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Cover Cropping And Organic Amendments To Improve Sandy Soils Under Organic Vegetable Production, Charles Williamson

All Theses

Coastal Plain soils in the Southeastern USA are typically sandy with poor soil structure, low soil organic carbon (SOC) content, and meager soil fertility that pose challenges to organic agriculture. Adding organic inputs is a strategy to improve these soils' physical, chemical, and biological characteristics. Here, we aim to investigate the impacts of Cover Cropping (CC) and manure inclusions on sandy soils under organic vegetable production. The experiment design was a randomized complete block with two treatments of manure application (with and without) and four CC treatments of cereal rye (Secale cereale), hairy vetch (Vicia villosa), …

Nitrogen Management In Rice Under Suboptimal Soil Conditions, Payton Suzanne Rhea

Graduate Theses and Dissertations

In Mid-South rice (Oryza sativa, L.) production, nitrogen (N) fertilizer management for pureline varieties is most often recommended as a single preflood (SPF) or two-way split (2WS) application in a direct-seeded, delayed-flood system. Most of the N fertilizer is typically applied at the four- to six-leaf stage onto dry soil, and the second application, if necessary, into the floodwater during early reproductive growth stages (referred to as midseason). Environmental factors frequently prohibit growers from applying early N fertilizer under optimal dry soil conditions. A study was conducted to determine the best N fertilization management practices to utilize in rice when …

The Binding Of The Micronutrient Transition Metals To The Alkylation Products Of Chemical Warfare Agent, Sulfur Mustard, And Thiols, Potentially Giving New Understanding To Physiological Effects Of Exposure And Increased Toxicity, Colin O'Donnell

Graduate Theses and Dissertations

Model compounds, 3,6,9-trithaiundecane-1,11-dicarboxylic acid (TTDPA), 2,5,8-trithianonane-1,9-dicarboxylic acid (TTDAA), and 1,11-diamide-3,6,9-trithiaundecane (TTDAce), closely related to the adducts formed by cysteine alkylation of the chemical weapon, sulfur mustard, were synthesized. It is shown that TTDPA forms complexes with key metal micronutrients: copper, nickel, cobalt, manganese, and zinc. Though the strength of binding to TTDPA varies, the complexes in many cases precipitate from solution. All metals produced a visible precipitate upon interaction with TTDPA under the conditions tested, however only Cu2+, Mn2+, and Zn2+ produced enough to be measured. The mass of formed precipitate seemed to peak at an equimolar ratio of TTDPA …

The North Platte River Valley: The Intersectionality Between Water Quality And People, Anni Poetzl

School of Natural Resources: Dissertations, Theses, and Student Research

The North Platte River (NPR) Valley of western Nebraska is a semi-arid watershed with row crop production, livestock production, and urban land use activity and has a population of diverse stakeholders. These land use activities contribute to the enrichment of surface waters, such as streams, which can affect human and ecosystem health, as well as economic development and recreational activities. The project objectives are to: (1) quantify the movement of dissolved inorganic nutrients from the land within the NPR Valley to the NPR via tributaries and canals, (2) identify spatiotemporal variability of nutrient limitation of periphyton growth within the NPR, …

Machine Learning-Based Methods For The Segmentation Of Scanning Electron Microscopy Images Of Fine-Grained Shale Samples, Binqian Yin

Earth & Environmental Sciences Dissertations - Archive

The segmentation of scanning electron microscopy (SEM) images is critical yet time-consuming for geological studies, as it will need to differentiate the boundaries for different mineral objects to facilitate subsequent analyses, such as porosity calculation. Recently, machine learning methods, especially convolutional neural networks (CNNs), have been explored to segment SEM images for fine-grained shale samples. However, existing methods fail to address two critical issues in the segmentation of shale rock images---insufficient labeled data and imbalanced objects. To this end, this dissertation has proposed a machine learning pipeline that consists of supervised, semi-supervised, and active learning stages to reduce manual efforts …

Calcite Spherulite Formations And Their Controls In Halophilic Bacterial Cultures, Zakaria Jibrin

UNLV Theses, Dissertations, Professional Papers, and Capstones

This study arose from an accidental discovery of calcite spherulites forming on colonies of various halophilic bacteria grown on solid Luria-Bertani medium made containing water from a brine pool in Death Valley, their natural habitat. Further studies with a large spherulite forming bacteria, Pseudoalteromonas haloplanktis, showed that calcite precipitation conditions were the consequence of bacteria using amino acids as a source of carbon and energy, a metabolism that produces NH3 and CO2 waste products. NH3 raises the pH of the medium, turning CO2 into CO32-. Calcium in the natural brine combines with CO32-. The resulting spherulitic calcite precipitation is nano-acicular …

Dynamic Soil Properties In The Lower Rio Grande Valley: Understanding Responses Of Infiltration Rate, Bulk Density, Aggregate Stability To Different Tillage Practices, Temiloluwa Faith Awotoye

Theses and Dissertations

Dynamic Soil Properties (DSPs) are soil properties that change in response to both natural and human-caused interruptions and pressures such as agro-based and wildland management. These soil properties can transform for months or even years in response to the farm use and management procedures. This research project investigates the relationship between different dynamic soil physical properties and tillage practices in the Texas Hidalgo sandy clay loam benchmark soil series. Data analyses was done to compare the effect of tillage to these soil physical properties and build a discussion about relationships between on-farm practices to other aspects of farm viability. We …

Dynamic Soil Properties In The Lower Rio Grande Valley: Carbon And Nitrogen Responses To Different Tillage Practices, Luzyannet Ballesteros Gonzalez

Theses and Dissertations

There has been increased attention in utilizing agriculture for carbon sequestration. Soil carbon and nitrogen are two dynamic soil properties (DSPs) that are indicators of soil health and function and have overlapping cycles. These soil properties change frequently as a result of environmental conditions and agricultural management practices. This study focuses on the impact of tillage practices in unirrigated agricultural fields in Hidalgo and Willacy counties located in South Texas on Hidalgo Sandy Clay Loam; With a particular focus on Soil Total Carbon (TC), Soil Inorganic Carbon (SIC), Permanganate Oxidizable Carbon (POXC), Carbon and Nitrogen ratio (C:N), Soil Organic Matter …

An Assessment Of Physical And Microbial Dynamic Properties Sensitive To Tillage Practices In Hidalgo Sandy Clay Loam Soils, Rocio N. Hernandez

Theses and Dissertations

Mechanized tillage is known to impact the dynamic physical, biological and chemical properties of a given soil, and as a result, can cause systematic harm to the soil’s function (Alam et al., 2014). The aim of this study is to assess how a series of land management tillage practices will impact dynamic physical and biological soil health parameters such as aggregation, carbon, respiration, and enzymatic activity (β-glucosidase). According to Acir et al (2020), the aforementioned soil parameters are both co-influenced and dependent, indicating a response to tillage is likely. A total of 198 samples of Hidalgo series soils were collected …

Fossil Mammals From Hickory Tree Cave, Sullivan County, Tennessee, Alexis Rivera

Electronic Theses and Dissertations

Hickory Tree Cave, also known as Big Spring Cave, is located in the southern Appalachians and is known for fossils that are considered to be Quaternary in age. Fossil mammals were identified and assigned to the lowest taxonomical level possible. Most remains are fragmented or digested and it seems likely that various taphonomic processes are responsible for the resulting assemblage. The site lacks the extreme boreal component of Pleistocene cave faunas in the region (e.g. Baker Bluff Cave), with most reported taxa inhabiting Appalachian deciduous forest environments in North America today. While the presence of tapir (Tapirus sp.) …

Us Scientific Leadership Addressing Energy, Ecosystems, Climate, And Sustainable Prosperity: Report In Brief From The Berac Subcommittee On International Benchmarking, Maureen Mccann, Patrick Reed, Ana Alonso, Ludmilla Aristilde, Massie S. Ballon, Crysten Blaby, Allison A. Campbell, Kenneth James Davis, Brian H. Davison, Ben Evans, Robert F. Fischetti, Serita D. Frey, Ann M. Fridlind, Efi Foufoula-Georgiou, Ramon Gonzalez, Michael N. Gooseff, Nathan Hillson, Janet Jansson, Klaus Keller, Markus Kleber, Costas Maranas, Gerald A. Meehl, Himadri Pakrasi, Jennifer Pett-Ridge, Kristala Prather, Johannes Quaas, G. Philip Robertson, Alistair Rogers, Tim Scheibe, Thomas R. Schneider, Gary Stacey, Margaret S. Torn, Kerstin Kleese Van Dam, Detlef Vuuren, John Weyant, Stan Wullschleger, Shaocheng Xie, Seung Yon (Sue) Rhee, Huimin Zhao

Faculty Publications

This document presents the subcommittee’s overarching and domain-specific findings and recommendations for the next decade, identified by consensus across the full BERAC subcommittee and experts interviewed for this assessment.

Ligand-Promoted Dissolution Of Uranyl Phosphate Across Scales, Brennan Ferguson

All Dissertations

The formation of uranyl phosphate precipitate is a remediation strategy because the low solubility of uranyl phosphate minerals, like chernikovite, limits the mobility of uranium in contaminated soils. However, organic ligands can complex with aqueous metal cations to form more soluble species. For example, citrate is a commonly occurring organic ligand produced by plants and microbes that increases the solubility of uranium and therefore the dissolution of uranyl phosphate minerals in the uranyl phosphate-citrate system. This effect is an important control on the mobility of uranium in organic-rich, and near-surface vegetated environments. Nevertheless, key aspects of the citrate-uranyl phosphate system …

Grapefruit Peel Biochar Applications For Immobilizing Copper And Lead In Soil, Michael Alfredo Navarro

Theses and Dissertations

This study investigated the efficacy of grapefruit peel (GP) derived biochar materials (two pyrolysis temperatures 450°C and 800°C) as a potential adsorbent to immobilize heavy metal (copper and lead) in a local sandy loam clay soil. A batch adsorption test with heavy metal concentrations at 50 mg L-1, and 100 mg L-1 revealed that soil itself had the highest immobilization percentage compared to the GP biochars. A soil column experiment was conducted to determine how much the GP biochar samples and the tested soil will exhibit adsorptive characteristics for heavy metals when 50 ml of 50 mg L-1 copper or …

Computational And Experimental Investigations Of Alkali Cation Interactions At The Rutile – Water Interface, Isaac Johnston

All Dissertations

Overall, the objective of this dissertation was to investigate the degree of sorption for the alkali cations on rutile to ascertain the impact of different cation properties, such as ion size and charge density, on sorption mechanics as well as probe how the ion may alter the surface – aqueous interface. Initial molecular dynamic simulations and batch experiments showed minimal surface sorption for any alkali cation at relatively low concentrations while simultaneously suggesting the enthalpy of deprotonation shifts slightly in the presence of the alkali cations at different ionic strengths. The cations are likely causing small reorientations of the near-surface …

Implementation Of Structure From Motion (Sfm) Technology For Edcuational Lessons, Valeria Veronica Martinez

Open Access Theses & Dissertations

Education is the most important obligation the humanity race has in order to evolve and thrive in the modern world. There are various applications for educators to teach valuable lessons to students, and not all deliveries will be the same for every lesson and for every student. Lesson being taught, the lesson delivery from educator to student often changes every time the lesson is implemented, depending on the learning ability of the students. Students have the ability to learn in different ways, such as the visual, auditory, kinesthetic, reading and writing learners (Oxford 2003). As educators aware of the four …

Using Ground Penetrating Radar To Investigate Controls On Pedogenic Calcium Carbonate Distribution In Dryland Critical Zones, Nohemi Valenzuela Garay

Open Access Theses & Dissertations

Caliche or pedogenic calcium carbonate (CaCO3) layers are a common feature of arid soils, but the environmental controls on their distribution are not fully understood. Caliche layers are thought to play an important role in shallow subsurface water storage and movement, due to their water retention capacity and ability to impede vertical water transport (Hennessy et al., 1983). Therefore, caliche distribution and stability play a role in controlling water distribution in arid lands. However, due to its largely subsurface nature, caliche can be difficult to investigate and map without significant effort. I hypothesize that noninvasive geophysical methods, such as ground-penetrating …

Diagnosing Excess Nitrogen In Rice Using Post-Season Tissue Samples, Kyle Hoegenauer

Graduate Theses and Dissertations

Proper nitrogen (N) management in rice production can be difficult to achieve without the aid of tools such as soil and tissue tests. There are no tests currently available to rice producers that determine whether N has been managed properly throughout the season or that detect instances of over fertilization. Rice stalk samples were collected from N response trials within 3 days of harvest from the primary Arkansas rice growing region in 2016-2018. Stalk samples were analyzed for N concentration through a KCl extraction and spectrofluorometric quantification. Samples analyzed with leaf material intact contained statistically different N concentrations than samples …

Spinosaurus Is Not An Aquatic Dinosaur, Paul C. Sereno, Nathan Myhrvold, Donald M. Henderson, Frank E. Fish, Stephanie L. Baumgart, Tyler M. Keillor, Kiersten K. Formoso, Lauren L. Conroy

Biology Faculty Publications

A predominantly fish-eating diet was envisioned for the sail-backed theropod dinosaur Spinosaurus aegyptiacus when its elongate jaws with subconical teeth were unearthed a century ago in Egypt. Recent discovery of the high-spined tail of that skeleton, however, led to a bolder conjecture that S. aegyptiacus was the first fully aquatic dinosaur. The "aquatic hypothesis' posits that S. aegyptiacus was a slow quadruped on land but a capable pursuit predator in coastal waters, powered by an expanded tail. We test these functional claims with skeletal and flesh models of S. aegyptiacus. We assembled a CT- based skeletal reconstruction based on the …

Substrate Availability And Not Thermal Acclimation Controls Microbial Temperature Sensitivity Response To Long-Term Warming, Luiz A. Domeignoz-Horta, Grace Pold, Hailey Erb, David Sebag, Eric Verrecchia, Trent Northen, Katherine Louie, Emiley Eloe-Fadrosh, Christa Pennacchio, Melissa A. Knorr, Serita D. Frey, Jerry M. Melillo, Kristen M. Deangelis

Faculty Publications

Microbes are responsible for cycling carbon (C) through soils, and predicted changes in soil C stocks under climate change are highly sensitive to shifts in the mechanisms assumed to control the microbial physiological response to warming. Two mechanisms have been suggested to explain the long-term warming impact on microbial physiology: microbial thermal acclimation and changes in the quantity and quality of substrates available for microbial metabolism. Yet studies disentangling these two mechanisms are lacking. To resolve the drivers of changes in microbial physiology in response to long-term warming, we sampled soils from 13- and 28-year-old soil warming experiments in different …

Key Pretreatment Technologies For Coalbed Gas Bioengineering And Review On Their Mechanism Of Action, Bao Yuan, Chang Jianing, Liu Xiangrong, Xia Daping, Wang Yaya

Coal Geology & Exploration

Coalbed gas bioengineering (CGB) is a new technology for the purpose of realizing the clean utilization of coal resources and the enhanced recovery of coalbed gas. To explore the key characteristics of the pretreatment technologies of CGB, hydrocarbon generation potential and its mechanism of action, conclusion and summary was made for various pretreatment technologies herein. Meanwhile, the pretreatment technologies were divided into three types according to the action mode of coal (organic matter) and bacteria (microorganism): microflora optimization and improvement, coal dissolution and oxidation, and biological stimulation and synergy. By comparing the capability of coal to generate methane through microbial …

Formation Mechanism Of Coalbed Methane In Dafosi Mine Field, Huanglong Coalfield, Liu Kaide, Yao Kaiwen, Chen Nengyuan, Fan Zhangqun, Li Shujia, Zheng Han, Yue Wenping, Li Xiaolong

Coal Geology & Exploration

Dafosi mine field is a typical low-rank coalbed methane (CBM) field in Binchang mining area of Huanglong Jurassic. There are many coalbed methane wells in the field, but few researches are performed on the formation mechanism of coalbed methane. Thus, it is of great guiding significance to clarify the geochemical characteristics and formation mechanism of coalbed methane (CBM) in the mine field, which could provide important basis for the analysis on productivity difference of high- and low-yield CBM Wells. For this reason, the samples of drained gas at the wellhead of six CBM wells, 22 coal samples of No.4 coal …

Sub-Recent Microfauna Within Allogenic Sediments At The Bottom Of A Deep Cave, Njemica (Biokovo Mt., Croatia), Tomislav Kurečić, Valentina Hajek Tadesse, Lara Wacha, Marija Horvat, Nina Trinajstić, Ivan Mišur

International Journal of Speleology

Clastic sediments deposited at the bottom of the vertical, nearly 1000 m deep Njemica Cave (Biokovo Mountain, Croatia) were analysed. Owing to the vertical morphology of the cave, the occurrences of clastic sediments are sparse. Small, up to decimetre-thick, undisturbed sediment accumulations situated near the siphon lake revealed interesting palaeontological and mineralogical data. These data are used as a useful proxy for discussing depositional processes, the provenance of the sediments and paleo-habitats of the subterranean fauna.

The sub-recent assemblages of ostracods were discovered within the sediment, and they were shown to be correlative to the known endemic species in the …

Microbial Ecology Of A Shallow Alkaline Hydrothermal Vent: Strýtan Hydrothermal Field, Eyjafördur, Northern Iceland, Katrina I. Twing, L. M. Ward, Zachery K. Kane, Alexa Sanders, Roy Edward Price, H. Lizethe Pendleton, Donato Giovannelli, William J. Brazelton, Shawn E. Mcglynn

Geosciences: Faculty Publications

Strýtan Hydrothermal Field (SHF) is a submarine system located in Eyjafördur in northern Iceland composed of two main vents: Big Strýtan and Arnarnesstrýtan. The vents are shallow, ranging from 16 to 70 m water depth, and vent high pH (up to 10.2), moderate temperature (Tmax ∼70°C), anoxic, fresh fluids elevated in dissolved silica, with slightly elevated concentrations of hydrogen and methane. In contrast to other alkaline hydrothermal vents, SHF is unique because it is hosted in basalt and therefore the high pH is not created by serpentinization. While previous studies have assessed the geology and geochemistry of this site, the …

Soil Microbial Communities Vary In Composition And Functional Strategy Across Soil Aggregate Size Class Regardless Of Tillage, Lukas T. Bernhardt, Richard G. Smith, Andrew S. Grandy, Jessica E. Mackay, Nicholas D. Warren, Kevin M. Geyer, Jessica G. Ernakovich

Faculty Publications

The physicochemical environment within aggregates controls the distribution of carbon and microbial communities in soils. Agricultural management, such as tillage, can disrupt aggregates and the microscale habitat provided to microorganisms, thus altering microbial community dynamics. Categorizing microbial communities into life history strategies with shared functional traits—as has been done to understand plant community structure for decades—can illuminate how the soil physicochemical environment constrains the membership and activity of microbial communities. We conducted an aggregate scale survey of microbial community composition and function through the lens of the yield–acquisition–stress (Y–A–S) tolerator life history framework. Soils collected from a 7-year tillage experiment …

The Nitrogen Dynamics Of Deer Cave, Sarawak, And The Role Of Bat Caves As Biogeochemical Sinks In Tropical Moist Forests., Joyce Lundberg, Donald A. Mcfarlane, Guy Van Rentergem

International Journal of Speleology

A better understanding of the role of bat caves as nitrogen sinks in tropical moist forest ecosystems can be expected to shed light on regional and spatial variability in nutrient recycling studies. We measured the nitrogen flux (in air and water) associated with a very large Chaerephon plicata bat colony in Deer Cave, Borneo, in the process generating a new, quantitative, estimate of the total bat population (774,828 ±48,320), and the first detailed modelling of an ammonia plume in a cave. Long-term storage of N does not occur in this wet cave. Our final budget numbers indicate that, of the …

Using Stable Isotope Analyses To Assess The Trophic Ecology Of Scleractinian Corals, Michael P. Lesser, Marc Slattery, Keir J. Macartney

School of Earth, Environmental, & Marine Sciences Faculty Publications

Studies on the trophic ecology of scleractinian corals often include stable isotope analyses of tissue and symbiont carbon and nitrogen. These approaches have provided critical insights into the trophic sources and sinks that are essential to understanding larger-scale carbon and nitrogen budgets on coral reefs. While stable isotopes have identified most shallow water (<30 m) corals as mixotrophic, with variable dependencies on autotrophic versus heterotrophic resources, corals in the mesophotic zone (~30–150 m) transition to heterotrophy with increasing depth because of decreased photosynthetic productivity. Recently, these interpretations of the stable isotope data to distinguish between autotrophy and heterotrophy have been criticized because they are confounded by increased nutrients, reverse translocation of photosynthate, and changes in irradiance that do not influence photosynthate translocation. Here we critically examine the studies that support these criticisms and show that they are contextually not relevant to interpreting the transition to heterotrophy in corals from shallow to mesophotic depths. Additionally, new data and a re-analysis of previously published data show that additional information (e.g., skeletal isotopic analysis) improves the interpretation of bulk stable isotope data in determining when a transition from primary dependence on autotrophy to heterotrophy occurs in scleractinian corals.

Effects Of Sowing Date And Phosphorus Fertiliser Application On Winter Survival Of Lucerne Cv. Aohan In The Northern Semi-Arid Region Of China, Z. L. Wang, Q. Zh. Sun, Y. W. Wang, Zh. Y. Li, Sh. F. Zhao

IGC Proceedings (1977-2023)

In the northern semi-arid region of China, winter survival is always a limiting factor for lucerne production, because low temperatures and a dry climate in winter (Zhou et al., 1993; Ma, 2000; Sun & Gui, 2001; Sun et al., 2003). An experiment was conducted to find an appropriate sowing date and P application rate in order to improve lucerne winter survival.

Ear Emergence Of Different Grass Species Under Finnish Growing Conditions, M. Niskanen, O. Niemeläinen, L. Jauhiainen

IGC Proceedings (1977-2023)

Timothy is the most commonly cultivated grass species in Finland. Swards cultivated for silage of hay are of pure timothy or timothy is the dominant species of the mixture. Successful timing of harvesting of the primary growth is very critical in Northern latitudes where the stand develops very rapidly at daylengths of above 18 hours with a daily mean temperature close to 20 °C. The primary growth has to be harvested within a very short period to obtain a yield of high and uniform quality. Short harvesting periods require high capacity harvest machinery which lead to high costs. If it …

Reasons For The Premature Decline In Astragalus Adsurgens Stands In Kerqin Sandy Land, Q. Zh. Sun, Z. L. Wang, J. G. Han, Y. W. Wang, G. R. Liu

IGC Proceedings (1977-2023)

Diseases partly account for reductions in Astragalus adsurgens, stand longevity. The effect of some cultural practices on the control of pests and diseases have been reported (Hou, 1986; Nan, 1996), but few reports have detailed the relationship among soil fertiliser status, diseases and premature stand decline. This study was conducted to investigate these relationships in order to extend the longevity of Astragalus adsurgens stands.

The Influence Of Fertiliser Application To Strip-Sown Grasslands On Herbage Production And Quality, A. Kohoutek, P. Komárek, V. Odstrčilová, P. Nerušil

IGC Proceedings (1977-2023)

To increase the productivity of dairy cattle in the Czech Republic requires an improvement in herbage quality and an increase in the net energy of herbage. The decrease in cattle numbers by 50 % and the expansion of the grassland area both result in a surplus of feedstuffs of low quality. Introduction of strip-seeding of legumes and grasses into grasslands in interaction with fertilisation provides a possible solution to this problem.