Master of Science / Department of Agronomy / Romulo P. Lollato / Winter wheat (Triticum aestivum L.) water limited yield potential in Kansas averages 5.2 Mg ha⁻¹; however, state-level yields rarely surpassed 3.4 Mg ha⁻¹. Our objective was to quantify the contribution of individual management practices to reduce wheat yield gaps (YG) economically. An incomplete factorial treatment structure established in a randomized complete block design with six replications was used to evaluate 14 treatments during two years in Manhattan, Belleville, and Hutchinson Kansas. Sites were combined based on tillage practice, growing region in Kansas, and disease pressure. Thus, Manhattan had low disease pressure, was no-tilled, and in eastern Kansas for 2015-16 and 2016-17 (two site years). Meanwhile, Belleville and Hutchinson had high disease pressure, were conventionally tilled, and in central Kansas for 2015-16 and 2016-17 (four site years). We individually added six treatments to a farmer’s practice control (FP) or removed from a water-limited yield control (Y[subscript]w), which received all treatments. Practices were additional split-nitrogen (N), sulfur (S), chloride (Cl), increased plant population, foliar fungicide, and plant growth regulator (PGR). Percent YG was calculated by block and site-year using the Y[subscript]w as reference for potential yield. Orthogonal contrasts indicated yield under no-till which had low disease pressure increased from the FP by the full Y[subscript]w (+0.37 Mg ha⁻¹), but also by the individual practices split-N (+0.28 Mg ha⁻¹), S (+0.26 Mg ha⁻¹), increased plant population (+0.36 Mg ha⁻¹), and fungicide (+0.18 Mg ha⁻¹). In the conventional till which had high disease pressure, wheat yield was increased by 1.18 Mg ha⁻¹ from the Y[subscript]w and by 1.44 Mg ha⁻¹ from the fungicide. The Y[subscript]w and split-N increased grain protein concentration in no-till and conventional-till on average by 9 g kg-1 and 12 g kg-1, respectively. Across all inputs, orthogonal contrasts indicated that the FP yield gap was 8% in no-till which had low disease pressure. Likewise, the orthogonal contrasts indicated that across individual treatments the YG was reduced by split-N (6%), S (5%), Cl (3%), increased plant population (8%), and fungicide (4%). Meanwhile, orthogonal contrasts indicated that the FP yield gap was 20% across all inputs and across individual inputs reduced to 5% from fungicide under conventional-till which had high disease pressure. Fungicide increased net return (+$106.57 ha⁻¹) under conventional-till which had high disease pressure, and increased plant population under no-till which had low disease pressure (+$36.65 ha⁻¹). While a high-cost input (i.e. fungicide) only economically reduced YG greater than 20%; however, a low-cost input (i.e. increased plant population) economically reduced YG less than 20%.

No description available.

Sudden stratospheric warmings (SSWs) are a key driver of winter climate variability in the Northern Hemisphere. SSWs are a disruption of the strong stratospheric westerlies over the winter pole in which the winds in the upper to middle stratosphere, from about 30 to 50 km above the surface, weaken and reverse and the polar cap temperatures increase by up to 50 K in only a few days. These events affect tropospheric conditions for the two months following, on average shifting the North Atlantic storm track equatorward and resulting in a negative Northern Annular Mode and North Atlantic Oscillation at the surface. These changes are associated with colder and drier than average conditions in Northern Europe and Eurasia and warmer and wetter than average conditions across Southern Europe, as well as high temperatures across North Africa, the Middle East, and Central Asia and increased cold air outbreaks in North America and Eurasia. This thesis examines this typical surface response to SSWs in several different contexts. We consider its relationship to other atmospheric phenomena and features, first quantifying its importance relative to the North Atlantic impacts of the El Niño-Southern Oscillation (ENSO) and then examining the role of ozone chemistry in modeling the surface response to SSWs. We also study the variability of the surface signature of SSWs, with the goal of understanding the uncertainty in magnitude and spatial pattern of surface climate patterns following SSWs and the relative roles of different sources of this uncertainty. After providing background and context in the first chapter, the second chapter studies interactions between SSWs and the El Niño phase of ENSO. El Niño affects climate in the North Atlantic and European regions, those most affected by SSWs, through tropospheric and stratospheric pathways. One of these pathways is increased SSW frequency. However, most SSWs (about 90\%) are unrelated to ENSO, and the importance for boreal winter surface climate of this frequency increase compared to other El Niño pathways remains to be quantified. We here contrast these two sources of variability using two 200-member ensembles of one-year integrations of the Whole Atmosphere Community Climate Model, one ensemble with prescribed El Niño sea surface temperatures (SSTs) and one with neutral-ENSO SSTs. We form composites of wintertime climate anomalies, with and without SSWs, in each ensemble and contrast them to a basic state represented by neutral-ENSO winters without SSWs. This approach allows us to isolate the distinct effects of ENSO and SSWs more clearly than was done in previous work. We find that El Niño and SSWs both result in negative North Atlantic Oscillation anomalies and have comparable impacts on European precipitation, but SSWs cause larger Eurasian cooling. These results indicate the potential impact of a strong El Niño on seasonal forecasting in the North Atlantic as well as the importance of resolving the stratosphere in subseasonal and seasonal forecast models to best capture stratospheric polar vortex variability. In the third chapter, we study the importance of interactive ozone chemistry in representing the stratospheric polar vortex and Northern Hemisphere winter surface climate variability. Modeling and observational studies have reported effects of stratospheric ozone extremes on Northern Hemisphere spring climate. Recent work has further suggested that the coupling of ozone chemistry and dynamics amplifies the surface response to midwinter SSWs. We contrast two 200-year simulations from the interactive and specified chemistry (and thus ozone) versions of the Whole Atmosphere Community Climate Model with constant year-2000 forcings. This experiment is thus designed to clearly isolate the impact of interactive ozone on polar vortex variability. In particular, we analyze the response with and without interactive chemistry to midwinter SSWs, March SSWs, and strong polar vortex events (SPVs). With interactive chemistry, the stratospheric polar vortex is stronger, and more SPVs occur, but we find little effect on the frequency of midwinter SSWs. At the surface, interactive chemistry results in a pattern resembling a more negative North Atlantic Oscillation following midwinter SSWs, but with little impact on the surface signatures of late winter SSWs and SPVs. These results suggest that including interactive ozone chemistry in model simulations is important for representing North Atlantic and European winter climate variability. In the fourth chapter, we turn from models to reanalysis and consider the uncertainty in the surface response to SSWs. While the qualitative features of the mean surface signature of SSWs in the North Atlantic and Europe are well-established, its uncertainties as well as other features of surface climate following SSWs are less well-understood. To address the question of robustness of the mean observed response to SSWs, we use bootstrapping with replacement to construct synthetic SSW composites from SSW events in reanalysis, creating an ensemble of composites comparable to the observed one. We then examine the differences across these synthetic composites. We find that the canonical responses of a negative North Atlantic Oscillation and associated temperature and precipitation anomalies in the North Atlantic and European regions in the months following SSWs are robust. However, the magnitude and spatial pattern of these anomalies vary considerably across the composites. We further find that this uncertainty is unrelated to vortex strength and is instead the result of unrelated tropospheric variability. These results have implications for evaluating the fidelity of forecast models in capturing the surface impact of SSWs, by comparing both the mean impact as well as the contribution from internal variability with observations. Overall, we demonstrate the complexity of interactions of sudden stratospheric warmings with other sources of variability in the Earth system. We find that the state of the polar vortex itself, the strength of downward propagation following the SSW, and the surface response can all be affected in important ways by these other components (e.g. tropospheric variability and Arctic ozone). We close by providing broader context for these results and looking towards continuing and future work in the field.

Sustainability of dairy production depends on their production of feed and finding ways to increase profitability through dairy production or even carbon (C) crediting and adding C inputs into the soil to sequester C. To increase farm profitability, dairy producers in Illinois, has intensified their feed production through integrating winter cereals such as winter cereal rye (Secale cereale) (WCR) into single season corn for silage (double cropping). Intensified cropping system allows for increased feed production, covering the soil year-round, and adding C inputs while minimizing nutrient loss mainly through runoff or leaching. Two management practices that improve the sustainability of corn silage – WCR double crop are harvesting date and nitrogen (N) management during the WCR phase of the production. This thesis has two main chapters. Chapter 1 evaluates the effect of harvesting date (five weekly harvest from late-March to early-May) with and without optimum N addition (0 vs. 47 kg N ha-1). Our objective was to evaluate harvesting date and spring N fertilization effect on WCR morphology, forage yield, nutrient removal, and quality. A quadratic model best explained an increase in WCR biomass in response to GDD (growing degree days) accumulation (R2 = 0.81). Increase in GDD linearly decreased WCR relative forage quality (RFQ). Benchmarking RFQ at 150 for dairy milk production indicates that WCR should be harvested at a GDD of 543 at which WCR plant height was 31.8 cm and dry matter (DM) biomass was 0.77 Mg ha-1. Benchmarking RFQ at 125 for heifer production indicated that harvest should occur at a GDD of 668 at which the WCR was 71 cm tall and its DM yield was 2.25 Mg ha-1. Nitrogen balances were negative at the no-N control treatment indicating a need for some N to maximize WCR yield. We found that a rate between 21 and 42 kg N ha-1 maximizes yields reflecting on slightly positive balances. Our results suggest that harvesting date can be predicted by GDD and should be adjusted for RFQ. We conclude that smaller than 42 kg N ha-1 N fertilizer is required for WCR production in soils with manure history and high soil organic matter (>30 g kg-1). Chapter 2 hypothesized that N fertilization of WCR as cover crop can increase nutrient recycling and C sequestration which offers C trading benefits to growers. We evaluated the effects of N fertilizer application in fall (0 vs. 56 kg N ha-1), and N fertilizer rates in spring (0, 23, 47, and 71 kg ha-1) on WCR dry matter (DM) biomass and cover crop quality. Results indicated that fall N fertilization had no effect on WCR biomass or quality reflecting on loss of applied N in the fall. Spring N application did not affect WCR biomass yield but increased N, P, and K concentrations, their uptake, C concentration, and decreased C:N and lignin:N ratios. We concluded that only spring N fertilization improves WCR cover crop benefits. Overall, we suggest that for high-quality forage, (RFQ at 150) WCR should be harvested at a GDD of 543 at which WCR plant height was 31.8 cm and dry matter (DM) biomass was 0.77 Mg ha-1. For RFQ of 125 (for heifer production), harvest should occur at a GDD of 668 at which the WCR was 71 cm tall and its DM yield was 2.25 Mg ha-1. Neither in fall nor in spring, N fertilization increase WCR C accumulation. Spring N fertilization reduces WCR C:N and lignin:N which are desirable for crop production.

No description available.

No description available.

Wheat production in the Pacific Northwest consists mainly of the soft white wheat market class. Over 80% of this wheat is exported. In recent years there has been an increase in soft white wheat production (due in a large part to improvements in the yielding capabilities of the genotypes grown in the Pacific Northwest). To expand into different commodity markets, it would be desirable to diversify and produce wheat cultivars representing more market classes and product uses. One opportunity would be to develop cultivars representing the Hard Red Winter market class. An effort to breed high yielding, high protein Hard Red Winter wheats is now underway at Oregon State University. This research was conducted to gain a better understanding of the components (genetic and/or environmental) that determine yield and grain protein content of hard red wheat genotypes. There were two general objectives of the research. One was to study the differences in nitrogen assimilation and remobilization in a diverse group of winter wheat genotypes grown in the different agricultural environments of Oregon. The second objective was to determine the efficacy of using "hill plots" (micro-plots) as a planting method to screen for agronomic and nitrogen assimilation traits in geneticly distinct genotypes which may be used as parents in breeding efforts. Results of this study indicate that genetic differences for nitrogen assimilation and remobilization do exist, and improvements in Pacific Northwest hard red wheat genotypes can be made with appropriate selection techniques. Data also indicate that the traditional high protein wheat genotypes (from the U.S. Great Plains) do not show an advantage from a grain protein concentration standpoint when produced in the Pacific Northwest. Additionally, the environment played a critical role in determining expression of harvest index, grain protein concentration, and nitrogen harvest index. Genotype by environment interactions were high, suggesting that zone-specific varieties may need to be developed in order to attain both high grain yields and high grain protein yields. / Graduation date: 1992

It has been established in New Zealand and internationally that morbidity and mortality tends to rise during colder winter months, with a typical 10-20% excess compared to the rest of the year. This study sought to investigate the spatial, temporal, climatic and demographic patterns and interactions of excess winter morbidity (EWMb) among the elderly in New Zealand. This was achieved through analysis of acute hospital admissions in New Zealand between 1996 and 2013 for all patients over the age of 60 with an element of circulatory or respiratory disease (N=1,704,317) including a primary diagnosis of circulatory (N=166,938) or respiratory (N=62,495) disease. A quantitative approach included ordinary least squares and negative binomial regression, graphical analysis and age standardisation processes. Admission rates and durations were regressed against a set of 16 cold spell indicators at a national and regional scale, finding significant spatial variation in the magnitude of EWMb. EWMb was ubiquitous across New Zealand despite climatic variation between regions, with an average winter excess of 15%, and an excess of 51% for chronic obstructive pulmonary disease (COPD). Statistically significant relationships were found between hospital admission durations and cold spells up to 28 days prior; however the magnitude would not be expected to have a significant impact on hospital resources. Nonetheless, there is potential for preventative public health strategies to mitigate less severe morbidity associated with cold spells. Patients over the age of 80 were particularly vulnerable to EWMb; however socioeconomic deprivation and ethnicity did not affect vulnerability. Patients residing in areas of high socioeconomic deprivation or identifying with Maori or Pacific Island ethnicity experienced significantly shorter admissions than other groups, and this warrants further investigation. Further investigation into winter COPD exacerbations and non-climatic factors associated with the EWMb are recommended. A comprehensive understanding of EWMb will enable preventative measures that can improve quality of life, particularly for the elderly population.

The frequency, magnitude, and atmospheric drivers of winter hydroclimatic conditions conducive to snowmelt in western Canada were evaluated. These hydroclimatic variables were linked to the mid-winter break-up of river ice that included the creation of a comprehensive database including 46 mid-winter river ice break-up events in western Canada (1950-2008) and six events in Alaska (1950-2014). Widespread increases in above-freezing temperatures and spatially diverse increases in rainfall were detected over the study period (1946-2012), particularly during January and March. Critical elevation zones representing the greatest rate of change were identified for major river basins. Specifically, low-elevation (500-1000 m) temperature changes dominated the Stikine, Nass, Skeena, and Fraser river basins and low to mid-elevation changes (700-1500 m) dominated the Peace, Athabasca, Saskatchewan, and Columbia river basins. The greatest increases in rainfall were seen below 700 m and between 1200-1900 m in the Fraser and at mid- to high-elevations (1500-2200 m) in the Peace, Athabasca, and Saskatchewan river basins. Daily synoptic-scale atmospheric circulation patterns were classified using Self-Organizing Maps (SOM) and corresponding hydroclimatic variables were evaluated. Frequency, persistence, and preferred shifts of identified synoptic types provided additional insight into characteristics of dominant atmospheric circulation patterns. Trend analyses revealed significant (p < 0.05) decreases in two dominant synoptic types: a ridge of high pressure over the Pacific Ocean and adjacent trough of low pressure over western Canada, which directs the movement of cold, dry air over the study region, and zonal flow with westerly flow from the Pacific Ocean over the study region. Conversely, trend analyses revealed an increase in the frequency and persistence of a ridge of high pressure over western Canada over the study period. However, step-change analysis revealed a decrease in zonal flows and an increase in the occurrence of high-pressure ridges over western Canada in 1977, coinciding with a shift to a positive Pacific Decadal Oscillation regime. A ridge of high pressure over western Canada was associated with a high frequency and magnitude of above-freezing temperatures and rainfall in the study region. This pattern is highly persistent and elicits a strong surface climate response. A ridge of high pressure and associated above-freezing temperatures and rainfall was also found to be the primary driver of mid-winter river ice break-up with rainfall being a stronger driver west of the Rocky Mountains and temperature to the east. These results improve our understanding of the drivers of threats to snowpack integrity and the generation of extreme hydrologic events. / Graduate

An increase in cycling mode share and cycling performance is an essential part of future transport development (Buehler and Pucher 2011; Schwanen 2015). In order to achieve the climate goals of the Federal Republic of Germany, the share of cycling must be significantly increased (BMVI 2021). An important part of this is to make cycling safe also in harsh weather conditions as seen in winter. While cycling mode shares have increased in the other seasons in recent years, a slump in cycling performance can be observed especially in winter (Nobis 2019). Studies to date have attributed this to weather conditions (temperature, precipitation) (Winters et al. 2011) and, above all, to the declining subjective feeling of safety among cyclists. Many German municipalities are therefore working on a winter service concept for cycling in order to mak.e cycling safe even in winter conditions. ... Therefore, an environmentally sound alternative for winter maintenance on segregated cycle paths that is acceptable to cyclists must be found. In many German cities but also globally, the challenge is to find a balanced solution between environmental protection and safe cycling. However, possible alternatives have to go through an approval process before they can be used. To solve those questions, we conducted several surveys which are summarized in this paper. lt consists of five sections: Section 2 highlights the wishes and demands on cycling(infrastructure) in winter from the cyclists' point of view. In section 3, the current state of winter maintenance in German cities is reviewed. Section 4 describes the selection and ecological footprint of alternative gritting materials, while section 5 describes the experiences of users in a field test. [From: Introduction]