Master of Science (MS), Ohio University, 2021, Plant Biology (Arts and Sciences)

Nitrogen and a variety of other nutrients are necessary for proper crop growth and to maximize marketable harvest for farmers, though traditional fertilizer methods to supplement these nutrients are lacking. Inorganic fertilizer can have detrimental environmental effects, can be pricey, and can damage farmers' soil over time. Brewer's spent grain (BSG) is a protein-rich, food-safe byproduct of the brewing industry that is available nearly worldwide and may become available nitrogen after breaking down into soil. Five common farm crops were planted, treated with two rates of BSG as well as inorganic fertilizer, and harvested to compare the effects of BSG to fertilizer — to determine if BSG could be a viable alternative for farmers to supply their crops with nutrients. The marketable yield of the harvests was analyzed and revealed that inorganic fertilizer did not perform significantly better than BSG throughout the experiment, which was conducted over the course of multiple growing seasons.

Committee: Arthur Trese (Advisor); Sarah Davis (Committee Member); David Rosenthal (Committee Member); Jared DeForest (Committee Chair) Subjects: Agriculture; Sustainability

Master of Arts, The Ohio State University, 2018, East Asian Studies

Since the 1960's China's agricultural system has gone through drastic changes. Modernization of this system necessitated adoption of key innovations, including new seed varieties, farm management practices, and the use of chemical fertilizers and pesticides. This thesis examines the impacts of three major transformations of China's agricultural economy, including the Socialist Period, the Green Revolution, and the Reform Period. A production function was used to estimate the effect of different agricultural inputs, regions, and decades for China's provincial grain production, including wheat, maize, and rice. The ordinary least squared estimates demonstrate the changes in China's agricultural system in this period. The North China Plain's (NCP) agricultural system was used as a case study, and demonstrated the changes in intensity of grain production from 1960-2016. Increasing chemical fertilizer use was found to be the most important change in China's agricultural inputs, as changes in other inputs such as land, labor, and agricultural machinery were constrained. Chemical fertilizer use was found to be more effective for grain production in the NCP compared to other provinces. However, high or poorly balanced chemical fertilizer applications in this region has important environmental health consequences. This fertilizer intensive production is reinforced by Chinese farmers' needs for ensured income and management practices introduced during the Green Revolution. China's environmental policy has had limited success in addressing these problems.

Committee: Karen Mancl (Committee Chair); Hongtao Yi (Committee Member); H. Allen Klaiber (Committee Co-Chair); Sathya Gopalakrishnan (Committee Member) Subjects: Agricultural Economics; Agriculture; Asian Studies

Master of Science, The Ohio State University, 2011, Horticulture and Crop Science

In the first experiment of this thesis, four different fertilizers were applied at three rates each in order to investigate their effect on growth and quality of New Guinea Impatiens (NGI ) (Impatiens hawkeri Bull.) ‘Paradise New Red.' Fertilizer treatments included 1) Peters Peat-Lite 20-4.4-16.6 water-soluble fertilizer (WSF), 2) Daniels 10-1.8-2.5 soybean-based fertilizer (SBF), 3) Osmocote Plus 15-4-10, 3- 4 month longevity controlled-release fertilizer (CRF), 4) and Contec-DG 15-4-10, 5-month slow-release turf fertilizer (AGT). SPAD readings, plant dry weight (DW), consumer preference ratings (CP), and cumulative flower number (CFN) were measured and used to calculate a total quality index and select ‘optimal' application rates for experiment two. SBF applied at equivalent rates of N fertilization resulted in higher dry weight and significantly lower EC than WSF. ‘Optimal' rates were determined to be 1) AGT at 2.14 kg-m-3, 2) CRF at 7.11 kg-m-3, 3) SBF at 150 mg-L-1 N, and 4) WSF at 75 mg-L-1 N. In experiment two, the effect of these ‘optimal' rates on plant growth, nutrition, and nutrient leaching were compared. One or more nutrient deficiencies were detected in every treatment except CRF. While SBF plants appeared healthy, necrotic spotting occurred due to K deficiency. AGT plants were rated the lowest by consumers, grew the least, had lower SPAD, and were generally less floriferous than other treatments. CRF leached the most nutrients, most notably N (94-524% more total N), especially early in the production period. N, P, K, and Mg losses were the most affected by leaching with clear water to reduce supraoptimal substrate EC. While SBF leached similar amounts of N as WSF even though it was fertigated at twice the rate, higher N leaching may have occurred due to unmeasured urea in leachate. Based on these results, three-month longevity CRF and AGT may not be suitable for NGI fertilization. In experiment three, the effect of temperature on nutrient leaching at (open full item for complete abstract)

Committee: Claudio C. Pasian (Advisor); Jonathan M. Frantz (Committee Member); Michelle L. Jones (Committee Member) Subjects: Horticulture

Master of Science, The Ohio State University, 2010, Horticulture and Crop Science

This thesis describes the effects of controlled-release fertilizers (CRF) of different formulations and longevities on nutrient leaching out of the containers and garden performance of Impatiens walleriana. In the first experiment, impatiens plants were grown with Osmocote Plus 16-9-12 formulation of 5-6 month (5-6M) and 8-9 month (8-9M) longevities placed at four positions in the container: Topdressed, Incorporated, Top-one-third and Bottom. A 150 mgL-1 N Peter's Professional water-soluble fertilizer (WSF) of 20-10-20 formulation was used as a control. Leachates were collected at every irrigation and the concentrations of N, P, and Fe in the leachates were measured. Shoot dry weight (DW) and canopy cover (CC) were also measured. Total amount of water leached and nutrients lost from CRF and WSF were quantified. WSF produced plants of similar quality as CRF treatments except when CRF was applied at the bottom of the container. This fertilizer placement resulted in plants with the lowest DW, CC and leached the most P and Fe. CRF applied as topdressed leached the highest amount of N. Irrigating with a known volume of WSF solution leached less N and P but more Fe than 5-6M treatment. The WSF leached similar amount of nutrients as 8-9M CRF. In a second experiment with the same fertilizers, the amounts of water, N, P and Fe leached or lost out of the containers during irrigation with a hose were quantified. Irrigating plants with a hose caused up to 62% more water loss and up to 95% more nutrient loss during irrigation with WSF than CRF. In a third experiment, Osmocote Plus 15-9-12 of 3-4, 5-6, 8-9 and 12-14 month longevities were applied at rates of 1.4, 3.4, 6.8, 10.2 and 13.6 kgm-3. The same WSF as in the first experiment was used as a control. Impatiens plants were grown in the greenhouse and consumer evaluations were performed. Plant CC, flower cover (FC) and DW were determined. Commercially acceptable plant quality was achieved with CRF application rates between 3. (open full item for complete abstract)

Committee: Claudios C. Pasian PhD (Advisor); Michelle Jones PhD (Committee Member); Pablo Jourdan PhD (Committee Member); Jonathan Frantz PhD (Other) Subjects: Agriculture

Master of Science, The Ohio State University, 1980, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1960, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2024, Chemistry

Effective soil fertility management requires accurate monitoring of nutrient levels while minimizing environmental impacts. This study explored the feasibility of Raman spectroscopy for real time nitrate (NO3-) quantification in agricultural soils. Long term studies highlight the negative effects of overfertilization, necessitating rapid, on-site analysis methods. A Mira handheld Raman spectrometer with orbital raster scanning was utilized to obtain representative soil spectra after soil homogenation. MATLAB and PLS Toolbox were used for spectral data processing, employing the Rolling Circle Filter and Whittaker Filters for baseline correction. Multivariate curve resolution analysis revealed distinct spectral components for both the soil and the NO3-, allowing for predictive modelling. The limits of detection for potassium nitrate (KNO3) in soil were found to be as low as 17% (%wt in soil), equating to a total soil nitrogen content of 2% (%wt in soil). A machine learning model showed promise on accurately predicting the concentrations of samples. These results demonstrate the efficacy of handheld Raman spectroscopy for NO3- quantification in soil. By providing rapid, non- destructive analysis, this technique enables informed fertilizer application decisions, mitigation of environmental risks, increased crop yield, and healthier soil overall.

Committee: Zac Schultz (Advisor); L. Robert Baker (Committee Member); Vicky Wysocki (Committee Member) Subjects: Chemistry

Master of Environmental Science, Miami University, 2023, Environmental Sciences

Applying fertilizers and deicers are two prevalent forms of property maintenance in the Midwest, however, these practices contribute to negative environmental impacts when applied incorrectly. While fertilizer use is well researched, deicer use on private properties is not. The objectives of this research are to 1) ascertain whether the patterns of fertilizer use are different from those of deicer in Hamilton County, Ohio and 2) determine what factors influence a resident's decision to use these materials. Survey data was collected from 110 single family households (38.9% response rate) to determine fertilizer and deicer usage and perceptions. Respondents are motivated by property appearance to apply fertilizers. In contrast, deicer use stems from safety concerns. Respondents were significantly more likely to consider the environmental impact of fertilizers than deicers and to try to use fertilizers in an environmentally safe manner. Additionally, respondents reported that using deicers is a more neighborly practice while using fertilizers reflects more positively on them as members of their neighborhood. These findings highlight key differences between residential motivations of fertilizer and deicer application. Identifying these differences can contribute to the development of more effective educational and outreach programs to reduce the negative environmental impacts of fertilization and deicing.

Committee: Amélie Davis Dr. (Advisor); Ryan Gunderson Dr. (Committee Member); Michele Simmons Dr. (Committee Member) Subjects: Environmental Science; Geography

Master of Science, The Ohio State University, 2023, Horticulture and Crop Science

Nitrogen is an essential nutrient used in the fertilization of turfgrass systems. Ways to increase efficiency, or reduce the quantity of nitrogen applied, have been studied and implemented into management practices. Nitrification inhibitors, such as dicyandiamide (DCD), have been added to stabilized nitrogen fertilizer blends for their potential to reduce the conversion of soil ammonium to the more unstable nitrate, which has a greater potential to be lost from the soil environment. While stabilized turfgrass fertilizers include DCD, limited data exists for its effectiveness in turfgrass systems. A thorough assessment of DCD would allow for targeted recommendations of its use and limitations. The objective of this study is to evaluate the efficacy of DCD fortified urea in enhancing the duration of turfgrass color, as well as nitrogen efficiency, compared to conventional urea. Both the DCD fortified urea and the conventional urea, at two rates (24 and 44 kg N ha-1 ), were applied to plots of ‘Penncross' Creeping bentgrass (Agrostis stolonifera) in a factorial randomized complete block design with repeated measures. Color analysis, clipping yields, control-adjusted nitrogen offtake, nitrogen recovery efficiency, and soil ammonium and nitrate levels were analyzed. Turfgrass treated with DCD-enhanced urea had a longer duration of color, increased clipping yields, increased control-adjusted nitrogen offtake, and greater nitrogen recovery compared to conventional urea. Soil ammonium and nitrate levels were not significantly affected. DCD appears to increase the duration of nitrogen available to turfgrass, thus leading to a longer duration of color, growth, and greater overall nitrogen efficiency

Committee: Karl Danneberger (Advisor); David Gardner (Committee Member); Edward McCoy (Committee Member) Subjects: Horticulture; Plant Sciences; Soil Sciences

Master of Science, The Ohio State University, 2021, Environmental Science

Lead (Pb) speciation in soil is key for bioavailability assessment and exposure risk to humans from Pb contaminated soils. Soil ingestion is the main exposure pathway in Pb contaminated soils and in vitro bioaccessibility assays (IVBA) can predict relative bioavailable (RBA) Pb in soil by mimicking the GI tract conditions without traditional expensive animal feeding studies. In situ soil remediation has been considered an effective ecological treatment option compared to ex-situ techniques. The use of amendments such as biosolids, biochar, compost and phosphorous (P) amendments have been effective to decrease RBA in soils and, in doing so, reducing human exposure to the contaminant. In this study, soil amendments including biosolids, compost, wood-ash, biochar, soluble phosphate (SP) and their combinations were applied to Pb contaminated soil. Soil samples were incubated for up to 6 months at constant temperature, moisture and humidity. Samples were taken at three time points 1 (t1), 4 (t2) and 6 (t3) months of incubation and analyzed for total metal content, bioaccessible Pb (%IVBA-Pb), bioaccessible arsenic (%IVBA-As), organic carbon content (Org C), pH, extractable P and other key properties to determine the best treatment to reduce bioavailability of lead while improving soil health. Phosphorous was the most effective amendment to reduce %IVBA-Pb. Whether as individual or combined amendments, SP and biosolids resulted in 25-50% reductions of %IVBA Pb. Organic C addition did not reduce %IVBA-Pb, indicating complexation was not relevant for chemical immobilization of Pb in the case of strongly acidic soils such as the ones used in this experiment. %IVBA-As was correlated with pH and not P addition nor Organic C addition. Biosolid addition produced, apart from an expected plant available P increase, a great increase in Mineralizable Nitrogen content in the soils. Considering the importance of Nitrogen as an essential nutrient in plant growth, these results ind (open full item for complete abstract)

Committee: Nicholas Basta Dr (Advisor); Olorunfemi Adetona Dr (Committee Member); David Barker Dr (Committee Member) Subjects: Chemistry; Environmental Science; Environmental Studies; Soil Sciences

Doctor of Philosophy, The Ohio State University, 2020, Horticulture and Crop Science

An intensive production system is used to produce greenhouse floriculture crops, marketed for their flowers and attractive foliage. Chemical, environmental, and cultural methods are used to manage biotic and abiotic stresses during production. Additional tools are needed by growers because of growing concerns around the negative impact of plant production on humans and the environment. The objective of this research was to evaluate potential tools to improve floriculture crop resilience under stress during production and post-production. Botrytis cinerea causes disease in most major greenhouse crops and is resistant to several fungicides. Additional control methods, like plant growth promoting bacteria (PGPB) that can improve plant performance by increasing plant resilience to stress are needed. A collection of 60 bacterial strains was evaluated in a dual culture assay and an initial greenhouse trial with Petunia × hybrida `Carpet Red Bright' to identify strains for the biocontrol of B. cinerea. Daily flower disease severity ratings were used to select seven strains that were evaluated in the validation greenhouse trial. Three Pseudomonas strains were selected for the greatest reduction in B. cinerea infection. The efficacy of PGPB and the plant's susceptibility to B. cinerea were affected by fertilization. Petunia × hybrida `Carpet Red Bright' was treated with bacteria or a commercial biocontrol product and fertilized with synthetic chemical or organic fertilizer at a low or high rate. Measured plant growth and flower disease severity revealed that plants with the high rate synthetic fertilizer were the largest and had the lowest disease severity. Reduction of disease severity varied between bacterial and fertilizer treatment combinations. Plants treated with one bacterium had reduced disease severity at the high rate synthetic chemical fertilizer but not at the low rate organic fertilizer. Specific fertility programs provide crops with needed macro and mi (open full item for complete abstract)

Committee: Michelle Jones (Advisor); David Francis (Committee Member); Francesca Hand (Committee Member); Pablo Jourdan (Committee Member); Matthew Kleinhenz (Committee Member) Subjects: Agriculture; Horticulture

Master of Science, The Ohio State University, 2020, Environmental Science

Non-point source pollution is the primary cause of reduced water quality in the United States. According to the EPA (2017), these loadings result primarily from fertilizer and manure application. One of the most widely used hydrological models to predict the effect of nitrogen and phosphorus fertilizer application on nutrient loadings is the Soil and Water Assessment Tool (SWAT). While important advances have been made to improve the SWAT model, their ability to capture the complexity of human land management behaviors within remains a major challenge. Currently, most SWAT model applications assume that farmer behaviors are relatively homogeneous. For example, this homogeneity is simplified as an actor who adopt the traditional or regular behavior or maximizes their benefit in a perfectly rational way. Meanwhile, for decades social scientists have explored farmers' behavior suggesting that farmers are not a homogeneous group, but rather their behaviors are complex and diverse. Therefore, the first chapter of my project is focused on assessing how realistically SWAT models capture farmers' fertilizer behavior. The second chapter of my project incorporates the results of the first chapter and analyzes the direct and interactive effect of behavioral and biophysical heterogeneity on the water quality of the Maumee River Watershed using SWAT. Results of this analysis point to opportunities to better represent farmers' fertilizer behavior in SWAT models, which could improve our ability to link changes in land use and management to water quality and increase the effectiveness of conservation program interventions.

Committee: Douglas Jackson-Smith Ph.D. (Advisor); Margaret Kalcic Ph.D. (Advisor); Robyn Wilson Ph.D. (Committee Member) Subjects: Environmental Science

Master of Science, The Ohio State University, 2020, Earth Sciences

The evolution of modern agricultural practices as a result of a growing global population has led to increases in the flux of agricultural chemicals and compounds to both natural waters and soils. The most studied of these impacts are the addition of nitrogen (N) and phosphorus (P) through the application of chemical fertilizers, leading to their increase in surface runoff from agricultural operations, causing eutrophication in natural waters. Uranium (U) is a trace element that is often associated with P-rich fertilizer use, having the potential to accumulate in soils, crops, and surface waters, due to its natural occurrence in phosphate rock, along with various weathering and erosional processes that make it mobile. Studies have suggested phosphorus fertilizer is a source of uranium contamination in natural waters and soils. This study investigates chemistry of agricultural soils treated with P-fertilizer and compares them with the chemistry of agricultural soils under different management practices. This study also characterizes historical Geographic Information System (GIS) data in order to correlate uranium concentrations in Ohio soils with Ohio's glaciated compared to non-glaciated surfaces, underlying bedrock geology, and current land use/land cover. Total U concentrations in the soils ranged from 2.7 – 5.4 μg/g, and the water-, base-, and acid-soluble concentrations of U ranged from 2.2 x 10^-4 – 1.4 x 10^-3, 0.09 – 0.58, and 0.27 – 0.76 μg/g, respectively. The average concentration of the sum of the U in each of the soluble/extractable phases gave a maximum value of 18% of the total U. Using previously published data from the USGS, there are higher U concentrations in soils from the glaciated portion of the State, as opposed to those from the unglaciated portion of Ohio. This research clearly demonstrates that soils having fertilizer application show no statistical difference in U compared to similar soils without fertilizer application.

Committee: William Berry Lyons (Advisor); Nicholas Basta (Committee Member); Rattan Lal (Committee Member) Subjects: Agriculture; Analytical Chemistry; Environmental Science; Geochemistry; Geographic Information Science; Soil Sciences

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2020, Photochemical Sciences

We present the study of Fe(III)-carboxylate photochemistry of natural polyuronates in aqueous solutions and in soft hydrogel materials with near UV and violet light. Described in this dissertation are the use of Fe(III)-carboxylate photochemistry for sustainable material applications such as surface modifications and controlled plant nutrient delivery. Quantitative photochemistry of the Fe(III)-alginate system in aqueous solutions was studied using near UV light, and the effect of factors such as alginate composition and solution pH was studied. Degradation of alginate chain with the photochemical reaction was observed by the changes in the solution viscosity. The photochemical reaction seemed to proceed through a radical species and the generation of carbon dioxide anion radical (CO2.-) was identified using Electron Paramagnetic Resonance (EPR) spectroscopy. We present all polysaccharide hydrogels prepared with agarose and carboxylate group containing pectin which showed photoresponsive behavior. Upon Fe(III) coordination and irradiation with 405 nm LED for various time intervals, these gels changed their pH, mechanical properties, porous structure and swelling properties. Based on the radical generation phenomenon, studies on polymerization of selected acrylic monomers using this Fe(III)-carboxylate photochemical system was studied. Other than polyuronate based hydrogels, fabrics with introduced carboxylate functionality showed their ability to polymerize acrylic monomers on their surface, and change their physical and mechanical properties with the use of light. Hydrogel beads prepared with alginate or alginate and other polysaccharide mixtures with Fe(III) showed their ability to absorb phosphate ions from model waste solutions. The solution phosphate concentration dependent phosphate uptake showed a maximum phosphate uptake around 1.5 mgg-1. Phosphate uptake above 1 mgg-1 was seen for a wide pH range of 4.8 - 11.5 due to the strong binding betwe (open full item for complete abstract)

Committee: Alexis Ostrowski PhD (Advisor); Pavel Anzenbacher PhD (Committee Member); George Bullerjahn PhD (Committee Member); Lewis Fulcher PhD (Other) Subjects: Agriculture; Biogeochemistry; Chemistry; Environmental Science; Geochemistry; Inorganic Chemistry; Materials Science; Polymers

Master of Science (MS), Ohio University, 2019, Environmental Studies (Voinovich)

Miscanthus x giganteus (miscanthus), a perennial rhizomatous grass with a C4 photosynthetic pathway, has the potential to reduce greenhouse gas (GHG) emissions as it sequesters carbon into soil. Although fertilizer application to miscanthus sometimes increases yield, especially after five growing seasons, unintended impacts of GHG emissions resulting from the application of fertilizer has also been documented. This study evaluated the effects of four different fertilization treatments (digestate from a biodigester, synthetic nitrogen fertilizer, hydrochar from hydrothermal carbonization of digestate, and a control) on soil GHG emissions and biomass yield of an established miscanthus stand grown on abandoned agricultural land. Soil greenhouse gas fluxes (including CH4, CO2, and N2O) were sampled in all treatments using the static chamber methodology. There were no significant differences in biomass yield among the four treatments. Average biomass yield varied from 20.2 Mg/ha to 23.5 Mg/ha between the four treatments. Even though there was no significant difference between CO2 fluxes in the four treatments over the growing season, the hydrochar treatment reduced CO2 fluxes by up to 34% compared to the control treatment. Applying digestate to miscanthus resulted in a CH4 source while nitrogen and hydrochar acted as CH4 sinks. Overall, fertilization did not improve biomass yield but the hydrochar treatment appeared to be a better alternative at reducing GHG fluxes when compared to the other treatments.

Committee: Sarah Davis PhD (Committee Chair); Jared DeForest PhD (Committee Member); Toufiq Reza PhD (Committee Member) Subjects: Agriculture; Alternative Energy; Biogeochemistry; Climate Change; Energy; Environmental Studies; Soil Sciences

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, The Ohio State University, 2018, Food, Agricultural and Biological Engineering

Digital agriculture technologies, connected devices, and sensor networks have enabled data-based decision making systems to be implemented at the farm level. Operational insights, revealed through investigations of data generated during field operations, such as seeding, have prompted development of new technologies for optimal input management. Intensive management of cropping inputs, even plant-specific management, has become commonplace for commercial agriculture. During field operations, an assessment of accuracy and uniformity for applied inputs is essential for operator feedback, verification of machine performance, and high density data collection. While advanced sensing systems are available for some field operations (i.e. planting, spraying), systems for assessment of granular fertilizer application have lagged. Sub-surface style fertilizer application systems apply products using a metering and pneumatic conveyance method that distributions the fertilizer to each row of a ground engaging implement. Currently, key performance metrics related to this application are not being measured; opportunities exist to quantify the applied rate of fertilizers for each row of the implement. Collection of data at this scale will allow for validation of application accuracy and uniformity, while recording geo-referenced field data on a row-by-row basis. The overarching goal of this research was to develop a machine vision method for application rate estimation and high-resolution mapping of granular fertilizers applied through pneumatic application systems. A machine-vision based imaging sensing system was developed for diagnosis of known inefficiencies related sub-surface fertilizer application. This system can estimate applied rates of granular fertilizers for each row of a sub-surface placement implement. This estimation is accomplished through acquiring images of pneumatic particle flows, quantifying the mass of fertilizer within individual images, and then modeling (open full item for complete abstract)

Committee: John Fulton PhD (Advisor); Scott Shearer PhD (Committee Member); Steve Culman PhD (Committee Member) Subjects: Agricultural Engineering

Doctor of Philosophy, The Ohio State University, 2018, Agricultural, Environmental and Developmental Economics

Smallholder agriculture in the developing world is subject to numerous risks and trends. This dissertation investigates the economic sustainability of mechanisms used by smallholder farmers to mitigate risk as they adapt to a changing environment. The first two essays focus on index-based drought insurance and its relationship to changing risk caused by climate change and the growth of rural microfinance programs. The third essay focuses on how smaller farm sizes due to rural population growth affect farmer incentives to invest in soil quality. The first essay utilizes a framed field experiment in Tanzania and a structural learning model to study how climate change affects the demand for index insurance programs. I find evidence that demand will likely not keep pace with rising premiums in the absence of subsidies, threatening the economic sustainability of these programs in areas of changing risk. The second essay utilizes an analytic theoretical model to study the interaction between index insurance and microfinance programs. I find that if premiums are sufficiently low, coupling index insurance and microfinance can help mitigate the moral hazard problem inherent in loan contracts. The third essay utilizes a theoretical model and a panel data set from Tanzania to test how decreased farm sizes caused by population growth affect investment in fertilizer and soil quality. I find that smaller farm sizes lead to greater fertilizer use, particularly for organic materials such as compost and manure, and an indeterminate effect on soil quality.

Committee: Mario Miranda (Advisor); Jon Einar Flatnes (Advisor); Abdoul Sam (Committee Member) Subjects: Agricultural Economics; Economics; Environmental Economics

Doctor of Philosophy, The Ohio State University, 1987, Graduate School

Committee: Not Provided (Other) Subjects: Agriculture

Doctor of Philosophy, The Ohio State University, 1982, Graduate School

Committee: Not Provided (Other) Subjects: Agriculture