Master of Science, The Ohio State University, 2021, Horticulture and Crop Science

Many farmers typically regard wheat as a “low input” crop and expect low yields and low returns. Conversely, some farmers intensively manage wheat with many inputs and expect high yields and returns. The objective of this research was to identify inputs that improve wheat grain yield, straw yield, and economic return and reduce deoxynivalenol (DON) concentration in the grain. An incomplete factorial, omission trial was established at two locations in Ohio (South Charleston and Custar) during the 2019-2020 and 2020-2021 growing seasons. Treatments consisted of intensive management (IM) which received all inputs, a traditional management (TM), and the individual addition or removal each input from the TM or IM, respectively. The inputs were a high seeding rate, a high N rate, a split application of N, a spring sulfur application, a fungicide application at Feekes 9, and a fungicide application at Feekes 10.5.1. Intensive management increased grain yield at three of the site-years during this study by an average of 0.83 Mg ha-1. At the South Charleston location, in general, the use of a fungicide at either timing proved to be important for protecting yield. The addition of a fungicide at Feekes 10.5.1 to the TM significantly protected yield both years by an average of 0.66 Mg ha-1 and the removal of this fungicide from the IM significantly decreased yield by 0.63 Mg ha-1 in 2021. Additionally, at the same location the addition of a fungicide at Feekes 9 to the TM and the removal of a fungicide from the IM significantly changed yield in 2020 by 0.81 and -0.71 Mg ha-1. At Custar, only one treatment significantly changed yield in either year. In 2021, the removal of split N from the IM significantly reduced grain yield by 0.44 Mg ha-1. Straw yield was not consistently affected by any treatment in this study. DON concentration was significantly reduced by the IM at South Charleston both years due to the addition of a fungicide at Feekes 10.5.1. Intensive management did not (open full item for complete abstract)

Committee: Laura Lindsey (Advisor); Pierce Paul (Committee Member); Tim Haab (Committee Member) Subjects: Agricultural Economics; Agriculture; Agronomy

Doctor of Philosophy, The Ohio State University, 2019, Environment and Natural Resources

Soil health is an emerging framework that seeks to integrate the physical, chemical, and biological components of soil. It is defined by the USDA as “the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans”. The breadth of this definition has allowed “soil health” to become a context-specific definition, letting soil health be defined in terms of the desired outcomes. In the context of agronomic nutrient management, the primary desired outcome is a tightening of the nutrient cycle to minimize losses to the environment. Here, I use the framework of soil health to understand how soil health indicators influence and are influenced by on-farm nutrient management practices. Three separate studies were conducted to: 1) understand the factors influencing the efficacy of the most widely used biological soil health metric, mineralizable carbon, 2) determine the effect of 12 years of phosphorus (P) restriction on biological and physical soil health in three Ohio sites, and 3) integrate biological soil health indicators into nitrogen (N) management strategies across the Corn Belt. The first study found that mineralizable C was variable across and within soil test labs. However, even after controlling for variations in methodology, a significant amount of the variability was soil-specific. The second study found very few effects of P restriction on soil biological and physical health. However, P restriction slightly increased organic P stocks and resulted in consistent shifts in the balance between the processed and easily-metabolized portions of the active C pool. In the third and final study, an increase in soil biological health was shown to increase the yields for a given N fertilization rate, as well as having slight predictive abilities in predicting whether a site would be responsive to N fertilization. This study also showed that soil biological health may be slightly increased at moderate N fertilization rates. C (open full item for complete abstract)

Committee: Steve Culman (Advisor); Michael Demyan (Committee Member); Kristin Mercer (Committee Member); Nicholas Basta (Committee Member); Jessica Logan (Committee Member) Subjects: Agronomy; Soil Sciences

Master of Science, University of Akron, 2024, Civil Engineering

Compost blankets have been used as a management practice over highway slopes, especially with disturbed soils, to mitigate runoff and soil erosion. However, it is yet to be employed in Ohio due to lack of research and specifications. This research focused on efficiency of 1”, 1.5” and 2” of Biosolids and Yard-waste compost blanket over 6:1 and 4:1 slope of disturbed soil in a lab-scale rainfall simulation, followed by field study on 1.5” Biosolids and Yard-waste. The assessment of vegetation coverage showed that Biosolids significantly outperformed both Yard-waste and control treatments (p<0.05). Grass density and health were notably better in Biosolids, although increasing compost thickness did not proportionally improve vegetation growth. Both Biosolids and Yard-waste effectively reduced runoff generation, with 2” Biosolids performing the best by reducing runoff volume by 96% to 98%. Compost blankets reduced total suspended solids (TSS) significantly compared to controls (p<0.05), particularly 2” Biosolids, which released the least TSS with almost 99.99% reduction. For Soluble Reactive Phosphorus (SRP), 2” Biosolids were the most effective treatment in reducing losses by 92% to 96% than control cases. Nitrate loss was not significantly reduced by any treatments on the 6:1 slope, but 1.5” Yard-waste (98%-99% reduction) and 2” Biosolids (86%-95% reduction) performed better than other treatments on the 4:1 slope. Both Biosolids and Yard-waste showed reduced Total Nitrogen (TN) and Total Potassium (TK) release compared to controls. With 98% to 100% TN reduction, 1” Yard-waste performed better than other treatments in both slopes. For TK, 1.5” Yard-waste had the highest reduction of 91% in 6:1 slope, but for 4:1 slope it was 1” Yard-waste with 84% reduction. Field tests compared 1.5” Biosolids and 1.5” Yard-waste with vegetated and unvegetated control cases, which demonstrated healthy vegetation growth in Biosolids within six weeks, requiring trimming to adhere to guid (open full item for complete abstract)

Committee: Teresa Cutright (Advisor); Ala Abbas (Committee Member); David Roke (Committee Member); Nariman Mahabadi (Committee Member) Subjects: Civil Engineering; Engineering; Environmental Engineering; Experiments; Geotechnology

Master of Science, The Ohio State University, 2022, Horticulture and Crop Science

One of humanity's biggest challenges in the 21st century involves mitigating and reducing anthropogenic impacts on the global environment. Biochar, a biomass-derived black C produced from the anoxic thermochemical conversion of biomass through a pyrolytic process, is gaining popularity as a potential soil amendment in agricultural soils. The application of biochar as a soil amendment and N management practices are some of the best agricultural practices (BAPs) that farmers could implement to reduce GHG emissions, improve soil health, and increase crop growth and yield. The effect of a commercial-grade softwood biochar (10 Mg ha-1) derived from pine was evaluated on growth, yield, and GHG emissions on corn (Zea mays L.) in three field sites in the U.S. Midwest, two in Ohio and one in Michigan. Additionally, greenhouse studies were conducted on the effects of biochar rates (0, 10, 20, and 40 Mg ha-1) and soil types (clay-loam, silt-loam, and sandy-loam) on corn seedlings. The objectives of the field studies were to understand the effects of a biochar application (B) and N management treatment (N), on (1) growth and yield of corn and (2) the GHG emissions mitigation potential in three soil types. The objectives of the greenhouse studies were to (1) measure how different rates of biochar would affect corn seedling emergence, height, and biomass, and (2) quantify an optimum biochar application rate. Both studies were set up as randomized complete block designs with four replications. In the field study, the biochar and N (B + N) treatment reduced CH4 and N2O emissions compared to the N treatment alone, while retaining the same yields when compared to the control. In the greenhouse study, the lower biochar rates (10 and 20 Mg ha-1) resulted in positive effects on corn seedling emergence and height. These studies are timely as there is a growing interest of farmers and growers in carbon farming and carbon trading, thereby, reducing their carbon footprint.

Committee: Laura Lindsey (Advisor); Kristin Mercer (Committee Member); Marília Chiavegato (Committee Member) Subjects: Agriculture; Agronomy; Climate Change; Horticulture; Soil Sciences

Master of Arts, Miami University, 2021, Geography

Agricultural land cover in the U.S. Midwest is a major source of nutrient pollution that has led to severe degradation of stream water quality. Previous studies have shown that land cover, stream morphology, and hydrology can influence stream nutrient concentrations. This study examines the impact of a forested state park on nutrient concentrations within an agriculturally dominated watershed. Water samples were collected biweekly from eight stream sampling sites along four creeks and processed for total nitrogen (TN), nitrate (NO3-), phosphorus (TP), and orthophosphate (PO43-). Hydrology, channel morphology, and remotely sensed vegetation data were also collected and analyzed within the study area. An analysis of covariance test (ANCOVA) and a regression coefficient t-test indicated that the state park significantly reduced NO3-, PO43-, and TP concentrations. The park as a whole did not significantly reduce TN concentrations, however, within one of the four creeks, significant decreases in TN concentrations were detected. Discharge was a significant driving factor for changes in TN, NO3-, and TP concentrations within one study creek and change in PO43- concentrations within an additional study creek. The normalized difference vegetation index (NDVI) was a significant predictor of reductions in TN concentrations within one of four study creeks, and NDVI was globally correlated with reductions in NO3- concentrations. The results of the study suggest that conservation of forested areas within agriculturally dominated watersheds can provide meaningful water quality improvements in the U.S. Midwest.

Committee: Bartosz Grudzinski PhD (Advisor); Thomas Fisher PhD (Committee Member); Jessica McCarty PhD (Committee Member); Michael Vanni PhD (Committee Member) Subjects: Environmental Management; Environmental Science; Geography; Natural Resource Management; Water Resource Management

Master of Science (MS), Bowling Green State University, 2020, Geology

Conventional tillage, a soil preparation practice to produce a fine seedbed, can disturb the soil profile by promoting soil compaction and soil organic matter (SOM) degradation. In contrast, conservation tillage, such as no-till and minimal tillage (30% or more crop residue) have the potential to sustain or increase soil organic carbon (SOC). Additional benefits of conservation tillage include; improvement to soil structure, reducing soil erosion, greater water retention, buffering soil temperatures, and greater crop residue retention. Conservation tillage practices promote nutrient retention in soils. Furthermore; Fe- and Mn-(oxy)hydroxide minerals play an important role in SOC stabilization and sequestration, which also promotes nutrient adsorption. This study aimed to 1) quantify SOC under varying agricultural managements, 2) qualitatively describe the degree of aromaticity and recalcitrance of SOC using fluorescence spectroscopy, 3) correlate SOC quantity with nitrogen and phosphorous retention in soils, and 4) understand the mineral phases responsible for the stabilization and sequestration of SOC, as well as phosphate and nitrate using a four-step chemical sequential extraction. Results showed that no till and minimal tillage sites consistently had greater SOC and fluorescence intensity in the humic-like acids region, when compared to conventional tilled fields. The SOC quality was obtained using relatively quick and cost-effective methods. No till and minimal tillage enhanced SOC stabilization. In addition, conservation tillage practices retained the largest total nitrogen and total phosphorous concentrations at all studied depths (0-30 cm), when compared to conventional tilled fields. Sequential extraction results showed that SOC was stabilized in the following order: crystalline Fe-oxides > amorphous Fe-oxides > Mn-oxides. Fe- and Mn-(oxy)hydroxide minerals can promote the stabilization and long-term sequestration of SOC via the formation of inner sphere (open full item for complete abstract)

Committee: Angélica Vázquez-Ortega Dr. (Advisor); Andrew Gregory Dr. (Committee Member); Ganming Liu Dr. (Committee Member) Subjects: Geology

Doctor of Philosophy, The Ohio State University, 1975, Graduate School

Committee: Not Provided (Other) Subjects: Agriculture

Doctor of Philosophy, The Ohio State University, 2010, Soil Science

This dissertation is comprised of three separate studies in soil science and fertility. The first component concerns the use of swine manure on a leguminous crop. Recent environmental pressure has been placed to limit the practice of applying animal manures to fields planned for soybean [Glycine max (L.) Merr] production because of the perceived hazard of excessive NO3 movement offsite. The objective is to evaluate the impact of manure application to soybean fields on soil NO3-N, N uptake and soybean crop productivity. A field experiment was established in the spring of 2007 and 2008. Liquid swine (Sus scrofa domestica) manure was applied at three different N rates (based upon manure analysis and estimated availability) using two application methods (surface application or injection). Commercial fertilizer treatments (same equivalent rates) were also included as positive controls. Soil samples to 60 cm and tissue samples were collected throughout the growing season. Even though N application did result in higher soil NO3- levels for some treatments, applications rates that were less than or equal to 135 kg ha-1 represented a lower risk of possible NO3-N movement. Nitrogen supplied via manure and commercial fertilizer resulted in larger N uptake than the controls, but grain yield was not improved. This reveals that despite the fact that soybeans can fix their own N, soybeans will absorb soil inorganic-N as a net N sink. The second chapter of the dissertation explores the interactions of foliar-applied manganese and the herbicide glyphosate on glyphosate-resistant weeds. Glyphosate is a metal chelating agent that interacts with cations essential to plant growth, and previous studies have shown interactions with Mn resulting in decreased herbicide efficacy and manganese metabolism issues. This study measured the effects of different formulations of glyphosate and manganese combinations as well as timing of the application. Of six site-years, one instance of manganese a (open full item for complete abstract)

Committee: Robert Mullen PhD (Advisor); Edward McCoy PhD (Committee Member); Peter Thomison PhD (Committee Member); Mark Loux PhD (Committee Member) Subjects: Agricultural Chemicals; Agriculture; Agronomy; Soil Sciences

Master of Science (MS), Bowling Green State University, 2006, Biological Sciences

The effects of management on threatened and endangered species are difficult to discern, and yet, are vitally important for implementing adaptive management. The federally endangered Karner blue butterfly (Karner blue), Lycaeides melissa samuelis, inhabits oak savanna or pine barrens, is a specialist on its host-plant, wild blue lupine, Lupinus perennis, and has two broods per year. The Karner blue was reintroduced into the globally rare black oak/lupine savannas of Ohio, USA in 1998. Current management practices involve burning 1/3, mowing 1/3, and leaving 1/3 of the lupine stems unmanaged at each site. Prescribed burning generally kills any Karner blue eggs present, so a trade-off exists between burning to maintain the habitat and Karner blue mortality. The objective of my research was to quantify the effects of this management strategy on the Karner blue. In the first part of my study, I examined several environmental factors, which influenced the nutritional quality (nitrogen and water content) of lupine to the Karner blue. My results showed management did not affect lupine nutrition for either brood. For the second brood, I found that vegetation density best predicted lupine nutritional quality, but canopy cover and aspect had an impact as well. Relatively lower host-plant nitrogen during the second brood was accompanied by a higher adult foraging rate, which suggests a trade-off of nutritional resources during these different life stages. For the second part of my study, I used surveys and behavior observations to quantify how the Karner blue responded to management treatments. Second brood females and males were more abundant in burned management units, and behavior observations revealed Karner blues avoided ovipositing in unmanaged management units. These management units were unburned for at least four years and were often characterized by a high leaf litter depth (>3.5 cm). Recolonizations of Karner blues from source populations within 120 meters was rapid (open full item for complete abstract)

Committee: Karen Root (Advisor) Subjects: Biology, Ecology