Natural Science Seminar Abstracts - Fall 2009

Note: All photos posted with the abstracts are photos made by the students who presented their work unless indicated.

Emily Shanblatt
September 14, 2009
Lead and Arsenic Concentrations in Lake Fontana, Lake Julian and Swannanoa River Sediment

Mentor: Dr. John Brock

Abstract: Lead and arsenic are toxic heavy metals which can cause a variety of adverse health affects.  Both metals enter the natural environment through many processes, including agricultural runoff, coal combustion, industrial runoff, and construction or demolition.  Once in lakes, rivers and streams, these metals are ingested by aquatic organisms, and bioaccumulate in their tissues.  When the organism is passed up the food chain, the metal content is passed on, thus eventually reaching humans through the ingestion of fish.  There is a direct correlation between metal content of fish and metal content of sediment. The main objective of the study was to determine lead and arsenic concentrations in sediment collected from Lake Fontana, Lake Julian and the Swannanoa River.  The method involved acid digestion, to extract the metals from the sediment and convert the sample to a liquid.  Analysis was run with an ICP-AES.  Calibration curves were made and showed strong correlations between the data and linear regression curve.  Lead and arsenic was found at each site, but in extremely low and safe concentrations; less than 3.91 ppm, except one sample at 8.20 ppm.  Compared to USGS values from Buncombe and Swain counties, the three tested sites showed concentrations lower than anything found in the USGS study.  Although the sediment analysis renders these bodies of water safe, monitoring and remediation are still recommended to reduce concentrations to zero.

Adam C. Cate
September 14, 2009
Possible Long Term Impacts of Log Landings on Oak-Hickory Forest of East Tennessee

Mentor: Dr. David Ellum

Abstract: Regardless of the silivculture prescription or harvest method, all logging operations require log landings. Landings are central locations where trees are cut to length, sorted and loaded onto trucks to be transported to market. Through the process of soil scarification, and repeated soil compaction, landings are the most disturbed section of a logging operation. The objective of this study was to determine if the early physical environment created at log landings might influence long term regeneration. Seven separate harvest sights where selected within Royal Blue Wildlife Management Area in East Tennessee.  Within each harvest block three fixed area one meter square plots where selected in the landing, and three in the harvest gap. Variables tested were compaction, percent bare mineral soil, vegetation height, and number of woody stems. A paired T-test was used to compare significant differences between variables within the landing to those outside. All test returned a significant difference (P< .0001). Soil compaction and percent mineral soil were higher in landings, and the number of wood stems and vegetation height were decreased at landings. This data suggest that the increased compaction from forest machinery, as well as scarification of the soil, leads to decreased germination success or destruction/removal of advanced regeneration. Management suggestions include subsoiling, to loosen soil, as well as planting native shrubs for structured wildlife habitat.

Douglass DeCandia
September 21, 2009

Sterility of Human-Manure Based Biochar
Mentors: Dr. Steven Cartier and Dr. Tim Meehan

Abstract: Biochar, when used as a soil amendment, can increase soil organic matter, ease water pollution and erosion, as well as sequester carbon from the atmosphere. By using humanure as the base for biochar, additional benefits can be achieved. These include the diversion of a potentially harmful substance from entering waterways, the conservation of water, and the creation of a carbon-rich soil amendment. The objectives were to, 1) design a method that reuses the resource of humanure, 2) to make biochar from humanure, and 3) to test the sterility of the biochar through comparing average bacterial colonies found in the biochar and in the raw compost samples. Partially composted humanure was collected from the two Clivus Multrum composting toilets in the Ecodorm on the Warren Wilson College campus, and dried for three weeks. Samples of the dried compost were taken and half were pyrolyzed to make biochar, and the other half were kept as raw compost samples. The samples of biochar and raw compost were then taken to the Warren Wilson biology lab, where one gram of each were diluted in 100 ml of sterilized water and then diluted to different concentrations, and plated on one of three growing mediums (Difco Tryptic Soy Agar, Difco Nutrient Agar, or Eosin Methylene Blue Agar). A total of 12 samples of biochar and 28 samples of raw compost were plated. In total, the average number of bacteria colonies found from the biochar samples was 4.7 x 103 colonies/gram and the average number of bacteria colonies found from the raw compost sample was 3 x 1010 colonies/gram. The raw compost was found to contain approximately 6 x 106 times as many bacteria colonies than the biochar. The results suggest that 1)the humanure-based biochar is more sterile than raw compost, 2)pyrolysis can be used to reuse humanure, and 3)the humanure-based biochar has the potential to be used as a soil amendment.

Kate Freeman
September 28, 2009

Feeding Preference for Vermont Songbirds at a Feeder

Mentor: Louise Weber, Ph. D.

Abstract: Backyard bird feeding can be a powerful conservation tool. Providing supplemental feed is known to increase species diversity and reproductive success.  Many species, including endangered neotropical migrants, rely on being fed throughout the year. The importance of providing a variety of birdseed has been recognized, but the most nutritionally sound food supplement is still not agreed upon. The objective of this study was to determine whether songbirds feeding in the Vermont summertime prefer a vitamin fortified seed mix or black oil sunflower seeds and to observe whether feeding patterns change over time. This study was conducted in Middlesex, Vermont from June 12, 2009 to August 14, 2009. Two identical feeders were randomly filled each day. Feeding rates were measured using a motion-censored camera taking a picture every time a bird visited the feeder. This study had only one replicate, but the large sample size makes the data worth contemplating. Results indicate that out of all the total visits, birds chose sunflower seeds 55% of the time. Of the species who frequented the feeders, arboreal feeders preferred sunflower seeds while groundfeeders chose the mix seed.  Late July was the busiest time for feeding; the month of July had 47.5% of all the total visits. This loosely correlates to the time when fledglings have hatched and birds are going into hyperphagia, preparing to migrate. Many endangered and threatened neotropical migrants rely on northeastern stopover sites to fuel them before fall migration. While there were more individual visitors to sunflower seeds, a greater number of species preferred mixed seed. This study suggests that it is beneficial to provide a variety of seeds in the backyard throughout the season to encourage species diversity and fitness.

Dylan Flynn
September 28, 2009

Bioacoustic Variation of the California Red Legged Frog, Rana draytonii.

Mentor: Dr. Robert Eckstein

Abstract: The California Red Legged Frog, Rana draytonii, is a federally listed threatened species, and the largest Native frog in the  Western United States. During their breeding season, from December to February, the male Rana draytonii produce a unique mating call.  Research has shown that the structure of anuran mating calls is effected by both surrounding environmental and the social conditions. My objective was to determine whether group calling size influences the call structure of individual Red Legged Frogs. Mating calls were recorded in the field at Point Reyes National Seashore, California. Corresponding water temperatures and calling group sizes were also recorded. Recording samples were measured for five parameters and analyzed using Raven Lite bioacoustic analysis software. Parameters were first assessed for temperature dependence using a multiple regression analysis test. If no significant temperature effect was found, the means of the two calling size groups were compared for a given parameter. If a parameter was found to be significantly effected by water temperature, the effect of calling size was assessed using a subsequent multiple regression analysis test. At the 95% confidence level there was no significant difference between the small and large calling groups concerning the following parameters: pulses per clutch and pulse rate parameters. However there was a significant difference between the small and large calling groups concerning the remaining three parameters: average clutch duration, average duration of the ultimate pulse, the average peak frequency of the ultimate pulse. This variation in call structure is constant with theories concerning competition and predation among frogs and could represent an evolutionary fitness benefit.

William Goldberg
October 12, 2009

The yeild potential of 5 cultivars of oryza Sativa (rice) in two western North Carolina Soils

Mentor: Dr.Laura Lengnick

Abstract: A rice (Oryza sativa) variety trial was conducted on the campus of Warren Wilson College during the summer and fall of 2009.  The objective of this study was to investigate the potential for local farmers to benefit from a growing demand for locally-produced specialty food grains by producing rice in Western North Carolina (WNC). The effect of soil type on the yield potential of five cultivars of rice recommended for organic production in WNC was evaluated in a greenhouse experiment. The selected soil types represent differences in ease of water management in a sustainable rice production system.  A randomized complete block experiment with two factors – soil type and cultivar – and five replications was conducted in the Morse Building greenhouse. Rice seedlings were transplanted into 4-in plastic pots filled with a 1:1 mix of field soil and promix.  Pots were continuously sub-irrigated with a standard fertilizer solution throughout the duration of the experiment.  Plant tiller numbers were recorded weekly from date of transplanting and were used estimate potential grain yield. There were no significant differences in tiller number due to soil type and no significant soil by cultivar interactions.  There were significant differences (p-value <0.0001) in tiller number among the cultivars tested, with the cultivars falling into three distinct groups.  Because the data reported in this study were taken prior to maximum plant tillering stage, the estimates of potential grain yield based on tiller number were lower than expected grain yields for all cultivars.

Brendan Kelley
October 12, 2009

Metal Concentrations in Warren Wilson College Garden Soil

Abstract: Metals occur naturally at trace concentrations in soil. Human activities like burning coal and turning soil change the concentrations of metals in the soil. Metals like magnesium and manganese are essential plant metals used in the construction of chlorophyll molecules for photosynthesis. Heavy metals like lead and cadmium have similar chemistry to these desired metals and are taken up by plant roots with the Mn and Mg metals. Soils with high concentrations of lead and cadmium have the potential to grow plants with similarly high metal concentrations. Leafy plants like kale, tobacco, and lettuce are notorious for sequestering any metals they can find in the phytoaccumulation process. Humans become subject to the toxic effects of ingested plant metals on the cardiovascular and nervous systems. With the recent exposure of soil during campus construction activities, the unclear history of pesticide use on Warren Wilson land, and elevated concentrations of heavy metals in local bodies of water, there is reason to investigate the concentrations of metals in the garden soil. My objectives involved measuring the concentrations of metals the garden soil, and determining if trace metals were influencing produce yields by comparing metal concentrations in fields with high and low productivity. I used my own method as an adaptation from the EPA 3050 B soil analysis method. Using ICP-AES to measure emission intensity of metals in soil I determined that the concentrations of metals were safe for human produce activities. Manganese metal concentrations are statistically different between high and low yield fields. There is a 95% chance that slightly decreasing manganese in the low yield fields will improve productivity. As a society we need better funding for environmental metal testing.

Jeremy Lekich
October 26, 2009

A Process to Convert Human Urine into an Effective Fertilizer

Mentor: Dr. Mark V. Brenner

Abstract: Most urine excreted in America goes first into the toilet, then to a sewage treatment plant, and finally to a nearby river; it is considered waste. Urine contains high concentrations of nitrogen, mostly in the form of urea. It also has contains phosphorus and potassium. Numerous studies show urine to be as effective and safe as commercial fertilizer. When urine is stored however, the nitrogen quickly converts to ammonia, which is toxic and can volatilize. The objective of this study is to create a process for the conversion of urine to a nitrate solution that could be used as an effective fertilizer. Conversion machines were designed and built using salvaged yogurt containers. Porous lava rocks were used in the machines to cultivate nitrifying bacteria. Urine was collected through public announcements. Collected urine was diluted and separated into four treatments: sitting urine, no lava rocks, lava rocks, and lava rock plus limestone. Each treatment had three replicates. Ammonia concentration, nitrate concentration, and pH were measured in each treatment and compared. At least partial nitrification exists in the treatments lava rocks and lava rocks plus limestone. Complete nitrification exists in lava rock plus limestone due to the presence of the pH buffer (limestone). This study suggests that nitrification could be a feasible way to store, transport, and apply human urine as a fertilizer. Research still needed include dilution ratio, storage capability, and success on a large scale.

Chris Nelson
October 26, 2009

The Relationship between Aqueous Cell Density of Escherichia coli and Surface Biofilm Initiation  

Mentor: Dr. Michael Torres

Abstract: Bacterial biofilms are multicellular bacterial associations often involving attachment to a surface, cell to cell communication, and an extracellular polysacharride based matrix (Kjelleberg, Givskov, 2007). Study and detection of biofilms is important to both industry and medicine as biofilms often cause problems in pipelines and can contribute to infection and disease (Kjelleberg, Givskov, 2007; Hall-Stoodley et al., 2004; Costerton et al., 1999; Dasgupta et al., 1994). Biofilms formation is triggered by environmental conditions and a cell density dependent signaling system, called quorum sensing (Kjelleberg, Givskov, 2007; Miller, Bassler, 2001).  Autoinducer two (AI-2) is the primary quorum sensing molecule used by E. coli to stimulate biofilm production (Barrios et al., 2005).  The addition of AI-2 to E. coli cultures causes an increase in mature biofilm mass (Barrios et al., 2005).
This study focused on the initiation of surface associated E. coli biofilms on glass slides submerged in Luria-Bertani (LB) liquid media.  The relationship between biofilm initiation and the cell density of the liquid environment was investigated. Additionally, this relationship was manipulated by three treatments.  First, cell free supernatant (CFS) from E. coli cultures were added at the time of inoculation. Second, cell free supernatant from cultures grown in media supplemented with glucose (.8%) was added at the time of inoculation. Glucose supplementation has been shown to increase AI-2 production (Surette and Bassler, 1998, Wang et al., 2004).  Finally, concentrated AI-2 (10uM) was added at the time of inoculation (Barrios et al., 2004).   
A positive relationship between biofilm initiated cells and the cell density of the liquid environment was found for two of the treatments (no CFS and CFS without glucose) at roughly 90% confidence.  However, no relationship was found between irreversibly attached cells and cells per ml when CFS from culture grown with glucose was added.
To compare the effects of the treatments that showed a positive relationship, the average ratios of biofilm initiated cells to cell densities of the liquid environments were compared. A T-test at 95% confidence did not confirm a significant difference between the treatments.  Also, the addition of concentrated AI-2 appeared to have no effect. 
One explanation for these results is that AI-2 only acts to stimulate biofilm mass accumulation in the form of extracellular matrix production and has no effect on initiation in terms of cellular attachment.  However, this claim is dependent on the relationship between cell density and biofilm initiation, which could not be strongly shown, and should be a focus of future work. 

Kopano Mmalane
November 2, 2009

Mentor: Dr. Victoria Collins

Abstract: Growth faltering and multiple micronutrient deficiency are common in children in developing countries. Zinc, Iron and copper are the three most abundant trace metals in a healthy human body. These metals are not generated by the body and therefore need to be consumed. Acanthocampa belina (Mophane caterpillar), is a common food source in Botswana. The study involved analyzing the Mophane caterpillar for zinc, iron, copper and for toxic metals arsenic and lead. Two sampling pools were used to determine if there is a difference in trace metal content from one harvest season to the next, December against May. Another sampling pool was added to the analysis to determine if the caterpillars in Selebi Phikwe, where the copper nickel smelter mine is situated, are different in trace metal content from the Bobonong area caterpillars. The average metal content for all the caterpillars was measured. Zinc 2190 ± 878 µg/serving, iron 3000 ± 1990 µg/serving, copper 104 ± 59.5 µg/serving, Lead 1.11 ± 3.56 µg/serving and arsenic 25.0 ± 29.5 µg/serving, where a serving is 10 caterpillars. A serving of caterpillars provides 44% of the zinc RDA for children, 30% of the iron RDA for children and 24% of the copper RDA for children. The toxic metal content of the caterpillars per serving was well below the FDA and European standard levels. There was no significant difference in trace metal content between the two different locations. There was a difference in zinc, iron and arsenic levels between the two different harvest seasons with a 95% confidence. The December harvest season had significantly higher levels of zinc, iron and arsenic.

Amy Kunkel
November 2, 2009

Natural Products as Anthelmintics

Mentor: Dr. Victoria Collins

Abstract: Helminth (worm) parasites affect economic success in all sectors of agriculture, causing multi-million dollar losses in animal agriculture yearly.  Three main classes of synthetic anthelmintics have been formulated, but in less than a decade resistance has been observed in all three.  Natural products may be effective alternative anthelmintics.  Three different natural products—clove oil (Eugenia aromaticum), tree tea oil (Melaleuca alternifolia), and papain isolated from Carica papaya—were studied from their anthelmintic effects.  The microscopic nematode, Caenorhabditis Elegans (C. elegans), was used as a model organism to estimate the toxicity of these products.  The objectives of this study were to establish toxicity testing protocols for. C. elegans at Warren Wilson College (WWC), determine toxicity of three different compounds on C. elegans, and use the data to form treatment plans and treat pigs on the WWC farm.  Concentrations from 0.1% to 100% of the three natural products were tested.  A dose-response curve was formed for clove oil, and the LD50= 0.175 % and the LD100= 2.0%.  Tree tea oil gave varied results with each replicate and exhibited low toxicity, and papain was not effective against C. elegans.  Based on the LD100 of clove oil and the measured gastrointestinal volume of a piglet, 5 – 10 ml of clove oil was chosen as an effective dose.  Thirty-two piglets were tagged and weighed for the experiment.  The piglets were then treated with, 10% clove oil (10 mL), 5 % clove oil (5 mL), or the positive control Ivomec.  The treatments were assigned in a block design with the sow represented by the block to rule out genetic influences.  Three-week weight gains were compared and no significant difference was seen between the litters or the 10 % clove oil, 5 % clove oil and Ivomec treatments.  Fecal floats were preformed showing no significant difference in parasite eggs per gram feces between the Ivomec treated piglets and the piglets treated with clove oil.  Clove oil appears to inhibit internal parasitic nematodes as well as the synthetic anthelmintic Ivomec.

Tully Herr
November 9, 2009

A Comparison of Trace Metal Concentrations in Fish Emulsion and Conventional Fertilizer

Mentor: Dr. John Brock

Abstract:  Fish emulsions are organic fertilizers that are made from the byproducts of the fish oil and seafood industries.  In comparison the conventional synthetic fertilizers organic fish emulsions have low NPK percentages, but they make up for this by a high number of micronutrients.  This study analyzed four brands of fish emulsion and one brand of conventional fertilizer for heavy metal contamination.  The heavy metal concentrations were compared to the Organic Materials Review Institute proposed standards for maximum allowable heavy metal concentrations in fertilizers (As-0.18ppm, Cd-0.05ppm, and Pb-1.25ppm).  Each sample was digested in accordance with the Environmental Protection Agency’s method 3050B.  The concentrations for each sample were analyzed using the inductively coupled plasma atomic emissions spectrometer (ICP-AES).  The four heavy metals that were analyzed were lead, cadmium, zinc, and arsenic.  The comparison of conventional fertilizer to organic fish emulsion fertilizer found the fish emulsions have significantly higher concentrations of arsenic, lead, and zinc (at the 95% confidence interval).  There was no significant difference in cadmium concentrations.  All heavy metal concentrations of the tested fertilizers fell below OMRI standards.  Due to high variability of the application rates for the fertilizers and increased uptake of heavy metals by hyper-accumulators there is a possibility of heavy high heavy metal contamination due to organic fish emulsions.

Renee Sniegocki
November 9, 2009

Glucosinolates and Brassica degradation products as nematicides for C. elegans.

Mentor: Dr. Victoria Collins

Abstract: Plant-parasitic nematodes (PPNs) are microscopic roundworms which feed on the living cells of plant tissues. By diverting nutrients and water, the nematode can hinder the growth of the plant. In North Carolina, PPNs have been documented to greatly reduce crop yields of species such as tomatoes, strawberries, and soybeans. Methyl bromide, a popular fumigant used for soil borne pests such as nematodes, was made illegal in 2005 due to its contribution to atmospheric depletion. As a result, there is a need for a practical pest control alternative to methyl bromide. Research shows that plants of the Brassica genus contain active compounds called glucosinolates which are capable of hydrolyzing with the enzyme myrosinase to form allelopathic compounds known as isothiocyanates. These isothiocyanates have been shown in vitro and in field studies to inhibit the growth and reproduction of various nematode species. The objectives were to first establish toxicity testing protocols for Caenorhabditis elegans, a usefel model for PPN species, at Warren Wilson College, and to then test the acute toxicity of G rapa var. perviridis on PPNs. After concluding the toxicity of B. rapa solution on C. elegans, the data could be used to suggest a useful field application of B. rapa for controlling PPNs. C. elegans were exposed to four concentrations of B. rapa solution for 30 minutes, washed, and then allowed to grow for 2 days before scoring. After three replicates were scored, the average % dead of each treatment was plotted against concentration on a dose response graph and analyzed. The RMSE of the curve fit was 8.38. The LC50 given by the curve fit was 68.7% concentration. The dose-response analysis shows that C. elegans show a significant response to B. rapa solution. Therefore, soil amendments of  could be used to suppress PPNs.

Eric John Soderholm
November 16, 2009

An Inventory of Native Bees on Warren Wilson College Pastures and the Determination of Seasonal Community Patterns

Mentor: Dr. Paul Bartels

Abstract: Recent concern has risen regarding an overall decline in pollinators in agricultural and natural ecosystems alike. Bees are considered the most central group in providing pollination services in North America. However, relatively little is known about the abundance or decline of the over 4,000 continental species. Only through diligent monitoring can speculation of native bee decline be substantiated and conservation efforts follow. The objective of this study was to conduct an intensive inventory of bees on the Warren Wilson College campus to act as a baseline for future monitoring efforts and to understand our region’s bee diversity. The secondary objective was to determine patterns of seasonal abundance, diversity and community structure of native bees from Warren Wilson College pastures. Although the literature alludes to patterns of seasonal change, a study of this intensity and scale on a single habitat type has never been conducted before. Sampling occurred on eight pastures once a month from April-May 2008. Pan traps were used due to their low capital investment, speed of deployment, and ability to limit sampling bias. The inventory yielded 87 species of bees, two of which have never been documented in the state of North Carolina. Seasonal differences were analyzed via one-way ANOVA. The abundance of bees, the number of species observed and the number of rare species all followed a pattern of mid season peak and a leveling off in the early and late season. Additionally, community oligarchies were observed across the season and were made up of 3-5 dominant species. The specific composition of oligarchies shifted over the season.

Lauren Bangasser
November 16, 2009

The Effect of Liquid Topical Soil Amendments on Compaction in a Sports Field

Mentor: Dr. Laura Lengnick

Abstract: Soil compaction is a serious problem in turfgrass management that leads to a poor quality and dangerous playing surface.  The turfgrass manager at Warren Wilson College, Tom Lamuraglia, has struggled to grow healthy grass on the soccer game field for some time and suspected that it was due to soil compaction.   The objective of this study was to test if ICT Organics Compost Tea and Earthright Soil Conditioner had an effect on compaction in the field.  Water was used as a negative control and the three treatments were laid out using a randomized complete block design to control for soil variation.  Each treatment was replicated four times.  The treatments were applied using a tractor sprayer on May 21, June 11, and July 16.  Three months after the final application soil strength and bulk density, both indicators of compaction, were measured in the field plots.  The soil strength (kPa) was measured ten times at two depths, 7.6 cm and 15.2 cm, in each plot using a soil penetrometer.  The bulk density (Mg/m3) was calculated by weighing three dry soil cores from two depths in each plot and dividing the weight by the bulk volume of the cores.  A one-way ANOVA was used to compare the means of the treatments for the two soil characteristics at both depths.  There was no significant difference between treatments in soil strength at either soil level.  The p-values for the upper and lower levels were 0.8139 and 0.6507 respectively.  There was also no significant difference between treatments in bulk density at either soil level.  The p-values for the upper and lower levels were 0.4861 and 0.5417 respectively.  Although the compost tea and Earthright may have provided other benefits to the turfgrass, this study was unable to verify the manufacturers’ claims that these products can reduce soil compaction.  The soil characteristics measured suggest that the compaction is too severe to be managed with topical amendments and that a physical solution to reduce the compaction will be necessary.

Stephen A. Briggs
November 23, 2009

Biochar: Production and Effect on Nitrate Leaching in The Warren Wilson College Corn Field

Mentors: Dr. Laura Lengnick and Dr. Tim Meehan

Abstract: Biochar, charcoal produced through pyrolysis and applied as a soil amendment has the potential to increase nutrient holding capacities in the soil and sequester carbon. Corn (Zea mays) demands high amounts nitrogen fertilizer to achieve yields that are considered productive and coupled with the low nitrogen use efficiency (NUE) of corn (Zea mays), the environmental damage due to the escape of nitrogen from the field system runs into the billions of dollars annually. The objectives of this study were three-fold, to produce and process 110 kg of charcoal, to measure the effect of biochar on nitrate concentration in the Warren Wilson College corn (Zea mays) field and to determine the effect of biochar on yield. Biochar was produced using the charcoal retort method and processed using a gasoline powered hammer-mill leaf shredder retrofitted with a 2mm sieve screen. The field experiment had 2 treatments, biochar and control replicated 12 times on 4m2 plots, and 3 variables, depth, date, and treatment. A total of 122 kg of biochar was produced, each biochar plot received 8 kg (23 tons / ha) of biochar. At planting 224 kg / ha nitrogen fertilizer was applied to the field. Half the plots were sampled on 9/26/2009 and the other half were sampled on 10/25/2009 where 1 soil core was extracted from the center of each plot and sampled at 10 cm, 20 cm, 70 cm and 122 cm. Soil samples were air-dried and then analyzed for NO3¬concentration using the Vernier nitrate ion-selective probe. Yield values are not available currently due to the late corn harvest this year. Depth, date, and treatment data was analyzed via a mixed-model ANOVA and no treatment significance was found, p = 7929. Biochar showed no effect on soil nitrate concentration during this study.

Colleen Vetti
November 30, 2009

Analysis of Kudzu (Pueraria lobata) Floral Volatiles

Mentor: Dr. Dean C. Kahl

Abstract:  Floral scent is the primary mechanism of communication between plants and pollinators (Dobson 1994, Reis et al. 2004).  Floral scent characteristics have been cited in previous research as having been selected for by specific pollinators because of the reciprocal, positive influence of pollinator specificity on both plant and insect reproductive success (Pellmyr 1986, Omura et al. 2000).  Many floral scents are composed of terpenes, a class of natural, volatile organic compounds which disperse readily at normal atmospheric pressure and temperatures (Metcalf 1987).  As of 2006, information regarding the floral scent chemistry of 991 species of flowering plants from 90 families was available (Knudsen et al. 2006).  Kudzu (Pueraria lobata) root and leaf volatiles as well as the reproductive limitations of this vine have been identified (Shibata et al. 1978, Miyazawa & Kameoka 1987, Abramovitz 1983).  There is no published research identifying the scent constituents of the kudzu flower.  In this study the major constituents present in the kudzu floral scent were identified.  Fifteen kudzu flower samples were collected from two sites. Floral volatiles were collected for one hour by solid phase microextraction (SPME) with a divinylbenzene/polydimethylsiloxane (DVB/PDMS) adsorbent fiber (Augusto et al. 2003, Deng et al. 2004, Raguso 2004).  An empty jar was used as a negative control.  Samples were injected directly into a Gas Chromatograph/Mass Spectrometer (GC/MS).  Samples were then analyzed and compounds were identified by three methods: library search, visual spectra analysis, and an analysis of retention times of standards of known structure.  Nine compounds were identified: 1-octen-3-ol or 3-octanone, two ocimene isomers, methyl anthranilate, α-farnesene, β-farnesene, two alkanes of unknown molecular formulas, as well as one compound which could not be identified.  Differences in the time of day of sampling may have affected relative percent composition of each compound in the floral scent mixture (Dobson 2006).

Chelsea Britt Gay
November 30, 2009

Soil Organic Matter on the Warren Wilson College Farm

Mentor: Laura Lengnick

Abstract: Soil organic matter (SOM) greatly influences a number of soil properties contributing to soil productivity and therefore is a key indicator of soil quality and sustainable land management. To date, there has been no regular monitoring of soil organic matter on the Warren Wilson College (WWC) Farm.  The objectives of this study were to: 1. create baseline data set of SOM on the WWC Farm and, 2. investigate the effect of management practices on SOM between crop types, in comparison to native soil, and over time.  A sampling plan was developed to create three different data sets that provided reliable estimates of SOM in 24 fields under crop rotation or permanent pasture.  Depending on the data set, 10-15 soil cores taken for each soil sample.  The Loss on Ignition procedure was used to measure soil organic carbon (SOC) and a regression equation was created in order to estimate SOM content from SOC.  Loss on Ignition and SOM data were highly correlated with an r value of 0.97 (P<0.0004). The % SOM of pasture fields was significantly higher than that of cultivated fields (non-paired t-test P = .0193). Within pastured fields there was no significant difference between the % SOM of the fenceline and the field (paired t-test P = .2223). In contrast, within cultivated fields the fenceline was significantly higher than that of the field (paired t-test P = .0001). Finally, within cultivated fields there was no significant difference in % SOM between 2002 to 2009 (paired t-test P = .6433). These results suggest that cultivation practices on our farm are effectively maintaining SOM at healthy levels and that pasture management is more successful than cultivation in building SOM. This preliminary data gives us a benchmark by which to evaluate the effect of management practices on SOM.

Nora Purcell
December 7, 2009

Identification and Characterization of Schools in Close Proximity to High Volume Roads in Metropolitan Atlanta, GA

Mentors: Dr. John Brock, Stephanie Foster

Abstract: Proximity to high volume roadways is associated with increased levels of traffic-related air pollutants and, consequently, with increased risk of cardiac, pulmonary, and immunologic morbidities. Children are at an increased risk of adverse health outcomes from exposure to traffic-related air pollution. Similarly, people of color have higher rates of hospitalization for respiratory ailments. Despite this growing body of evidence, many schools are located in close proximity to roadways where they are exposed to elevated levels of air pollution. This study identifies Atlanta schools within 150 m of high volume roads and seeks to determine whether being a public, private, majority African American, or majority Caucasian school is a risk factor for being within 150 m of such a road. School addresses from the National Center for Educational Statistics were geocoded into a GIS. High volume roads, those with >10,000 vehicles per day, were identified by GIS analysis. Using a buffer analysis, 224 of 1162 total geocoded schools were found to be within 150 m of high volume roads. The odds ratio for public schools: private schools is 3.0 (95% confidence interval = 2.1 – 4.4). The odds ratio for majority African American schools: majority Caucasian schools is 1.8 (95% confidence interval = 1.3 – 2.6). These results indicate that not only are a high number of students exposed to elevated levels of traffic-related air pollution based on their schools’ proximity to a high-volume road, but that the effects are not distributed evenly between school types, with public and majority African American schools at greater risk. Given the magnitude and unequal distribution of air pollution exposures identified in this study, possibilities for mitigating the adverse health outcomes in existing schools should be explored and implemented immediately. Additionally, future school construction should consider proximity to high volume roads as a possible health risk.