes in vegetation inputs

    Creator:
    Brewer, Elizabeth Ann
    Abstract:
    Changes in the type and amount of plant inputs can occur gradually, as with succession, or rapidly, as with harvesting or wildfire. With global change it is anticipated that both gradual and immediate scenarios will occur at increasing frequency. Changes in vegetation inputs alter the quality and quantity of soil...
    Resource Type:
    Dissertation
    Full Text:
    Input. Abstract approved: ______________________________________ David D. Myrold

  • Carbon cycling and priming of soil organic matter decomposition in a forest soil following glucose additions

    Creator:
    Diaz, David D.
    Abstract:
    Soils are a globally significant carbon (C) pool and have the potential to respond to elevated CO2 and environmental changes through positive feedback cycles that enhance the turnover of soil organic matter (SOM). Understanding the mechanisms governing the turnover of SOM is particularly important for modeling the fate of C...
    Resource Type:
    Masters Thesis
    Full Text:
    OF THE THESIS OF David D. Diaz for the degree of Master of Science in Soil Science presented on

  • An Examination of Factors Controlling the Activity of Ammonia- and Nitrite-oxidizers in Diverse Soils

    Creator:
    Giguere, Andrew T.
    Abstract:
    Nitrification is a critical step in the global nitrogen cycle involving the biological oxidation of ammonia (NH₃) to nitrite (NO₂⁻ ) and then to nitrate (NO₃⁻). The first step in nitrification is carried out by NH₃-oxidizing bacteria (AOB) and archaea (AOA), and the second by NO₂⁻-oxidizing bacteria (NOB). In addition...
    Resource Type:
    Dissertation
    Full Text:
    : _______________________________________________________________________ Peter J. Bottomley David D. Myrold Nitrification is a critical step