The effect of serial (multiple-year) organic matter (OM) amendment on soil properties has been described in some cropping systems, although less is known about the effect of serially amended field soils on soil-borne plant diseases. The objectives of this study were to describe the effects of the third and fourth years of annual, serial amendment with dairy manure solids on 1) soil physical and biological properties and 2) severity of sweet corn root rot. Plots were amended with five rates of separated dairy manure solids annually for three years. In the fourth year, plots were split and only half of each plot was re-amended. Soil physical properties [bulk density, free and occluded particulate organic matter (POM), soil water retention, total porosity, gravimetric moisture content] and biological properties [microbial activity (as hydrolysis of fluorescein diacetate; FDA) and microbial biomass-C] were assessed each year in all treatments. Root rot severity was assessed in situ and in the greenhouse with multiple sweet corn (Zea mays L. cv Golden Jubilee) bioassays conducted in the amended field soils. Necrosis of the radicle and nodal roots was assessed when plants reached the 6- leaf stage. Amendment rate was positively associated with increases in soil properties that serve as indicators of soil quality, such as POM content, total porosity, microbial biomass, and FDA activity. In the third year after amendment, weak root rot suppression was observed in-field and was associated with FDA activity. By the fourth year of serial amendment this trend was no longer evident, however evidence from the high-rate treatment that was not re-amended (3HNRA) pointed to an emerging suppressive mechanism that persisted up to 13 months after the third amendment. Factors that may be interacting over time to generate observed disease suppression in these serially amended soils include: short-term post-amendment microbiostasis, soil moisture retention, inoculum potential, and a novel suppressive mechanism. / Graduation date: 2006

A tidal and sea level survey was begun in Yaquina Bay, Oregon, on 8 May, 1964. A continuous recording tide gage was installed at the pier of the Oregon State University Marine Science Center. An harmonic analysis of the observed data was made, and the major tidal constants were compared with those published by the Coast and Geodetic Survey. A program was written for the IBM 1410 computer, so that the tide could be predicted at any time using the tidal constants for the Newport area. An investigation of the "meteorological tide" was made by comparison of the predicted and observed tides. River stage, sea level variation, barometric pressure, and wind were considered. Lastly, a comparison was made between the predicted tide at Newport and the predicted maxima and minima of the tide at Newport as determined using the Coast and Geodetic Survey's tide table. / Graduation date: 1965

Graduation date: 1979

Graduation date: 1983

Graduation date: 1942

Graduation date: 1971

Graduation date: 1974

Graduation date: 1974

Graduation date: 1975

Graduation date: 1975