Title page for ETD etd-02212006-173715


Type of Document Master's Thesis
Author Fajardo, Gabriela Isabel
URN etd-02212006-173715
Title Physical and Chemical Soil Properties of Ten Virginia Department of Transportation (VDOT) Mitigation Wetlands
Degree Master of Science
Department Crop and Soil Environmental Sciences
Advisory Committee
Advisor Name Title
Daniels, Walter Lee Committee Chair
Aust, Wallace Michael Committee Member
Galbraith, John M. Committee Member
Perry, James E. III Committee Member
Whittecar, G. Richard Committee Member
Keywords
  • Redox Features
  • Hydric Soils
  • Bulk Density
  • Organic Amendment
Date of Defense 2006-01-30
Availability unrestricted
Abstract
In 1998, the Virginia Department of Transportation (VDOT) adopted standards for soil handling and amendments to improve created non-tidal wetland soil conditions. This study was conducted in sites where these new reconstruction practices were supposedly being implemented. Specific objectives were (i) to determine the relative effects of soil reconstruction practices on mitigation site soils, (ii) to assess the degree to which hydric soil indicators were present, and (iii) to evaluate the relative edaphic potential of mitigation site soils. Soil physical, chemical and morphological properties were analyzed in ten mitigation wetlands located in Virginia’s Piedmont and Coastal Plain. Surface soil pH was high due to liming, although some sites demonstrated low subsoil pH, indicating the presence of sulfidic materials. Nutrient levels varied, while C:N ratios were low (<25:1), suggesting a high quality organic matter complex. Organic amendments were generally applied at a rate of 4% soil organic matter content. Actual measured carbon content was <2.6% (<50 Mg ha-1). Sites not receiving organic materials and associated tillage had root-limiting bulk densities at the surface, while the majority of sites had root-limiting subsoil (30 cm) bulk densities due to weakly developed soil structure and a lack of deep ripping practices. Many sites also contained high sand content (>50%), which may negatively affect other soil properties. Nine sites had confirmed Hydric Soil Indicators, with their occurrence in a site as high as 70%. Soil reconstruction methods need to incorporate higher organic amendment rates and/or routine disking/ripping practices to improve mitigation wetland soil conditions.
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