Stringent pollutant regulations on diesel-powered vehicles have resulted in the development of new technologies to reduce emission of nitrogen oxides (NOx). The urea Selective Catalyst Reduction (SCR) system and Lean NOx Trap (LNT) have become the two promising solutions to this problem. Whilst the LNT results in a fuel penalty due to periodic regeneration, the SCR system with aqueous urea solution or ammonia gas reductants could provide a better solution with higher NOx reduction efficiency. This thesis describes an experimental investigation which has been designed for comparing the effect NOx abatement of a SCR system with AdBlue urea spray and ammonia gas at 5% and 4% concentration. For this study, a SCR exhaust system comprising of a diesel particulate filter (DPF), a diesel oxidation catalyst (DOC) and SCR catalysts was tested on a steady state, direct injection 1998 cc diesel engine. It featured an expansion can, nozzle and diffuser arrangement for a controlled flow profile for CFD model validation. Four different lengths of SCR catalyst were tested for a space velocity study. Chemiluminescence (CLD) based ammonia analysers have been used to provide high resolution NO, NO2 and NH3 measurements across the SCR exhaust system. By measuring at the exit of the SCR bricks, the NO and NO2 profiles within the bricks were found. Comparison of the measurements between spray and gas lead to insights of the behaviour of the droplets upstream and within the SCR bricks. From the analysis, it was deduced that around half to three quarters of the droplets from the urea spray remain unconverted at the entry of the first SCR brick. Approximately 200 ppm of potential ammonia was released from the urea spray in the first SCR brick to react with NOx. The analysis also shows between 10 to 100 ppm of potential ammonia survived through the first brick in droplet form for cases from NOx-matched spray input to excess spray. Measurements show NOx reduction was complete after the second SCR bricks. Experimental and CFD prediction showed breakthrough of all species for the short brick with gas injection due to the high space velocity. The long brick gas cases predictions gave reasonable agreement with experimental results. NO2 conversion efficiency was found higher than NO which contradicts with the fast SCR reaction kinetics. Transient response was observed in both cases during the NOx reduction, ammonia absorption and desorption process. From the transient analysis an estimate of the ammonia storage capacity of the bricks was derived. The amount of ammonia slippage was obtained through numerical integration of the ammonia slippage curve using an excel spreadsheet. Comparing the time constant for the spray and gas cases, showed a slightly faster time response from the gas for both NOx reduction and ammonia slippage.

Winter wheat, with an annual average acreage of about 300,00o acres, forms an integral part of the farm economy of Utah. For many years intermountain agronomists and farmers alike have known dry-land wheat production to be limited by low summer rainfall. In the past 15 years, however, it has become apparent through intelligent research that in many cases lack of nitrogen has been the limiting factor. When this occurs, winter wheat production can be increased by correcting this nitrogen deficiency. It has also become apparent that a lack of nitrogen is responsible for much of the ppor quality wheat received by wheat processors form certain areas of the United States. To supple the neede nitrogen broth commercial fertilizers and green-manure crops have been used, but of particular importance at this time are commercial fertilizers. Unitl 1949 investigators of this problem used soil applications of either organic or inorganic nitrogen fertilizers in their studies. In that year Finney and Shellengerger (Kansas State College) began the first of their tests using "NuGreen" a synthetic urea fertilizer containing 44% nitrogen, as a foliage spray. Other experiemtns have shown that if large amounts of nitrogen fertilizer are added to dry farm wheat during a dry year, the yield may actually be reduced because the early vegetative growth is stimulated and the limited soil moisture is not able to bring about satisfactory maturity. It would seem that if nearly all of the nitrogen were withheld until the what was nearly mature, and then added as a spray, the danger of excessive early stimulation might be avoided while the protein content of the wheat might be increased. The results obtained by all of these tests were encouraging enough to warrant a study here in Utah of winter wheat fertilization involving the use of "NuGreen". It was proposed that the study be conducted on dry lands representative of intermountain conditions, and that it cover a two-year period. It was inteded that in the first year a preliminary of "feeler" test would be conducted to determine whether or not it was feasible to spray nitrogen on wheat. The intent was, that if favorable resutls were secured, this preliminary test would be followed in the second year by a more extensive study to obtian detailed information as to what effect urea spray might have on winter wheat. Objectives of these studies were: 1. To find the stage of maturity of the wheat plant at which urea spray would give the greatest protein increase. 2. To fidn the stage of matureity of the wheat plant at which urea spray would give the greatest yield increase. 3. To determine what amount of nitrogen, when supplied as urea, would tive the greatest stimulus to yield and protein, or both. 4. To compare the accepted practice of supplying nitrogen by soil application with the new method of adding it as a foliage spray.

Encore azaleas are popular ornamental plants for their full sun tolerance, coldhardiness, low maintenance requirements, and reblooming habit in spring, summer, and fall. With their varying growth rates and multiple blooms during a growing season, there is limited information on the nutrient and irrigation requirements of Encore azalea cultivars. The objectives of this study were to investigate the optimum nitrogen (N) requirement of Encore azalea ‘Chiffon’ during a growing season and determine how irrigation frequency and fertilization practices (rates, methods, and timing) affect plant growth and nutrient uptake using both a traditional plastic container and a paper biocontainer. One-year-old liners of Encore azalea ‘Chiffon’ were treated with different N fertigation rates, irrigation frequencies, and sprayed with 3% urea or water in late fall. Plants were investigated for their growth responses and flower production, and analyzed for nutrient and carbohydrate status in different studies when they were grown in both a traditional plastic container and a biodegradable container made from a mix of recycled paper. The biocontainers increased plant growth index, plant dry weight, leaf area, root growth, and uptake of both macro- and micronutrients using N rates of 10, 15, and 20 mM. During a growing season, the biocontainer-grown plants had three flushes of growth while the plastic container-grown plants had only two. The third flush of growth on the biocontainer-grown plants occurred in mid-September, resulting in greater dry weight and N uptake than with plants grown in plastic containers. One irrigation per day resulted in higher flower count and greater root length and surface area. Foliar urea application in late fall was effective in improving plant N status by increasing plant N concentration and content without affecting plant dry weight, but decreased tissue concentrations of glucose, fructose, sucrose, and starch to varying degrees.