There are two major problems associated with soil acidity and lime response investigations: A. Determining how much lime (100% "available" CaCO��� equivalent) is required to raise a soil pH (or degree of acidity) from its existing level to a specified level - presumably where need for lime is eliminated. B. Determining responses of different crops on different soils to lime; and defining some chemical measurement of the soil that will predict the response of a specified crop. Investigations in this study were limited to the first problem. Liming characteristics of 45 acid Willamette Valley soils, representing the major agricultural soil associations, were determined by incubating the soils with increments of CaCO���. The lime required to bring the soils to the specified pH levels of 6.8, 6.4 and 6.0 varied widely within the respective pH levels. Relationships between soils, however, as determined by the value of the incubation curve slope (meq. of CaCO��� /100g of soil required to raise soil pH by one unit), were improved by grouping into related soils. Laboratory measurements of other soil chemistry parameters were compared with changes in pH to determine if a satisfactory quick laboratory procedure could be developed to measure the incubation lime requirement of soils with different chemical characteristics. Measurements of soil pH were made by three different methods: (1) in the supernatant of a 1:2 soil to water suspension; (2) in the sedimented paste of the 1:2 soil to water suspension; and (3) in the supernatant of a 1:2 soil to 1 N KCl suspension. Lime requirement with a buffered solution was measured in limed and unlimed soils by use of the SMP (Shoemaker, McLean, and Pratt) buffer method. Soil samples treated with increments of lime were analyzed for extractable Al and exchange acidity by titration and the unincubated soils were analyzed for exchange acidity determined by subtracting exchangeable bases from CEC measured at pH 7. 0 and pH 6. 0. Results of the correlation analyses showed that the SMP buffer method should prove useful for predicting the incubation lime requirement. Correlation coefficients for these two values were .89, .90 and 86, respectively, to reach pH levels of 6.8, 6.4 and 6.0. Soil pH measurements, extractable Al, and exchange acidity determinations did not provide as good a basis for determining incubation lime requirements, Regression equations were calculated for the SMP buffer/incubation lime requirement relationships. The purpose of this study was to identify the changes in soil chemical measurements that take place with application of lime. No attempt was made to determine whether a crop might respond to an application of lime on an acid soil. The assumption was made that yield could be related to specific pH or soil acidity levels that could be measured in the laboratory. Therefore, the problem was approached by studying procedures that might determine the application of lime required to reach a specified pH or soil acidity measurement. It anticipated that field trials for evaluating lime response will be carried out in the future to evaluate the usefulness of the SMP buffer method which showed promise in this regard. / Graduation date: 1972

Graduation date: 1997

This research consists of two related yet distinct studies: an observational study of the surface character of the penetration of marine air into the southern Willamette Valley and a climatological study of the summertime air masses of northwestern Oregon. For the observational study, temperature and estimated wind data were gathered by automobile. Mesoscale analysis of several cases indicate that the Marine Air Penetration (MAP) occurs regularly in approximately the same area and is strongly controlled by the topography. Qualitative observation and reasoning strongly suggests that the strong winds and increased stability at the top of the marine layer have an adverse effect upon agricultural field fires. Results of the climatological study indicated that the application of the partial collective method of analysis to July maximum temperature data from the U.S. Climatological Network yielded a meaningful air mass climatology for northwestern Oregon. To our knowledge, this is the first time that the partial collective method has been applied to a region with mountainous areas west of the Rocky Mountains or to the mesoscale. / Graduation date: 1981

Graduation date: 1999

Graduation date: 1997

Large scale disruption of natural habitats worldwide has led to concern over the effects of habitat fragmentation on wildlife populations. Small scale experiments may be a useful tool for discovering effects of fragmentation over larger landscape scales. I sought to explore the potential for using voles as an experimental model system, at a small scale, to discover mechanisms that may affect other species at different spatial scales. I compared over-winter demography of gray-tailed voles, Microtus canicaudus, in two experimental landscapes, consisting of fragmented and continuous habitat, to assess the effects of habitat fragmentation. I chose winter as the time frame of the experiment because it poses harsh conditions for voles and because seasonal bottlenecks may affect population persistence. Population size, population growth rates, reproduction, recruitment, survival and movements, were monitored using mark-recapture methods in 8, 0.2-ha enclosures planted with alfalfa. The habitat within the enclosures was manipulated into 2 configurations of equal area, 1 large continuous patch (625 m��), and a mosaic of 25 small patches (each 25 m��), prior to the introduction of 12 pairs of animals/enclosure. I hypothesized that population size and growth rates, reproduction, recruitment, and survival would be greater for vole populations in continuous habitats than for populations in fragmented habitats. Additionally, I hypothesized that movements would be more restricted within fragmented habitat because the voles would perceive the area between habitat patches as a barrier. I did not detect significant differences between vole populations in continuous and fragmented treatments. However, populations residing in fragmented habitat showed higher variability over the study period. Populations in both treatments decreased throughout the winter period and all became extinct by the end of the study. Reproduction occurred only during the fall period, and there were no significant differences between treatments. Movements were not different between treatments, or between male and female voles, but movements did increase over time. Survival appeared to be higher for male voles in continuous habitat than in fragmented habitat, but female vole survival was similar between treatments. Survival was influenced by weather conditions, and predation. These results contrast with a previous experiment during the summer season, and indicate that seasonal bottlenecks may be important to consider when studying habitat fragmentation. Extinction of populations in both treatments demonstrates that small populations are extremely vulnerable to both environmental and demographic stochastic events. / Graduation date: 1997

Fiber flax (Linum usitatissimum L.) production in the Willamette Valley ended in Oregon around 1957 before newly developed technology and fiber cultivars were available. The purpose of this research was to explore the use of modern methods and new cultivars. Field studies were conducted to evaluate cultivars and optimum cultural practices that would produce the highest yield and best fiber quality in the Willamette Valley on Woodburn silty clay loam. A study was conducted to assess the winter hardiness of fifty flax cultivars. The effect of four different pull dates on straw and fiber yield and fiber quality were investigated at two sites in 1995 and 1996. Pulling in stage 2, 3, or 4 resulted in an increase in straw yield over pulling in stage 1 in 1996. No differences were detected in fiber yield or caustic weight loss in response to pull date in either year. An acceptable pulling window is stages 1-3 (range of 900 to 1300 growing degree days). Retting took 13 weeks in both years. Rainfall during the retting period was 10.7 cm in 1995 and 6.9 cm in 1996. A field study was conducted in 1995 and 1996 to test the effect of three nitrogen (N) levels (50, 75, and 100 kg ha�����) and three fiber flax cultivars (Ariane, Cascade, and Viking) on straw yield. There was a significant increase in yield with increased N levels in 1996. Higher levels of N increased yield in all three cultivars in both years. Lodging of 'Cascade' increased with increased N levels in 1995. The effect of three planting dates on yield and stand density of Ariane fiber flax were investigated in 1995. The 31 March planting date produced the most retted straw (9704 kg ha�����). A fall-planted winter cultivar experiment was conducted during 1994-95 and 1995-96. In 1994-95, four varieties (Ariane, Texala, Viking, and Hyslop Cascade) had greater winter survival than Linore, the check variety. Only Linore withstood the second winter. / Graduation date: 1997

Graduation date: 1994

xiii, 67 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / The bedrock aquifer of the Southern Willamerte Basin, Oregon, USA, is contaminated with arsenic at concentrations as high as several ppm. Single-well push-pull tests were conducted to investigate how microbial metabolisms control arsenic occurrence and levels in the aquifer. Test solutions containing ethanol were injected into the aquifer; dissolved gases, groundwater, and sediments were then sampled to monitor the speciation of carbon, iron, sulfur, and arsenic. Ethanol amendment stimulated a series of microbial metabolisms, including arsenate reduction, iron reduction, and sulfate reduction. Arsenate reduction converts arsenate to arsenite; iron reduction produces ferrous iron; sulfate reduction releases sulfide. Arsenite and ferrous iron then combine with sulfide and form arsenic sulfide and iron sulfide minerals. Results of the experiments demonstrate that the interactions among microbial metabolisms and mineral precipitation influenced arsenic contamination in the aquifer. These results shed new light on potential bioremediation strategies in the area. / Committee in Charge: Dr. Qusheng Jin, Chair; Dr. Mark Reed; Dr. Samantha Hopkins

During the summer of 1974 chemical conditions in the lower reaches of the Willamette River, Oregon were similar to those in other rivers currently experiencing nuisance algal growth problems. Temperature and chemical nutrients are not limiting. Relatively high populations of phytoplankton and productivity values for upstream periphyton beds and surface waters suggest moderately eutrophic conditions. However, with increased depth in the lower river, and a constant euphotic zone, the amount of photosynthetically available light is reduced. With sufficient depth and complete mixing the critical depth is exceeded. Primary productivity rates are subsequently limited by low light availability in the lower river.