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  • Effects of 20 years of litter and root manipulations on soil organic matter dynamics

    Creator:
    Wig, Jennifer D.
    Abstract:
    Globally, the forestry sector is the second largest contributor of greenhouse gases, and sustainable forest management is a major target of international environmental policy. However, there is the assumption underlying many policy recommendations that an increase in above-ground carbon stocks correspond to long term increases in ecosystem carbon stocks, the...
    Resource Type:
    Masters Thesis
    Full Text:
    in soil respiration rates, probably due to decreases in moisture and organic matter content, but

  • Effect of iron redistribution in soils on cesium magnetometer surveys at the Oregon State University research dairy

    Creator:
    Rogers, Michael
    Abstract:
    Contamination events at Oak Creek, which runs through Oregon State University Research lands, prompted investigations into alternate transport mechanisms for moving liquid effluent from OSU Diary lands to Oak Creek. Magnetometer surveys conducted at the Diary identified magnetic signatures spatially associated with sub-surface locations of drain tiles, a 12-inch pipe,...
    Resource Type:
    Dissertation
    Full Text:
    magnitude of the Earth's magnetic field by 500 nT or more [11] Variations in soil iron content can produce

  • Assessing the role of reactive metal species in soil organic matter cycling using chemical imaging

    Creator:
    Keiluweit, Marco
    Abstract:
    Intimate associations with reactive metal species permanently protect soil organic matter (SOM) from microbial access and oxidation, contributing to the build-up of organic carbon (C) stocks in soils. It is increasingly recognized, however, that such associations can be reversible and that reactive metal species might even facilitate the oxidation of...
    Resource Type:
    Dissertation
    Full Text:
    ABSTRACT OF THE DISSERTATION OF Marco Keiluweit for the degree of Doctor of Philosophy in Soil Science

  • Carbon fluxes across three climatically-distinct forest chronosequences in Oregon

    Creator:
    Campbell, John
    Abstract:
    Biometric and gas exchange techniques were used to measure soil respiration (soil surface CO₂ efflux) and NEP (Net Ecosystem Production) across three climatically-distinct forest chronosequences in Oregon. Results indicate significant forest type, age, and forest type x age interaction effects on annual soil respiration. A regional age class distribution skewed...
    Resource Type:
    Dissertation

  • Estimating plant-available nitrogen release from manures, composts, and crop residues

    Creator:
    Gale, Eric S.
    Abstract:
    In order to properly utilize organic amendments as nitrogen sources, reliable methods to estimate plant-available nitrogen (PAN) are needed. The objectives of this study were to (1) evaluate the use of crop and soil responses in fertilizer N equivalence (FNE) calculations, (2) examine the relationships between the C/N ratio, total...
    Resource Type:
    Masters Thesis
    Full Text:
    relationships held for only certain ranges. Pre-plant inorganic soil N tests and the pre-sidedress nitrate test

  • Exploring mechanisms that drive the development of reversible soil hydrophobicity

    Creator:
    Woolverton, Priscilla B.
    Abstract:
    This study focuses on one widespread characteristic of poor soil quality: hydrophobic soil. Previous research has produced conclusive evidence to show that soil hydrophobicity is affected by soil organic matter (SOM) and soil water content (WC). Hydrophobicity that responds to changes in WC is a unique form of surface hydrophobicity...
    Resource Type:
    Masters Thesis
    Full Text:
    as to why soil moisture content impacts the expression of soil hydrophobicity (Doerr and Thomas

  • The effects of land use on stream nitrate concentrations : from the catchment scale to the regional scale

    Creator:
    Poor, Cara J.
    Abstract:
    This work furthers the understanding of processes occurring in catchments that affect stream nitrate concentrations using two different approaches: a temporally intensive case study of three headwater catchments with varying land use (through storm event monitoring) and a spatially intensive study on the regional scale (through statistical modeling) of 1st-4th...
    Resource Type:
    Dissertation
    Full Text:
    storm response (i.e., depletion of soil water nitrate, addition of fertilizer, etc.), and how the

  • Temporal and spatial variability of groundwater nitrate in the southern Willamette Valley of Oregon

    Creator:
    Mutti, Jeffrey Glenn
    Abstract:
    Groundwater nitrate contamination is a well-documented issue in the Southern Willamette Valley (SWV) of Oregon, as a Groundwater Management Area (GWMA) has recently been declared. As a GWMA, groundwater nitrate monitoring must occur until regional concentrations are below 7 mg/L NO3-N. However, the presence of temporal variability can make it...
    Resource Type:
    Masters Thesis
    Full Text:
    into nitrate. Since nitrate is an anion that is highly soluble with virtually no retardation in soil

  • Distinguishing biological and physical controls on soil respiration

    Creator:
    Phillips, Claire L.
    Abstract:
    Soil respiration, or the combined CO₂ emissions from roots and soil microorganisms, constitutes one of the largest losses of carbon (C) from terrestrial ecosystems. The major drivers of soil respiration, which include soil moisture, temperature, and substrate quality, have been known for some time. Nevertheless, correlations between these drivers and...
    Resource Type:
    Dissertation
    Full Text:
    October 23, 2009 Title: Distinguishing Biological and Physical Controls on Soil Respiration Abstract

  • Quantifying C and N contents and isotope signatures of SOM pools in the H. J. Andrews DIRT plots

    Creator:
    Keirstead, Heath
    Abstract:
    The mechanisms governing short- and long-term belowground carbon dynamics need to be understood. As part of a larger project developed to assess the effect of quantity and quality of litter inputs on the rate of soil organic matter (SOM) formation, I examined SOM in the H. J. Andrews Detritus Input...
    Resource Type:
    Masters Thesis
    Full Text:
    to the soil is much lower in nitrogen content than is needed by the respiring microbes. Plant leaves