Dissertations / Theses: 'Agricultural engineering'

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Kim, Yung-Chul. "Agricultural Teachers' Attitudes Toward Adult Agricultural Education in Ohio Comprehensive High Schools." The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392800394.

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Kirnak, Halil. "Developing a Theoretical Basis for Demand Irrigation of Acer Rubrum." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392735898.

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Cederstrom, Myriam Ransenberg 1955. "Spectroradiometric and color analysis of soil organic carbon and free iron oxides along a climosequence." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278235.

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Surface soil samples from a climosequence were studied with the purpose of relating color, reflectance variations and texture to contents of organic carbon and free iron oxides. Information on the physicochemical properties of the soils were obtained with a fine resolution spectroradiometer, a chromameter and by laboratory analyses. The effect of soil organic carbon and free iron oxides is shown by the varying shape of the soil spectral curves. Both the chromameter and the spectroradiometer detected the varying amounts of organic carbon and free iron oxides in soil. Silt had a positive, highly significant relationship with organic carbon. Clay and silt had a positive highly significant relationship with free iron oxides.

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Pereira, Gilberto Alves. "Sistema experimental de monitoramento e controle para casas de vegetação baseado em redes de controle distribuído LonWorks." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3141/tde-09062006-091835/.

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O cultivo protegido em casas de vegetação possibilita produção vegetal de maior qualidade e em qualquer época do ano. A tecnologia tem papel preponderante no controle desses ambientes, embora nem sempre seja satisfatoriamente empregada. Soluções convencionais, como as que utilizam Controladores Lógicos Programáveis, ou sistemas com tecnologia proprietária predominam nas soluções oferecidas. A evolução da tecnologia de comunicação vem possibilitando a difusão do uso da tecnologia de redes de computadores em outras aplicações, as chamadas redes de controle, possibilitando a mudança de paradigmas na concepção de sistemas de monitoramento e controle. Os sistemas com arquitetura centralizada tendem a dar lugar aos com arquitetura distribuída, e o uso da Internet possibilita a supervisão e operação de qualquer lugar. Este trabalho discute a adoção da tecnologia de redes de controle em casas de vegetação, envolvendo aspectos de sua arquitetura, distribuição da inteligência, crescimento incremental, flexibilidade e custos. Ele foi aplicado a uma casa de vegetação do Instituto de Biociências da Universidade de São Paulo, dotada de sistema de automação convencional, para a implantação e avaliação de um sistema experimental baseado na rede de controle com a tecnologia LonWorks®. Utilizaram-se nós inteligentes comercialmente disponíveis e um nó desenvolvido em laboratório. A implementação permitiu a verificação experimental das vantagens e desvantagens da utilização da abordagem distribuída em relação à centralizada. Constatou-se a facilidade de implementação, redução no cabeamento, flexibilidade e interoperabilidade da solução. Contudo, os custos tendem a ser mais elevados na abordagem distribuída, no que se refere às ferramentas de apoio e nós inteligentes. Além da avaliação de aplicação da nova tecnologia, propõe-se uma seqüência de passos a se seguir na migração de um sistema convencional para um sistema de controle distribuído, e apresenta-se a disponibilização do sistema desenvolvido como um Web Lab, que possibilita a realização de experimentos remotamente.
Protected agriculture using greenhouses allows high quality crops and in any time of the year. The technology has a preponderant role in the control of these environments, although no always successfully. Conventional solutions, such as Programmable Logic Controllers, or systems with proprietary technology are predominant. The evolution of the communication technology is making possible the diffusion of computer networks use in other applications: control networks start to awake the interest of both researchers and users, changing the paradigm of monitoring and control systems conception. The traditional systems with centralized architecture tend to be replaced by distributed technology, and the Internet use makes possible the supervision and control from anywhere. This work discusses the control networks technology applied to greenhouses, involving architecture aspects, intelligence distribution, incremental growth, flexibility and costs. For the implementation and assessment of an experimental system based on LonWorks® technology, a greenhouse at Instituto de Biociências at Universidade de São Paulo was used. Off the shelf intelligent nodes were used and an experimental node was developed. The implementation made possible the experimental verification of advantages and disadvantages of the use of distributed and centralized approach. It was evidenced easiness of implementation, cabling reduction, flexibility and interoperability of the solution. However, the costs tend to be raised in the distributed approach, referring to support tools and intelligent nodes. Besides the new technology application evaluation, a step-by-step sequence is proposed for the migration from a conventional system to a control system, and presents a Web Lab system that enables remote experimentation.

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Marques, Guilherme Fernandes. "Economic representation of agricultural activities in water resources systems engineering /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.

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Donkor, Joseph. "Evaluation of the Potential for Direct-Fed Microbials to Enhance Utilization of Phosphorus in Broiler Chickens." Thesis, Tennessee State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10641460.

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Feed accounts for about 60–68% of the total cost of poultry production. Chicken cannot efficiently absorb organic or phytin-bound phosphorus, thus about 70–80% of dietary or plant based phosphorus is excreted in the manure of broiler chickens. The goal of this research was to identify microbes with the potential to improve utilization of a plant source of phosphorus in the gastrointestinal tract (GIT) of broilers.

A total of 8,082 sequences were obtained using a metagenomic approach, with 61% of those sequences representing 5,030 species of various bacterial organisms. The highest proportion of bacteria was Massilia which represented 46% of the total dominant microbial population, Bacteroides (9%), Streptomyces (6%), Bacillus (6%), and 18 different species each constituting less than 5% of these dominant microbes. Three microbes Lactobacillus, Enterococcus, and Bifidobacterium (LEB) with the potential to hydrolyze free phosphorus were isolated and characterized. The isolated microorganisms maintained the ability to grow at all the different pH ranges (1–5), and bile concentrations of 0–3.5%. Also, the ability of the bacteria to hydrolyze free phosphorus was evaluated in-vitro. The effect of the three bacteria on performance of 400 day- old Ross broilers was evaluated during an eight-week period. The results indicated that broiler chickens fed probiotic bacteria at the rate of 100 or 150 mg/kg of feed consumed 12.0% and 17.8% more feed, respectively, and increased body weight gain by 5.9% and 8.4%, respectively, when compared with the control birds. Broiler chickens fed diets containing the probiotics at 100 or 150 mg/kg of feed retained 15.2% and 17.5% of phosphorus as against 8.6 % for the birds on the diets without the bacteria. Except for birds on dietary treatment LEB-150, which had a higher mortality (7.3%), the remaining six dietary treatments had mortality ranging from 2.0–3.3% which was less than that of the controls birds (4.5%).

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Hernandez, Ricardo. "Growth and development of greenhouse vegetable seedlings under supplemental LED lighting." Thesis, The University of Arizona, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3600283.

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The greenhouse industry is interested in light emitting diodes (LEDs) as a light source supplement to solar light to improve plant growth and development. Before LEDs can be adopted as supplemental light for greenhouse crops, plant responses to LED spectral quality need to be investigated. Tomato and cucumber seedlings were grown under different supplemental blue and red photon flux ratios (B:R ratios) under high (16-19 mol m^–2 d^–1) and low (5-9 mol m^–2 d^–1) solar daily light integrals (DLIs). The supplemental daily light integral was 3.6 mol m^–2 d^–1. A treatment without supplemental light served as a control. Both tomato and cucumber seedlings had increased growth rate and improved morphology when grown under the supplemental LED light compared to the control. However, no significant differences were observed for any growth and morphological parameters measured in this study between the different B:R ratios for both cucumber and tomato transplants under high DLI conditions. Cucumber seedlings showed a tendency to decrease dry mass, leaf number and leaf area under low DLI conditions with increasing B:R ratio. Tomato seedlings did not show any differences between the different B:R ratios under low DLI conditions. Seedlings growth and morphology under supplemental LED light were compared to those under supplemental high pressure sodium (HPS) light. Cucumber seedlings under supplemental HPS light had greater shoot dry mass than those under the supplemental red LED light. Tomato shoot dry mass showed no differences between the HPS and red LED supplemental light treatments. Cucumber seedlings were also grown under supplemental LED pulsed lighting and supplemental LED continuous lighting. Cucumber seedlings showed no differences in shoot dry mass and net photosynthetic rate between the treatments. Collectively, these studies concluded that red LED is preferred for supplemental lighting and the increase of blue light does not offer any benefits unless the efficiency of blue LEDs largely exceeds the red LEDs. The results of this research can be used for fixture development by LED manufactures and as a decision making tool for the adoption of supplemental LED lighting by greenhouse growers.

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Siqueira, Rafael Telles Tenorio de. "Characterizing nitrogen deficiency of maize at early growth stages using fluorescence measurements." Thesis, Colorado State University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10138898.

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Among all nutrients that are important for crop production, nitrogen (N) is one of the least efficiently utilized, mainly due to its high mobility in soil. The possibility of using crop sensing in real-time to detect variability in N deficiency within a field has the potential to enhance N efficiency, increase crop yield, and reduce potential environmental risks and crop production costs. Potassium (K), another important crop nutrient, can also lead to higher yield when applied in the right amount and manner. Real-time fluoro-sensing is a new technology for crop sensing and studies have shown that it could enable variable rate nutrient management for precision agriculture practices. The objective of this study was (1) to evaluate if fluorescence sensing can detect variability of N and K in crop canopy at early growth stages of maize (prior to V6 crop growth stage) under controlled condition (greenhouse), (2) to evaluate the effect of different fertilization dosages of N over the plant growth, and (3) to verify if induced fluorescence can detect in situ N variability at early growth stages of maize. Research was conducted in two stages, first in a greenhouse condition and later in field spread over three site-years. The greenhouse research was conduct in year 2011 and plants were grown in plant-pots with silica sand and supplied with modified Hoagland solution with different rates of N and K. Field trials were conducted in year 2012 and 2013 in northern Colorado. For the greenhouse study, data collected via fluorescence sensor (Multiplex^®3) were analyzed using ANOVA and Tukey’s HSD to test significant differences among treatments in each experiment. For the N experiment, regression analysis between the seven fluorescence indices and N uptake was performed for the 12 days of data acquisition at five different growth stages (i.e. 2-leaf to 6-leaf growth stages) and coefficient of determination was used to identify the best fluorescence indices to detect N status. Also, root mean square error (RMSE) was used to test the precision of the estimates for each index. Results of this study indicated that all fluorescence indices were able to detect N variability in maize canopy prior to V2 growth stage. However, the fluorescence indices failed to identify K deficiency as the maize plants with K treatments showed small variability at early crop growth stages. For the field study, two site-years had 5 N rate treatments applied as UAN 32% (urea ammonium nitrate; 32-0-0), while one site-year had 6 N treatments applied pre-planting. Sensors used in this study were the Multiplex^®3 for fluorescence sensing and the GreenSeeker^® for reflectance sensing (NDVI). Sensor measurements were correlated with aboveground biomass, N content, and N uptake measured at two growth stages (V6 and V9 maize growth stage). The aboveground biomass, N content, N uptake, yield, and sensors readings were analyzed using ANOVA and Tukey’s HSD to test significant differences among the N treatments. Also, a regression tree between N uptake and the fluorescence indices was fitted along with the coefficient of determination (R²). The N rates had no effect on aboveground biomass, N content and N uptake (for both sampled growth stages). Under field conditions, fluorescence indices failed to detect N variability in maize at early growth stages for all three site-years. This finding may require further investigation, as for most of the N treatment plots, maize plants had sufficient N levels and another biotic or abiotic stress may be responsible for unexplained differences in N variability as measured by fluorescence sensor. Contrasting findings under greenhouse conditions versus field conditions limit the application of fluorosensing sensor. Further field studies are needed to evaluate the potential of this sensor for detecting N variability in situ.

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Clyma, Howard Earl 1963. "Using soil properties to predict the effectiveness of electro-osmotic tillage." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278115.

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A study of electro-osmotic draft reduction was conducted to determine the effectiveness of electro-osmosis content and apparent resistivity, tillage speed, and electrical voltage and current were measured to determine a relationship which predicts the effectiveness of electro-osmosis in reducing draft force. The application of electro-osmosis resulted in a reduction in draft force for all tested conditions in the loam soil, with a maximum reduction of 39.4 percent. Water content was a good predictor of resistivity with a regression coefficient of 0.944. Resistivity was a significant predictor of draft force for all test configurations with an average regression coefficient of 0.8173. A comparison of water content and resistivity regression coefficients indicates that the difference between the coefficients is not large enough to choose one variable as a better predictor than the other of the effects of electro-osmosis on draft force.

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Simas, Maria Joao Correia de 1966. "Soil water determination by natural gamma radiation attenuation." Thesis, The University of Arizona, 1993. http://hdl.handle.net/10150/278348.

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The purpose of the study was to determine the soil moisture content by measuring the naturally occurring gamma radiation in the soil. A calibration procedure was developed both in laboratory and in the field. In the laboratory, two different sample sizes were used: three-inch diameter, and 18-inch diameter columns, both 15 cm long. Small size soil samples (three-inch diameter) cannot be used to predict the calibration curve in the field, whereas the larger soil samples (18-inch diameter) calibration may be used to predict the field calibration curve. The prediction limits for the calibration curve done in the field are of ±5%, which is an unacceptable level of precision. It was also observed that the distance between the detector and the soil should always be kept constant, and that the top 15 cm of the soil contribute to approximately 95% of the radiation measured at the soil surface.

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Colaizzi, Paul Dominic. "Ground based remote sensing for irrigation management in precision agriculture." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/280497.

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The relationship between remotely sensed canopy temperature and soil moisture was studied. The objectives were to relate two remotely sensed canopy temperature-based indices, the Crop Water Stress Index (CWSI) and the Water Deficit Index (WDI), to soil moisture through the water stress coefficient, to estimate soil moisture depletion with the CWSI and the WDI, and to develop a remote sensing system aboard a linear move irrigation system that would provide field images of the WDI at one-meter spatial resolution. Studies were conducted in Maricopa, Arizona during the 1998 and 1999 seasons with cotton (Gossypium hirsutum, Delta Pine 90b). In 1998, the field was surface irrigated (low frequency irrigation), and the CWSI was calculated from canopy temperature measurements using stationary infrared thermometers. In 1999, the field was irrigated with a linear move system (high frequency irrigation), and the WDI was calculated using measurements made by the on board remote sensing system. Both the CWSI and the WDI were correlated to soil moisture through the water stress coefficient. Soil moisture depletion could be estimated using the CWSI under low frequency irrigation, but could not be estimated using the WDI under high frequency irrigation. These differences were attributed to the range of soil moisture resulting from infrequent surface irrigation vs. frequent irrigation using the linear move. High spatial resolution images of the WDI could nonetheless monitor water stress throughout the field from partial to full canopy cover, which demonstrated that ground-based remote sensing is feasible for irrigation management in precision agriculture. This application of remote sensing provides an opportunity to improve water use efficiency.

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Oliveira, Aureo Silva 1965. "Determination of head lettuce crop coefficient and water use in central Arizona." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282779.

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The assessment of crop evapotranspiration (ET) has received intensive research due to its critical role in irrigation management and water conservation studies. Because weather conditions largely determine ET, various methods based on meteorological factors have been developed to estimate ET rates. In order to accommodate the concept of reference crop ET (ETo), evaluation of weather data quality has been addressed. In this research, 9 year (1989-1997) weather data from the AZMET weather station at the Maricopa Agricultural Center were used to compare daily and 10 day average ETo estimated by the Hargreaves (HARG), FAO 24 Penman (FAOP), and FAO Penman-Monteith (FAOPM) methods. Before ET calculation, the weather data were evaluated for the influence of aridity at the weather station site and sensor calibration/malfunctioning problems. Corrections were made on temperature and solar radiation data. Reference ET as reported by the AZMET was also considered for comparison purposes. In general, the weather data correction decreased ETo estimates 18.3%, on average. The highest reduction (23.5%) was obtained with the FAOPM method. When this method was used as the standard for ETo estimate comparison, the FAOP method corrected for site aridity ranked first as predictor of ETo despite its tendency for overestimation. At the Maricopa Agricultural Center, a two year field research (Fall-Winter of 1996/97 and 1997/98) was carried out to derive head lettuce (Lactuca sativa L.) crop coefficient (Kc) and to investigate the effects of ETo method in the shape and values of the crop coefficient curve. For the periods of low crop ET, the 2 year (Kc) from the HARG, FAOP, and FAOPM methods did not differ significantly. However, in the peak demand period, crop coefficients derived from the three methods peaked at different values. The predicted peak (Kc) was 0.87, 0.72, and 0.82 for the HARG, FAOP, and FAOPM methods, respectively. These results reflect the tendency of ETo underestimation by the HARG method and overestimation by the FAOP method under and conditions. Crop coefficients derived in the 96/97 growing season were then used to investigate the effects of (Kc) and ETo mismatching in the water use and yield of lettuce during the 97/98 growing season. To reach such objectives, an experiment design in Latin square with four replications and four treatments was carried out. Differences in seasonal water depth were as high as 33 mm among treatments. The analysis of variance revealed that the treatments did not induce lettuce marketable yield statistically different at the 5% significance level.

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Kibalama, Josephat S. "The assessment of agricultural mechanization in Uganda : perspective engineering options and strategies /." Connect to resource, 1993. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1195574781.

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Compaleo, Joshua David. "Split Ring Resonator Design for Agricultural Based Applications." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1452981065.

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Abdulhussain, Mohamed Fidahussain 1964. "Gravity bubbler irrigation systems on steep slopes converted to bench terraces." Thesis, The University of Arizona, 1994. http://hdl.handle.net/10150/278410.

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Gravity bubbler irrigation is a new mode of irrigation activated by the existing pressure in conventional irrigation supply channels. In gravity flow systems on steep slopes, pressure increases in the downstream sections of the pipe and must be dissipated for uniform application. A design procedure for gravity bubbler irrigation systems on inclined steep slopes or converted to bench terrace systems is described in detail. The design is based on the use of orifices as energy dissipating devices. Laboratory tests were conducted to determine graphical relationships and coefficients for estimating the head loss for an orifice made from PVC. The head loss coefficient is a function of the orifice to pipe diameter ratio and can be expressed by an equation of the form Ko = abetab where a and b are constants determined from test data and beta is the ratio of diameters. A prototype gravity bubbler irrigation system was designed and installed.

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Suarez-Rey, Elisa Maria. "Subsurface drip irrigation of bermudagrass turf in Arizona: Benefits and limitations." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/280210.

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Subsurface drip irrigation was compared to sprinkler irrigation on bermudagrass turf during three consecutive years using tertiary treated wastewater. Irrigation amount required by each treatment, visual appearance of the grass, shoot biomass production, and soil salinity were measured, and potential management problems were identified. The amount of irrigation water applied via subsurface irrigation was similar or higher than that applied via sprinkler irrigation for a turf of similar quality. Shoot biomass production did not differ between both irrigation methods when similar amounts of water were applied. Soil salinity, measured as electrical conductivity, was monitored at the beginning and end of each season. The changes in electrical conductivity at the end of every irrigation season did not negatively affect the appearance of the turf in any of the years. Emitter clogging by root intrusion was identified as a potential problem in the subsurface drip irrigation system. A series of greenhouse experiments were conducted to evaluate the effect of different herbicides and acids at several concentrations on root intrusion into subsurface drip emitters. The first greenhouse experiment was a study intended to identify chemical concentrations that could inhibit bermudagrass root growth in soil without negatively affecting the visual appearance of the grass. As a result, two herbicides, trifluralin and thiazopyr, and one acid, phosphoric acid, were selected for a second greenhouse experiment. The second greenhouse experiment focused on the effects of the two herbicides and the acid on root intrusion into subsurface drip emitters. Only the emitters treated with thiazopyr at the highest dose were completely clean, root-free emitters.

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Haberland, Julio Andres. "AgIIS, Agricultural Irrigation Imaging System, design and application." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279836.

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Remote sensing is a tool that is increasingly used in agriculture for crop management purposes. A ground-based remote sensing data acquisition system was designed, constructed, and implemented to collect high spatial and temporal resolution data in irrigated agriculture. The system was composed of a rail that mounts on a linear move irrigation machine, and a small cart that runs back and forth on the rail. The cart was equipped with a sensors package that measured reflectance in four discrete wavelengths (550 nm, 660 nm, 720 nm, and 810 nm, all 10 nm bandwidth) and an infrared thermometer. A global positioning system and triggers on the rail indicated cart position. The data was postprocessed in order to generate vegetation maps, N and water status maps and other indices relevant for site-specific crop management. A geographic information system (GIS) was used to generate images of the field on any desired day. The system was named AgIIS (A̲gricultural I̲rrigation I̲maging S̲ystem). This ground based remote sensing acquisition system was developed at the Agricultural and Biosystems Engineering Department at the University of Arizona in conjunction with the U.S. Water Conservation Laboratory in Phoenix, as part of a cooperative study primarily funded by the Idaho National Environmental and Engineering Laboratory. A second phase of the study utilized data acquired with AgIIS during the 1999 cotton growing season to model petiole nitrate (PNO₃⁻) and total leaf N. A latin square experimental design with optimal and low water and optimal and low N was used to evaluate N status under water and no water stress conditions. Multivariable models were generated with neural networks (NN) and multilinear regression (MLR). Single variable models were generated from chlorophyll meter readings (SPAD) and from the Canopy Chlorophyll Content Index (CCCI). All models were evaluated against observed PNO₃⁻ and total leaf N levels. The NN models showed the highest correlation with PNO₃⁻ and total leaf N. AgIIS was a reliable and efficient data acquisition system for research and also showed potential for use in commercial farming systems.

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Carvalho, Lara. "Small-scale combustion of agricultural biomass fuels." Licentiate thesis, Luleå tekniska universitet, Energivetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18748.

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The ambitious targets of the European Union in increasing the use of renewable energies to 20% of Europe’s energy needs, call for urgent changes, including in the biomass sector. The share of solid biomass for heating purposes could be further increased by replacing oil- and gas-fired furnaces with biomass boilers and by expanding the spectrum of biomass raw materials for small-scale combustion systems. The interest in using non-woody biomass fuels for heat production has been increasing in Europe due to two main factors. First, the market for fossil fuels is unstable and their prices are continuously rising. Second, the increase competition for woody biomass between the heating sector and other industries, have increased the price of wood. As a result, the interest for alternative biomass fuels is growing rapidly, covering woody materials of low quality, energy crops and forest residues.The present work aims at investigating the technical feasibility of using non-woody biomass fuels in existing small-scale combustion appliances developed for burning wood. Therefore, combustion tests with different non-woody biomass fuels and in different combustion appliances were performed in standard laboratory conditions and in households under real life conditions (field tests). The laboratory tests were performed using eight different fuels (straw, Miscanthus, maize, vineyard pruning, hay, wheat bran and Sorghum) while in the field tests straw, Miscanthus and maize were burned. The gaseous and particle emissions, the slag tendency and the efficiency of the combustion systems operated with non-woody biomass fuels were analysed and when possible compared with the legal requirements defined in FPrEN 303-5. The limitations of the investigated combustion appliances when operated with non-woody biomass fuels were analysed and discussed.Non-woody biomass fuels could be used for heat production in existing combustion appliances as long as the systems are adapted for burning high ash content fuels. Among the investigated fuels, Miscanthus, vineyard pruning and hay could be burnt in most of the tested combustion appliances while fulfilling the legal European requirements (defined in FprEN303-5) in terms of emissions and efficiency. The non-woody biomass fuels showed problems with ash accumulation and slag formation and could only be burned without unwanted shutdowns in combustion appliances adapted to manage high ash content fuels. Straw, wheat bran and maize were the most problematic fuels regarding slagging. The combustion appliances require appropriate technological developments to manage the strong variability in terms of chemical and thermal properties of the non-woody biomass fuels. The results of the laboratory tests were generally in agreement with the field test results.

Godkänd; 2012; 20121113 (joakim); LICENTIATSEMINARIUM Ämne: Energiteknik/Energy Engineering Examinator: Professor Marcus Öhman, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Diskutant: Ph.D, Ass. Senior Lecturer Markus Broström, Institutionen för tillämpad fysik och elektronik, Umeå universitet Tid: Tisdag den 18 december 2012 kl 10.00 Plats: E246, Luleå tekniska universitet

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Lines, Jeffrey A. "The suspension characteristics of agricultural tractor tyres." Thesis, Cranfield University, 1991. http://dspace.lib.cranfield.ac.uk/handle/1826/8069.

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A method used to measure the radial suspension properties of agricultural tractor tyres is described. The stiffness and damping of a range of tyres have been measured. The effects on tyre stiffness and damping coefficient of rolling speed, inflation pressure, load, amplitude, frequency of vibration, driving torque, surface type, tyre size, ply rating, construction, wear and age are reported. A relationship is developed which enables the stiffness of a rolling tyre to be estimated from the tyre size, age and inflation pressure. It is shown that this is a more accurate estimate of rolling tyre stiffness than measurement of the stiffness of a stationary tyre. The measured tyre characteristics are used to predict the vibration of a single degree of freedom system and of a four wheel tractor. Significant improvements in accuracy are found when the results are compared with those obtained using stationary tyre characteristics. The frequencies of the natural pitch and vertical modes of vibration are usually predicted to within ± 10%. Predictions of rms acceleration levels are less accurate. Further improvements in modelling accuracy should be achieved by more accurate measurement and modelling of the suspension characteristics of the drive wheels in the longitudinal direction.

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Ono, Eiichi. "Monitoring of nutrient solution for hydroponically grown sweetpotato (Ipomoea batatas)." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279921.

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Monitoring the nutrient dynamics in the nutrient solutions of hydroponically-grown sweetpotato plants gave the following results. (1) Monitoring the concentrations of critical individual chemical species over time in the hydroponic solution would allow for optimal nutrient management: (a) While the time variation in the Electrical Conductivity (EC) level of a hydroponic solution could suggest normal nutrient uptake, nitrate uptake inhibition, or increased nitrate uptake, the time variation in EC levels could not identify which specific nutrient species were being inhibited or increased in their uptake; (b) Even when the total nitrate assimilation per plant increased over time, the specific nitrate uptake over time actually decreased significantly and correlated well with the saturation of average growth rate, justifying the addition of nitrogen in the solution to achieve optimal growth during the plant's vegetative phase; (c) Doubled-N by ammonium resulted in the significant suppression of the uptake of nitrate and potassium as well as calcium, phosphorus, magnesium, iron and boron, among others; (d) Under doubled-N by nitrate, approximately twice as much nitrate was taken up from the solution relative to the control, indicating that the uptake of nitrate was nitrate-concentration-dependent; (e) Under doubled-N by nitrate, the uptake of potassium was unaffected; and (f) Doubled-K, designed to initiate sweetpotato rooting, significantly suppressed nitrate uptake as desired and kept the potassium uptake unaffected. (2) The fairly reasonable regularity of time variation of EC level and nutrient uptake would allow for mathematical modeling, useful for biomass prediction and stress diagnostics: (a) EC modeling over time by exponential fits resulted in reasonably acceptable r-squares under doubled-N by nitrate treatment and the control condition; (b) EC changes in the standard solution provided reasonable inverse correlation with the plant's average growth rate; (c) Exponential fitting of nitrate concentrations over time resulted in reasonable r-squares both for the doubled-N by nitrate treatment and the control condition; and (d) Under the doubled-K treatment, nitrate uptake was significantly suppressed, so that the resulting variation in nitrate concentration over time deviated significantly from that for the control condition or even that for the doubled-N by nitrate treatment, indicating physiological stress for the plants.

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Tanksley, Koli. "Soil, groundwater, and alfalfa yield response to manure and compost applications in an arid environment." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280334.

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The assessment of environmental degradation from farming practices has received recent attention due to the concern for sustainable agriculture. The United States Department of Agriculture and the Environmental Protection Agency have set forth the Unified National Animal Feeding Operation Strategy to protect the nation's water resources from contamination. The Unified Animal Feeding Operation Strategy requires that field application of manure, a common fertilization method and manure disposal practice, may not exceed crop nutrient needs. This requirement necessitates studies to determine how the multiple variables involved interact so that farmers may comply with the regulation. In this research, the effects of the application of manure, both fresh and composted, on a production alfalfa (Medicago sativa L.) field was examined. Manure and compost were applied to a production alfalfa field to determine the impact on alfalfa yield, soil nutrient content, and the potential for nitrate leaching. A conventional "no nitrogen added" treatment was also maintained as a control. Manure and compost were applied after each harvest in amounts such that the amount of nitrogen removed in the alfalfa harvest was replaced with the same amount of nitrogen in manure or compost. Application rates varied from 35 to 476 kg nitrogen ha⁻¹ after each harvest. It was found that the finer particles of the compost incorporated into the soil profile better than the chunky form of the manure. Soil analysis down to 150 cm depth showed that the compost treatment plots contained nearly 3000 kg total nitrogen ha⁻¹, the manure plots contained about 1750 kg ha⁻¹, and the no nitrogen plots had approximately 1400 kg ha⁻¹. Final PO₄-P soil analysis revealed that compost plots contained about 125 kg PO₄-P ha⁻¹, manure plots had approximately 115 kg ha⁻¹, and no nitrogen plots had only 20 kg ha⁻¹. Alfalfa yield did not vary between treatments throughout the one and a half year study. Also, no detectable nitrate or phosphate was found in the leachate collected from each of the treatments.

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Jia, Xinhua. "Electrokinetic management of nitrate movement in drip irrigated soils." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280615.

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Nitrate contamination of surface and groundwater has become a serious concern in many agricultural areas throughout the world. The major source of nitrate contamination is believed to be nitrogen fertilizer from agricultural fields. Best Management Practices have been developed to guide fertilizer use and minimize nitrogen losses, but do not address control of nitrate movement from the crop root zone. It is proposed that an in-situ method, electrokinetics (EK), could be used to control nitrate movement, retaining it near the root zone. Lysimeter experiments were conducted to evaluate the effect of parallel electrodes on pH and nitrate distribution in field soils subjected to an electrical input. However, the expected results, increased nitrate retention, reduced sodium and calcium concentration and lower pH values near the anode, were not attained consistently in the test soils with and without Sudan grass. Small scale experiments in a vertical, partially saturated sandy soil column (25 cm height by 14 cm diameter) were conducted to evaluate the optimal EK parameters. After 80 mA current for 6 h the nitrate was retained near the anode, with the highest measured nitrate concentration of 7155 mg/L within 5 mm of the anode. The nitrate concentration at the cathode was 1/5 of the inflow solute concentration (221 mg/L). The pH was 11 near the cathode, 3.5 near the anode, and showed little changes in intermediate layers. The results demonstrate that in sandy soils nitrate can be strongly retained near the anode, even against gravity effect. As the percentage of illite clay in the soil increased, the EK effect decreased; due to the increase of fine clay particles both the transports of ions and the water were inhibited. The loam soil showed some increase in the nitrate concentration near the anode, but the clay soil showed no change. An increase of pH near the cathode was seen in all soils. The electrical potential analysis showed the sandy soil required the highest electrical potential 97.23 V, loam soil was 18.24 V and clay soil was 14.22 V.

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Salazar, Moreno Raquel. "Multiple criteria analysis of economic, environmental and water use problems in an irrigation district of Mexico." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284229.

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The Alto Rio Lerma Irrigation District (ARLID), located in the state of Guanajuato in Mexico, is an agricultural area whose sustainability depends partially upon groundwater withdrawal for crop irrigation. Because of high pumping demands and current land-management practices, water levels in the regional groundwater aquifers have declined severely, resulting in aquifer overdraft. The potential adverse consequences of this overdraft cannot be overstated, as the long-term economic viability and environmental integrity of the region is threatened. In order to analyze this economic, environmental, and water use problems in this region, simulation of the agricultural system was performed and associated water use impacts quantified under different management scenarios. Linear programming identified the 12 optimal cropping patterns, and then multi-criteria decision-making methodologies were applied to rank and identify the best cropping pattern (satisficing solution). The GLEAMS model was used to simulate the amounts of water, nitrate, and pesticides in both runoff and percolation for each cropping pattern. In order to quantify the economic and environmental impacts of aquifer overdraft, two attributes were used; pumping costs and an aquifer exploitation coefficient. Three multiple criteria methods: Q-analysis, ELECTRE II, and the Range of Value Method, were evaluated and the latter method was selected to analyze the payoff matrix for the ARLID, where 12 alternatives, each with 13 attributes, were considered. The results show the best alternative for effectively balancing environmental with economic considerations was the farming practice, consisting of land leveling, growing vegetables such as red tomato, and controlled groundwater withdrawals to preserve aquifer sustainability. Low water availability does not necessarily reduce farmer's profits, if new water saving alternatives are applied, combined with more profitable crops. Given that ROV method only considers full compensation between objectives, this research contemplate an extension for the nonlinear case in order to assess the whole range of values of the objective function. The final findings suggest that the best methodology was to apply L1 in the lower levels and then L2 for the highest level in the hierarchy. In this manner, the partial compensation between objectives is considered and also the decrease in the uncertainty of alternatives selection.

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Boonmung, Suwanee. "Evaluation of DRIFTS technique with PLS regression for determination of added mineral nitrogen in soil." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/289864.

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Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) in both near infrared (NIR) and mid infrared (MIR) has been previously shown to be effective in quantifying soil nitrogen (N) concentrations when calibrated using numerous field soil samples. However, such an approach provides samples that likely contain substantial correlations between physical and chemical properties. To address these concerns, the performance of DRIFTS coupled with PLS regression in NIR regions, 5,000-4,000 cm⁻¹ (2,000-2,500 nm) and 6,500-5,500 cm⁻¹ (1,540-1,820 nm), and the M1R region, 3,400-2,400 cm⁻¹ (2,940-4,170 nm), was assessed first through analysis of the concentration of mineral N (ammonium (NH₄⁺) (0-50 ppm) and nitrate (NO₃⁻) (0-200 ppm)) artificially incorporated into a series of silica sand and clay samples with a consistent particle size. The influence of the reduction of sand particles to silt was also analyzed quantitatively. Subsequently, the Pima clay loam soil was evaluated and the concentration ranges of 0-200 ppm NH₄⁺ and 180-1,000 ppm NO₃⁻ were added in soil samples. All three regions provided good measurement of NH₄⁺ but the MIR region was significantly more useful for NO₃⁻ measurement in sand. The detection limits for the measurement of mineral N in sand with particle sizes within 212-300 μm using the MIR region were 9 ppm NH₄⁺ (7 ppm NH₄-N) and 36 ppm NO₃⁻ (8 ppm NO₃-N). For silt (particles less than 53 mum), the most effective model was the MIR region for both NH₄⁺ and NO₃⁻ measurements, yielding the detection limits of 15 ppm NH₄⁺ (12 ppm NH₄-N) and 50 ppm NO₃⁻ (11 ppm NO₃-N). The MIR region also performed reasonably well with soil samples but both NIR regions provided poor results. The detection limits for NH₄⁺ and NO₃⁻ measurements in soil were 100 ppm NH₄⁺ (78 ppm NH₄-N) and 330 ppm NO₃⁻ (75 ppm NO₃-N) with the correlation coefficients (R²) of roughly 80% and 90%, respectively. The spectral range of 2,900-2,400 cm⁻¹ was the effective common range for mineral N measurement in sand, silt, and soil samples.

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Uribe-Chavez, Armando. "A numerical model and semi-analytic equations for determining water table elevations and discharges in non-homogeneous subsurface drainage systems." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/289956.

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A free water surface finite element model was developed. The method was implemented with the Galerkin approach to solve the Laplace equation in the saturated region. It was developed in the object oriented Visual C ++ computer language to permit easy update and drawing of the adaptive mesh. For each time step, the new water table position was calculated based on flux across the water table, a Brooks-Corey equation mass balance for the unsaturated region, and an equation that calculates water table position for the saturated region. An equation was developed to calculate a drainage transfer coefficient, alpha, based on percentage of perforated area in the drain tube wall. The drainage transfer coefficient was incorporated into the finite element model as a Fourier boundary condition. To validate the finite element model, its results were compared with the Kirkham equation results for steady state recharge of three subsurface drainage systems. The finite element model was used to calibrate a semi-analytical frozen stream tube model for subsurface drainage of heterogeneous soils. The first step in the calibration procedure is to run the finite element model for steady state recharge and calculate the water table height divided by recharge rate (the stream tube resistance to flow) as a function of distance between drains. Least squares regression is used to fit a polynomial logarithmic equation, called the resistance function, to the stream tube resistance to flow vs. distance from the drain curve. A differential equation based on the principle of conservation of mass and application of Darcy's law to the frozen stream tube was solved to obtain an equation that calculates stream tube flow rate and final water table elevation as a function of the resistance function and initial water table elevation. An example was developed for a non-homogeneous subsurface drainage system to illustrate the use of the semi-analytical model to predict water table fall and discharge.

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Suarez-Romero, Armando. "Retractable roof greenhouse: Potential for Solanaceae production in semi-arid regions." Thesis, The University of Arizona, 2006. http://hdl.handle.net/10150/292089.

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Retractable Roof Greenhouses are a new trend in the greenhouse industry. They allow the improvement of many nursery and crop production practices in semi-arid regions. Hydroponically grown peppers and tomatoes were tested to evaluate possible year-round cultivation in this kind of structure that permits high radiation exposure. Control systems based on radiant surfaces temperatures were developed to integrate, cost effectively, the environmental factors that influence the plants' development and yield, including: air temperature, solar radiation and wind speed. Yields of 7.4 kg m⁻² and 33.0 kg m⁻² were obtained respectively for top quality pepper and tomatoes. These yields were similar or slightly lower than conventional greenhouses in the similar price range and design complexity. This makes the retractable roof greenhouse a mediocre structure for pepper and tomato production in southern Arizona. Radiant surface temperature was found to be a useful parameter for the control of the retractable roof greenhouse climate.

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Bon, Tom A., and Henry L. Kucera. "Agricultural and Biosystems Engineering Capstone Course Evolution at North Dakota State University." American Society of Agricultural and Biological Engineers, 2005. https://hdl.handle.net/10365/31010.

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The approach to the department's capstone design course has changed considerably since the 1960s. The general evolution of the course has proceeded from extended laboratory exercises to individuals working on self-defined projects to team-based projects. Interactions between the capstone course and other courses have been attempted with varying success. This paper presents the development of the NDSU Agricultural and Biosystems Engineering Department' s capstone course and thoughts on possible future modifications to the course.
Agricultural and Biosystems Engineering
College of Graduate and Interdisciplinary Studies

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Prigg, David B. "DESIGN OF A HYDRAULICALLY-ACTUATED HEXAPOD ROBOT FOR ORGANIC FARMING." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1588002562729248.

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Marouelli, Waldir Aparecido 1958. "Improving chemigation efficacy by controlling droplet size distribution of oil-based pesticides." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282265.

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For chemigation of nonsoluble pesticides, small oil-pesticides droplets (dmax tend to wash-off from foliage while large droplets tend to stick. Large droplets (dmax are buoyant, tend to rise in the irrigation pipeline and exit at the beginning of the pipeline; thus, uniformity and efficacy are poor. For this research, a new chemigation system was proposed. The system removes water from the irrigation pipeline, injects the oil-pesticide into the water stream, increases dispersion velocity in successively smaller tubing diameters, and finally injects the dispersion back into the irrigation pipeline. The higher velocity flow with high turbulent shear forces breaks the oil-pesticide into desired size droplets. Droplet break-up research was reviewed, and a model developed to predict maximum droplet size and size distribution. A maximum relative error of 40% was observed when dmax predicted by the model was compared against literature data. Equations to predict friction factor in helically coiled pipes and effective viscosity of oil-in-water dispersions were evaluated. The friction factor predicted by the Ito equation was in good agreement with the experimental data. Effective viscosity of soybean oil- and kerosene-in-water dispersions was predicted satisfactorily by the Richardson equation with k₄ = 2.5. Finally, center pivot field experiments were conducted using the new and conventional chemigation systems. For the conventional system, the soybean oil uniformity coefficient along the lateral was 61%, and oil applied over the last tenth of irrigated area was 9% of the initial concentration. For the new system, the uniformity coefficient was 73% and 98% for dmax of 875 mum and 98 mum, respectively; oil applied over the last tenth of the area was 27% and 90% of the initial concentration. Field data were compared with those predicted from a pipeline transport model for nonsoluble pesticides. Agreement between the model and the field data was excellent for both experiments using the new chemigation system. Based on the field results and simulation analyses, droplets < 150 μm should be desirable to keep the discharge uniformity coefficient over 97%, for 0.92 ≤ ρ(d)/ρ(c) ≤ 1.04.

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Damak, Maher Ph D. Massachusetts Institute of Technology. "Droplet deposition on hydrophobic surfaces for agricultural sprays." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/101814.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 51-55).
This thesis presents a study of the in-situ precipitation of polyelectrolytes during droplet impacts and its applications in enhancing the retention efficiency of sprays. Large amounts of agricultural sprays are wasted worldwide, due to the poor retention on hydrophobic plants. As the harmful effects of pesticides in particular are more and more pointed out, there is an increasing pressure to reduce their use and make their spraying more efficient. Current solutions, mainly based on surfactants, all have limitations. Here, we present a novel idea based on the modification of the surface of the plant. By precipitating opposite polyelectrolytes, in-situ, we create sparse pinning sites that pin the contact lines of the impacting droplets from the spray and prevent them from bouncing off. We first study the behavior of the impact of two droplets containing oppositely charged polyelectrolytes on a hydrophobic surface. We then study the precipitation process of two polyelectrolytes and develop a model that predicts the outcome of a double drop impact. Finally, we show the macroscopic applications of this study, by using simultaneous spraying. Simultaneously spraying dilute opposite polyelectrolytes on a superhydrophobic surface leads to a large increase in the liquid retention and the coverage of the surface. The behavior has been shown to hold for different polyelectrolytes and surfaces, making this method suitable for a range of applications.
by Maher Damak.
S.M.

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Huang, Shen S. B. Massachusetts Institute of Technology. "Evaluation of pre-packaged agricultural drip irrigation kits." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74494.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 67-69).
The purpose of this thesis is to conduct user testing and performance evaluation of two different agricultural pre-packaged drip irrigation kit (PDIK) systems: Chapin Bucket Kit and International Design Enterprises (IDE) drip kit. PDIK systems are a cost-effective type of appropriate technology for the developing world because they reduce agricultural water consumption and can increase crop yield over other methods of irrigation. Overall user testing indicates preference for the IDE drip kit because of ease of installation, low cost, and suitable size for the average household plot. On the other hand, the Chapin Bucket Kit performs better in laboratory evaluation in terms of emitter performance, materials strength, and filter clogging . Ultimately, it is up to users to decide what are the trade-offs that can be made when choosing a PDIK system. This study is conducted under the MIT Development Lab Technology Evaluation and Verification Program (D-lab TEV) and has been financially supported by the MIT Public Service Center and the MIT Department of Foreign Languages and Literature.
by Shen Huang.
S.B.

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32

Stroh, Oliver. "A hearing protection intervention system for agricultural workers." Thesis, University of Iowa, 2019. https://ir.uiowa.edu/etd/6863.

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Twenty-two million US citizens are exposed to hazardous noise at work each year, putting them at risk for noise induced hearing loss. Noise induced hearing loss is preventable, cumulative, and irreversible with net economic impact estimated at $123 billion. While agencies such as the Occupational Safety and Health Administration have regulations in place to reduce noise induced hearing loss, these regulations are rarely enforced for agricultural workers. These workers have a low rate of hearing protection usage, with several studies finding that almost half of farmers never use hearing protection devices. Additionally, farmers have twice the hearing loss in higher frequencies and three times in mid-range frequencies than non-farmers. Use of hearing protection can reduce noise induced hearing loss, and agricultural workers are interested in increasing their usage. This makes them a promising group to target with a hearing protection intervention. This paper describes a system that combines a smartphone with a USB based noise dosimeter that can read within +/- 2 A-weighted decibels of a Class 2 sound level meter providing daily noise exposure monitoring. This device is worn by the agricultural worker throughout a work day, collecting location, accelerometer, and audio data. The data is then transferred onto the server and presented to the agricultural worker using a locally hosted website, giving personalized data of loud noise exposures that can be understood without the need for a safety specialist. The dosimeter’s data allows the agricultural worker to explore what sound pressure levels they are exposed to and get an estimate of their total noise exposure. The GPS, paired with audio clips of loud noises, allows the agricultural worker to determine what activities put them at risk of noise induced hearing loss, which are good indications of where to place hearing protection devices. The system was tested on a farm, comparing its output with several reference instruments. A-weighted, 1-second averaged sound pressure levels, GPS, and accelerometer data were collected while performing a variety of tasks indoors and outdoors. The smartphone’s external noise dosimeter read within +/- 2 dBA of the Class 2 reference dosimeter 59% of the time. The GPS devices had an average error of sub-4 meters between and the accelerometers had a mean absolute error of less than 0.1 g.

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Elbanna, E. B. E. "Agricultural machinery selection : Soil strength and operational timeliness." Thesis, University of Edinburgh, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371883.

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Richards, Johanna. "Drought assessment tools for agricultural water management in Jamaica." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97212.

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Increasing urban development, in addition to changing climatic conditions, are just a few of the factors negatively impacting Jamaica's water resources. Therefore, conceptual tools are required for the management of water resources during water scarce conditions. Such tools include drought indices, irrigation requirement guidelines and computer simulation models for irrigation planning.Monthly irrigation demands were calculated for three sites in Jamaica: Savanna-la-mar in the parish of Westmoreland, Beckford Kraal in the parish of Clarendon, and Serge Island in the parish of St. Thomas. This was done using simulated monthly available soil moisture values averaged over a 30 year period, for both vegetables and sugarcane. The greatest irrigation demands were found to be in the dry period of January to April, as well as July to August for Savanna-la-mar and Beckford Kraal. Serge Island, however, needs irrigation throughout the year. Two drought indices, the Standardized Precipitation Index (SPI) and the Normalized Difference Vegetation Index (NDVI), were used for the study sites. Both indices were correlated to simulated monthly available soil moisture. It was found that the relationship between each index and soil moisture varies from month to month, with drier months resulting in better correlations than wet months. Predicted available soil moisture values have been calculated for the different SPI categories. It was found that available soil moisture is lowest in the months of March and April. In addition, irrigation requirements were determined for the Moderately Dry and Severely Dry SPI categories of drought in the drier months of the year, for the three study locations, for both vegetables and sugarcane.SWAT was used to model the hydrology of the Rio Nuevo watershed in St. Mary, Jamaica. SWAT was calibrated and validated using measured streamflow data from the period 2002 to 2007, and achieved satisfactory model performance, with a Nash-Sutcliffe Efficiency of 0.78 for calibration and 0.52 for validation. The SWAT model results were used to determine streamflow capacity for irrigation demands in an agricultural sub-basin of the watershed, and it was found that during the drought year of 2000, there was not enough streamflow to meet irrigation demands of January and March.
L'augmentation du développement urbain et les changements climatiques ne sont que deux des multiples facteurs ayant un impact néfaste sur les ressources hydriques de la Jamaïque. A cet effet, des outils conceptuels sont nécessaires à la gestion des eaux en période de sécheresse. De tels outils sont par exemple les indices de sécheresse, les guides d'irrigation et les planificateurs d'irrigation (par exemple le SWAT, Soil and Water Assessment Tool). Les demandes nettes en irrigation de trois sites jamaïcains ont été calculées: Savanna-la-mar (Westmoreland), Beckford Kraal (Clarendon) et Serge Island (St-Thomas). Ces calculs sont basés sur les moyennes des conditions mensuelles d'humidité disponible des soles, échelonnées sur une période de trente ans et en provenance de sites où sont produits des légumes et de la canne à sucre. La période sèche de janvier à avril connait les plus grandes demandes d'irrigation. La période de juillet à août pour les sites de Savanna-la-mar et Beckford Kraal connait aussi des demandes importantes. Le site de Serge Island a besoin d'irrigation tout au long de l'année. Deux indices de sécheresse ont été développés pour les sites d'études : l'Indice de Précipitation Standardisé (IPS) et l'Indice de Végétation de Différence Normalisée (IVDN). Tous deux ont été corrélés afin de simuler l'humidité mensuelle disponible des soles. Les résultats démontrent que la relation entre chaque index et l'humidité des soles varie de mois en mois, les mois plus secs offrant de meilleures corrélations que les mois plus humides. Les prédictions d'humidités disponibles des soles ont été calculées pour les différentes catégories d'IPS. L'humidité disponible des soles est au plus bas pour les mois de mars et d'avril. De plus, les demandes en irrigation pour la production de légume et de canne à sucre ont été déterminées pour les catégories d'IPS Modérément Sec et Sévèrement Sec de sécheresse dans les mois plus secs de l'année, et ce dans les trois sites étudiés. SWAT a été utilisé pour modeler l'hydrologie du basin versant de Rio Nuevo dans la région de St-Mary en Jamaïque. SWAT a été calibré et validé en utilisant des mesures de débit couvrant la période 2002 à 2007. Les performances du modèle sont considérées satisfaisantes, ayant obtenu une Efficacité Nash-Sutcliffe de 0.78 pour la calibration et de 0.52 pour la validation. Les résultats obtenus ont été utilisés afin de déterminer les capacités du débit à répondre aux demandes d'irrigation d'un bassin inférieur du bassin versant. Il a été déterminé que pour la sécheresse de 2000, le débit était insuffisant et ne pouvait répondre aux demandes d'irrigation de janvier à mars.

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Lange, Jennifer Marie. "Engineering analysis of the air pollution regulatory process impacts on the agricultural industry." Thesis, Texas A&M University, 2008. http://hdl.handle.net/1969.1/85899.

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The EPA press release dated February 23, 2004 states that the three Buckeye Egg Farm facilities had the potential to emit more than a combined total of 1850 tons per year of particulate matter (PM). This number was based on flowrate calculations that were three times higher than those measured as well as a failure to include particle size distributions in the emissions calculations. The annual PM emission for each facility was approximately 35 tons per year. The EPA was unjustified in requiring Buckeye Egg Farm to obtain Title V and PSD permits as the facilities could not have met the thresholds for these permits. Engineers need to be concerned with correctly measuring and calculating emission rates in order to enforce the current regulations. Consistency among regulators and regulations includes using the correct emission factors for regulatory permitting purposes. EPA has adopted AERMOD as the preferred dispersion model for regulatory use on the premise that it more accurately models the dispersion of pollutants near the surface of the Earth than ISCST3; therefore, it is inappropriate to use the same emission factor in both ISCST3 and AERMOD in an effort to equitably regulate PM sources. For cattle feedlots in Texas, the ISCST3 emission factor is 7 kg/1000 hd-day (16 lb/1000 hd-day) while the AERMOD emission factor is 5 kg/1000 hd-day (11 lb/1000 he-day). The EPA is considering implementing a crustal exclusion for the PM emitted by agricultural sources. Over the next five years, it will be critical to determine a definition of crustal particulate matter that researchers and regulators can agree upon. It will also be necessary to develop a standard procedure to determine the crustal mass fraction of particulate matter downwind from a source to use in the regulatory process. It is important to develop a procedure to determine the particulate matter mass fraction of crustal downwind from a source before the crustal exclusion can be implemented to ensure that the exclusion is being used correctly and consistently among all regulators. According to my findings, the mass fraction of crustal from cattle feedlot PM emissions in the Texas High Plains region is 52%.

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Bootsma, Erik Jan. "Mapping time-series evapotranspiration for agricultural applications." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-448787.

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Fresh water provides a range of essential services and is often used for irrigation purposes. Decreasing precipitation and increasing temperatures caused by climate change together with increased usage by humans has put these resources under stress, especially in relatively dry areas. This project takes a closer look at the irrigation of agricultural areas in the Guadalquivir river basin in southern Spain. An indication of irrigation intensity is attained by estimating the evapotranspiration using the S-SEBI method. This method is based on the surface energy balance and uses Landsat satellite images as its main input. Secondarily, a random forest classifier is trained to differentiate between irrigated and non-irrigated agricultural areas. Evaluation of these implementations produced a Root Mean Squared Difference of 0.8mm/day for daily actual evapotranspiration and an overall accuracy close to 80% for classification of irrigated areas. The results indicate that both the level of evapotranspiration and the irrigated agricultural surface area were stable over the period 2000-2020. This should not be taken to indicate that current freshwater management is therefore sustainable. This project shows the value ofcloud-computing services such as Google Earth Engine for remote sensing research. With this tool evapotranspiration estimation and irrigation classification was performed on an unprecedented temporal and spatial scale.

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Sarkar, Soumen. "Dynamic modeling of an articulated forestry machine for simulation and control." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27255.

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Recently, robotic technology has begun to play an important role in forestry operations. An important class of forestry machines is comprised of systems equipped with a mobile platform fitted with an articulated arm carrying a tree processing head. The dynamics of such systems are needed for simulation and control purposes. In contrast to conventional industrial manipulators, which are mounted on stationary bases, a mobile manipulator is dynamically coupled with its base. Base compliance, non-linearity and coupled dynamics result in positioning inaccuracies which in turn give rise to control problems.
The dynamics of the FERIC forwarder forestry machine including its compliant tires were developed and implemented symbolically in compact form with the help of an iterative Newton-Euler dynamic formulation. Various models with increasing complexity were derived. Based on a simplified dynamics model, a valve-sizing methodology was developed and used to size hydraulic proportional valves of the machine's actuators.
System parameters have been obtained by various methods, including use of blueprints, weighing, solid modeling and various experiments. A set-point feedforward controller was designed and the machine's responses for various inputs were obtained to analyze the dynamic behavior of the system. Although initial simulations were done in Matlab and Simulink, C programs were developed for increased speed of execution. In addition, techniques to minimize computation time have been developed and applied to result in almost real time simulation.

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Mu, Bin. "System modelling, identification and coordinated control design for an articulated forestry machine." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27245.

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This thesis describes the modelling of electrohydraulic actuation systems of a prototype forestry vehicle, the experimental identification of the dynamic models parameters and control strategies for forestry operations.
The linear graph method is selected to derive comprehensive models of three electrohydraulic actuation subsystems, i.e. the swing, boom and stick subsystems, on the vehicle based on modelling of individual components. A new approach is proposed, then, to integrate rigid-body dynamic models with the actuator dynamic models to result in a complete machine model.
Off-line parameter identification procedures are used, including the least-square method. A series of experiments is performed to obtain numerical values for the parameters involved in the system models. The experimental setups are described in detail and new procedures are explained. The model validation studies show that the mathematical models closely represent the dynamic characteristics of the forestry machine.
The concept of coordinated control in teleoperation is studied. The resolved motion rate control strategy shows superiority over conventional joint-based control in heavy-duty forestry machines. Two inverse Jacobian manipulator control schemes, based on velocity and on position servo schemes, are introduced and evaluated under various operating conditions. The results provide guidelines for the design and implementation of manipulator controllers on a forestry machine.

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39

Moreno-Urquiza, Magdalena 1967. "Intelligent data acquisition system for continuous measurements of soil moisture in the field." Thesis, The University of Arizona, 1993. http://hdl.handle.net/10150/278271.

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A data acquisition system to collect soil moisture readings at 60 field locations was developed. The system predicted a resistance value from a measured counts per time. An error was associated with the measured counts and time, however, this error was minimized by increasing the time for resistance measurement. The effect of temperature was minimized by an automatic calibration of the system before collecting readings. The Watermark electrical resistance moisture sensor was used to sense water content. The system, including eight sensors, was tested in the field. The data collected was difficult to explain. An evaluation of the Watermark sensors indicated a large variation from sensor to sensor, and also indicated a marked influence of soil texture on sensor resistance.

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McIntosh, Dennis. "Reducing the environmental impact of aquaculture." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/289234.

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Aquaculture has great potential to help supply the nutritional needs of a growing population. To date, however, the benefits that aquaculture can have, have largely been overshadowed by the environmental degradation some segments of the industry have caused. The following body of work describes my efforts to help reduce the environmental impacts of aquaculture. By integrating aquaculture production into traditional agriculture, the impact of farming on already limited water resources and the reliance on chemical fertilizers can be reduced. Recent expansion of the aquaculture industry in Arizona has made it possible to study the integration of olive groves with marine shrimp culture. In chapter 3, I describe the characterization and evaluation of the effluent from an inland, low-salinity shrimp farm as a potential source of irrigation water. I found that 0.41 kg of ammonia-nitrogen, 0.698 kg of nitrite-nitrogen, 8.7 kg of nitrate-nitrogen and 0.93 kg of total phosphorus (TP) were made available as fertilizer each day in the effluent water. Based on the results of this first study, I decided to conduct a farm trial to quantify the effects of these shrimp farm effluents on olive trees. This work is described in chapter 4. Trees in all treatment groups grew an average of 40.1 cm over the four month study period. While growth of trees irrigated with shrimp farm effluent did not improve in respect to the other treatments, our results do indicate that irrigating with low-salinity water had no noticeable negative effects. Chapter 5 describes work conducted in Idaho, as part of a larger study aimed at reducing the effluent loads of phosphorus (P) from high density, flow-through aquaculture facilities. Research steps were taken to establish a relationship between TP and the carbon 12/13 isotope ratio (δ¹³C) and/or the nitrogen 14/15 isotope ratio (δ¹⁵N). Our findings suggest that both δ¹⁵N and δ¹³C are good better proxies for P, after correcting for P retention. A linear regression of %P (corrected) on δ¹³C and δ¹⁵N resulted in R2 values of 0.843 and 0.8622, respectively. This suggests that by tracking δ¹⁵N and/or δ¹³C through a high-density, flow-through aquaculture facility over time I will be able to determine the residence time of P with a high degree of accuracy.

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41

Reynolds, Curt Andrew 1960. "Estimating crop yields by integrating the FAO crop specific water balance model with real-time satellite data and ground-based ancillary data." Thesis, The University of Arizona, 1998. http://hdl.handle.net/10150/192102.

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The broad objective of this research was to develop a spatial model which provides both timely and quantitative regional maize yield estimates for real-time Early Warning Systems (EWS) by integrating satellite data with groundbased ancillary data. The Food and Agriculture Organization (FAO) Crop Specific Water Balance (CSWB) model was modified by using the real-time spatial data that include: dekad (ten-day) estimated rainfall (RFE) and Normalized Difference Vegetation Index (NDVI) composites derived from the METEOSAT and NOAA-AVHRR satellites, respectively; ground-based dekad potential evapo-transpiration (PET) data and seasonal estimated area-planted data provided by the Government of Kenya (GoK). A Geographical Information System (GIS) software was utilized to: drive the crop yield model; manage the spatial and temporal variability of the satellite images; interpolate between ground-based potential evapotranspiration and rainfall measurements; and import ancillary data such as soil maps, administrative boundaries, etc.. In addition, agro-ecological zones, length of growing season, and crop production functions, as defined by the FAO, were utilized to estimate quantitative maize yields. The GIS-based CSWB model was developed for three different resolutions: agro-ecological zone (AEZ) polygons; 7.6-kilometer pixels; and 1.1-kilometer pixels. The model was validated by comparing model production estimates from archived satellite and agro-meteorological data to historical district maize production reports from two Kenya government agencies, the Ministry of Agriculture (MoA) and the Department of Resource Surveys and Remote Sensing (DRSRS). For the AEZ analysis, comparison of model district maize production results and district maize production estimates from the MoA (1989-1997) and the DRSRS (1989-1993) revealed correlation coefficients of 0.94 and 0.93, respectively. The comparison for the 7.6-kilometer analysis showed correlation coefficients of 0.95 and 0.94, respectively. Comparison of results from the 1.1-kilometer model with district maize production data from the MoA (1993-1997) gave a correlation coefficient of 0.94. These results indicate the 7.6-kilometer pixel-by-pixel analysis is the most favorable method. Recommendations to improve the model are finer resolution images for area planted, soil moisture storage, and RFE maps; and measuring the actual length of growing season from a satellite-derived Growing Degree Day product.

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42

Lopez, Sabater Carlos Joaquin. "An empirical model of hydraulic roughness for overland flow." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/280353.

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This research has developed a method for estimating hydraulic roughness coefficients for overland flow models in a dynamic approach, to more effectively simulate runoff on natural, agricultural and urban slopes. The hydraulic roughness coefficients are then generated with a series of neural networks. First, a laboratory experiment was designed to explore the effects of soil microtopography, slope and Reynolds number on the magnitude of Darcy-Weisbach, Manning and Chezy roughness coefficients. It was found that three parameters were necessary to describe the soil surface microtopography. Neural networks developed in a preliminary phase were able to reproduce the roughness coefficients obtained in the laboratory experiment by using five predictor variables: bed slope, Reynolds number, and the three parameters used to describe the microtopography. However, these networks failed to generate roughness coefficients for different input variables (generalization). Second, more complex algorithms were developed as combinations of neural networks in parallel. The algorithm output, the sought hydraulic roughness estimate, was estimated with the arithmetic average of the individual network outputs. Results presented in this study demonstrate that combining multiple neural networks reduced the prediction error and improved on the generalization ability of the neural networks. It was also observed that the estimate accuracy was influenced by the characteristics of the dataset, and especially by the relationship between the roughness coefficient and Reynolds numbers. Finally, a field experiment was performed to explore the applicability of the algorithms. A numerical model based on the 1-D diffusion approximation to the Saint Venant equations was constructed, and two surface irrigations were performed to collect data to test the model estimates. The model was used under two scenarios: (1) with constant hydraulic roughness coefficients, and (2) using variable hydraulic roughness predicted with the algorithm. Discharge at the end of the plot and irrigation front advance estimated using both models matched the observations well. However, when using a variable hydraulic roughness, the front was initially delayed until there was a sufficient surface storage to push it forward. The methodology described in this research should be useful for 2-D overland flow models applied to natural slopes with unsteady rainfall.

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Simmons, Gregory Sinclair. "Studies on dispersal of a native parasitoid Eretmocerus eremicus and augmentative biological control of Bemisia tabaci infesting cotton." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284117.

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In the mid-1980s, a new biotype of Bemisia tabaci was introduced into the southern U.S. causing extensive damage to agricultural crops throughout the region. An augmentative biological control project was initiated using a native parasitoid, Eretmocerus eremicus to determine its efficacy against B. tabaci infesting cotton in the desert areas of California and Arizona. A series of experiments were conducted in 1992-1995: release rate studies in cages and open fields; parasitoid dispersal within fields to determine movement rates after point release; and experiments to determine the parasitoid-host spatial relationship. Cage release rate studies, demonstrated that rates of parasitism could be increased 61 to 79% in the highest release treatments, with reductions in whitefly densities of 80 to 100% relative to control treatments. Cotton yields in the high release treatments peaked at 2.5 bales/ac and were 2.6 to 4.2 times greater than in control treatments. Effective release rates were estimated to be equivalent to 770,000 to 1.1 million parasitoids/ha. Field releases equivalent to 7.9 million parasitoids/ha resulted in a peak rate of parasitism of 42% but there were no statistical differences in parasitism, whitefly densities, or cotton yield; relative to no-release plots. High levels of whitefly immigration from surrounding crops, and parasitoid dispersal from release plots, diluted the effects of release. In a second field release rate study, releases equivalent to 2.0 to 3.0 million parasitoids/ha increased levels of the percentage of discovered leaves to greater than 80%. Parasitoid dispersal was analyzed with mark-recapture experiments and data were fit to a diffusion model. One female wasp flew 82 m in one day though the majority of wasps flew a few meters or less. Estimated diffusion rates and median dispersal distances were 0.40 to 0.71 m²/min and 2.4 to 4.4 m/(4 to 8) days respectively. Analysis of dispersal data suggested that releases on 20 m centers would provide effective coverage within a field. Density independent parasitism was common at the spatial scale of leaves and plants. There was positive density dependence for the percentage of discovered leaves suggesting that parasitoids aggregate to high density patches of whitefly but fail to achieve high levels of parasitization possibly due to egg limitation or mutual interference.

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44

Fukumura, Kazunari 1956. "Electrokinetic nitrate removal from porous media." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/290595.

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Nitrate movement under simultaneous influence of hydraulic, electric and chemical gradients was investigated. A one-dimensional ion migration model was developed and compared with laboratory column experiments. Operation of subsurface drainage with an electrode was discussed as an application. The ion transport equation was developed utilizing non-equilibrium thermodynamics. Onsager's reciprocal relations were applied to reduce the number of linear phenomenological coefficients that relate flux to driving forces. Then phenomenological coefficients were expressed using known or measurable physical, chemical and electrical properties of solute and porous media. Developed equations were numerically solved by the Integral Finite Difference Method in one dimension. The numerical results were validated with analytical solutions of simple boundary conditions as well as the results obtained from laboratory column experiments for two or three applied gradients. Without water flow, nitrate concentration increased at the anode by 2.5 times after 100 hrs of 30 V application. Three initial concentrations, 10, 100 and 500 ppm NO₃-N, were tested. A log normal relation between elapsed time and relative concentration increase at the anode was obtained. Two flux rates (0.112 and 0.225 cm min⁻¹), and three inflow concentrations (100, 500 and 1000 ppm NO₃-N) were used to evaluate nitrate transport in the column. Nitrate concentration at the anode increased by 10 to 20% at the end of all experiments. However, the concentration in the column was same as inflow concentration. The application of electrokinetic nitrate removal by installed subsurface drainage with on-off (no flow then flush out) operation is recommended over a continuous flow approach. The numerical model results showed very low flux rates (i.e. 2.68 x 10⁻³ cm min⁻¹) are required for nitrate accumulation in a sand column, and the experimental results confirmed no accumulation at a flux rate of 0.112 cm min⁻¹.

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45

Batchily, Abdul Karim 1952. "Use of Chroma Meter color measurements to evaluate the organic carbon, iron, and water content of soils." Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/277947.

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The soil color components of 127 samples from five Arizona Agricultural Research Centers and 52 WEPP samples occurring in various parts of the U.S.A. were evaluated using a Minolta Chroma Meter. This instrument is designed to minimize the variability in color determination utilizing a built-in light source to generate a primary source of radiation. Simple and multiple linear regression equations relating Hue, Value, and Chroma color components were obtained to predict the organic carbon and iron content of these soils. The results show that using global data is less reliable than specific groupings of soils. Moist value and moist chroma moist are the two most important color components in estimating the organic carbon content of soils. Chroma and Hue were highly correlated to iron at all moisture levels. Chroma was least affected by soil moisture, but Value and Hue consistently decreased for all soils.

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46

Sparkes, Simon Timothy. "Agricultural analysis by plasma emission spectroscopy with slurry atomisation." Thesis, University of Plymouth, 1986. http://hdl.handle.net/10026.1/2145.

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The three electrode direct current plasma (DCP), has been investigated for the analysis of samples introduced using aqueous solution nebulisation, hydride generation and slurry atomisation. For aqueous solutions, simplex optimisation with signal to background ratio as the criterion of merit, vertical viewing position was found to be most critical. A continuous-flow hydride generator was interfaced to the DCP via a modified sample introduction chimney. Optimisation indicated that total sample introduction gas flow rates were essentially similar to those for conventional nebulisation and that vertical viewing position was again critical. Generation conditions for lead hydride were also simplex optimised. Acid, sodium hydroxide, and hydrogen peroxide concentration were all found to be critical. Detection limits for hydride generation were: As 4 ng cmˉ³, Se 4 ng cmˉ³, Pb 10 ng cmˉ³. Arsenic and selenium were accurately determined in various reference materials. The determination of Mg in aqueous slurries of kaolin was optimised using the Mg(II) 279.079 nm line and conventional sample introduction. Vertical viewing position was again critical with the optimum on the boundary of the analytical zone and over the plasma core. A reduction of emission intensity at high slurry concentrations (> 12%), was observed. Particle size was the most important parameter in slurry atomisation, < 5 µm being preferred. Soils, milk, plant materials and sewage sludges were successfully analysed by slurry atomisation. Where necessary, particle size was reduced using simple grinding procedures. For fibrous materials, prior matrix carbonisation was advantageous. Results obtained using these procedures and simple aqueous calibration showed excellent agreement with certified values of reference materials. Electron number density (ne), excitation temperature (Texc) and ionisation temperature (Tion), were measured for two series of kaolin slurries, (1-20% m/V), one containing 5 g 1ˉ¹ lithium as enhancement buffer. For the slurries containing added lithium, Texc and ne were found to be reduced with increasing slurry concentration. Observed decreases in analyte emission with increased sample loadings (> 12%), are considered to be consistent with proposed excitation models.

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Quigley, Andrew Douglas. "A study of tractor tyre braking on agricultural land." Thesis, Heriot-Watt University, 1986. http://hdl.handle.net/10399/1053.

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48

Faborode, M. O. "The compression and relaxation behaviour of fibrous agricultural materials." Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372931.

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Smith, Derik Lafayette, and Satya Prakash Dhavala. "Using big data for decisions in agricultural supply chain." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81106.

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Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 53-54).
Agriculture is an industry where historical and current data abound. This paper investigates the numerous data sources available in the agricultural field and analyzes them for usage in supply chain improvement. We identified certain applicable data and investigated methods of using this data to make better supply chain decisions within the agricultural chemical distribution chain. We identified a specific product, AgChem, for this study. AgChem, like many agricultural chemicals, is forecasted and produced months in advance of a very short sales window. With improved demand forecasting based on abundantly-available data, Dow AgroSciences, the manufacturer of AgChem, can make better production and distribution decisions. We analyzed various data to identify factors that influence AgChem sales. Many of these factors relate to corn production since AgChem is generally used with corn crops. Using regression models, we identified leading indicators that assist to forecast future demand of the product. We developed three regressions models to forecast demand on various horizons. The first model identified that the price of corn and price of fertilizer affect the annual, nation-wide demand for the product. The second model explains expected geographic distribution of this annual demand. It shows that the number of retailers in an area is correlated to the total annual demand in that area. The model also quantifies the relationship between the sales in the first few weeks of the season, and the total sales for the season. And the third model serves as a short-term, demand-sensing tool to predict the timing of the demand within certain geographies. We found that weather conditions and the timing of harvest affect when AgChem sales occur. With these models, Dow AgroSciences has a better understanding of how external factors influence the sale of AgChem. With this new understanding, they can make better decisions about the distribution of the product and position inventory in a timely manner at the source of demand.
by Derik Lafayette Smith and Satya Prakash Dhavala.
M.Eng.in Logistics

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Kärkkäinen, Ela, Åsa Älgbrant, and Simon Kronberg. "Fibres from agricultural hemp waste." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-26573.

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There is an increasing demand for natural fibres in the textile industry as a consequence of the negative impact of the industry on the environment. Svensk Hampaindustri (SHI) is currently growing hemp in Sweden for its seeds. This leaves residue in the form of hemp stems that could be processed for textile products. Today this residue material is not used for anything, however there is a desire that it could be used for added value. This study investigates the possibility of extracting fibres from the hemp residue mechanically and using them in applications. Hemp, a variety of Cannabis sativa L., is a multipurpose low-input crop cultivated for its seeds, fibres and hurds. Hemp fibre is a bast fibre, derived from the plant’s outer stem tissues. To extract hemp fibres from hemp stems, the first step is to separate the fibre bundles from the other, non-fibrous parts of the stem. This process is done using various mechanical methods. In order to ease the separation, hemp stems are retted. Retting is a biological process that uses enzymatic activities to degrade the pectins and thus making the separation easier. Retting is one of the most considerable challenges towards a wider use of hemp fibres. Water retting offers high fibre-quality but consumes high amounts of water and causes effluents in the wastewater. Dew retting offers a high fibre yield and low labour costs but will result in a lower fibre-quality. Alternative methods that can contribute with a more consistent fibre yield and quality are available, but with an economic uncertainty for the farmers that limits the competitiveness of the hemp fibre. The hemp material provided by SHI was unretted and needed to be broken down by means of mechanical processing in order to extract the fibres. This was done using a domestic blender. The crushed material was then carded using a hand carding machine to achieve oriented and clean fibres. The obtained fibres were then evaluated for their length and fineness. Three different types of nonwoven were made using the hemp fibres: NW1, NW2 and NW3. NW1 consists of 100% hemp, whereas NW2 and NW3 are 80/20 blends of hemp and PLA. NW1 was needle punched, NW2 was thermally bonded and NW3 was manufactured by both thermal bonding and needle punching. The produced nonwovens were evaluated by their air permeability, thermal conductivity, sound absorption, drapability and tensile strength. The results from the study showed that it is possible to extract unretted fibres using mechanical methods. The fibres are quite coarse and therefore more suitable for industrial applications. The different production methods for the nonwovens gave different results which supports the diversity of hemp applications. This study suggests that the residue should be used rather than be disposed of.

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Dissertations / Theses on the topic 'Agricultural engineering'

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