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.

Master of Science / Department of Grain Science and Industry / Subramanyam Bhadriraju / During heat treatment, the ambient temperature of grain-processing facilities is raised to 50-60°C for at least 24 hours to manage stored-product insects. Young larvae (first instars) of the red flour beetle, Tribolium castaneum (Herbst), are the most heat tolerant stage at 50-60°C. A thermal death kinetic (TDK) model predicted survival of T. castaneum young larvae exposed to six constant elevated temperatures between 42 and 60ºC. The model is based on logarithmic survival of T. castaneum as a function of time and logarithmic reduction in larval survival as a function of temperature. The model was validated with 12 independent temperature datasets collected during heat treatments of pilot-scale and commercial grain-processing facilities. Young larval survival in plastic boxes/vials with flour was used to validate model predictions. The heating rate to 50°C from the ambient among the 12 datasets ranged from 0.9-7.8°C/h. Mean absolute deviations between observed and predicted larval survival for 10 of the 12 datasets ranged from 2.1-11.4%; it was 16.2 and 18.3% for two other datasets. The TDK model can be used to predict survival of young larvae of T. castaneum based on time-dependent temperature profile obtained at any given location during heat treatment of grain-processing facilities. In three commercial grain-processing facilities heat treatments were conducted for 24-27.7 hours using forced-air gas heaters. Temperatures attained and survival of 20 eggs, 20 young larvae, and 20 adults of T. castaneum in bioassay vials at various locations were determined. Across all three facilities, 5 out of 2720 adults in 136 vials, 1 out of 960 young larvae in 48 vials, and 0 out of 1760 eggs in 88 vials were alive at the end of the heat treatment. In each facility, the time in hours for 1% predicted survival of T. castaneum young larvae was positively related to how quickly temperatures reached 50°C, and negatively related to rate of heating to 50°C from the ambient, time above 50°C in hours, and the maximum temperature. Bioassays with T. castaneum life stages and the TDK model can be used to gauge effectiveness of facility heat treatments.

Master of Science / Department of Grain Science and Industry / Bhadriraju Subramanyam / A synthetic zeolite (Odor-Z-Way, sodium aluminum silicate) used for odor adsorption was tested for its ability to control adults of stored-grain insects on wheat and on concrete petri dishes used to simulate floors of empty bins. Insect species tested included unsexed adults of the lesser grain borer, Rhyzopertha dominica (F.); rice weevil, Sitophilus oryzae (L.); maize weevil, Sitophilus zeamais (Motschuslky); red flour beetle, Tribolium castaneum (Herbst), and sawtoothed grain beetle, Oryzaephilus surinamensis (L.). Two formulations were evaluated under laboratory conditions (28±1⁰C and 65±1% r.h.): coarse zeolite (with 90% of particles having a mean diameter at or below 155 µm) and fine zeolite (with 90% of particles having a mean diameter at or below 47.0 µm). On concrete, arenas in 9-cm diameter Petri dishes were sprinkled with the synthetic zeolite to provide deposits of 0 (control), 5 and 10 g/m[superscript]2. Mortality was assessed at times ranging from 10 minutes to 24 hours followed by 48 hours recovery on wheat. Mortality in adults of the five species increased as the rate of application and the duration of exposure increased. Concrete Petri dishes sprinkled with the fine zeolite yielded percent mortality greater or equal to that observed with the coarse zeolite- sprinkled Petri dishes. Bioassays on wheat were conducted using two dosage rates: 0.1 to 3.0 g/kg for R. dominica and 0.05 to 1.0 g/kg for the other insect species. Mortality was assessed 7 days post- infestation. A concentration of 0.75 g/kg of fine or coarse zeolite achieved 100% mortality in adults of S. zeamais, T. castaneum, and O. surinamensis. All adults of S. oryzae were killed using 0.50 g/kg of coarse or fine zeolite. Adults of R. dominica were the least susceptible: 2.50 g/kg of fine zeolite and 3.0 g/kg of coarse zeolite were required for 100% mortality. Mortality generally increased with the concentration of zeolite applied on wheat. Efficacy was not related to particle size. This is the first study showing the efficacy of a synthetic zeolite against adults of five species of stored-product insects on concrete and wheat. Synthetic zeolites can be a suitable alternative to currently used pesticides for treatment of empty bin floors and stored wheat for insect control.

Doctor of Philosophy / Department of Grain Science and Industry / Praveen V. Vadlani / Lactic acid is an important platform chemical that has long history and wide applications in food, polymer, pharmaceutics and cosmetic industries. Lactic acid has two optical isomers; namely D-lactic acid and L-lactic acid. Racemic mixture of lactic acid are usually used as preservatives and ingredients in solvents, or as precursors for different chemicals. Currently there is an increasing demand of optical pure lactic acid as a feedstock for the production of poly-lactic acid (PLA). PLA is a biodegradable, biocompatible and environmental friendly alternative to plastics derived from petroleum based chemicals. Optically pure D or L-lactic acid is used for the synthesis of poly D or L- lactic acid (PDLA, PLLA). Blend of PDLA with PLLA results in a heat-resistant stereocomplex PLA with excellent properties. As a consequence, large quantity of cost effective D-lactic acid is required to meet the demand of stereocomplex PLA. Lignocellulosic biomass is a promising feedstock for lactic acid production because of its availability, sustainability and cost effectiveness compared to refined sugars and cereal grain-based sugars. Commercial use of lignocellulosic biomass for economic production of lactic acid requires microorganisms that are capable of using all sugars derived from lignocellulosic biomass. Therefore, the objectives of this study were: 1) to produce high level of optically pure D-lactic acid from lignocellulosic biomass-derived sugars using a homofermentative strain L. delbrueckii via simultaneous saccharification and fermentation (SSF); 2) to develop a co-culture fermentation system to produce lactic acid from both pentose and hexose sugars derived from lignocellulosic biomass; 3) to produce D-lactic acid by genetically engineered L. plantarum NCIMB 8826 ∆ldhL1 and its derivatives; 4) to construct recombinant L. plantarum by introduction of a plasmid (pLEM415-xylAB) used for xylose assimilation and evaluate its ability to produce D-lactic acid from biomass sugars; and 5) to perform metabolic flux analysis of carbon flow in Lactobacillus strains used in our study. Our results showed that D-lactic acid yield from alkali-treated corn stover by L. delbrueckii and L. plantarum NCIMB 8826 ∆ldhL1 via SSF were 0.50 g g[superscript]-1 and 0.53 g g[superscript]-1 respectively; however, these two D-lactic acid producing strains cannot use xylose from hemicellulose. Complete sugar utilization was achieved by co-cultivation of L. plantarum ATCC 21028 and L. brevis ATCC 367, and lactic acid yield increased to 0.78 g g[superscript]-1 from alkali-treated corn stover, but this co-cultivation system produced racemic mixture of D and L lactic acid. Simultaneous utilization of hexose and pentose sugars derived from biomass was achieved by introduction of two plasmids pCU-PxylAB and pLEM415-xylAB carrying xylose assimilation genes into L. plantarum NCIMB 8826 ∆ldhL1, respectively; the resulting recombinant strains ∆ldhL1-pCU-PxylAB and ∆ldhL1-pLEM415-xylAB used xylose and glucose simultaneously and produced high yield of optically pure D-lactic acid. Metabolic flux analysis verified the pathways used in these Lactobacillus strains and provided critical information to judiciously select the desired Lactobacillus strain to produce lactic acid catering to the composition of raw material and the optical purity requirement. This innovative study demonstrated strategies for low-cost biotechnological production of tailor-made lactic acid from specific lignocellulosic biomass, and thereby provides a foundational manufacturing route for a flexible and sustainable biorefinery to cater to the fuel and chemical industry.