227 research outputs found
Optimum cereal combine harvester operation by means of automatic machine and threshing speed control
The method by which automation of agricultural machinery can be developed is illustrated in the case of cereal combine harvesting. The controlled variables are machine forward speed and threshing cylinder peripheral speed. Four control systems have been developed that optimise these speeds on the basis of harvest costs minimisation, which includes variable and fixed costs of the machine and those of machine- and timeliness losses. The evaluated systems make use of a varying number of input process variables and control the machine speed exclusively, or both machine speed and threshing speed. The financial benefits from these control systems were calculated by means of a computer simulation. The research required in developing the models and control systems is discussed in detail. The simulation results demonstrate that control of low-frequency variations in crop properties brings some slight benefit and indicate that timeliness losses are of great importance to optimisation.<p/
Agricultural Research Division 100th Annual Report, July 1, 1985, to June 30, 1986
This 100th Annual Report contains lists of current faculty, active projects, refereed journal publications, brief descriptions of research in selected areas, and the financial report for the period July 1, 1985, through June 30, 1986. Research programs in agriculture, home economics, and natural resources at the University of Nebraska have changed greatly since the U.S. Congress approved the establishment of an Agricultural Experiment Station in each state with the passage of the Hatch Act on March 2, 1887. Although Hatch funds account for a smaller proportion of the total research expenditures in the program today, this legislation continues to be an important source of funding for addressing priority problems that require long-term research projects.
Faculty conducting research in agriculture, home economics, and natural resources in the University of Nebraska Institute of Agriculture and Natural Resources carry research appointments in the Agricultural Research Division. Most faculty are on joint appointments with teaching responsibilities in the College of Agriculture or the College of Home Economics or serve as extension specialists with appointments in the Cooperative Extension Service. As of June 30, 1986, the 136 full-time equivalents in the Agricultural Research Division were distributed among 200 faculty.
The Agricultural Research Division faculty are located on the East Campus of the University of Nebraska in Lincoln and at the District Research and Extension Centers at Clay Center, Concord, North Platte, and Scottsbluff. The University of Nebraska Agricultural Researc
Agricultural Research Division 100th Annual Report, July 1, 1985, to June 30, 1986
This 100th Annual Report contains lists of current faculty, active projects, refereed journal publications, brief descriptions of research in selected areas, and the financial report for the period July 1, 1985, through June 30, 1986. Research programs in agriculture, home economics, and natural resources at the University of Nebraska have changed greatly since the U.S. Congress approved the establishment of an Agricultural Experiment Station in each state with the passage of the Hatch Act on March 2, 1887. Although Hatch funds account for a smaller proportion of the total research expenditures in the program today, this legislation continues to be an important source of funding for addressing priority problems that require long-term research projects.
Faculty conducting research in agriculture, home economics, and natural resources in the University of Nebraska Institute of Agriculture and Natural Resources carry research appointments in the Agricultural Research Division. Most faculty are on joint appointments with teaching responsibilities in the College of Agriculture or the College of Home Economics or serve as extension specialists with appointments in the Cooperative Extension Service. As of June 30, 1986, the 136 full-time equivalents in the Agricultural Research Division were distributed among 200 faculty.
The Agricultural Research Division faculty are located on the East Campus of the University of Nebraska in Lincoln and at the District Research and Extension Centers at Clay Center, Concord, North Platte, and Scottsbluff. The University of Nebraska Agricultural Researc
Laser Based Density Detection of Standing Wheat Stubble
Penetration of a laser beam through wheat stubble was used as a measure of stubble density. A low power, heliumneon laser was positioned perpendicular to travel direction. A photo detector was used to determine penetration duty cycle after the beam passed through the stubble. Penetration duty cycle measured on a simulated wheat crop gave a good indication of crop density. The laser beam appeared to penetrate the simulated crop at densities where direct transmission was blocked. Some reflection of the laser beam occurred through simulated wheat stalks and off the filter on the sensor. Tests in standing wheat stubble offered little indication that the detector could accurately indicate crop density. Correlataon coefficients between stalk density and detector readings ranged between 0.60 and 0.07. A statistical model was developed to describe the system and eliminate the affect of hidden stalks. The model demonstrated the insensitivity experienced at higher stubble densities.Agricultural Engineerin
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A physiological basis to crop improvement and agronomic development
Despite of the documented impacts of the so-called green revolution, food security in the world faces new challenges in terms of population growth, increases in no-agricultural land use (urbanization), and climate change. Trends in food security show that the world community is operating within two limits of food system: (i) the quantity of food that can be produced under a given climate; and (ii) the quantity of food needed by a growing and changing population. Therefore, taking food security successfully into the future requires novel approaches to boost agricultural productivity in order to balance food supply and demand without expanding the agricultural land.
To date, progress in wheat yield has been largely the result of the development of dwarf varieties through introgression of reduced height (Rht) genes. The height reductions arising from the presence of these genes increased yield by alteration of partitioning of dry matter and nitrogen in favour of the spike. However, increased partitioning through additional reductions in plant height is not likely; as comparative studies indicate that wheat yield is reduced when plants are shortened beyond a threshold, and most of the modern cultivars have reached the optimal height. Therefore, this dissertation aimed to identify the physiological attributes able to produce yield increases in the Rht genotypes with the optimal heights.
Approaches based on physiological understanding of yield are necessary for developing genotypes combining high yielding potential and agronomic traits of superior adaptation, and for understanding yield limiting factors. Yet, direct measurement of physiological variables is often difficult or expensive; as an example, measuring plant water status in the field is problematic, with techniques such as psychrometry generally only being suitable for laboratory studies. Therefore, proxy such as tissue RWC may be a good alternative measure of plant water status. We aimed to address these questions with three components of experimental research :(i) proxy-based screening to increased photosynthetic rate and water use efficiency in wheat; (ii) determinants of increased HI in lines with different Rht genes (b, c) when incorporated into contrasting background wheat genomes (B, D), and the relative effect on N partitioning during grain filling; (iii) analyses of stable isotopes (δ²H, δ¹⁸O, δ¹⁵N and δ¹³C) in an agronomic perspective in alley cropping systems associated with adjacent N₂ fixing trees, in terms of hydraulic redistribution, N availability and crop yields.
In this thesis, the proxy-based approach to crop selection was defined as a surrogate-based (proxy and surrogate used interchangeably) screening of cultivars for morphological, anatomical, and physiological traits of performance or crop environmental responses. The research proposed steps for conducting a proxy-based crop selection programme. A comparative screening of 23 Eps cultivars and ranking for traits of photosynthetic and water use efficiency showed the correlative relationships of SLA to An, WUEi, leaf N, Δ¹³C, Kh, leaf RWC, and IVD. Additionally, it was observed that IVD may influence WUE and Amax. It was suggested that these relationships of SLA to traits of photosynthesis possibly resulted from the association of SLA and the leaf biochemical characteristics.
Attention was also given to examining the mechanistic foundations that determine the relationship between plant height and yield. The results showed the straw-shortening significantly correlated both with Amax and Kh; and SLA decreased with the level of dwarfing; and the Amax related both Kh and SLA. Therefore, it was proposed that the straw-shortening may affects Amax by exerting a controlling influence over Kh through SLA. Moreover, both the partitioning of N to spike and the flag leaf N were related to plant height and growth stage. Additionally, the increased post-anthesis partitioning of N to grain associated with high N uptake rate and high MRT of N were probably the traits behind increased NUE and NHI. The data also indicated that increased grain number per spike, kernel weight and reduced peduncle length might be the driver of the increased HI in this experiment.
The test of the hypothesis that there might be practical application of the analyses of the natural abundance of stable isotopes (δ²H, δ¹⁸O, δ¹³C, and δ¹⁵N) and isotopic mixing model by IsoSource to understand plant interactions in terms of water redistribution and nitrogen transfer and uptake in agroforestry systems, indicated a consistent gradient in depletion of wheat xylem water δ²H, δ¹⁸O, and δ¹⁵N in leaf as moving further away from the tree line. The data also reflected a consistent pattern of isotopic values (δ²H, δ¹⁸O, and δ¹⁵N) in wheat in the proximity of the tree being similar to that of the tree, suggesting they were using the same source of water and N. Similarly, an isotopic mixing model data showed that the crops in the proximity of the trees accessed considerably amounts of the water and nitrogen redistributed by trees. The study also indicated the improvement in water use efficiency, chlorophyll content, grain number per spike, and grain yield for the crops nearest to the trees for a distance up to 5 m.
In conclusion, selection for increased HI should shift focus from reduced plant height to include increased grain number and kernel weight, increased partitioning of N to spike, reduced peduncle length, and low SLA. Finally, the hypothesis that efflux of water and N in agroforestry system from tree roots in topsoil and influences a number of physiological functions of neighbouring crops was confirmed by isotopic and physiological data
Alternative Crops for Ethanol Fuel Production: Agronomic, Processing, and Economic Considerations
This report is a result of the fuel alcohol research team\u27s broadened focus during 1983. A comprehensive literature review was carried out to explore alternative starch and sugar crop alternatives for ethanol fuel production. Although the literature search was quite inclusive with respect to geographic regions, special emphasis was given to the agronomic and economic potential of various fuel alcohol crops in the Northern Plains region of the U.S., of which South Dakota is a part, and in LDCs of Asia, Africa, and Latin America. Our intent was to thereby determine possible energy crops deserving of more fuel alcohol research attention in the Northern Plains and also provide a document of use to ourselves and others considering various crops for fuel alcohol production in LDCs. Development assistance agencies, and universities such as SDSU which work with them, must be able to assess the energy producing potential of agricultural economies, along with food and fiber producing potentials. One kind of energy production that may be technically and economically feasible in some LDCs is fuel alcohol production from starch and sugar crops. (In this report, the terms alcohol and ethanol are used interchangeably.
Biomass Wastes for Energy Production
Environmental problems are forcing a rethinking of the world’s energy supply system. In parallel, there is an increasing amount of global solid waste production. A fundamental shift toward greater reliance on biomass wastes in the world’s energy system is plausible because of ongoing major technological advances that hold the promise of making the conversion of biomass into high-quality energy carriers, like electricity and gaseous or liquid fuels, economically competitive with fossil fuels. Therefore, waste-to-energy systems have become a paramount topic for both industry and researchers due to interest in energy production from waste and improved chemical and thermal efficiencies with more cost-effective designs. This biomass shift is also important for industries to become more efficient by using their own wastes to produce their own energy in the light of the circular economy concept. This book on “Biomass Wastes for Energy Production” brings novel advances on waste-to-energy technologies, life cycle assessment, and computational models, and contributes to promoting rethinking of the world’s energy supply systems
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