Evaluating Opportunities for Integrated Crop Livestock Systems in Eastern Nebraska

Current agricultural systems focused on production of few commodities are facing production, economic, and environmental challenges. To address these challenges, Integrated Crop Livestock Systems (ICLS) have emerged through three primary methods 1) perennial grasslands for grazing and/or hay production, 2) crop residue grazing, and 3) cover crop grazing. To evaluate potential of ICLS mitigating current challenges, a field scale model ICLS was developed in 2015. The ICLS includes 4-ha each of ‘Newell’ smooth bromegrass (Bromus inermis L.), ‘Liberty’ switchgrass (Panicum virgatum L.), and ‘Shawnee’ switchgrass. The ICLS also included 8-ha of continuous corn (Zea mays L.). In 2016, only hay was harvested from perennial grasslands and in 2017, 2018, and 2019 the perennial grasslands were grazed. Following grazing, the switchgrass varieties were harvested for residual biomass production post-senescence. Continuous corn included residue removal treatments with and without a cover crop. This thesis reports results from three studies. To evaluate the response of cool-season annual grass cover crops to defoliation, a greenhouse study, in conjunction with a replicated field experiment, was conducted in 2018-2019 and 2019-2020. Results showed small grains used as cover crops had decreased survivability and biomass production when defoliated during early plant establishment. Production data from the ICLS was used to construct enterprise budgets to evaluate system profitability on marginally productive cropland. The ICLS was not consistently more profitable than continuous corn production. However, baling hay only and removing grazing from the ICLS was more profitable than continuous corn production. To evaluate ICLS as a mitigation strategy for soil GHG emissions, soil N2O and CH4 were measured during each growing season in the perennial grasslands and continuous corn. Results suggested that 1) grazing perennial grasslands did not consistently impact soil GHG emissions, 2) crop residue and cover crop management may impact soil N2O emissions, and 3) continuous corn production resulted in greater soil N2O emissions than perennial grasslands due to higher application amounts of synthetic N fertilizer. The results from this research can provide options for producers implementing ICLS and insight for further development of ICLS for Eastern NE that meet production, economic, and environmental challenges. Advisors: Daren Redfearn and Rob Mitchel

G.H. Hardy: Mathematical Biologist

Godfrey Harold Hardy (1877-1947), the magnificent analyst who “discovered” the enigmatic Ramanujan and penned A Mathematician’s Apology, is most widely known outside of mathematics for his work in genetics. How did Hardy, described by his colleague C.P. Snow as “the purest of the pure,” become one of the founders of modern genetics? We explore this question in light of Hardy\u27s own ideas about pure and elegant mathematics

Integrating remote sensing with nutrient management plans to calculate nitrogen parameters for swine CAFOs at the sprayfield and sub-watershed scales

No Abstract

Using remote sensing to calculate plant available nitrogen from industrial hog CAFOs in North Carolina at the sprayfield and sub-watershed scales

Duplin county, NC has the highest hog-population density of any county in the United States. Liquid manure from industrial-sized hog concentrated animal feeding operations (CAFOs) is stored in open-air lagoons and sprayed onto sprayfields as fertilizer. Hog CAFOs are regulated by the NC Department of Environment and Natural Resources (DENR) based on their ability to have nutrient management plans (NMPs) that have balanced plant available nitrogen (PAN) so that the estimated portion of nitrogen that remains available for crops to use after irrigation is absorbed. Objectives of this research are to quantify the difference in permitted PAN between CAFO point and sprayfield area locations at two sub-watershed scales in Duplin county by conducting a review of all 485 active CAFOs and creating a sprayfield spatial database. Second, a new method incorporating remote sensing data identifies annual PAN for crops on sprayfields and two sub-watershed scales in Duplin county between 2010-2014

A LONGITUDINAL, LANDSCAPE-SCALE FIELD STUDY ASSESSING THE EFFECTS OF COMMERCIAL HOG OPERATIONS ON MICROBIAL QUALITY OF SURFACE WATERS IN NORTH CAROLINA, USA

North Carolina is one of the leading states in the USA for swine production on commercial hog operations (CHOs). Swine manure from CHOs contains bacteria and antibiotic resistance elements (AREs) and there is concern that CHOs act as sources of fecal bacteria and AREs to surface water through precipitation-driven runoff or leaching. While research has found high concentrations of bacteria and AREs downstream of CHOs, this work did not adequately take into account other fecal sources. Additionally, few studies have appropriately controlled for background levels of resistance so that the effects of CHOs on dissemination of AREs in the environment is difficult to assess. A longitudinal, landscape-scale field study was designed to determine whether there were effects of CHOs on microbial water quality while addressing concerns of bias and confounding between observational groups. This work compared similar, small, agricultural watersheds with (n=13) and without (n=9) CHOs over one year and found higher measures of E. coli, swine-associated gene marker, pig-2-bac, and antibiotic resistant E. coli in watersheds with CHOs compared to those without. Resistance to highest priority antibiotics was only observed in sites with CHOs. A multiple linear model was constructed to determine whether higher concentrations of E. coli in sites with CHOs were a result of differences in environmental conditions or exposure to confounding fecal sources. Modeling showed that even when controlling for large effects from precipitation and effects from confounding fecal sources, CHOs contributed E. coli to surface water and had a larger effect compared to human and wildlife sources. Results suggest that microbial water quality is poorer with increasing CHO size and proximity to surface water and that some CHOs may act as sources for human pathogens and AREs in surface water. These results have implications for state and federal policy, suggesting a need to recognize and regulate the discharge from CHOs during dry and wet conditions through discharge permits and/or CHO-specific management plans. Mitigation strategies that should be considered include improvements to CHO manure and land management practices aimed to reduce loading of fecal bacteria to surface water and to limit bacterial transport.Doctor of Philosoph

A New Megalonychid Sloth From the Late Wisconsinan of the Dominican Republic

An unusually well preserved skull, mandible, and indisputably associated post-cranial elements of new sloth, Acratocnus (Miocnus), were recovered from a cave in Jaragua National Park, Dominican Republic. The animal died lying in a rimstone pool and was rapidly coated with a thin calcite patina. We have documented a late Wisconsinan age for this specimen by inorganic 14C radiometric dating of the patina, with supporting data on the carbon systematics of the speleothems in this cave. This sloth is described as a new species on the basis of the distinctive morphology and relative size of cranial and mandibular features. We consider the close relationship between Acratocnus of the Dominican Republic and Puerto Rico to constitute clear evidence for late Tertiary inter-island dispersal of this lineage, congruent with similar evidence from other West Indian terrestrial mammal orders

N-Terminal Pro–B-Type Natriuretic Peptide in the Emergency Department: The ICON-RELOADED Study

Background Contemporary reconsideration of diagnostic N-terminal pro–B-type natriuretic peptide (NT-proBNP) cutoffs for diagnosis of heart failure (HF) is needed. Objectives This study sought to evaluate the diagnostic performance of NT-proBNP for acute HF in patients with dyspnea in the emergency department (ED) setting. Methods Dyspneic patients presenting to 19 EDs in North America were enrolled and had blood drawn for subsequent NT-proBNP measurement. Primary endpoints were positive predictive values of age-stratified cutoffs (450, 900, and 1,800 pg/ml) for diagnosis of acute HF and negative predictive value of the rule-out cutoff to exclude acute HF. Secondary endpoints included sensitivity, specificity, and positive (+) and negative (−) likelihood ratios (LRs) for acute HF. Results Of 1,461 subjects, 277 (19%) were adjudicated as having acute HF. The area under the receiver-operating characteristic curve for diagnosis of acute HF was 0.91 (95% confidence interval [CI]: 0.90 to 0.93; p < 0.001). Sensitivity for age stratified cutoffs of 450, 900, and 1,800 pg/ml was 85.7%, 79.3%, and 75.9%, respectively; specificity was 93.9%, 84.0%, and 75.0%, respectively. Positive predictive values were 53.6%, 58.4%, and 62.0%, respectively. Overall LR+ across age-dependent cutoffs was 5.99 (95% CI: 5.05 to 6.93); individual LR+ for age-dependent cutoffs was 14.08, 4.95, and 3.03, respectively. The sensitivity and negative predictive value for the rule-out cutoff of 300 pg/ml were 93.9% and 98.0%, respectively; LR− was 0.09 (95% CI: 0.05 to 0.13). Conclusions In acutely dyspneic patients seen in the ED setting, age-stratified NT-proBNP cutpoints may aid in the diagnosis of acute HF. An NT-proBNP <300 pg/ml strongly excludes the presence of acute HF

Climate-Related Hazards: A Method for Global Assessment of Urban and Rural Population Exposure to Cyclones, Droughts, and Floods

Global climate change (GCC) has led to increased focus on the occurrence of, and preparation for, climate-related extremes and hazards. Population exposure, the relative likelihood that a person in a given location was exposed to a given hazard event(s) in a given period of time, was the outcome for this analysis. Our objectives were to develop a method for estimating the population exposure at the country level to the climate-related hazards cyclone, drought, and flood; develop a method that readily allows the addition of better datasets to an automated model; differentiate population exposure of urban and rural populations; and calculate and present the results of exposure scores and ranking of countries based on the country-wide, urban, and rural population exposures to cyclone, drought, and flood. Gridded global datasets on cyclone, drought and flood occurrence as well as population density were combined and analysis was carried out using ArcGIS. Results presented include global maps of ranked country-level population exposure to cyclone, drought, flood and multiple hazards. Analyses by geography and human development index (HDI) are also included. The results and analyses of this exposure assessment have implications for country-level adaptation. It can also be used to help prioritize aid decisions and allocation of adaptation resources between countries and within a country. This model is designed to allow flexibility in applying cyclone, drought and flood exposure to a range of outcomes and adaptation measures