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.