The goal of this research was to determine the interactions between forage and tree components of a silvopasture system. Two studies were performed on adjacent sites established in 1995 at Virginia Tech's Kentland Research Farm. The objectives of the studies were to: 1. Determine the influence of honey locust and black walnut silvopastures on indicators of soil quality when compared to open pasture. 2. Determine if silvopasture systems changed forage mass production and soil water compared to open pastures. The study on soil quality indicators was performed in a previously grazed silvopasture. Samples were collected from the upper 15 cm of soil at three distances from the tree rows. Total N (p= 0.0219), total C (p= 0.0216), extractable P (p= 0.063), extractable K (p= 0.0347) and microbial organic C (p= 0.0255) were greater in honey locust silvopastures. The highest concentration of soil nutrients and best soil physical and chemical properties were observed 1.5 m from the tree stem. Forage growth and soil water were measured in silvopastures in 2006 and 2007. In 2006 there was higher forage growth in the black walnut and honey locust than beneath 70% shade cloth. In 2007, with a 50% shade cloth, forage growth was similar in all treatments. Initial soil water content was highest under shade cloth in 2006. In 2007 the rate of soil drying was lowest beneath the shade cloth. The presence of trees did not negatively effect forage growth and silvopasture systems improved the soil quality indicators compared to open pasture. / Master of Science

How can we as design professionals contribute to increase the use of less carbon-intensive materials to build our growing cities? Cities are experiencing a resurgence in population growth and therefore the building industry ought to attend this demand with sustainable solutions. One way of responding to the growing urban population and increase demand for housing as well as to make efficient use of our limited resources is to increase the density in our cities. Since steel and concrete have high material strengths, we currently use either steel, concrete or composites of them to build skyscrapers. Unfortunately, both of these materials have a large carbon footprint. The design community has the challenge to achieve net-zero emissions buildings by the year 2030, and the efforts now should be focused on using less carbon intensive materials, such as timber. While cultures around the world have built with wood for centuries, recent technological innovations, such as Cross Laminated Timber (CLT), is allowing for new applications of wood as the main structural material and the potential to use it for large-scale projects. However, as expected with a new building material some constrains have still to be overcome. For my thesis, I desired to explore this issue through the design of a tall building using mass timber as its main structural material. Engineered timber is here, the future is bright! / Master of Architecture

Brown patch, caused by <i>Rhizoctonia solani</i> Kuhn, is an important disease on tall fescue (TF, <i>Festuca arundinacea</i> Schreb, synonym <i>Schedonorus phoenix</i> (Scop.) Holub). <i>Rhizoctonia zeae</i> Voorhees, a related pathogen, causes similar symptoms. Confusion over which <i>Rhizoctonia</i> species is causing symptoms and subjective visual evaluations of disease severity may contribute to variability in observed BP resistance of TF cultivars at multiple locations. The objectives of this study were to develop an objective digital image analysis (DIA) method for evaluating disease and to use DIA to screen tall fescue plant introductions (PIs) for resistance to <i>R. solani</i> and <i>R. zeae</i>. There was a strong correlation (r² = 0.97) between actual disease severity, measured by applying lesioned tissue of a known area to healthy leaves, and DIA calculated disease severity using scanned images of individual leaves (DIA-IL). The accuracy and precision of visual evaluations and DIA evaluations of entire plants (DIA-WP) were evaluated using DIA-IL as a standard of accuracy. Accuracy of DIA-WP was not significantly different from visual evaluation accuracy. Precision was significantly higher for DIA-WP. Evaluation of PIs and putatively BP resistant TF cultivars for resistance to <i>R. solani</i> and <i>R. zeae</i> using DIA-WP identified clones within each PI that ranked high for resistance to <i>R. solani</i> or <i>R. zeae</i>. No clones were identified with high resistance to both <i>R. solani</i> and <i>R. zeae</i>. Improved precision of DIA evaluation methods and inclusion of <i>R. zeae</i> in BP resistance breeding may decrease variability of TF cultivar performance across locations. / Master of Science

Grass clippings may be recycled onto nearby areas of turf as an alternative to disposal of clippings in landfills. In May, 1991, two field studies were initiated to evaluate grass clippings as a nitrogen (N) source for tall fescue (Festuca arundinacea, Schreb. Rebel’) turf, and to determine the maximum feasible loading rate of clippings onto tall fescue turf. Test plots in both studies received additional clippings from adjacent donor plots. In the first study, grass clippings alone were applied to 2.2 m² test plots at rates of 1 "plot equivalent harvest" (PEH), 2 PEH, and 4 PEH; where PEH is the amount of clippings harvested from 2.2 m² of donor plots. In the second study, test plots had clippings removed (Rem), clippings returned (Ret), Ret+1 PEH, and Ret+3 PEH. These four clipping treatments were arranged in a factorial combination with three fertilizer-N rates: low (73 kg N ha⁻¹ yr⁻¹), medium (147 kg N h⁻¹ yr⁻¹), and high (220 kg N h⁻¹ yr⁻¹). Donor plots received identical fertilizer-N applications as test plots. For both studies, N uptake generally showed a linear response to total N applied. Clipping-N produced roughly the same amount of growth and N uptake as the fertilizer-N, even as the rate of N uptake varied with time. In both studies, soil nitrate levels remained low until excessive clippings smothered the turf and caused a reduction in N uptake. Soil nitrate concentration tended to decrease with depth for all plots. Soil total Kjeldahl nitrogen (TKN) levels did not differ among treatments, suggesting that clipping-N was not being stored in the soil. At the end of both growing seasons, thatch accumulation was less than 12mm in all plots. In general, increased additions of clippings resulted in improved color, density, and growth. However, at the very high rates of added clippings, excess biomass caused turf thinning, chlorosis, and low growth. Thus, if grass clippings are applied at rates that are low enough to prevent these problems, they can be an effective N source for tall fescue. Furthermore, in order to dispose of the maximum amount of clippings, tall fescue should not be fertilized. / Master of Science

For the rapid establishment of optimal conditions for a genetic transformation system for tall fescue, several factors influencing transient gene expression were studied in protoplasts, after the reporter β-glucuronidase (GUS) gene was introduced by electroporation. In a time-course study of transient gene expression, GUS activity peaked at 24 h after electroporation. Among the different field strength conditions tested, maximum GUS activity was observed at 750 V/cm. Increases in the amount of plasmid DNA to 80 μg/ml led to increased GUS activity. GUS activities increased in linear fashion with increasing protoplast densities up to 2 x 10⁶/ml. Age of suspension cells from which protoplasts were derived influenced transient expression with maximum GUS activity obtained in 3 and 5 day old suspensions. These results show that transient expression studies can be used to optimize electroporation parameters rapidly. Results of such rapid assays can be used as a basis for further studies on stable transformation of this important turf-grass species. / Master of Science

see document / Master of Science

Urban soils are typically degraded due to land disturbance. The poor quality physical and chemical properties of the soil can benefit from application of organic amendments. Local sources of such amendments are biosolids, which are treated domestic wastewater sludges. The objective of this experiment was to compare effects of various high quality biosolids-based soil amendments with synthetic fertilizer on the growth and quality of tall fescue (Schedonorus arundinaceus) under two different soil moisture regimes. The research site was a disturbed soil at the Virginia Tech Turfgrass Research Center in Blacksburg, Virginia. The experimental design was a split plot with irrigation regime as the main factor and soil amendments as the split factor. All treatments were arranged in four randomized complete blocks. The study was established in late summer 2013. Soil amendment treatments, applied prior to seeding in September 2013, were: 1) inorganic N, P, K applied according to soil test laboratory recommendations; 2) anaerobically digested, dewatered biosolids to supply agronomic N rate; 3) anaerobically digested, dewatered biosolids blended with sand and sawdust to supply agronomic N rate; 4) anaerobically digested, dewatered biosolids blended with sand and sawdust to supply agronomic P rate; and 5) composted biosolids to supply agronomic N rate. The agronomic N rate for the turfgrass was 224 kg of estimated plant available nitrogen (PAN) ha-1. Inorganic fertilizer was applied to supply annual P and K requirements prior to seeding in late summer, and the N was split into three application timings (September 2013, April 2014, and June 2014). Supplemental fertilizer N to achieve full agronomic N rate was applied to the treatment plots that received the agronomic P rate of blended biosolids-sand-sawdust. The area was seeded on September 13, 2013 with a tall fescue blend at a rate of 488 kg ha-1. Following full tall fescue establishment, in June 2014, two irrigation regimes, consisting of 0% and 80% evapotranspiration replacement every three days, were initiated. The study had three phases denoted as the pre-drought, drought, and recovery phases which started in April and concluded in August of 2014. Turfgrass color and quality, volumetric soil moisture percentage to a 5 cm depth, normalized difference vegetative index (NDVI), clipping yield, and turfgrass N uptake were measured bi-weekly throughout the growing season. During the first May through July 2014 irrigation season, results were that the fertilizer control consistently provided improved responses relative to the biosolids amended treatments. Clipping yield, quality, and NDVI were all significantly greater in the inorganic fertilizer treatment, but volumetric soil moisture percentages were slightly greater in the biosolids treatments. Turfgrass responses appeared to have been associated with plant available nitrogen, which was lower in the biosolids treatments than in the fertilizer treatment. Calculated PAN for the biosolids products was too low to achieve ideal turfgrass growth and quality. Improving the estimated PAN and/or splitting the organic amendment application times should improve the growth and quality of the turfgrass. / Master of Science

Three yearling and three 2-year-old Saddlebred horses were used to determine seasonal differences in apparent digestibility of Ky 31 tall fescue (Festuca arundinacea Schreb.) pasture by horses. Three trials were conducted with collection periods beginning August 27, 1984; January 8, 1985; and June 3, 1985. Each 72 h collection period followed a 2 wk preliminary grazing period. The horses were given a pulse-dose of Yb impregnated fescue forage at 0 h, and fecal grab samples were taken at 6, 12, 18, 24, 30, 36, 48, 60, and 72 h after dosing. Fecal output was estimated from Yb concentration in the feces. Apparent digestibilities of dry matter (DM), acid detergent fiber (ADF), neutral detergent fiber (NDF), crude protein (CP), and cellulose were estimated using indigestible NDF as an internal marker. Forage DM intake was calculated using the formula (fecal output/(100- % forage DM digestibility) x 100). Estimated DM intake and fecal DM were 4.5 and 1.7 kg/d for August; 7.5 and 2.7 kg/d for January; and 6.4 and 2.8 kg/d for June, respectively. Percent ADF and NDF were highest (P<.05) and apparent digestibilities of these components were lowest (P<.05) for the spring forage. / Master of Science

Low and high endophyte infected stockpiled tall fescue was harvested, chopped and ensiled in 210 liter metal drums, double lined with polyethylene bags. Endophyte infection averaged 4 and 70%, respectively, for the low- and high-endophyte fescue. A metabolism trial was conducted with 24 wethers fed diets consisting of 100% low-endophyte fescue silage, 50% low-endophyte and 50% high-endophyte fescue silage, and 100% high-endophyte fescue silage. Chopped alfalfa hay was used as a control forage. Single samples were analyzed, so statistical treatment of chemical composition was not possible. However, certain numerical differences were recorded. Lignin was higher for the high-endophyte than the low-endophyte fescue. Dry matter, CP, and ash were similar for the fescue silages. The high-endophyte fescue silage was lower in P, Mg, S, K, Fe, Cu, Mn, Zn, and Al than the low-endophyte silage. Digestibilities of DM, NDF, and cellulose were higher (P<.01) for fescue silages than alfalfa hay. Level of endophyte infection did not affect digestibility of DM, NDF or cellulose. Among silage treatments, apparent absorption of N, expressed as g/d, showed a linear effect (P<.05), with the lowest value obtained for sheep fed 100% high-endophyte fescue silage. Apparent absorption and retention of Ca were higher for silages than alfalfa. Among the silage diets, apparent absorption of P decreased linearly (P<.01) with increased endophyte level. Apparent absorption of K decreased linearly (P<.01) with increased endophyte level, but the effect was related to intake. Serum prolactin concentrations of the wethers fed fescue silage showed a linear decrease (P<.05) with increased proportion of endophyte-infected fescue. Endophyte infection of fescue appears to affect N and mineral metabolism. / Master of Science

The work seeks toward further developing a novel robotic platform capable of stable three legged locomotion. This will be accomplished by creating a robust and adaptable robotic platform capable of executing different walking strategies and taking multiple continuous steps. Previous iterations of this platform have been developed, all of which have used a single gait strategy. This study will seek to develop two new strategies. The first of which is a modification of the original strategy with theoretically improved gate robustness. A second strategy will seek to implement more advanced control techniques to create a fully stable balanced gait. / Master of Science