Master of Science, The Ohio State University, 2015, Animal Sciences

An experiment was conducted to compare bacterial counts of environmental mastitis pathogens in composted recycled manure solids bedding with those in fresh recycled manure solids. Eighteen Holstein cows were housed in 1 pen with 18 stalls. One row of 9 free stalls included mattresses and was bedded weekly with composted recycled manure solids. The second row of 9 free stalls included mattresses and was bedded weekly with fresh recycled manure solids. The back one-third of these stalls toward the alleyway was covered in 25 to 50 mm of bedding. Samples were taken from the back one-third of 4 stalls for both treatments on d 0, 1, 2, and 6 for each week. After 3 wk, bedding treatments were switched between rows, making the total duration 6 wk. Mean total gram-negative bacterial counts were lower in the composted recycled manure solids on day 0 and 1 compared with fresh recycled manure solids. Tetracycline resistant gram-negative bacteria were lower in composted recycled manure solids for d 0, 1, and 2 compared with fresh recycled manure solids. Coliforms and Streptococcus spp. bacteria were lower in composted than fresh recycled manure solids on d 0. Klebsiella spp. bacteria were reduced in composted recycled manure solids compared with fresh on d 0 and 6. Fresh recycled manure solids had a higher DM for d 1 and 2 compared with composted recycled manure solids. Ash content was higher in composted recycled manure solids compared with fresh recycled manure solids throughout the trial for d 0, 1, 2, and 6. Composting recycled manure solids was successful in reducing tetracycline resistant gram-negative bacteria as well as increasing ash. Despite the increase in ash after composting, bacterial counts in composted recycled manure solids were elevated throughout the trial after use as bedding. Composting recycled manure solids used as free stall bedding had minimal effect on reducing environmental mastitis pathogen exposure to teat ends.

Committee: Joseph Hogan (Advisor); William Weiss (Committee Member); Michael Lilburn (Committee Member) Subjects: Animal Sciences

Master of Science, The Ohio State University, 2008, Food Agricultural and Biological Engineering

Composting offers the potential to significantly reduce problems associated with manure management including odors, pathogens, ground water pollution, and utilization costs. Two variables that directly affect on-farm composting costs are windrow size and windrow turning frequency. However the size of a windrow is limited by the depth of penetration of oxygen and high temperatures as well as available equipment. In this study three full scale compost sets were set-up at the Ohio Agricultural Research and Developing Center (OARDC) compost pad to evaluate the effects of turning frequency, pile size and seasonal variability on physical (temperature, oxygen, bulk density, moisture and weigh loss), chemical (volatile solid loss, pH, Carbon and Nitrogen concentrations) and biological (plant growth bioassays and microbial community structure) parameters during dairy manure/sawdust composting (DM+S). Based on these data the operational costs for producing and transporting compost were estimated and compared to those for liquid manure and fertilizer. The three treatments consisted of a set of windrows (A) which were turned using a self propelled and tractor drawn windrow turner every three days for a total of 32 turns during 16 weeks, a second set (B) that was turned once every ten days and a third set (C) consisting of much larger piles turned that was also turned every ten days with a loader. All three sets were composted in both winter and summer for 120 days. The hypotheses of the study was that; turning frequency, pile size and season do not significantly affect compost process parameters or the final chemical, physical or biological properties of cured composts. Results showed that neither physical chemical nor biological properties of the final cured composts were significantly affected by turning frequency, season or pile size (p > 0.05). During composting, he the surface area, oxygen concentrations and Total nitrogen losses were significantly affected by pile size ( (open full item for complete abstract)

Committee: Frederick Michel PhD (Advisor); Harold Keener PhD (Committee Member); Brian McSpadden Gardener PhD (Committee Member); Warren Dick PhD (Committee Member) Subjects: Agricultural Engineering

Master of Science, The Ohio State University, 1974, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1981, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2021, Animal Sciences

Livestock and poultry production are the leading contributors to NH3 emissions in the United States. While NH3 is not itself a greenhouse gas (GHG), it forms nitrous oxide and small particulate matter (PM2.5, i.e, smog) that is of concern for environmental agencies and poses human health risks. Nitrogen also can leach into soil and potentially cause eutrophication of water sources. For livestock producers, N loss from manure is costly, both from the perspective that it is going unused by the animal and that the manure will not serve as useful a fertilizer for crop production. Acidifying dairy manure with addition of strong acids, such as HCl or H2SO4, is the most widely studied method of reducing NH3 emissions but increases the cost for manure management. Reducing the dietary cation-anion difference (DCAD; Na + K -Cl - S) is a strategy typically used to reduce hypocalcemia after parturition, but we hypothesized that DCAD can be a potential strategy to lessen the environmental impact of the dairy industry when applied to lactating cows. Urine pH can be reduced with the inclusion of anionic salts in cow rations, thus perhaps influencing the overall pH of the manure slurry. Two experiments were designed to evaluate the effectiveness of feeding a diet with reduced DCAD to lactating cows to mitigate manure NH3 emissions while still maintaining milk production and nutrient digestibility. In the first experiment, 27 cows were randomly assigned to 1 of 3 diets with differing DCAD (193, 101, and 1 mEq/kg DM). The DCAD did not affect milk yield but tended to decrease milk fat yield without affecting milk fat content as DCAD decreased. Milk protein yield was not different among treatments. In addition, nutrient digestibility (i.e., DM, OM, NDF) did not differ among treatments. The low DCAD diet successfully reduced pH of urine and manure, but manure incubation did not result in statistical differences in NH3 emissions among treatments. Ammonia emission was probably not red (open full item for complete abstract)

Committee: Chanhee Lee (Advisor) Subjects: Animal Sciences

Master of Science, The Ohio State University, 2020, Plant Pathology

It has been documented that beneficial plant-associated bacteria have contributed to disease suppression, growth promotion, and tolerance to abiotic stresses. Advances in high-throughput sequencing have allowed an increase in research regarding bacterial endophytes, which are microbes that colonize the interior of plants without causing disease. Practices associated with minimizing the use of off-farm resources, such as reduced tillage regimes and crop rotations, can cause shifts in plant-associated bacteria and its surrounding agroecosystem. Integrated crop–livestock systems are an option that can provide environmental benefits by implementing diverse cropping systems, incorporating perennial and legume forages and adding animal manure through grazing livestock. It has been found that crop-livestock systems can increase soil quality and fertility, reduce cost of herbicide use and improve sustainability, especially for farmers in poorer areas of the world. This work explores how crop-livestock systems that integrate chicken rotations can impact tomato plant growth, as well as soil and endophytic bacterial communities. Tomato plants were subjected to greenhouse and field studies where biomass was assessed, and bacterial communities were characterized through culture-dependent and -independent approaches. In greenhouse experiments, the greater percent of chicken grazed soil incorporated in the planting substrate, the greater the stunting of tomato seedlings. In the field study, bacterial communities differed significantly by sample origin and plant development stage, regardless of chicken grazing history. Our findings suggest stronger contribution of agricultural management practices during early plant stages on endophytic microbiome, as opposed to later on in the host lifecycle. Taxonomic composition of dominant groups of recovered endophytic bacterial isolates were consistent with those found by amplicon sequencing. Plots with history of chicken grazing had a sig (open full item for complete abstract)

Committee: Maria Soledad Benitez-Ponce Ph.D. (Advisor); Christine Sprunger Ph.D. (Committee Member); Jonathan Jacobs Ph.D. (Committee Member) Subjects: Agriculture; Biology; Ecology; Microbiology; Plant Pathology; Soil Sciences

Doctor of Philosophy, University of Toledo, 2019, Spatially Integrated Social Science

The goal of this study was to identify areas that were prone to nutrient transport from land application of manure based on environmental conditions including length of streams and flood hazard potential in those areas. Additionally, the study aimed at developing an economic utility for producers in transporting manure in the Maumee Watershed in North-west Ohio targeted at reducing the potential environmental impacts that may arise from over application. The initial basic feasible solution of the Hitchcock transportation model was used to simulate the distribution of manure from 31 dairy and swine concentrated animal feeding facilities to agricultural census block groups (soybeans and corn) in the Maumee Watershed within NW Ohio. The model considered the supply and demand capacity of nearby livestock operations (origin) and agricultural census block groups (destinations) respectively. The second objective was to identify areas that were prone to nutrient transport as determined from the model results based on environmental conditions related to floodplain and length of streams dataset using the Getis-Ord GI* statistic. Finally, using the objective function of the transportation problem, the transportation costs associated with hauling manure from the source to the destinations was calculated. The distribution of manure showed an unbalanced transportation problem such that available farmland that could receive manure exceeded the supply of the livestock operations. The findings suggest there is adequate agricultural land for manure distribution in the watershed. Additionally, areas indicating clustering in distribution of manure were further examined to determine potential for nutrient transport off the land and into nearby waterbodies based on the environmental conditions used. Approximately 98% of receiving agricultural census block groups fell in the EC-1 classification, which indicates a very low potential for environmental conditions to influence nutrient (open full item for complete abstract)

Committee: Patrick Lawrence (Advisor); Peter Lindquist (Committee Member); Kevin Czajkowski (Committee Member); Kenneth Kilbert (Committee Member); Daryl Dwyer (Committee Member) Subjects: Geography

Doctor of Philosophy, The Ohio State University, 2019, Food, Agricultural and Biological Engineering

The U.S. egg industry is the world's second-largest egg producer with an annual production of 5.6 billion kilograms of eggs and provides 81,515 jobs and $22.77 billion to the economy. Due to the very large-scale and concentrated operations, the egg industry is facing crucial challenges in reducing its significant environmental impacts and solving indoor air quality problems. Egg production is a significant contributor of air emissions to the atmosphere, especially ammonia (NH3) emission, which has caused serious concerns on health and the environment, such as soil and water acidification, visibility impairment, and respiratory diseases. Effective management and mitigation of NH3 emissions from layer operations are urgently needed but are limited because of the lack of effective tools for estimating NH3 emissions. It is also in the egg industry's and the public's interests to understand the health and environmental impacts of NH3 on the neighboring communities. The U.S.EPA regulatory air dispersion model AERMOD needs to be evaluated for its performance in estimating NH3 dispersion after being emission from layer houses. In addition, heat stress is a serious problem in layer houses with annual losses of $61-98 million nationwide due to impaired egg production. Global warming further worsens the heat stress problem due to increasing events of hot weather and heavier precipitation. Exposure to high-concentration NH3 is another risk to layers and workers. It damages layers' immune system and egg production and affects workers' health. The problems of heat stress and NH3 exposure are aggravated in layer houses due to non-uniform airflow resulted from current ventilation systems. The knowledge of the spatial and temporal distribution of heat stress and NH3 concentrations inside layer houses is essential for assessing the associated risks of layers and workers and developing mitigation strategies, but is not yet available. This dissertation aims to fill the gap by de (open full item for complete abstract)

Committee: Lingying Zhao (Advisor); Albert Heber (Committee Member); Jiqin Ni (Committee Member); Heather Allen (Committee Member); Ann Christy (Committee Member); Gil Bohrer (Committee Member) Subjects: Agricultural Engineering; Environmental Engineering

Master of Science, The Ohio State University, 2018, Food, Agricultural and Biological Engineering

Current water quality targets for Lake Erie call for a 40% reduction in total phosphorus (TP) and dissolved reactive phosphorus (DRP) from 2008 levels from the Maumee River watershed. Previous studies have shown pathways to reaching these targets through widespread implementation of agricultural best management practices due to the large impact agriculture has on the water quality discharged from the watershed. Approximately 88% of the total phosphorus delivered to Lake Erie from the watershed comes from agricultural fertilizer and manure applications. Although a large focus on achieving these water quality targets is on management of agricultural land practices, many unknowns exists about the impact manure applications have on the water quality discharged from the watershed. To investigate how permitted, large-scale livestock operations plan to manage their manure, Permits and Inspection Reports submitted to and conducted by the Ohio Division of Livestock Environmental Permitting for 48 Confined Animal Feeding Facilities (CAFFs) in northwestern Ohio were examined. Results from this analysis found that dairy manure likely traveled further from its source than swine manure and much liquid manure was planned to be applied in the growing season (July-October). Furthermore, results indicated that CAFFs were generally following their approved Manure Management Plans. In 2014, 65% of acres receiving manure had soil phosphorus levels below 50 ppm (Bray P1). In 2015, 69% of acres receiving manure had soil phosphorus levels below 50 ppm (Bray P1). Results also highlight that approximately 80% of swine and 75% of cattle within the study area are not housed on permitted operations and approximately 100% of solid poultry manure produced within the study area is managed through Distribution and Utilization. Little public information regarding manure management is available for non-regulated livestock or for manure managed in Distribution and Utilization. To simulate impa (open full item for complete abstract)

Committee: Jay Martin (Advisor); Margaret Kalcic (Committee Member) Subjects: Agricultural Engineering; Environmental Engineering; Environmental Management; Livestock

Master of Science, The Ohio State University, 2017, Food, Agricultural and Biological Engineering

Phosphorus is an essential nutrient for life, but excess phosphorus in runoff from manure applied to agricultural fields can lead to negative environmental impacts such as harmful algal blooms. Water-extractable phosphorus (WEP) is correlated with phosphorus runoff from land-applied manure, but can change depending on the water content of a sample. Understanding how total phosphorus (TP) and WEP partition through livestock manure management systems can aid attempts in preventing phosphorus pollution of watersheds by increasing knowledge of how to remove it at its source. A number of dairy farms use solid-liquid separation in order to make the manure easier to handle. This produces a mostly solid material which can be re-used in the dairy barns as bedding for the cows, as well as a mostly liquid material which is applied to the fields. However, little is known about the partitioning of WEP through solid-liquid separation. This study investigated the partitioning of TP and WEP through manure management systems on two dairy farms using screw presses and anaerobic digestion to treat the manure produced by the dairy cows. Samples were taken at various stages throughout the manure management systems, to determine important characteristics at each stage. Manure followed two main paths: direct solid-liquid separation of manure diluted with liquid effluent from the separators, or anaerobic digestion of the diluted manure before solid-liquid separation. On Farm B, the liquid effluent of the separators could only be accessed after the streams mixed together, causing difficulties in analyzing the potential for phosphorus removal in each separator individually. Measurements at all important management points on Farm A were available, however, and analysis of those results shows that phosphorus partitioned into the separated solid effluent stream from the separator at a higher proportion than would be expected if the phosphorus partitioned in the same way as the liquid manure (open full item for complete abstract)

Committee: Harold Keener (Advisor); Ajay Shah (Committee Member); Jay Martin (Committee Member) Subjects: Agricultural Engineering; Environmental Engineering

Doctor of Philosophy, The Ohio State University, 1974, Graduate School

Committee: Not Provided (Other) Subjects: Engineering

Doctor of Philosophy, The Ohio State University, 1969, Graduate School

Committee: Not Provided (Other) Subjects: Engineering

Master of Science (MS), Ohio University, 2014, Plant Biology (Arts and Sciences)

The number of certified organic farms is increasing, however organic matter suitable for composting is often limited in availability. Testing additional agroindustrial wastes for their suitability in composting could benefit the industry. In this project, composts produced from brewers' spent grains/sawdust and from horse manure/sawdust were compared for their effects on yield of kale, beets, and peas. Percent of total N for untreated plots, horse manure compost and brewers' spent grain compost amended plots were 0.2, 0.4, and 0.25 respectively. Neither compost treatment significantly improved yields in season one and brewers' spent grain/sawdust compost significantly decreased yield in kale (P < 0.05). However in the second season kale yield was significantly increased by the horse manure compost (P = 0.03) and fresh grain additions (P = 0.05). Although the composts provided additional nutrients to the plots other factors may have attributed to the lack of significant growth benefits in season one.

Committee: Arthur Trese (Advisor) Subjects: Agriculture; Botany; Environmental Studies; Food Science; Horticulture; Plant Biology

Master of Science, The Ohio State University, 2013, Environmental Science

Contamination of produce is a critical food safety issue and may result from airborne bacteria transmitted during manure application. We conducted a field experiment to determine the distance pathogens can be transferred by air during manure application, and the survival of the pathogens on produce. Romaine lettuce and slicing tomatoes were planted in rows in plots (8 m2) that were arranged in a completely random design. Liquid dairy manure was spread in a 5-m-wide band next to and perpendicular to the end of the rows. Agar plates, located 24 cm above the ground and at the point nearest the manure spreading (0 m downwind), 15, 30, and 122 m downwind, and 15 m upwind, were left open for 5-15 min after application. Lettuce leaves and tomato fruits were collected before and 15 min after application, then on post application days 1, 3, 5, and 7. Vegetable samples were agitated with PBS, and the resulting solutions were plated. All plates were incubated at 37°C for 36 h, and bacterial colonies (CFU/ml) were counted. The number of airborne bacteria on open agar plates was highest at 0 m downwind. Bacteria decreased between 0 and 30 m downwind (P<0.05). Number of bacteria was consistently higher on lettuce leaves than on tomato fruits (P<0.001). Counts on lettuceleaves often peaked on Day 5 (P<0.05); counts on tomato fruits peaked on Day 7 (P<0.001). Low temperature, high relative humidity, and high rainfall may have contributed to high bacteria counts on vegetables (P<0.001). From this study's results, we can infer that airborne bacteria transport from liquid manure decreases between 0 and 30 m downwind, that survival of bacteria on vegetables may be related to weather conditions, and that lettuce leaves may capture more airborne bacteria than tomato fruits. Our research provides evidence that spreading of liquid dairy manure closer than 122 m to a vegetable field may contribute to contamination of field-grown produce.

Committee: Douglas Doohan (Advisor); Jeffrey Lejeune (Committee Co-Chair); Richard Moore (Committee Member) Subjects: Food Science; Horticulture; Microbiology

Doctor of Philosophy, The Ohio State University, 2012, Food, Agricultural and Biological Engineering

There is an ongoing need to develop more sustainable systems for producing energy and treating wastes. Anaerobic digestion is one type of technology that can meet this need. The sustainability and microbial community dynamics of ambient temperature anaerobic digesters was evaluated by this research. An emergy analysis of the EARTH University Taiwanese model anaerobic digesters was performed, and the results were compared to other forms of energy production. The results of this analysis indicate that the EARTH University digester was a more sustainable system than traditional sources of energy production such as oil and natural gas. The success of the EARTH University digesters was due, in part, to the tropical climate of Costa Rica that provides favorable ambient temperature year round for anaerobic digestion. The remainder of this dissertation focused on the analysis of the microbial community dynamics in variable temperature anaerobic digesters. The results of the microbial community analysis of the Waterman fixed-dome digester showed that there are significant shifts in the structure of the both the Archaeal and Bacterial communities that coincided with digester re-inoculation as well as temperature and loading rate changes. Following re-inoculation, the predominant Archaea shifted from the hydrogenotrophic Methanobrevibacter to the acetoclastic Methanosarcina which was the most abundant Archaea in the inoculum. Methonosarcina was replaced by another acetoclastic methanogen, Methanosaetae after the resumption of digester loading in the summer of 2010. Methanosaetae began to decline in abundance as the digester temperature cooled in the fall of 2010 and Methanobrevibacter increased in abundance through the end of the study period. The third chapter of this dissertation was a laboratory experiment that investigated the relationship between temperature, organic loading rate and the structure of the microbial communities in the laboratory digesters. At loading (open full item for complete abstract)

Committee: Jay F. Martin PhD (Advisor); Jiyoung Lee PhD (Committee Member); Fred Michel PhD (Committee Member) Subjects: Agricultural Engineering; Alternative Energy; Ecology; Microbiology

Doctor of Philosophy, The Ohio State University, 2012, Food, Agricultural and Biological Engineering

Low rate digesters are widely used in tropical and subtropical regions to produce energy from livestock manure. The fixed dome model is the most popular digester in China. These digesters are affordable, simple to operate and can produce the daily energy needed for a family from 5-10 pigs or cows. However, they often suffer from poor biogas production and potential digester failure during the seasonal transition from mesophilic (25-45°C) to psychrophilic temperatures (5-25°C ) in temperate climates. Three investigations were conducted on the anaerobic digestion of diluted dairy manure in temperate climates at variable mesophhilic and psychrophilic temperatures to describe limitations and identify design and management improvements. The first study characterized the performance of a modified fixed-dome digester in temperate climates to identify factors that affect biogas production. The second study investigated the effect of the source of inoculum and the inoculum substrate ratio (ISR) on the methane production and stability during the start-up of low rate digesters. The final study diagnosed the effect of organic loading rates (OLR) on biogas production, and identified organic loading rates that prevent the acidification during transition from summer to winter temperatures. The first study made it clear that temperature and the organic loading rate were the key variables to be controlled in later studies attempting to improve low rate digester performance during colder temperatures. In the case of temperature, it is recommended to keep the digester temperature above 20 °C. For the system and climate of this study, it was not possible to maintain this temperature with burial and insulation, and will necessitate supplemental heating to maintain temperatures above 20°C year round. Furthermore, the results demonstrate the need to reduce the organic loading rate during warmer months to make the digester less vulnerable to souring as temperature declines. The second st (open full item for complete abstract)

Committee: Jay Martin (Advisor); Karen Mancl (Other); William Mitsch (Other); Yebo Li (Other) Subjects: Alternative Energy

Doctor of Philosophy, The Ohio State University, 2012, Soil Science

Soil, our planet's most abundant natural resource, requires mindful agronomic management to support an increasing world population. Soil fertility management provides a central tool to address nutrient-deficient soils and soils where excess nutrients move from the field potentially impairing the environmental. The three projects in this dissertation evaluated different aspects of agronomic decisions faced yearly by farmers in both the developed and developing world. These studies addressed both degraded and highly productive soils, and also considered soil impacts on plant productivity. All of the studies were field-based and carried out with a corn crop. The Ohio-based work was conducted on research farms in northeast, northwest and west-central parts of the state, whereas the work in Kenya was conducted in coordination with private landowners. In western Kenya, our study investigated a control plus three composted-manure placement options: spread evenly across the field and incorporated before planting (broadcast), below the seed (hole) and next to the row of seeds (banding), and no compost (control). Phosphorus availability and plant productivity were assessed for each compost placement treatment. All farm locations had soils that were moderately acidic. In terms of crop yield, the hole method tended to increase yield on the soils with low fertility, while no differences between the control and the placement treatments were observed on the moderate fertility farms. An Ohio-based study, the “Phosphorus Trial,” examined five rates of a commercial phosphorus fertilizer applied using both broadcast and banding methods. The goals of the study were to evaluate more efficient use of phosphorus, which, when eroded with soil particles or lost via fertilizer runoff, can negatively affect the environmental through impairment of water bodies and results in an economic loss to the grower. Data from two site-years revealed a higher yield for 140 kg ha-1 broadcast over the con (open full item for complete abstract)

Committee: Edward McCoy PhD (Advisor); Robert Mullen PhD (Committee Member); Pierce Paul PhD (Committee Member); Peter Thomison PhD (Committee Member); John Cardina PhD (Committee Member) Subjects: Agriculture; Agronomy; Soil Sciences

Master of Science, The Ohio State University, 2011, Environment and Natural Resources

Ohio livestock and poultry farms generate between 14.5 and 16.8 million tonnes of manure annually. A good source of nutrients, this manure is typically spread on cropland for use by future crops. A considerable amount of manure is hauled during winter due to the soil being saturated in spring and fall. Frozen soil can support heavy equipment and producers can alleviate pressure on limited storage facilities. The practice of applying manure to frozen/snow covered ground is not recommended, but is a necessity for many small animal operations. The United States Department of Agriculture – Natural Resource Conservation Service has guidelines in place for manure applications that occur on frozen/snow covered ground, but they have not been adequately tested to determine their utility. A project was established at the Ohio Agricultural Research and Development Center to test the effectiveness of a 61-m setback from field edge to applied manure. Other NRCS practices for applications to frozen and snow covered soil were followed where applicable. Based upon two-site years from this study, observing a 61-m setback distance below application of liquid dairy manure (while following other criteria set forth in NRCS Practice Standard 633) did decrease nutrient transport by overland flow when the field slope is relatively flat (~2% or less). Application of dairy manure up to the field edge represents a significant risk of nutrient transport and should be discouraged completely.

Committee: Robert Mullen PhD (Advisor); Charles Goebel PhD (Committee Member); John Cardina PhD (Committee Member) Subjects: Agriculture; Environmental Management; Livestock; Natural Resource Management

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

Doctor of Philosophy, The Ohio State University, 2008, Food Agricultural and Biological Engineering

Three investigations were conducted on small-scale digesters in Costa Rica to optimize their ability to treat animal wastewater and produce renewable energy. The first study investigated variability in biogas quality and water pollutant reductions in seven digesters located at small-scale farms in Costa Rica. The second study investigated the production of electricity using combined biogas from swine and dairy digesters. The final study investigated increases in biogas production by co-digesting swine manure and used cooking grease in 12 field-scale digesters. This study assessed methane production, wastewater pollutant reductions, and fertilizer utility.The digester variability study revealed that the digesters maintain high reductions in organic matter (84.1 %), produce biogas with a high percentage of methane (66.3 %), and produce a fertilizer that has 78.3 % more NH4-N. In the electricity production study, the dairy and swine digesters produced 27.5 and 6.0 m3/day of biogas, with 62.6 and 76.4 % methane, respectively, and reduced organic matter by 86.1 and 91.9 %, respectively. Eighty-two percent of the farm's 2-hour peak electricity demand (25.8 kW/day) was met. The $21,000 capital cost of the digester project will be recovered in 10 years through electricity savings and reductions in wastewater fines. If the generator were more appropriately sized for the farm, the capital recovery time would have been 7.6 years. Co-digestion experiments were conducted on 12 field-scale digesters using three replications of four treatment groups: the control (0%) and 2.5, 5, and 10 % used cooking grease (by volume) combined with swine manure. The 2.5 % treatment increased the methane production by 111%. No additional benefits were seen by increasing the grease concentration beyond 2.5 % due to the lower quality of biogas produced. No adverse effects were observed from co-digesting with 2.5 % grease in terms of organic matter removal, pathogen reduction, and grease removal. Th (open full item for complete abstract)

Committee: Jay Martin (Advisor); William Mitsch (Committee Member); Ann Christy (Committee Member); Tuovinen Olli (Committee Member) Subjects: Agricultural Engineering