Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 23-24).

Thesis (M.S.)--University of Tennessee, Knoxville, 2010. / Title from title page screen (viewed on July 23, 2010). Thesis advisor: Kimberly L. Jensen. Vita. Includes bibliographical references.

Thesis (M.S.)--University of Tennessee, Knoxville, 2009. / Title from title page screen (viewed on Nov. 5, 2009). Thesis advisor: James A. Larson. Vita. Includes bibliographical references.

The universal adoption of biomass materials as an alternate fuel source to fossil fuels for transportation and electricity has been hindered by the high transportation costs involved in fuel production. Optimization of these initial costs will make the eco-friendly fuels more economically viable. Biomass is a promising feedstock for biofuels primarily because it is a renewable and sustainable resource. Among the most studied grassland crops, switchgrass is a perennial warm-season grass and has been identified as a potential energy crop. This research focuses on evaluating various physical parameters which affect the economic feasibility of packaging and transporting switchgrass from the field to the biorefinery. The switchgrass was harvested using a mower conditioner followed by field chopping after varying drying periods. The first harvesting period spanned from early November to mid December 2007 and the second was August to October 2008. Densification properties of chopped switchgrass were studied under compression. The effects of compressive stresses (41 to 101 kPa), number of strokes (1 to 10), moisture content (9 to 62 percent) and chopping length (63 and 95 mm) on the densification of chopped switchgrass were studied. The final dry matter density (DMD) increased with the compressive stresses and the number of strokes, small chop length and low moisture content. The maximum free-standing DMD obtained was 245 kg/m^3.

Growing interest in biomass crops for energy production has focused attention on Panicum virgatum L. (switchgrass) as a promising perennial feedstock native to much of North America. Switchgrass may be processed into products such as pulp and paper, ethanol, and fuel pellets. A robust C4 grass, switchgrass typically produces 10-12 dry tonnes/ha on agricultural soils in average growing conditions; this study shows that reduced but substantive yields are also possible on soils rendered unsuitable for food crop production by lead contamination over the acceptable level of 70 ppm. Switchgrass offers not only tolerance to lead in the soil environment, but also the potential for extraction of lead contaminants. Integrating the growth of switchgrass for biomass with phytoremediation could provide greater opportunity for biomass production, while eventually increasing the suitability of such lands for agricultural production. This study examines the potential for using switchgrass to remove lead from the soil and to translocate the contaminant to the leafy portions of the plant, where it could be removed from the site through biomass harvest. Roots of plants treated with 6000 and 10000 ppm lead solution from the time of seeding displayed some morphological changes and growth inhibition, yet, produced biomass comparable to expected yields and removed up to 0.1% of the applied lead solution. Established switchgrass displayed few morphological changes and no significant loss of biomass when treated with lead acetate solution while extracting lead into harvestable tissues. As the primary root is the organ through which water, solutes and heavy metals pass into the plant, the dense, fibrous root system of switchgrass may aid in the ability of this plant to extract contaminants from soil without significantly hindering above ground biomass production. Switchgrass grown on brownfield soil, with contamination levels of up to 23600 ppm translocated lead into harvestable tissues without significant changes in biomass production or growth characteristics. However, symptoms of phytotoxicity were observed in switchgrass grown on soil containing 36100 ppm lead. Atomic absorption spectrometry and inductively coupled plasma analyses indicate that lead accumulation in harvestable tissues of switchgrass occurs at rates comparable to those in previous studies. The presence of dark staining deposits, detected by light microscopy in the root and shoot tissue of switchgrass treated with high concentrations of applied lead (13800, 10000), suggests an adaptive response within the plant. Successful integration of phytoremediation with growth of biomass crops such as switchgrass may provide effective reclamation of contaminated soils, while contributing to a sustainable energy economy. / Thesis (Master, Biology) -- Queen's University, 2007-08-02 11:34:42.469

Thesis--Auburn University, 2009. / Abstract. Vita. Includes bibliographical references (p. 29-30).

Digitized by Kansas State University Libraries

Master of Science / Department of Agronomy / Humberto Blanco / The use of renewable feedstocks to produce cellulosic ethanol is quickly becoming a reality as facilities to produce cellulosic ethanol are scheduled to open in the upcoming years. Initial feedstocks for these facilities are thought to be crop residues such as corn (Zea mays L.) and wheat (Triticum aestivum L.) residues. However, additional feedstocks, such as perennial warm-season grasses (WSG), maybe needed to meet the demands of these bioenergy facilities. Thus, the development of regional dedicated energy crop systems is a high priority. Our objectives were to: a) assess the impacts of growing WSG on water storage, soil physical and hydraulic properties, soil organic carbon (SOC) dynamics, and water and wind erosion as compared with row crops, b) assess the impacts of growing WSG on biomass and forage production and quality and c) determine the most adaptable WSG species to dryland conditions. A number of dedicated energy crops and their performance across three different moisture regimes in Kansas were studied. Biomass yield, soil physical and hydraulic properties, and soil water and wind erosion parameters were measured between August 2010 and August 2012. Additionally, forage quality under two cutting systems (biofuel and forage) and two harvest heights (0.1 m and 0.2 m) and water infiltration was determined in 2011. Differences in bulk density, water retention, infiltration and SOC were found to be minimal. However, differences in wind and water erosion parameters indicate that WSG can protect soil from erosion. Furthermore, soil water data indicate that WSG are better suited to use early season moisture to accumulate biomass than annual row crops. Yield results indicate that a two cut hay system with a 0.1 m cutting height can produce more biomass compared with a one cut biofuel system. Additionally, the hay system improved forage quality parameters. Data collected from this project provided insights into the viability of growing various dedicated energy crops across the region during the first five years of production.

The benefits from energy crops are debated. This two-year study was designed to investigate nitrous oxide (N2O) emissions, yield and ash content from fertilized bioenergy crops switchgrass and reed canary grass with and without inter-seeded red clover. Overall, N2O emissions were less than 1kg N2O-N ha-1 in the first year and around 100g N2O-N ha-1 in the second year with a N fertilizer effect in the first year. Plots inter-seeded with red clover received half the N fertilizer of pure grass stands but showed no difference in N2O emissions compared to the pure stands and also had higher ash content. Cumulative soil mineral N responded to N fertilizer addition but no effect of crop type was evident in 2008 and 2009. Yields for both crops were unresponsive to N fertilizer addition while pure switchgrass yielded higher than inter-seeded switchgrass in 2008 and switchgrass had lower ash content.

Thesis (M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references (p.101-109).