Digital Commons Network^™

Silver Engineered Nanomaterials And Ions Elicit Species-Specific O2 Consumption Responses In Plant Growth Promoting Rhizobacteria, Ricky W. Lewis, Jason M. Unrine, Paul M. Bertsch, David H. Mcnear Jr.

Plant and Soil Sciences Faculty Publications

Metal containing engineered nanomaterials (ENMs) are now commonly used in various industrial and commercial applications. Many of these materials can be transformed during waste water treatment and ultimately enter terrestrial ecosystems via agriculturally applied biosolids. It is unclear how agriculturally important soil microbes will be affected by exposure to environmentally relevant, sublethal concentrations of ENMs and their transformation products (i.e., ions, aggregates, etc.). A method was developed, which puts O₂ consumption responses in terms of viability, and tested by examining the toxic effects of Ag⁺, Zn²⁺, and Ni²⁺ ions on the plant growth promoting …

A Novel Diffuse Fraction-Based Two-Leaf Light Use Efficiency Model: An Application Quantifying Photosynthetic Seasonality Across 20 Ameriflux Flux Tower Sites, Hao Yan, Shao-Qiang Wang, Kai-Liang Yu, Bin Wang, Qin Yu, Gil Bohrer, Dave Billesbach, Rosvel Bracho, Abdullah F. Rahman, Herman H. Shugart

School of Earth, Environmental, & Marine Sciences Faculty Publications

Diffuse radiation can increase canopy light use efficiency (LUE). This creates the need to differentiate the effects of direct and diffuse radiation when simulating terrestrial gross primary production (GPP). Here, we present a novel GPP model, the diffuse-fraction-based two-leaf model (DTEC), which includes the leaf response to direct and diffuse radiation, and treats maximum LUE for shaded leaves (ɛmsh defined as a power function of the diffuse fraction (Df)) and sunlit leaves (ɛmsu defined as a constant) separately. An Amazonian rainforest site (KM67) was used to calibrate the model by simulating the linear relationship …

Physical Water Scarcity Metrics For Monitoring Progress Towards Sdg Target 6.4: An Evaluation Of Indicator 6.4.2 “Level Of Water Stress”, D. Vanhama, A. Y. Hoekstra, Y. Wada, F. Bouraoui, A. De Roo, Mesfin Mekonnen, W. J. Van De Bund, O. Batelaan, P. Pavelic, W. G.M. Bastiaanssen, M. Kummu, J. Rockström, J. Liu, B. Bisselink, P. Ronco, A. Pistocchi, G. Bidoglio

Daugherty Water for Food Global Institute: Faculty Publications

Target 6.4 of the recently adopted Sustainable Development Goals (SDGs) dealswith the reduction ofwater scarcity. To monitor progress towards this target, two indicators are used: Indicator 6.4.1 measuring water use efficiency and 6.4.2 measuring the level of water stress (WS). This paper aims to identify whether the currently proposed indicator 6.4.2 considers the different elements that need to be accounted for in a WS indicator.WS indicators compare water use with water availability.We identify seven essential elements: 1) both gross and net water abstraction (or withdrawal) provide important information to understand WS; 2) WS indicators need to incorporate environmental flow requirements …

Characterization Of The Relationships Between Soybean Yield, Trifoliolate Leaf Chloride Concentration, And Cultivar Chloride Inclusion/Exclusion Rating, Dillon Cox

Graduate Theses and Dissertations

Chloride toxicity is recognized as yield limiting problem in soybean [Glycine max (L.) Merr.] production. Limited information is available to accurately diagnose and manage Cl toxicity. The only recommendation for Cl toxicity management is to plant an excluder cultivar, however the cultivar Cl sensitivity rating system (excluder, includer, and mixed) does not appear to capture the variability in cultivar Cl tolerance. The objectives of this research were to i) develop critical tissue-Cl concentrations in which yield loss occurs for excluder and includer cultivars and ii) investigate the variability in cultivar Cl ratings. A study was conducted across five site-years using …

Development Of Lower Rio Grande River Water Quality Transportation Numerical Model For Bi-National River Management, Jose O. Gonzalez

Theses and Dissertations

Traditionally, water quality modelling has focused on modelling individual water bodies. However, water quality management problems must be analyzed at the larger scale to include influences from various water bodies that are interconnected. This paper provides a study on the hydrologic and quality transportation calculation by developing a hydrodynamic (unsteady state) channel routing model using a water-balanced approach. A one dimension Lagrangian river model was developed and applied to the 210 plus miles for the lower Rio Grande River Basin from the Falcon Dam to the head water of Brownsville that pours onto the Gulf of Mexico. This model can …

Trophic Dynamics Of Flathead Catfish In The Missouri River Bordering Nebraska, Dylan R. Turner

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

Understanding the trophic dynamics of large, riverine ecosystems is complex and requires knowledge from several inputs and outputs of the ecosystem. Most riverine ecosystems have been altered in some way whether through damming, channelizing, or diverting water. The Missouri River is not immune to these anthropogenic alterations. The river has dams throughout its middle portion and is channelized from Sioux City, Iowa to its confluence with the Mississippi River. Flathead Catfish pylodictus olivarius are one of the most ecologically harmful introduced species but little research has looked at the influence native populations of Flathead Catfish have on native prey populations …

Assessing Landslide Susceptibility With Gis Using Qualitative And Quantitative Methods In Knox County, Nebraska, Christian J. Cruz

Department of Geography: Dissertations, Theses, and Student Research

This thesis assesses landslide susceptibility using data from LiDAR DEMs, land cover, and soil surveys. Data were assessed quantitatively through Bayesian logistic regression within a geographic information system (GIS) and statistical software to produce a landslide susceptibility map. The study area exhibits moderate relief where bluffs along the Missouri River valley gradually recede into rolling loess-mantled hills further to the south and southeast in Knox County. The six factors used to determine susceptibility to landslides are: land cover, parent material, slope aspect, slope curvature slope degree, and soil series. My findings show an increase in slope is the most significant …

Uas-Collected Multispectral Imagery For The Identification Of Rangeland Vegetation In A Southern Mixed-Grass Prairie, Adam Rusk

Master's Theses or Doctor of Nursing Practice

The interest in using unmanned aerial systems (UAS) for remote sensing of natural resources and ecology has grown rapidly in recent years and continues to develop. Recent improvements in the cost, size, and accessibility of consumer-grade UASs are now facilitating image collection on low-flying UAS platforms. Rangelands provide a unique opportunity to explore the uses of UAS remote sensing due to their large spatial extent and spatial and temporal heterogeneity. This study focuses on the use of UAS’s to identify rangeland vegetation in a southern mixed-grass prairie in Kansas. Two primary questions were asked: 1) Do small UASs with low-cost …

Stable Isotope Diet Analysis Of Teleoceras Fossiger From The High Plains Of Kansas, Patrick J. Wilson

Master's Theses or Doctor of Nursing Practice

Stable isotope geochemistry provides a way of examining both modern and ancient ecosystems. One important use of stable carbon isotopes is to determine the amount of C3 versus C4 plant biomass in the diet of herbivorous mammals. C3 plants have a more negative stable carbon isotope ratio (δ13C) than C4 plants because of the different photosynthetic pathways each type uses. These different δ13C values are preserved in the hydroxyapatite of herbivores upon consumption of the different plant types. The purpose of this study it to use δ13C values from serial samples of tooth enamel from six isolated permanent molars of …

Sclerocactus Wetlandicus: Habitat Characterization, Seed Germination And Mycorrhizal Analysis, Kourtney T. Harding

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Uinta Basin hookless cactus (Sclerocactus wetlandicus) is a threatened species native to Eastern Utah. The cactus is found in a landscape highly disturbed by non-renewable energy production. To understand the environmental conditions that support natural growth of this cactus, we asked what types of plants were present in the same areas as the cactus, and if the types of plants were different in environments that were disturbed. From our assessment, we determined that the types of plants present in disturbed areas were drastically different from those present in undisturbed locations. Areas previously used for energy production are …

Δ13c And Δ15n In The Endangered Kemp’S Ridley Sea Turtle Lepidochelys Kempii After The Deepwater Horizon Oil Spill, Kimberly J. Reich, Melania C. López-Castro, Donna J. Shaver, Claire Iseton, Kristen M. Hart, Michael J. Hooper, Christopher J. Schmitt

United States Geological Survey: Staff Publications

The Deepwater Horizon explosion in April 2010 and subsequent oil spill released 3.19 × 106 barrels (5.07 × 108 l) of MC252 crude oil into important foraging areas of the endangered Kemp’s ridley sea turtle Lepidochelys kempii (Lk) in the northern Gulf of Mexico (GoM). We measured δ13C and δ15N in scute biopsy samples from 33 Lk nesting in Texas during the period 2010 to 2012. Of these, 27 were equipped with satellite transmitters and were tracked to traditional foraging areas in the northern GoM after the spill. Differences in δ13C between the oldest and newest scute layers from 2010 …

Molecular And Optical Properties Of Tree-Derived Dissolved Organic Matter In Throughfall And Stemflow From Live Oaks And Eastern Red Cedar, Aron Stubbins, Leticia M. Silva, Thorsten Dittmar, John T. Van Stan

Earth, Environment & Sustainability: Faculty Publications

Studies of dissolved organic matter (DOM) transport through terrestrial aquatic systems usually start at the stream. However, the interception of rainwater by vegetation marks the beginning of the terrestrial hydrological cycle making trees the headwaters of aquatic carbon cycling. Rainwater interacts with trees picking up tree-DOM, which is then exported from the tree in stemflow and throughfall. Stemflow denotes water flowing down the tree trunk, while throughfall is the water that drips through the leaves of the canopy. We report the concentrations, optical properties (light absorbance) and molecular signatures (ultrahigh resolution mass spectrometry) of tree-DOM in throughfall and stemflow from …

Responses Of Terrestrial Ecosystem Phosphorus Cycling To Nitrogen Addition: A Meta-Analysis, Qi Deng, Dafeng Hui, Samuel Dennis, Chandra Reddy

Agricultural and Environmental Sciences Faculty Research

Aim

Anthropogenic additions of nitrogen (N) are expected to drive terrestrial ecosystems toward greater phosphorus (P) limitation. However, a comprehensive understanding of how an ecosystem's P cycle responds to external N inputs remains elusive, making model predictions of the anthropogenic P limitation and its impacts largely uncertain.

Location

Global.

Time period

1986-2015.

Major taxa studied

Terrestrial ecosystems.

Methods

We conducted a meta-analysis including 288 independent study sites from 192 articles to evaluate global patterns and controls of 10 variables associated with ecosystem P cycling under N addition.

Results

Overall, N addition increased biomass in plants (+34%) and litter (+15%) as …

Geoengineering, Marine Microalgae, And Climate Stabilization In The 21st Century, Charles H. Greene, Mark E. Huntley, Ian Archibald, Léda N. Gerber, Deborah L. Sills, Joe Granados, Colin M. Beal, Michael J. Walsh

Natural & Applied Sciences Faculty Publications

Society has set ambitious targets for stabilizing mean global temperature. To attain these targets, it will have to reduce CO2 emissions to near zero by mid-century and subsequently remove CO2 from the atmosphere during the latter half of the century. There is a recognized need to develop technologies for CO2 removal; however, attempts to develop direct air-capture systems have faced both energetic and financial constraints. Recently, BioEnergy with Carbon Capture and Storage (BECCS) has emerged as a leading candidate for removing CO2 from the atmosphere. However, BECCS can have negative consequences on land, nutrient, and water use as well as …

Wayne E. Sabbe Arkansas Soil Fertility Studies 2016, Nathan A. Slaton

Arkansas Agricultural Experiment Station Research Series

Rapid technological changes in crop management and production require that the research efforts be presented in an expeditious manner. The contributions of soil fertility and fertilizers are major production factors in all Arkansas crops. The studies described within will allow producers to compare their practices with the university’s research efforts. Additionally, soil-test data and fertilizer sales are presented to allow comparisons among years, crops, and other areas within Arkansas.

Selecting Summer Annual Varieties Using Yield And Digestibility, Christopher D. Teutsch

Kentucky Alfalfa and Stored Forage Conference

Although cool-season grasses can provide ample and high quality forage for grazing livestock in the spring and fall, forage growth during the summer months is often restricted by high temperatures (Figure 1). In contrast warm-season annual grasses are most productive during the summer months and do not reach peak growth until temperatures approach 90 degrees Fahrenheit. Summer annual grasses such as forage sorghum (Sorghum bicolor (L.) Moench), sudangrass (Sorghum bicolor (L.) Moench), sorghum-sudangrass hybrids, and pearl millet (Pennisetum americanum (L.) Leeke) can provide high quality summer grazing for ruminant livestock in many regions of the United States.

Why Is Intake Reduced When Cattle Are Fed Tall Fescue?, James L. Klotz

Kentucky Alfalfa and Stored Forage Conference

A major problem for the cattle producer that utilizes tall fescue forage is the unrealized or reduced gains in body weight in growing animals. This result has been reproduced across numerous studies evaluating cattle performance on tall fescue (Hoveland et al., 1983; Boling, 1985; Schmidt et al., 1986; Goetsch et al., 1987). Cattle have gained from 30 to 100% less consuming toxic endophyte-infected tall fescue compared to consumption of an endophyte-free tall fescue (Paterson et al., 1995). This effect of reduced gain is a consequence of a fungal endophyte present within the grass that produces toxins called ergot alkaloids. Fungal …

Cover Crop Root Contributions To Soil Carbon In A No-Till Corn Bioenergy Cropping System, Emily E. Austin, Kyle Wickings, Marshall D. Mcdaniel, G. Philip Robertson, A. Stuart Grandy

Faculty Publications

Crop residues are potential biofuel feedstocks, but residue removal may reduce soil carbon (C). The inclusion of a cover crop in a corn bioenergy system could provide additional biomass, mitigating the negative effects of residue removal by adding to stable soil C pools. In a no-till continuous corn bioenergy system in the northern US Corn Belt, we used 13CO2 pulse labeling to trace plant C from a winter rye (Secale cereale) cover crop into different soil C pools for 2 years following rye cover crop termination. Corn stover left as residue (30% of total stover) contributed 66, corn roots 57, …

Microbial Interactions In The Phyllosphere Increase Plant Performance Under Herbivore Biotic Stress, Muhammad Saleem, Nicole Meckes, Zahida H. Pervaiz, Milton B. Traw

Plant and Soil Sciences Faculty Publications

The phyllosphere supports a tremendous diversity of microbes and other organisms. However, little is known about the colonization and survival of pathogenic and beneficial bacteria alone or together in the phyllosphere across the whole plant life-cycle under herbivory, which hinders our ability to understand the role of phyllosphere bacteria on plant performance. We addressed these questions in experiments using four genetically and biogeographically diverse accessions of Arabidopsis thaliana, three ecologically important bacterial strains (Pseudomonas syringae DC3000, Xanthomonas campestris, both pathogens, and Bacillus cereus, plant beneficial) under common garden conditions that included fungus gnats (Bradysia spp.). …

Moderator Biographies, Heart Of America Grazing Conference

Kentucky Grazing Conference

No abstract provided.

Cover Crops/Annuals And Grazing, Roger Staff

Kentucky Grazing Conference

The use of annual forages (cover crops), both summer and winter, have been utilized for several years. When cover crops first were used to extend the grazing season, it began with one to three species in a mixture. That was before the soil health benefits were being observed and discussed as they are now. There have been a wide variety of planting methods used: airplanes, helicopters, conventional and No-till drills. Some seeding methods is simply broadcast on the soils surface and lightly tilled in or just rained in depending upon the weather. Then we discovered the herbicides and amounts used …

Mitigating The Challenges Of Grazing Lush, Spring Forages, W. Travis Meteer

Kentucky Grazing Conference

During the winter season most cattle are supplemented with dry forages, grains, and co-products. This ration is balanced and delivered to cattle. Then spring comes along and cattle are put out to grass. While green grass solves a lot of problems associated with winter feeding (manure, pen maintenance, calf health, and labor demands), it can pose nutritional challenges. Lush, spring forage has three major challenges when it comes to meeting cattle nutrition requirements.

Seedhead Suppression In Tall Fescue With Chaparral Herbicide, E. S. Flynn, P. B. Burch

Kentucky Grazing Conference

Tall Fescue (Lolium arundinaceum (Schreb.)) is cool-season perennial grass found in pastures throughout the Eastern US, most commonly in the transition zone. It’s tolerance to extreme temperatures, drought, poor soil fertility, heavy grazing, and pests have made it a reliable forage base for livestock pastures. Released in 1943, ‘KY-31’ tall fescue was quickly adopted by cattle producers and now inhabits an estimated 40 million acres in the US.

Soon after its adoption, cattle producers began to notice a reduction in animal performance and signs that animals were heat stressed following tall fescue consumption. These symptoms were an indication of an …

Fescue Tolerance Testing, Monty Kerley

Kentucky Grazing Conference

Fescue toxicosis is characterized by clinical symptoms such as vasoconstriction, immunosuppression, and poor thermoregulation. Fescue toxins bind to membrane receptors of cells that control constriction of blood through capillaries responsible for heat dissipation. When cattle consume toxic tall fescue, they lose ability to move blood to their skin where heat can be lost to the environment. As they lose this ability they become more prone to heat stress. In the winter, this lack of blood flow leads to other clinical symptoms, such as fescue foot and loss of tail switch, that occur from restricted blood flow.

Research Update: Beef Cattle Management Considerations For Grazing Tall Fescue, Frank Ireland

Kentucky Grazing Conference

It has been reported that 8 million beef cattle graze an estimated 35 million acres of endophyte-infected tall fescue in the United States with the majority of tall fescue being produced in the Midwest and southeastern regions of the United States. In the presence of the endophytic fungus, ergot alkaloids are present that when consumed by beef cattle results in decreased animal performance as measured in reduced weight gains, lower body condition scores, decreased conception rates, rough hair coats and the inability to regulate body temperatures. It has been estimated that this loss in animal performance accounts for a $600 …

Foreword And Conference Information [2017], Matt Bunger

Kentucky Grazing Conference

This is the front matter of the proceedings.

Nanoscale Measurement Of Trace Element Distributions In Spartina Alterniflora Root Tissue During Dormancy, Huan Feng, Yu Qian, J. Kirk Cochran, Qingzhi Zhu, Wen Hu, Hanfei Yan, Li Li, Xiaojing Huang, Yong S. Chu, Houjun Liu, Shinjae Yoo, Chang Jun Liu

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

This paper reports a nanometer-scale investigation of trace element (As, Ca, Cr, Cu, Fe, Mn, Ni, S and Zn) distributions in the root system Spartina alterniflora during dormancy. The sample was collected on a salt marsh island in Jamaica Bay, New York, in April 2015 and the root was cross-sectioned with 10 μm resolution. Synchrotron X-ray nanofluorescence was applied to map the trace element distributions in selected areas of the root epidermis and endodermis. The sampling resolution was 60 nm to increase the measurement accuracy and reduce the uncertainty. The results indicate that the elemental concentrations in the epidermis, outer …

Pathways To Increasing Farmer-Led Investments In Sustainable Agricultural Water Management In Sub-Saharan Africa, Douglas J. Merrey, Peter G. Mccornick, Molly C. Nance

Daugherty Water for Food Global Institute: Faculty Publications

Without a transformative leap forward in the use of irrigation, Africa will continue falling short in the struggle to feed its growing population, improve its people’s nutrition, grow its economies, adapt to the impacts of climate change, and eliminate poverty. While Africans must lead this transformation for it to be successful, the international community can help African countries substantially increase the use of more productive and sustainable water management practices and unlock the potential of farmer-led irrigated agriculture. Achieving highly productive irrigated agricultural systems in Africa requires an enabling environment that facilitates the full engagement of farmers, public and private …

Effects Of Biochar Treatment Of Municipal Biosolids And Horse Manure On Quality Of Runoff From Fescue Plots, Rachel Williams, Dwayne R. Edwards

Biosystems and Agricultural Engineering Faculty Publications

Land-applied horse manure and municipal biosolids can increase nutrient and bacteria concentrations in runoff. Biochar has been demonstrated to have beneficial impacts on nutrient retention and runoff quality when used to treat other land-applied organic soil amendments (e.g., poultry manure). The objective of this study was to evaluate the effects of biochar addition to horse manure and municipal biosolids on runoff concentrations of nutrients and fecal coliforms. Biochar was added at 5% to 8% (wet basis) to horse manure and biosolids that were applied to 2.4 m x 6.1 m fescue plots followed by application of simulated rainfall (102 mm …

The Acceleration Of Dissolved Cobalt's Ecological Stoichiometry Due To Biological Uptake, Remineralization, And Scavenging In The Atlantic Ocean, Mak A. Saito, Abagail E. Noble, Nicholas Hawco, Benjamin S. Twining, Daniel C. Ohnemus, Seth G. John, Phoebe Lam, Tim M. Conway, Rod Johnson, Dawn Moran, Matthew Mcilvin

School of Geosciences Faculty and Staff Publications

The stoichiometry of biological components and their influence on dissolved distributions have long been of interest in the study of the oceans. Cobalt has the smallest oceanic inventory of inorganic micronutrients and hence is particularly vulnerable to influence by internal oceanic processes including euphotic zone uptake, remineralization, and scavenging. Here we observe not only large variations in dCo:P stoichiometry but also the acceleration of those dCo:P ratios in the upper water column in response to several environmental processes. The ecological stoichiometry of total dissolved cobalt (dCo) was examined using data from a US North Atlantic GEOTRACES transect and from a …