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A test of the differentiation of soil series within the Willamette catenaPomerening, James A. 10 June 1960 (has links)
Graduation date: 1961
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A statistical study of the correlation between the surface and surface geostrophic winds in the Wilamette ValleyAndrews, Leta 23 October 1974 (has links)
Relationships among the surface wind, horizontal synoptic-scale
pressure gradient and topography are studied in the Willamette Valley
in western Oregon. Terrain features alter the standard surface wind-pressure
gradient relationship such that the angle between the surface
wind and the surface geostrophic wind is most frequently 60°.
In winter the surface flow is predominantly southerly and surface
geostrophic flow varies from southerly to westerly. Little diurnal
change occurs in the average surface wind, the average surface
geostrophic wind and their relationship with each other because the air
in the valley is generally stably stratified throughout the day.
Partially in response to the northward extension of the subtropical
anticyclone summertime surface winds and surface geostrophic
winds are northerly, except during afternoon episodes of
marine air invasion when surface winds are westerly. The pressure
gradient is 88% less intense in summer but the ratio of the magnitudes
of the surface wind and surface geostrophic wind, R, is 125%
greater than in winter. However, a sharp summertime morning
maximum in R of -0.67 is diminished by early afternoon as differential
surface heating establishes a strong afternoon pressure
gradient.
When the surface geostrophic wind vector is cross-valley, the
surface wind is still most frequently parallel to the valley and the
surface geostrophic wind speed is largest and most variable.
Because of the importance of terrain and meso-scale events,
little correlation between the surface winds and synoptic-scale pressure
gradient is found. / Graduation date: 1975
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Nitrogen available to winter wheat as influenced by previous crop in a moist xeric environmentQureshi, Maqsood Hassan 06 April 1999 (has links)
Rotating wheat with other crops is a common practice in the Willamette Valley of
western Oregon. Depending upon previous crop and soil type, current N fertilizer
recommendations for wheat in the Willamette Valley vary widely. Excessive fertilizer
poses environmental risk, whereas lower N inputs than required by the crop represent
economic losses to growers. Growers and their advisors face the challenge to minimize
the environmental risk, and at the same time to maintain or increase economic returns.
Questions are often raised concerning the efficient use of N fertilizer and accurately
predicting the amount of N needed by wheat following different crops.
The first study measured growth, N uptake and N use efficiency (NUE) of winter
wheat grown after either a legume or oat for three years. In all three growing seasons,
winter wheat showed higher biomass, N uptake and NUE when grown after a legume
than after oat. The contribution of legume was evident before the wheat was fertilized in
spring, indicating that legume N had mineralized in fall or winter.
Contribution of soil N to wheat suggested that fertilizer N can be reduced by 44 kg N ha�����
if a legume is grown previously. Nitrogen use efficiency estimated 50 to 70 days after N
application by isotopic method (24 to 94%) was comparable with that estimated simply
by difference (21 to 94%) at the same time.
The second study predicted gross mineralization rates using analytical models.
Comparable N mineralization was predicted by a model assuming remineralization and a
model assuming no remineralization, suggesting that remineralization was negligible. In
the spring, mineralization-immobilization turnover was at a lower pace than expected in
both rotations. In two growing seasons, gross mineralization rates were higher where the
previous crop was legume (0.37 to 0.74 kg����� ha����� day�����) as compared to where oat was
grown previously (0.14 to 0.6 kg����� ha����� day). Negative net mineralization indicated that
fertilizer N was immobilized in the oat-wheat rotation.
The third study evaluated calibration and digestion techniques used to determine
elemental concentration in grasses. Use of a dry ashed standard to calibrate the ICP
spectrometer generated highly variable calibration curves and was not a viable calibration
method. Good agreement was found between chemical and microwave digested
standards. Dry ashing resulted in considerable S and Mn losses, whereas, perchloric acid
digestion and microwave digestion showed similar results. Our study suggests that if
routine analysis are to be performed for macro nutrients or involve trace level work, the
best method is microwave digestion with chemical standard calibration of ICP
spectrometer. / Graduation date: 1999
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Population characteristics of exotic plants in a Willamette Valley native prairieLantz, Lisa E. 25 April 1997 (has links)
Graduation date: 1998
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Influence of movement corridors on enclosed populations of the gray-tailed vole : do immigrants affect reproduction and dispersal of residents in a patchy environment?Davis-Born, Renee 08 April 1997 (has links)
I monitored demography, movement, and reproductive behavior of gray-tailed voles, Microtus canicaudus, in experimental habitat patches with and without corridors. I tested the hypotheses that reproductive rate, juvenile recruitment, and population size and growth rate would be affected negatively by immigrants that were introduced to resident groups (+ male and + female treatments). I hypothesized that "strangers" would commit infanticide thus decreasing juvenile recruitment. Second, I determined if movement corridors facilitated dispersal among habitat patches, thus potentially increasing infanticide, but decreasing reproductive inhibition of opposite-sex relatives by allowing them to separate (corridor treatment). Experiments were conducted in 12 0.2 ha enclosures planted with alfalfa that was fragmented into four patches (each 156 m��) separated by 12.5 m of bare ground. Introduction of unfamiliar conspecifics did not adversely affect reproductive rate, juvenile recruitment, population size, density, or growth rate. Corridors facilitated dispersal movements with males moving more than did females; however, corridors did not result in an even distribution of animals in the four patches. Unconnected habitat patches resulted in female- rather than the typical male-biased dispersal and females dispersed at lower body mass than in controls. Males that did not disperse from their natal patch exhibited a slight delay in sexual maturation.
I conclude that movement is deterred in patchy environments, enhanced with corridors, and differentially affects males and females. Behavioral factors that affect an individual's dispersal or reproductive pattern should be considered in landscape planning. / Graduation date: 1997
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Evaluation of soil and plant analyses as components of a nitrogen monitoring program for silage cornMarx, Ernest S. 21 August 1995 (has links)
Graduation date: 1996
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Pollination and pollinators of pumpkin and squash (Cucurbita maxima Duchesne) grown for seed production in the Willamette Valley of western OregonGavilánez-Slone, Jenny M. 29 August 2000 (has links)
'Golden Delicious' winter squash (GDWS), Cucurbita maxima Duchesne,
provides significant amounts of pollen (24 mg) and nectar (236 μl), but with a low
reward of 14% nectar sugar. The quantity of nectar produced per GDWS flower
differed between sites and floral sex. The GDWS male flowers had 25% higher
sugar concentration than female flowers. There was no statistical difference in the
percent of nectar sugars per flower between sites, but the interaction between site
and floral sex was statistically significant for the amount of nectar and percent of
nectar sugars. Pollen production per flower differed significantly between sites
with the most productive site producing 27% more, and 45% more than the other
sites.
Pollination efficiency of honeybees and bumble bees was assessed with
field cages (1.8x1.8x1.8 m). No significant differences were found except for the
interaction between the bee treatment and year on number of fruit per cage. This
significant difference reflects the increase in fruit number produced by honey bees
in 1997.
The effect of distance from honey bee hives on fruit and seed quality was
tested, and found significant only for B- and C-seeds weight, which were both less
in the plots farthest from the nearest group of honey bee hives. Placement of honey
bee hives in fields of ≤120 ha appears not to be critical for adequate pollination of
GDWS. Other pollinators (excluding honey bees) were frequent visitors to the
squash flowers studied here - for example, Bombus spp., Megachilids, Halictids,
etc. These other pollinators, mostly bumble bees, accounted for 3.55% of all bee
visits.
Honey bees visited proportionately more female flowers in the morning,
and progressively switched to the more abundant male flowers in the afternoon.
This bias differed by site and year. Bumble bees visited proportionally slightly
more male GDWS flowers than did female flowers and did it in a similar rate
throughout the day. From 15 minute observations each hour of individual female
GDWS flower, we calculated that they received approximately 80 honey bee visits
per day. / Graduation date: 2001
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Arsenic Mobilization from Silicic Volcanic Rocks in the Southern Willamette ValleyFerreira, Gabriela Ribeiro de Sena 31 March 2016 (has links)
Volcanic tuffs and tuffaceous sediments are frequently associated with elevated As groundwater concentrations even though their bulk As contents (~ 5 mg kg-1; Savoie, 2013) are only marginally greater than the average crustal abundance of 4.8 mg g-1 (Rudnick & Gao, 2003). Thus, As mobilization must be facilitated by conditions particular to these rocks. Alkaline desorption, anionic competition, reactive glass dissolution, and reductive dissolution of iron oxides are proposed processes of As release from volcanic rocks. Geogenic As contamination of groundwater in the southern Willamette Valley in western Oregon has been well-documented since the early 1960s, and previous studies have identified the Little Butte Volcanics Series and Fisher and Eugene Formations as the source of As contamination.
This study examines 19 samples from 10 units of ash flow tuffs and tuffaceous sediments within the Fisher Formation and Little Butte Volcanics Series, representing a range of weathering and devitrification, to determine conditions of mobilization and mineralogical constraints that control As release into solution. Leachate studies were conducted over a range of pH from 7 to 11, phosphate concentrations from 10 μM to 100 mM, and in time series from 4 to 196 hours. Results demonstrate that silicic volcanic tuffs are capable of mobilizing As in concentrations above regulatory limits at pH conditions produced naturally by the tuffs (pH 8-9) or with moderate concentrations of P (10-100 μM). Alteration products, e.g. zeolites and clays, appear to be the primary host phases for mobile As. Samples that do not contain these alteration products tend to produce concentrations of As well below regulatory limits and often below the instrument detection limits of this study. The type of alteration may influence As mobilization: tuffs containing more clays tend to mobilize As through surficial desorption, and tuffs containing more zeolites tend to mobilize As by dissolution or formation of colloids. Additionally, one volcaniclastic sample demonstrates that extremely elevated concentrations of As, up to 1000 μg/L are possible as a result of oxidative dissolution of As-bearing sulfide phases.
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Bird use of revetted riverbanks in the Willamette ValleyPerry, Clifford Brian 01 January 1977 (has links)
Over 115 miles of rock revetments that serve to protect river banks have been constructed in the Willamette Basin. In this study the spring and summer bird use of Willamette Basin revetments is examined. Revetments that had not been recently cleared of most woody vegetation and blackberries were found to have significantly greater total and breeding bird use than cleared revetments. Possible factors affecting bird use, such as vegetation on revetments and vegetation adjacent to revetments are examined using linear regression analysis. The results of this study are compared with results of previous work in riparian forests along the Columbia River. It is concluded that revetments represent significant avian habitat, especially for "edge species," and that present maintenance practices involving removal of vegetation adversely affect bird use.
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Residue management and yield characteristics of fine fescue seed cropsSchumacher, Derek David 29 April 2005 (has links)
Chewings fescue [Festuca rubra L. subsp. fallax (Thuill.) Nyman] is a desired
turfgrass with dense sod forming capabilities and superior shade tolerance. Thermal
residue management (open-field burning) has traditionally been used to remove post-harvest
residue and maintain seed yield over the life of the stand. However, alternative
non-thermal residue management practices have been observed to produce adequate
seed yields dependent upon cultivar.
Strong creeping red fescue (F. rubra L. subsp. rubra) is desired for
its prolific tillering capacity and creeping rhizomatous growth habit. In contrast to
Chewings fescue, maintenance of seed yield in strong creeping red fescue has only
been profitably produced under thermal residue management. Slender creeping red
fescue [F. rubra L. var. littoralis (Vasey)] is a desired turfgrass with a compact, less
rhizomatous growth habit, similar to Chewings fescue in desirable turf attributes.
However, little is known about the effects of post-harvest residue management in
slender creeping red fescue.
The objectives of this study were: 1) to evaluate seed yield and yield
components among different cultivars to thermal (open-burning), and non-thermal
(flail low and flail high) post-harvest residue management; 2) to evaluate harvest
index and percent cleanout to thermal and non-thermal residue management in
different cultivars; and 3) and to provide an economic analysis of thermal and non-thermal
residue management in all cultivars based on partial budgeting.
Three post-harvest residue management treatments (burn, flail low and flail
high) were applied over the course of two years. Seed yield components measured
included: total dry weight, fertile tiller number, spikelets per panicle, florets per
spikelet, and panicle length. Final seed yield in each cultivar and residue management
treatment method was determined after seed harvest and conditioning. Seed yield
component analysis was conducted over three production seasons.
Chewings fescue, strong creeping red fescue, and slender creeping red fescue
cultivars responded differently to residue management as indicated by a residue
management by cultivar interaction. In 2003 and 2004, residue management by
cultivar interactions were evident in seed number, seed weight, fertile tiller number,
percent cleanout, harvest index, and seed yield. Residue management by cultivar
interactions occurred in spikelets per panicle in 2003, whereas in 2004 a residue
management by cultivar interaction occurred in panicle length and florets per spikelet.
In 2004, non-thermal flail low, and thermal residue management resulted in
significantly greater spikelets per panicle in all cultivars. Thermal residue management
resulted in the greatest number of spikelets per panicle.
Results indicate that thermal residue management best maintained seed yield in
most subspecies and cultivars across both years. However, in 2003, non-thermal flail
low residue management produced profitable seed yield in only Marker slender
creeping red fescue. In contrast, thermal residue management resulted in poor seed
yields in Marker slender creeping red fescue and enhanced yields in Seabreeze slender
creeping red fescue in 2003. However, following the second year of thermal treatment
in 2004, Marker and Seabreeze both had lower seed yields, thus exhibiting the only
negative impact of thermal management among the cultivars tested in this study.
Moreover, upon review of an economic analysis, Marker slender red fescue was the
only cultivar that produced a positive net return of $78 and $4 ha⁻¹ under non-thermal
residue management in 2003 and 2004, respectively. Furthermore, in 2003, thermal
residue management net return increases ranged from $104 ha⁻¹ to -$996 ha⁻¹ in
Barnica and Shademark, respectively. In 2004, thermal residue management net return
increases ranged from $115 ha⁻¹ and $1,332 ha⁻¹ in Seabreeze and Shademark,
respectively.
Poor seed yields were observed in all strong creeping red fescue cultivars
under non-thermal residue management across both years of the study. This may be
attributed to an observed reduction in fertile tiller number and seed yield. In addition,
percent seed cleanout was increased with non-thermal residue management. In 2004,
as stand age increased, thermal residue management resulted in greater seed yields in
all cultivars and species, except both cultivars of slender creeping red fescue. Thus,
this study provided substantial evidence that thermal residue management has the
potential to maintain or increase fine fescue seed yield as stands age as well as to
maintain stand profitability. / Graduation date: 2005
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