Master of Science / Department of Agronomy / Johnathon D. Holman / Kraig L. Roozeboom / Replacing fallow periods with cover crops can provide many benefits including soil quality improvements and reduced nitrogen fertilizer requirements. Field experiments were established near Garden City, KS with winter wheat and fallow phases as main plots, thirteen legume or non-legume cover crops, continuous winter wheat, and fallow as subplots, and cover crop termination method as sub-subplots. Treatments containing triticale had greatest water use efficiency (19.9 kg ha[superscript]-1 mm[superscript]-1) and aboveground biomass (3550 kg ha[superscript]-1), but subsequent winter wheat yields were reduced due to a reduction in volumetric water content. Increased soil residue through greater cover crop biomass resulted in increased precipitation storage efficiency during the fallow period, but water requirements to produce biomass depleted soil moisture more than growing a low biomass crop or fallow. In years of above-average precipitation, low biomass cover crops might be grown with little to no negative effect on subsequent wheat yields. A second field experiment was established near Manhattan, KS with fallow, double crop soybean, and four cover crop treatments planted after wheat harvest in a winter wheat-grain sorghum-soybean no-till cropping system, with five nitrogen treatments applied to the sorghum crop to estimate nitrogen contribution of the cover crops. Greatest above ground biomass production and nitrogen accumulation was observed with sorghum-sudan grass. At the 0 kg ha[superscript]-1 N rate, grain sorghum yields were reduced 1200 kg ha[superscript]-1 following sorghum-sudan grass, while all other cover crop treatments provided a 20-30 kg ha[superscript]-1 N equivalent benefit. Sorghum yields might be reduced following large biomass producing cover crops when nitrogen is limiting, but a small nitrogen benefit might be realized following low C:N ratio cover crops. Cover crop productivity and their subsequent effects on grain sorghum performance were evaluated in field studies established near Manhattan and Hutchinson, KS in 2008 and 2009. Sixteen summer or fall cover crop species were planted in no-tillage winter wheat stubble and evaluated for biomass production, nitrogen concentration, and nitrogen accumulation. Summer annual grass species produced the greatest biomass, 3392 kg ha[superscript]-1 and greater, and legume species accumulated the greatest amounts of nitrogen, averaging 43 kg ha[superscript]-1. Grain sorghum yields were 867 kg ha[superscript]-1 greater following summer cover crops compared to fall cover crops. Cover crops had a significant effect on sorghum performance, with yields 1240 kg ha[superscript]-1 greater following legume cover crops.

Master of Science / Department of Agronomy / Johanna A. Dille / No-till producers can manage weeds by including cover crops during the fallow phase as part of an integrated weed management plan. Field experiments were conducted between 2007 and 2009 to quantify the influence of cover crops on weed emergence, biomass accumulation, and seed production. Field experiments were established near Garden City, KS with winter wheat or fallow as main plots and cover crop treatments as subplots including five spring- and five fall-sown individual or mixtures of crop species and a no-cover chemical fallow. Separate1-m2 quadrats were seeded with kochia or downy brome at 500 seed/m2. Kochia density was reduced by 75% and biomass reduced by 88% in fall-sown cover crops compared to chemical fallow across growing seasons. Spring-sown cover crop mixtures reduced kochia biomass in 2009 when kochia emergence was delayed. Downy brome biomass decreased exponentially as cover crop biomass increased. A second field experiment was established near Manhattan, KS with soybean, winter wheat, or grain sorghum phases of the rotation as main plots and six cover crop treatments as subplots sown after winter wheat harvest. Paired Palmer amaranth 1-m2 quadrats were seeded with 500 seed/m2 in each cover crop subplot. One quadrat was protected from any herbicide application made to the cover crop or to the grain sorghum. Combining burndown application with high biomass-producing cover crops reduced Palmer amaranth emergence and biomass. Influence of cover crop presence reduced early season Palmer amaranth emergence in the subsequent grain sorghum phase. Optimal seeding rate of forage soybean sown in winter wheat stubble and its impact on Palmer amaranth and downy brome emergence and growth were evaluated in field studies established near Manhattan and Hesston, KS in 2008 and 2009. Soybean was no-till drilled after wheat harvest at five rates ranging from 100,000 to 600,000 seeds/ha. A no-cover chemical fallow treatment was included. Separate 0.5-m2 quadrats were seeded with Palmer amaranth at 100 seed/0.5 m2 or with downy brome at 250 seed/0.5 m2. Three termination methods evaluated were killing frost, glyphosate application, or crop rolling. Palmer amaranth density was not affected by treatments but biomass decreased as soybean seeding rate and crop biomass increased. Downy brome emergence was less with rolled or sprayed termination methods in one site year as timing of termination was optimal. High biomass producing cover crops sown during the fallow phase of a crop rotation reduced weed emergence, density, and biomass accumulation. Cover crops can be part of an integrated weed management plan in Kansas.

Master of Science / Department of Agronomy / Scott A. Staggenborg / With the increase in bio-energy production there is also an increase in by-products. Without proper disposal, these by-products might cause future economic and/or ecological problems. Land application has potential as a disposal and/or nutrient cycling method if these by-products have nutritive value for agricultural crops. The purpose of the study was to compare the use of two by-products of bio-energy production, dry distillers grains (ethanol) and charcoal(pyrolysis), as fertilizer with urea in corn (Zea mays L.). The experiment consisted of four location-years in Kansas. Treatments were dry distiller’s grains (DDG) no-till and tilled for four location-years and char no-till and tilled for three location-years. No-till urea was used as a baseline for comparison at all location-years. The Nitrogen rates ranged from 45 to 180 kg N ha-1. All source material was spring applied before tillage and planting. The corn yields for DDGs and urea were the almost the same across tillage treatments and locations. For DDG no-till, DDG tilled, and urea, the rates at which to achieve the same yields were 97, 111, 78 kg N ha-1, respectively. Corn yields for char at all rates and tillage treatments were the same as no fertilizer. The char, because of immobilization or lack of decomposition, did not contribute to the nitrogen needs of the corn. Neither material showed any inhibitory or otherwise negative effects on the corn in terms of grain yield compared with the control. But both DDGs and char had to have large amounts of material applied to achieve the same amount of nitrogen as urea. Land application of DDGs and char has potential merit for disposal/nitrogen cycling with DDGs being preferred for its nitrogen contribution.

Master of Science / Department of Agronomy / William T. Schapaugh Jr / Fusarium virguliforme, the soilborne fungus which causes sudden death syndrome (SDS) of soybean, and Heterodera glycines Ichinohe, soybean cyst nematode (SCN), are two economically important pathogens in the Midwest. The pathogens are often found together in soybean (Glycine max (L.) Merr.) fields. This study was conducted to determine the effect of soybean genotype, F. virguliforme populations, and H. glycines populations have upon yield and to examine the interaction between the two pathogens. In 2008 and 2009, four genotypes with different levels of resistance to SDS and H. glycines were planted at seven environments. F. virguliforme and H. glycines soil populations were quantified at planting, midseason, and harvest. At the end of the growing season, area under the disease progress curves of SDS, F. virguliforme root populations, and H. glycines reproductive indices were determined and plots harvested for seed yield. Soil populations of F. virguliforme and H. glycines at planting, midseason, and harvest varied across environments. Within environments, generally, they were not significantly different. Seed yield varied within and across environments. As disease pressure increased, the performance of resistant genotypes increased compared to susceptible genotypes. Genotypes resistant to SDS yielded higher than susceptible genotypes. There were negative correlations between yield and disease rating and F. virguliforme root populations. F. virguliforme soil populations and H. glycines populations at planting were positively correlated. It is important to manage both SDS and H. glycines in fields with a history of the two diseases. This can be achieved through genetic resistance. Information in this study will improve decisions regarding genotype selection to minimize losses to SDS and H. glycines.

Master of Science / Department of Grain Science and Industry / Hulya Dogan / Kansas is the top wheat-producing state, providing about 1/5 of the yearly wheat crop in the U.S. Therefore, the quality of wheat grown in Kansas is a primary concern of the milling and baking industry. Quality of wheat flour is measured through analysis of protein, dough rheology, and baked product characteristics. This study characterized four commonly-grown Kansas hard red winter wheat cultivars chosen to span the largest possible range of protein contents and baking qualities. Flour protein content and moisture was determined by NIR, and composition was assessed using SE-HPLC. Dough empirical rheological and mixing characteristics were determined by farinograph and mixograph recording dough mixers. Rheological measurements of fundamental dough properties were performed through strain sweeps, frequency sweeps, temperature sweeps, creep-relaxation, and stress relaxation on a rheometer. All cultivar flours were baked to assess baking quality through evaluation of loaf volume, texture profile analysis (TPA), C-cell, and x-ray microtomography (XMT). Overley and Karl 92 have the two highest protein contents, respectively, and are not significantly different in percent of unextractable polymeric protein (UPP). Generally, cultivars with higher protein and percent UPP (Overley and Karl 92) gave larger loaves, much more expanded air cells, thinner cell walls, greater void fractions, and better mixing properties. Lower TPA firmness was found for Overley, corresponding with its larger XMT fragmentation index, existence of large air cells, and high void fraction. In contrast, 2137 gave the lowest XMT fragmentation index, low void fraction, larger cell wall thicknesses, and a significantly firmer (P< 0.05) crumb structure. Protein content was found to have an inverse relationship with the elastic nature of dough in fundamental rheological measurements since small amplitude measurements generally do not give good correlations to baking quality. Stress relaxation gave the most useful information about flour quality through its relaxation spectra. Flours with high total polymeric protein percentages could be identified through their higher relaxation spectra. Starch gelatinization properties of the flours were different for RVA and rheometer temperature sweeps. All of these tests have helped characterize the four Kansas wheat cultivars chosen for this study.

Master of Science / Department of Agronomy / Nathan O. Nelson / Phosphorus (P), an essential nutrient for plant growth and animal needs, has been identified as an ubiquitous water quality impairment in the United States. In Kansas, a major agricultural state, P loading to the surface waters is a top priority because of the critical role of P enrichment in eutrophication processes and resultant water quality degradation. The objective of this study was to quantify the P sorption and desorption of both stream sediments and upland soils in two Kansas watersheds with contrasting degrees of animal agriculture; Upper West Emma Creek (UWEC) and Red Rock Creek (RRC) watersheds. In-stream sediments were collected from banks, pools, riffles and depositional features. Soils were sampled from wheat, row crop, pasture, and manure-amended fields. Stream water samples were taken under baseflow and storm flow conditions. Our analyses of sediments and soils included equilibrium P concentration at zero net P sorption (EPC[subscript]0), maximum adsorption capacity (P[subscript]max), anion exchange extractable P (P[subscript]lab) and degree of P saturation (DPS). Water samples were analyzed for dissolved reactive phosphorous (DRP). Bank erosion pins were installed in order to estimate bank erosion rates in both watersheds. Results showed that in-stream sediments do not have much more sorption capacity remaining indicated by low P[subscript]max and high DPS. A comparison between mean P[subscript]lab of stream sediments (8.8 mg P kg[superscript]-1 soil) versus field soils (61.2 mg P kg[superscript]-1 soil) reflected that they represent a relatively minor long-term P supply. Of the stream sediments, bank soils had the highest Plab concentrations (24.8 mg P kg[superscript]-1 soil) and would be the largest in-stream P source. Manure-amended fields had the highest Plab (118.6 mg P kg[superscript]-1 soil) due to continued inputs of manure-based P; therefore, representing a large available P pool. Bank erosion contributed about 41% and 11% of the total sediment load in UWEC and RRC respectively. Sediments loads indicated that RRC has more upland sediment inputs than UWEC. Moreover, DRP during storm flow was higher at RRC than UWEC, indicating higher P inputs in RRC from upland soils. Finally, in order to minimize P inputs to the stream system, bank stabilization should be addressed in UWEC and upland best management practices should be implemented in RRC.

Master of Science / Department of Agronomy / Allan K. Fritz / Fusarium head blight (FHB), caused by Fusarium graminearum, is an important cereal disease in humid and semi-humid wheat growing regions. In recent FHB epidemics in the USA, FHB dramatically reduced wheat yields and grain quality due to mycotoxin contamination. Five types of FHB resistance have been reported, but resistance to disease spread within a spike (Type II) and low deoxynivalenol (DON) accumulation in infected kernels (Type III) have drawn the most attention. A Chinese Spring-Sumai3 chromosome 7A substitution line (CS-SM3-7ADSL) was reported to have a high level of Type II resistance, but quantitative trait locus (QTL) on chromosome 7A has never been mapped. To characterize QTL on chromosome 7A, we developed 191 Chinese Spring-Sumai3-7A chromosome recombinant inbred lines (CRIL) from a cross between Chinese Spring and CS-SM3-7ADSL and evaluated the CRIL in a greenhouse for both types of resistance in three experiments. Two major QTL with Sumai 3 (SM3) origin, conditioning Type II and Type III resistance were mapped in chromosomes 3BS and 7AC. QTL on chromosome 3BS corresponds to Fhb1, previously reported from SM3, whereas 7AC QTL, designated as Fhb5, is a novel QTL identified from SM3 in this study. Fhb5 explains 22% phenotypic variation for Type II resistance and 24% for Type III resistance. Marker Xwmc17 is the closest marker to Fhb5 for both types of resistance. Fhb1 and Fhb5 were additive and together explained 56% variation for Type II and 41% for Type III resistance and resulted in 66% reduction in FHB severity and 84% in DON content. Both QTL showed significant pleiotropy effects on Type II and Type III resistance, suggesting both types of resistance may be controlled by the same gene(s). Haplotype analysis of SM3’s parents revealed that Fhb5 originated from Funo, an Italian cultivar. A survey of worldwide germplasm collection of 400 accessions showed that Fhb5 is present mainly in Chinese cultivars, especially in Funo-related accessions. Further, Fhb5 is the second major QTL from SM3 and have potential to be used in improving wheat cultivars for both types of resistance.

Doctor of Philosophy / Department of Agronomy / Dorivar Ruiz Diaz / Winter annual weeds (WAW) could affect nitrogen supply for corn production. The objectives of first study were to determine the diversity and abundance of WAW and to evaluate the effect of delaying herbicide applications on nitrogen supply and no-till corn response. Research was conducted in 2010 and 2011 at 14 sites in eastern Kansas. A factorial arrangement of three herbicide application dates (Nov.-Mar., April, and May) and five N rates were used. The three most abundant WAW across sites were henbit, purslane speedwell, and horseweed. Delaying herbicide application until April significantly reduced early corn N uptake by 52 mg N plant-1, chlorophyll meter readings at silking by 3.4%, and grain yield by 0.48 Mg ha-1 across sites. An additional 16 to 17 kg N ha-1 was needed to maintain yield if herbicide application was delayed until April. Starter and foliar micronutrient fertilization can potentially increase corn and soybean yield. The objectives of the second study were to evaluate crop response from combinations of starter and foliar fertilizers that contain N-P-K mixtures with and without a blend of micronutrients at four sites for each crop under irrigated conditions. No early corn growth or yield increase was attributed to application of micronutrients (Fe, Mn, Zn, Cu, and B) beyond what was achieved with N-P-K starter fertilization. There was an increase in soybean height (8 cm) and yield (293 kg ha-1) with starter fertilizer containing N-P-K plus micronutrients over the control. No increase in corn or soybean yield was obtained with foliar fertilization. The objective of the third study was to compare soil mobility and changes in soybean nutrient concentration in the leaf and seed from Mn and Zn sources (EDTA and oxysulfate) at two sites. Zinc sources were more mobile in the soil. Both Zn sources increased seed Zn concentration. Manganese oxysulfate increased seed Mn concentration. However, soybean trifoliolate leaf and seed Mn concentration decreased with soil-applied Na2EDTA and MnEDTA. This response was attributed to formation of FeEDTA and increased Fe supply that reduced root Mn absorption. Manganese EDTA is not recommended for soil application.

Master of Science / Department of Horticulture, Forestry, and Recreation Resources / Charles Barden / Riparian forests are more effective than other land cover types at stabilizing stream banks during high water events. Tree trunks and roots can slow flood-waters, thus retaining sediment deposition within riparian areas instead of downstream in reservoirs. This project is part of a larger, multi-agency study on reducing sedimentation of federal reservoirs. Between August 2010 and May 2012, riparian forests were assessed in the watersheds of three northeast Kansas lakes: Atchison County, Banner Creek, and Centralia City. The predominant land use in those watersheds is agricultural, with Atchison and Centralia watersheds dominated by cropland and Banner dominated by grassland. Plot dimensions were 50ft by 30ft (1500 ft[superscript]2) measured from the top of the streambank outward to the extent of the predetermined active channel width (ACW). Forty-four plots were assessed across the three watersheds. Data collected in each plot were used to determine the basal area (BA) in ft[superscript]2 per acre, trees per acre (TPA), tree height by crown class, and quadratic mean diameter (QMD) by species. Results showed some trends in BA and TPA among the three watersheds, however differences were not significant. The average BA of trees in riparian woodlands in the Centralia watershed was 155 ft[superscript]2 (dominated by cottonwood (Populus deltoides) with some honeylocust (Gleditsia triacanthos)); the Atchison and Banner watersheds showed an average BA of 120 ft[superscript]2. The Atchison watershed was dominated by honeylocust and walnut (Juglans nigra) but the Banner watershed was dominated by bur oak (Quercus macrocarpa) and hackberry (Celtis occidentalis). However, the Atchison watershed had the most TPA (194), as well as the tallest trees of the three watersheds. The Atchison watershed had the highest QMD in oak, whereas the Banner and Centralia watersheds had the highest QMD in cottonwood. Banner watershed had more plots with seedlings, whereas Atchison watershed had more plots with saplings. Overall, forest regeneration primarily comprised hackberry seedlings and saplings, with hickory saplings more common in the Banner watershed. For each watershed, the composition and structure of riparian vegetation differed but not significantly.

Master of Science / Department of Agronomy / Rob M. Aiken / Mary Beth Kirkham / Prior studies indicate clumped planting can increase grain sorghum yield up to 45% under water deficit conditions by reducing tiller number, increasing radiation use efficiency, and preserving soil water for grain fill. The objective of this study was to evaluate effects of planting geometry on sorghum grain yield. The field study was conducted in seven environments with two sorghum hybrids, four populations, and two planting geometries. Crop responses included leaf area index, yield, and components of yield. Delayed planting decreased yield by 39%, and a later maturing hybrid increased yield, relative to an early hybrid, by 11% under water sufficiency. Clumped planting increased the fraction of fertile culms (culms which formed panicles) from 5-14%. It reduced the number of culms m-2 by 12% under water limiting conditions (at one of two locations) but increased culms m-2 16% under water sufficiency. Seeds per panicle and seed weight generally compensated for differences in panicles m-2, which were related to different planting population densities. Although agronomic characteristics of hybrids varying in maturity have been widely studied, little information exists concerning their physiological differences. Therefore, the objective of the greenhouse study was to determine if stomatal resistance, leaf temperature, and leaf chlorophyll content differed between two DeKalb grain sorghum [Sorghum bicolor (L.) Moench] hybrids. They were DKS 36-16 and DKS 44-20, of medium-early and medium maturity, respectively, when grown under field conditions in Kansas. Seeds were planted in a greenhouse. Stomatal resistance and leaf temperature were measured 55 days after planting with a Decagon Devices (Pullman, WA) diffusion porometer, and chlorophyll content was measured 119 days after planting with a Konica Minolta (Osaka, Japan) SPAD chlorophyll meter. The two hybrids did not differ in stomatal resistance, leaf temperature, chlorophyll content, height, and dry weight. Their difference in maturity was not evident under the greenhouse conditions. Future work needs to show if hybrids of different maturities vary in physiological characteristics