Master of Agribusiness / Department of Agricultural Economics / Allen M. Featherstone / During the past 10 years, ethanol production in the United States has grown exponentially. From 2000 to 2009 U.S. ethanol production increased from 1.6 billion gallons annually to 10.8 billion gallons annually. In 2010, U.S ethanol production increased by 23 percent from 2009 to 13.23 billion gallons. The increase in ethanol production was due to lawmakers reacting to skyrocketing oil prices by implementing a Renewable Fuels Standard (RFS) in 2005 and expanding the RFS in 2007. The RFS requires the use of specified amounts of biofuels, such as ethanol, through the year 2022. The creation of the RFS represented a step beyond lawmakers’ usual policy of using the tax code to promote ethanol production. There is a long history of encouraging ethanol production by using the tax code, but the implementation of a biofuels mandate is new and therefore there is not a great deal of research on the effects of such a policy. This study analyzes U.S. oil, unleaded gasoline, corn and ethanol prices dating back to 1985 to determine the impact that the RFS has had on corn prices. The key question answered is whether the creation and expansion of the RFS has brought the instability of the oil market into the corn market. The prices that an ethanol plant in western Kansas paid for the grain it used to produce ethanol and the price that the plant received for the ethanol that it produced are also analyzed. The plant began operation in January 2004, so it is possible to analyze the grain and ethanol prices both before and after the implementation and expansion of the RFS. To study the impact of the RFS creation and expansion, the prices were analyzed to see if there was an increase in the correlation after the creation and expansion of the RFS. Regression analysis of the national corn prices and the prices that Western Plains Energy paid for the grain that it used to produce ethanol; and regression analysis of the national price of ethanol and the price that Western Plains Energy sold its ethanol for were also used to study the impact of the RFS. Finally, the vector autoregression (VAR) model is used to analyze the dynamic relationships between the variables in the system: corn price, oil price, ethanol price and unleaded gasoline price. The analysis of the correlation reveals that both at the national and plant level grain and oil prices track much more closely together after the creation and then expansion of the RFS. The VAR reveals that there is some relationship between corn and oil prices contemporaneously. The correlation matrix of residuals reveals that there is not a strong correlation between national corn and oil prices. The results suggest the need for greater research in this area. The creation and expansion of the RFS represented a step into uncharted territory and the consequences are still not known.

Master of Agribusiness / Department of Agricultural Economics / Michael R. Langemeier / The cattle market has drastically changed over the last half century. Today, ranchers and farmers are faced with various governmental regulations as well as fluctuating grain and fuel prices. While beef may still be a commodity, it can be sold in specialized markets, in markets that have enhanced consumer demand. It is nearly impossible for a producer with a small herd to compete with a larger ranch if they are selling their cattle as a commodity. The primary economic objective of the producer is to generate revenue. Producers must be profitable to remain in business as well as provide a livelihood for their family. Providing a quality product is part of the business model. Choice within a marketplace is beneficial for producers and consumers. That said forage-fed beef will prosper in marketplaces where consumers desire their product more than alternate products. If producers are intent on progressively growing their market share, Georgia-grown, forage-fed beef must be marketed correctly. This includes promoting it on a basis of locally grown, pasture raised, and other attributes consumer’s desire. The results of the marketing survey present data that may be helpful when marketing Georgia-grown, forage-fed beef. The weekly consumption of beef products provided insight into the potential scope of the market. Approximately 39 percent of respondents consumed beef products three or more times per week. Additionally, 43 percent of the respondents were not familiar with forage-fed beef. This is a significant share of the market that is possibly open to a new product like Georgia-grown, forage-fed beef. Similarly, traceability of the product was an important feature that customers preferred. In addition to a larger selection of naturally produced beef products, respondents also indicated they were willing to pay more for the product. Approximately 49 percent of the respondents indicated that they would be willing to pay up to a dollar more per pound for Georgia-grown, forage-fed beef. Another 30 percent of the respondents indicated that they would be willing to pay more than $1 per pound for Georgia-grown, forage-fed beef. The results of the survey appear to offer opportunities for producers of Georgia-grown, forage-fed beef to expand their market share.

Master of Science / Department of Entomology / David C. Margolies / James R. Nechols / Many crops grown in greenhouses are damaged by the twospotted spider mite, Tetranychus urticae. The predatory mite, Phytoseiulus persimilis, is a commercially-available predator that is commonly used to control twospotted spider mites on greenhouse crops; but its efficacy varies among crops, and it is generally ineffective at low prey densities. In general, predator foraging efficiency depends on how well predators find prey patches, the length of stay in prey patches, and consumption of prey while in prey patches. With respect to P. persimilis, I asked how this predator responds to different prey distributions, as might be encountered at different stages of spider mite infestations. I also asked how components of foraging, namely consumption rate and dispersal tendency, affected predator efficiency. To examine the former, I established T. urticae eggs on 6-leafed cucumber plants in two distributions. To examine the latter, I imposed artificial selection on a population of P. persimilis to create a line that exhibited extremely high consumption and one that demonstrated a greater tendency for dispersal. Subsequently, foraging efficiency was assessed by observing predator oviposition and consumption of twospotted mite eggs on individual leaves of 6-leafed cucumber plants. The number of eggs laid by predators corresponded to the number of prey consumed regardless of predator line. In addition, predators from both lines distributed their eggs proportional to where they fed. However, prey consumption differed between selected lines in response to prey distribution. Predators selected for high consumption fed more on the basal leaf where they were released; whereas prey consumption by the high dispersal and control lines were more evenly distributed throughout the plant. These results contribute to a better understanding of how foraging behavior is modified in plant landscapes under different levels of expression of foraging traits. They also indicate that predator release strategies likely would need to modified in accordance with the kind of foraging trait(s) used in artificial selection programs. In general, my research, when combined with future studies at a broader landscape level, will facilitate decisions by biological control practitioners about whether changes in foraging efficiency resulting from artificial selection justify the cost investment of producing selected lines of P. persimilis

Master of Science / Department of Agronomy / Scott A. Staggenborg / In recent years, subsurface drip irrigation (SDI) acres have increased substantially. The use of SDI on corn (Zea Mays L.) in the Great Plains has increased due to increased land costs, reduced irrigation water availability, and higher commodity prices. Applying phosphorus (P) fertilizer through a SDI system becomes a major advantage, but further investigation of the interaction between water and fertilizer is needed. Sub-surface drip irrigation systems can be used to better improve the application efficiencies of fertilizers, applying in wet soil-root zones can lead to better uptake of soil applied materials. The objectives of this study were to determine how corn responds to P fertilizer applied via SDI and to create methodologies to simulate fertilizer and irrigation water compatibility tests for use in SDI systems. A plot sized SDI system was installed near Manhattan, KS to evaluate P treatments. Eight separate P fertilizers were applied via SDI mid-season at a rate of 34 kg P2O5 ha-1 and split-plots were created with 2x2 starter band at planting. Nitrogen was a non-limiting factor, with 180 kg N ha-1 applied as urea. Both starter fertilizer and injected fertilizer affected corn grain yield as indicated by the starter by treatment interaction. Split applying starter fertilizer at planting increased yield. A secondary laboratory study was conducted to evaluate the water and fertilizer interactions. A filtration system was used to simulate field conditions and each fertilizer/water mix was filtered through a 400 mesh filter paper to evaluate fertilizer precipitant formation. Sixteen common fertilizers were analyzed with different rates of Avail. Differences were observed between fertilizer treatments, visually and quantitatively. A secondary P soil movement field study was performed to quantify P concentrations around the SDI emitter. Soils were sampled in a 30.5 cm by 30.5 cm square adjacent to the emitter on a control treatment and a fertilized treatment, in both years of the study. Visual and quantitative differences were observed between the two treatments in both years of the study. When P fertilizers were added to the SDI system, higher P concentrations were found very close to the emitter orifice. Control treatments exhibited lower P concentrations around the emitter than fertilized treatments.

Master of Science / Department of Agricultural Economics / Kevin C. Dhuyvetter / Structural change within the industry, improved management, and volatility in commodity markets are reasons to evaluate and monitor the dairy industry in the future. The dairy industry has shifted concentration of production between regions over time. The Southern High Plains region, including the states of Colorado, Kansas, Oklahoma, New Mexico, and Texas, has undergone cow inventory growth in the past ten years. Dairies have become more concentrated, management has become more refined, and the commodity markets have become more volatile. Education and tools are readily available to producers with issues on reducing production, animal health, and feed losses. Financial risk is a key area producers have limited knowledge and resources. Mitigating this risk is essential in today‟s marketplace to maximize gains and margins as well as create opportunities for the operation to succeed and be financially sound. There are several resources which approximate returns based on either a point in time reference or complete user input. This study allows users to reflect on 21 years of historical data, 1990-2010, as well as plug in their own data or use default market data to estimate projected returns over the next 12 months. This study also builds a modeling framework that will allow historical dairy returns to be estimated and future returns projected on a regular basis. Over time average herd size has grown to reduce cost per head and producers are more efficient, milk production per cow has increased to over 70 pounds per day. Historically prices have increased over time, but the spread between highs and lows has escalated. This model solidifies that milk price and production are key revenue drivers while feed, replacement costs, and labor are large cost components at 39, 17, and 6 percent, respectively. Additionally, changing market prices can intensify the gain or loss an operation will incur over the short term, the projection model shows 2011 just below breakeven due to strong commodity markets. Dairy operations in the Southern High Plains region have shown positive returns in 108 of 252, 43 percent, months with greatest negative annual returns 2006 and 2009.

Master of Science / Department of Civil Engineering / Steven K. Starrett / Current aquaponic technology ranges from backyard hobbyist to technologically advanced commercial production. A single source for protein (fish) and nutrients/vitamins (vegetables), development of a technologically simplified commercial-scale system is a realistic solution for many impoverished nations. This study develops a simplified aquaponic facility to be implemented in rural northern Uganda. Research objectives were to: (1) identify simplified commercial-scale system design components, (2) establish a water quality baseline, (3) identify plant/tilapia production ratios, (4) identify construction materials available in northern Uganda, (5) integrate culturally familiar elements, (6) complete preliminary facility design, and (7) calculate facility water balance. The study established that a viable simplified design achieves: (1) water circulation with weir gravity flow and one return pump, (2) tank cleaning with strategically sloped floors and manual waste siphoning, and (3) breeding control with raised bottom fishnets. Submerged aeration is critical to optimal fish growth, and cannot be eliminated despite surface aeration’s low energy appeal. Baseline water quality parameter values of DO > 3 mg/L, pH > 5.5, and TAN > 3 mg/L (2 mg/L average) were established for the pilot study configuration and hydraulic retention time (HRT). A plant/tilapia ratio of 2.5 ft[superscript]2/lb was identified for the proposed facility’s design. The simplified design was assessed compatible with concrete block construction local to northern Uganda. Incorporating the following culturally familiar elements will facilitate technology adoption: utilize native fish (tilapia) and vegetable crops identified in community markets, replace commercially produced plant tank raft components with woven matting from locally available natural materials, and identify the unfamiliar proposed tank design with newly adopted raceway culture techniques at a well-known Ugandan national fishery institute. A proposed facility preliminary design represents local materials, identified plant/tilapia ratio, minimum HRT, and simplified design components for tilapia densities ranging from 12 to 3 gal/lb. With the facility supplied by both rainwater and groundwater, corresponding water balances for 12 to 3 gal/lb densities ranged from a 9,735 gal/yr well supply demand to a 10,984 gal/yr rainwater surplus.

Doctor of Philosophy / Department of Grain Science and Industry / Sajid Alavi / The Renewable Fuel Standard (RFS) in the Energy Independence and Security Act of 2007 has set the goal of 36 billion gallons of annual ethanol production in the U.S. by 2022, which is equivalent to 17.5% of the current gasoline consumption in the U.S. However, corn ethanol is expected to plateau at a level of 7.3% of current gasoline consumption on an energy-equivalent basis. Thus, it is essential to utilize a variety of substrates including lignocellulosic biomass from perennial energy crops such as switch grass, crop residues such as corn and sorghum stover, and agri-industrial co-products such as soybean hulls and wheat bran. Lignocellulosic substrates have a recalcitrant nature and require a pretreatment step that is critical for efficient enzymatic hydrolysis of cellulose and hemicellulose to fermentable sugars. In this study, soybean hulls were used as a model substrate for cellulosic ethanol. A novel thermo-mechanical pretreatment process using extrusion was investigated and compared with two traditional pretreatment methods, dilute acid and alkali hydrolysis, with regard to structural changes in the lignocellulosic substrate, and glucose and ethanol yields. The effect of extrusion parameters, such as barrel temperature, in-barrel moisture and screw speed, on glucose yield from soybean hulls was determined. Optimum processing conditions were screw speed of 350 rpm, maximum barrel temperature of 80C and 40% in-barrel moisture content, resulting in 95% cellulose conversion to glucose. Compared with untreated soybean hulls, the cellulose to glucose conversion of soybean hulls increased by 69.5, 128.4 and 132.2% for dilute acid, alkali and thermo-mechanical pretreatments, respectively. Glucose and other hexose sugars such as mannose and galactose were effectively fermented by Saccharomyces cerevisiae, resulting in ethanol yields of 13.04–15.44 g/L. Fermentation inhibitors glycerol, furfural, 5-(hydroxymethyl)-2-furaldehyde (HMF) and acetic acid were found in the thermo-mechanically pretreated substrate, ranging in concentrations from 0.072–0.431, 0–0.049, 0–0.023 and 0.181–0.278 g/L, respectively, which were lower than those reported from acid hydrolyzed substrates. The economic feasibility of commercial cellulosic ethanol production processes employing dilute acid hydrolysis and thermo-mechanical pretreatment were compared using a system dynamics modeling approach. It was concluded that low feedstock cost and high sugar conversion are important factors that can make cellulosic ethanol production commercially viable. Thermo-mechanical pretreatment was a more promising technology as compared to dilute acid hydrolysis because of the lower capital and operating costs, and higher sugar conversion.

Master of Science / Department of Agronomy / Johanna Dille / Nitrogen (N) fertilizer intended for the crop may benefit highly competitive weeds to the detriment of the crop. A field experiment was conducted in 2009 to determine the influence of increasing N fertilizer rates and increasing Palmer amaranth densities on weed biomass and grain sorghum biomass and yield. Three rates were 0, 67, and 134 kg N ha-1 and natural populations of Palmer amaranth were thinned to densities of 0, 0.5, 1, 2, 4, and 8 plants m-1 of row. Palmer amaranth biomass increased as weed density and N rates increased. Weed-free grain sorghum yields were similar across all three N rates, and parameter estimates of yield across Palmer amaranth densities were not different between N rates. Based on the parameter estimates from the rectangular hyperbola model, initial slope (I) as density approached zero was 16%. Maximum expected yield loss (A) at high Palmer amaranth densities was 68%. Palmer amaranth showed a high response to N and the higher N rate increased the ability of the weed to reduce grain sorghum yield. A greenhouse experiment was conducted to determine the influence of six N rates on growth of six selected plant species, including grain sorghum, soybean, yellow foxtail, velvetleaf, Palmer amaranth and shattercane. Covariance analysis was performed with N rate as a covariate. Biomass of all species increased as N rate increased in both runs of the study. Soybean responded the least to N rate of all species in regards to biomass, height and leaf area production. In the first run, the biomass of three grass species (grain sorghum, yellow foxtail, shattercane) had similar estimates of slope and intercept of biomass across N rates. In the second run, the biomass slopes of grain sorghum and shattercane differed from soybean and were the only slopes that differed between species. Palmer amaranth had the highest rate of response as N increased but slopes of height were similar for Palmer amaranth, grain sorghum and shattercane. Soybean leaf area slopes were different from grain sorghum, yellow foxtail, and velvetleaf, but all other slopes were not different among species. Addition of N to grain sorghum increased weed growth and resulted in more yield loss as a result of weed density. The greenhouse study demonstrated that grain sorghum and Palmer amaranth increased in response similarly to the addition of N. Alternative N fertilizer management could play a role in minimizing Palmer amaranth impacts in grain sorghum production.

Doctor of Philosophy / Department of Grain Science and Industry / Yong Cheng Shi / This study focused on in-vitro digestibility and pasting properties of cross-linked (CL) starch with different amylose contents and different cross-linking levels, as well as physicochemical properties of extruded wheat flours with different amylose contents and functionality of amylopectin and cross-linking in improving the textural and physical properties of oat flour extrudates. Starch was CL by phosphorylation using a mixture of sodium trimetaphosphate and sodium tripolyphosphate at the ratio of 99:1 under alkaline condition. The digestibility of highly CL maize starches with different amylose contents was determined by Englyst, Available Carbohydrate Dietary Fiber and Association of Official Analytical Chemists (AOAC) Method 991.43 methods. CL waxy and normal maize starch granules swelled much more at higher temperatures, resulting in significantly lower total dietary fiber content than high-amylose maize starch. The alkali treatment study on low levels of cross-linking in starch affected the ratios of total bound phosphate esters which changed the degree of starch swelling, crytallinity and pasting properties of the CL starch. The study on the mechanism of the digestive enzymes and the extent of digestion during the incubation of CL wheat starch in AOAC Method 2009.01 showed progressive digestion after 16 h of incubation, which may not reflect in-vivo response in human. Extrusion of normal and waxy wheat flours resulted in the breakdown of starch and an increase in the insoluble protein, which affected the textural and structural properties of extrudate. High energy input played a major role in radial expansion of normal hard wheat extrudate, whereas higher amylopectin in soft waxy wheat flour was a dominant factor in determining the radial expansion when compared to normal soft wheat. Inclusion of soft waxy wheat in the oat flour formulations at 18% moisture content improved the textural and structural properties of extrudates. Low cross-linking level of CL waxy maize starch in oat flour formulation increased the void fraction and reduced the breaking strength of extrudates, whereas higher cross-linking levels of CL starches improved the resistant starch level on oat flour formulation but had very poor structural and textural properties.The study offers a good insight on the properties and digestibility of CL starch, as well as using low levels of CL starch to improve textural properties of nutritional extruded products. In addition, study on the extrusion of wheat flours with different amylose and protein contents provides knowledge on the influence of chemical compositions and energy input on the physico-chemical properties of extrudates.

Doctor of Philosophy / Department of Biological and Agricultural Engineering / Donghai Wang / Sorghum distillers dried grains with solubles (DDGS), canola and camelina meals are the main co-products resulting from grain-based ethanol or oil production. The main objective of this research was to study physicochemical properties of proteins isolated from DDGS, canola and camelina meals and their adhesion performance. Acetic acid-extracted sorghum protein (PI) from DDGS had superior adhesion performance in terms of dry, wet and soak adhesion strength compared to acetic acid-extracted sorghum protein (PF) from sorghum flour and aqueous ethanol-extracted sorghum protein (PII) from DDGS. PI had a significantly higher wet strength (3.15 MPa) than PII (2.17 MPa), PF (2.59 MPa), and soy protein without modification (1.63 MPa). The high content of hydrophobic amino acids in PI (57%) was likely the key factor responsible for high water resistance. Canola protein was extracted from canola meal and modified with different concentrations of NaHSO3 (0 to 15 g/L) during protein isolation. Unmodified canola protein showed the highest wet shear strength of 3.97 MPa cured at 190 °C. Adhesion strength of canola protein fractions extracted at pH 5.5 and pH 3.5 (3.9-4.1 MPa) was higher than the fraction extracted at pH 7.0. NaHSO3 slightly weakened adhesion performance of canola protein; however, it improved handling and flow-ability due to breaking of disulfide bonds in proteins. Albumin, globulin, and glutelins were isolated from camelina meal. Adhesion performance of globulin fraction behaved better than glutelin fraction. The greatest wet shear strength of globulin was 3.3 MPa at curing a temperature of 190 °C. Glutelin had a more protein aggregation compared with globulin, as indicated by higher crystallinity and thermal stability, and dense protein aggregate. This compact structure of glutelins may partially contribute to lower adhesion strength as compared to globulin.