Environmental Sciences Commons^™

Exploring Soil Microbial Dynamics In Southern Appalachian Forests: A Systems Biology Approach To Prescribed Fire Impacts, Saad Abd Ar Rafie

Doctoral Dissertations

Prescribed fires in Southern Appalachian forests are vital in ecosystem management and wildfire risk mitigation. However, understanding the intricate dynamics between these fires, soil microbial communities, and overall ecosystem health remains challenging. This dissertation addresses this knowledge gap by exploring selected aspects of this complex relationship across three interconnected chapters.

The first chapter investigates the immediate effects of prescribed fires on soil microbial communities. It reveals subtle shifts in porewater chemistry and significant increases in microbial species richness. These findings offer valuable insights into the interplay between soil properties and microbial responses during the early stages following a prescribed fire. …

Impact Of Cover Crop Species Diversity On Soil Nutrient Availability And Crop Productivity, Amanda Kramer

Masters Theses

Cover crops provide multiple environmental benefits that improve both soil and water quality; however, farmers only utilize them on approximately 5% of harvested U.S. cropland. Low adoption rates are attributed to yield impact concerns, seed and planting costs, and lack of advocacy. This study, which began in October 2019, assessed the effects of nitrogen rate and cover crop diversity on weed biomass, soil coverage, in-situ residue decomposition, soil nitrogen and phosphorus availability, and cash crop yield to better understand the costs and benefits of cover crop adoption at two locations in Tennessee (Milan and Spring Hill). Treatments were replicated 4 …

The Characterization Of Dynamic Soil Properties And Their Relation To Soil Organic Carbon In East Tennessee Soils, Shannon Marissa Newell

Masters Theses

Quantifying how dynamic soil properties (DSPs) are affected by different management regimes is essential for understanding how these vital resources can be better managed. The Dewey soil series is a critical soil series in East Tennessee. For this study, the University of Tennessee, Knoxville (UTK) worked alongside the National Cooperative Soil Survey (NCSS) in an effort to better understand the dynamics of the Dewey soil series through a wide range of DSP data. To accomplish this, Dewey soil was collected from five sites which are considered representative of five management regimes: well-managed cropland (WMC), poorly-managed cropland (PMC), well-managed pasture (WMP), …

Evaluation Of Microbiometer As A Tool To Estimate Soil Health In A West Tennessee Cotton Crop, Daniel T. Sain

Masters Theses

Healthy soils are critical for optimized yields and sustainability in agriculture. Soil health testing can provide valuable information on how management practices are affecting soil health. In west Tennessee, existing soil health tests were unable to discern between significant differences in management practices. A new soil health test called microBIOMETER® has been developed by Prolific Earth Sciences® (Montgomery, NY). MicroBIOMETER® utilizes a new methodology for estimating microbial biomass and uses that estimate as a soil health score. This test has not been validated for use in west Tennessee. This research was focused on the validation of microBIOMETER® in a continuous …

Conservation Agriculture As A Climate Change Mitigation Strategy In Zimbabwe, Deb O'Dell, Neal Eash, Bruce B. Hicks, Joel Oetting, Thomas J. Sauer, Dayton M. Lambert, Tarirai Muoni, Joanne Logan, James A. Zahn, John J. Goddard

Biosystems Engineering and Soil Science Publications and Other Works

There is a need to quantify agriculture’s potential to sequester carbon (C) to inform global approaches aimed at mitigating climate change effects. Many factors including climate, crop, soil management practices, and soil type can influence the contribution of agriculture to the global carbon cycle. The objective of this study was to investigate the C sequestration potential of conservation agriculture (CA) (defined by minimal soil disturbance, maintaining permanent soil cover, and crop rotations). This study used micrometeorological methods to measure carbon dioxide (CO₂) flux from several alternative CA practices in Harare, central Zimbabwe. Micrometeorological methods can detect differences in …

Impact Of Soil Water Content On Bermudagrass Athletic Field Performance, Kyley Hampton Dickson

Doctoral Dissertations

Soil water content (SWC) influences the consistency and performance of athletic fields. Two studies were conducted at the University of Tennessee Center for Athletic Field Safety (Knoxville, TN) to determine SWC impact on the performance of hybrid bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis, Burtt-Davy, ‘Tifway’] on silt loam (cohesive) and sand root zone conforming to United States Golf Association (USGA) specifications (noncohesive) root zones. Soil water content treatments for the cohesive soil averaged 0.10 m³/m³ (+/- 0.035), 0.17 m³/m³ (+/- 0.035), 0.26 m³/m³ (+/- 0.035), and 0.35 …

Opportunities In Sustainability: Maize Seeders For The Developing World And Alternative Fertilizers In The United States, Rebecca Mattingly Harman

Masters Theses

Sustainable agricultural systems are needed for both large and small-scale farmers the world over. Central to the sustainability of these systems is the availability of cheap and effective seeders for smallholder farmers and effective utilization of less energy intensive nitrogen sources. In the first two chapters, this thesis considers maize seeders for smallholder use in a Conservation Agriculture system. To sustain the smallholder sector, soil fertility and soil erosion must be addressed and a Conservation Agriculture model seeks to improve soil conditions in agriculture. The technologies available to smallholder farmers, though, need to be tested in a no-till system before …

Reaping The Benefits Of Conservation Tillage: Implications Of Increased Soil Organic Matter And Aggregation In Surface Soils, Kenna Elizabeth Rewcastle

Chancellor’s Honors Program Projects

No abstract provided.

Investigating The Effects Of Urbanization On Residual Forest Soils In Knox Co., Tennessee, Benjamin Lee Reichert

Masters Theses

As the process of urbanization advances across the country, so does the importance of urban forests, which include both trees and the soils in which they grow. Soil microbial biomass, which plays a critical role in nutrient transformation in urban ecosystems, is affected by factors such as soil type and the availability of water, carbon, and nitrogen. However, the microbial dynamics of urban forest soils remain largely unknown. A key mechanistic link between plant species diversity and ecosystem function is heterotrophic microbial communities that inhabit the soil and mediate principal processes that control ecosystem carbon (C) and nitrogen (N) cycling. …

Measuring Carbon Dioxide (Co2) Flux Of Agricultural Practices In Sub-Saharan Africa, Debra Blumberg O'Dell

Masters Theses

Agriculture has an important role in addressing two of the world’s most pressing problems: meeting global food demand and mitigating climate change. If agriculture is not practiced sustainably it will fail to meet future food demand and likely intensify the pace of global climate change. There are some agricultural practices, such as Conservation Agriculture, that can produce food sustainably and have the potential to mitigate climate change. However it is not clear which agricultural practices contribute to climate mitigation and by how much. By measuring the carbon dioxide (CO2) emissions of specific agricultural practices, the ability of practices to sequester …

Stability, Erosion, And Morphology Considerations For Sustainable Slope Design, Isaac Andres Jeldes Halty

Doctoral Dissertations

The construction of more natural and sustainable earth slopes requires the consideration of erosion and runoff characteristics as an integral part of the design. These effects not only result in high costs for removal of sediment, but also a profound damage to the ecosystem. In this dissertation, innovative techniques are developed such that more natural appearing slopes can be designed to minimize sediment delivery, while meeting mechanical equilibrium requirements. This was accomplished by: a) examining the fundamental failure modes of slopes built with minimum compaction (FRA) to enhance quick establishment of forest, b) investigating the geomechanical and erosion stability of …

Adsorption Of Antimony By Birnessite And The Impact Of Antimony On The Electrostatic Surface Properties Of Variable-Charge Soil Minerals, Kalyn Alaine Vergeer

Masters Theses

Antimony (Sb) is a toxin that can be found in high concentrations in the soil due to anthropogenic sources. Antimony exists in soil as Sb(V) in the monovalent antimonate hydroxyanion. The adsorption mechanisms of Sb(V) are not well-characterized. The objective of this study was to further elucidate Sb(V) adsorption mechanisms by examining the impact of adsorption on surface charging characteristics of gibbsite, goethite, birnessite, and kaolinite. Also examined was Sb(V), SO₄ [sulfate], and PO₄ [phosphate] adsorption by birnessite. Electrophoretic mobility and potentiometric titrations were employed to examine the ζ-potential [zeta-potential] and net proton surface charge density as a …

The Effects Of Land-Use Change On The Hydrological Properties Of Andisols In The Ecuadorian Paramo, James Joseph Hartsig

Masters Theses

The Ecuadorian páramo is characterized by unique soil properties that allow the ground to hold large amounts of water. These páramo grasslands support Andean cities and communities as a source of water for municipal, industrial, and agricultural use. Although recent research has suggested that changes in land use can decrease the amount of water and affect the water-holding capabilities of the soil, the hydrologic effects of different land uses, including burning for livestock grazing and pine planting for carbon credits, are currently under debate.

This research tested hypotheses about moisture-related properties of páramo soils under different land uses at two …

The Effects Of Changes In Water Content On Uranium(Vi) Leaching In Sediment Mixtures Containing Gravel, Andrew Weber Moore

Masters Theses

This study is aimed at understanding the physical and chemical effects that changes in water content have on uranium leaching in sediment containing gravel. It was hypothesized that leaching will be more efficient under unsaturated conditions because flow will be restricted to the smallest pores and will have the most contact with the uranium contaminated sediment. Under saturated conditions, a large portion of the flow will bypass the < 2 mm material, and in turn not come into contact with uranium contaminated material. Batch adsorption and desorption experiments were performed on < 2 mm ERDF sediment to determine the linearity and reversibility of sorption processes and to aid in the interpretation of the leaching experiments. Results of the desorption experiments on aged, contaminated sediments show that the mass percent of sorbed U(VI) released to solution decreased as the sorbed concentration of U(VI) decreased. The opposite trend was observed on freshly contaminated sediments. This indicated that aging increased U(VI) affinity for the solid phase and was attributed to either the crystallization of calcite, which incorporated a portion of the sorbed U(VI) as it crystallized, or the presence of voids in basaltic lithic fragments accessed by diffusion. Column leaching experiments were performed at two water contents on artificially contaminated sediment collected from the Department of Energy’s (DOE) Hanford Site, Washington state. The sediment contained 81.3% gravel (> 2 mm) by mass. Non-reactive tracers were well fit with the convection-dispersion equation (CDE) at both high and low water contents indicating physical equilibrium. The column experimental data were fitted to an …