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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

A Framework for assessing Alternative Agro-Ecosystems: finding Multi-Functional Solutions for Sustainable urban landscapes.

Thiesen, Thais H, Ms. 09 November 2016 (has links)
Creating sustainable urban landscapes in light of growing population pressures requires interdisciplinary multi-functional solutions. Alternative agro-ecosystems described as food forests, permaculture gardens, and/or edible landscapes among others could offer potential ways to address the social, economic and ecological goals of various stakeholders simultaneously. The present research used a unique rubric, the Permaculture and Agro-ecosystems Sustainability Scorecard (PASS) that combines existing agricultural and landscape sustainability indicators in order to assess alternative agro-ecosystems. The rubric evaluates provisioning, regulating, supporting and cultural ecosystem services such as pollinator presence, biodiversity, pesticides and fertilizer use, carbon sequestration and human interactions. The PASS was used to score twelve sites in South Florida that meet specific criteria in the small farm, residential and public space categories. The results showed that the majority of the sites scored highest in the supporting services provided, followed by regulating and cultural services and lowest in the economic services category.
62

Effects of Row Width and Seeding Rate on Yield and Other Agronomic Characteristics of Three Soybean Cultivars

Kithcart, Russell 01 July 1978 (has links)
Soybeans have traditionally been grown in rows wide enough to allow mechanical cultivation and to increase lodging resistance. Improved cultivars and herbicides have permitted farmers to obtain yield advantages from narrower rows. The growth response of soybeans to variations in row width and seeding rates depends upon the cultivar and geographic location. “Williams,” “Mitchell,” and “Essex” cultivars were planted at row widths of 18, 36, 54, and 72cm. at seeding rates of 33, 67, 100 and 134 kg/ha in multi-row plots. Data were collected from each plot for seed yield, lodging, plant height, height of lowest pod, seed and population per square meter. Results indicate that soybeans grown in 18 cm. rows produce higher yields than those grown in 72 cm. rows. The only effect on yield due to seeding rates was found within the cultivar Mitchell where intermediate seeding rates produced highest yields. Lower seeding rates were found to result in podding closer to the ground and to cause a decrease in seed size. Row width, seeding rate, and cultivar had no effect on lodging or plant height. Row width and seeding rate had no effect on maturity date.
63

Evaluation of Herbicides for Suppression of Rhizome Growth from Johnsongrass (Sorghum halepense L.) in Corn and Soybeans

Oakes, John 01 January 1977 (has links)
Johnsongrass (Sorghum halepense L.) presents a serious problem in the production of corn and soybeans in Kentucky. Various rates of the thiocarbamates, dinitroanilines, carbamates, amides, ureas, and triazines were used in association with the crops corn (Zea mays L.) and soybeans (Glycine max L.) to determine the degree of suppression on rhizomatous johnsongrass infesting the previously named crops. Suppression was determined by selecting areas within each treated plot, counting the number of culms, then harvesting johnsongrass rhizomes. Dry weights of rhizomes were then determined as a measure of rhizome suppression. Results show that of the various herbicides and rates used, none were significantly different in their degree of rhizome suppression.
64

Evaluation of S-734 and BAS 9052 for Control of Johnsongrass (Sorghum halepense) in Soybeans (Glycine max)

Ochoa, Julio Beingolea 01 December 1981 (has links)
Johnsongrass is one of the more limiting factors in soybean production and is the most serious weed problem in the Southeastern United States. Actually, different herbicides are used in johnsongrass control, and still there are new herbicides which are being tested. Two experimental herbicides for johnsongrass control in soybeans are BAS 9052 and S-734. The experiments were conducted in 1980 and 1981 with the objective to evaluate the effectiveness of S-734 alone and in combination with mefluidide and BAS 9052, BAS 9052 applied early or late postemergence, trifluralin, alachlor, and fluchloralin for seedling and rhizome johnsongrass control. In both areas S-734 was applied at 0.8, 1.1, and 1.7 kg/ha, S-734 at rates of 0.8, 1.1, and 1.7 kg/ha was combined with mefluidide at 0.3 kg/ha, S-734 at rates of 1.1 and 1.7 kg/ha was also combined with BAS 9052 at 0.6 kg/ha, BAS 9052 was applied at 0.6, 0.8, and 1.1 kg/ha early or late postemergence. Trifluralin and fluchloralin were applied at rate of 1.1 kg/ha in seedling study and 2.2 kg/ha in rhizome study. Alachlor was applied at rates of 3.4 and 4.5 kg/ha in seedling study. The results of the experiments showed that there were similarities and differences in the response of rhizome and seedling johnsongrass to the treatments. The control of johnsongrass, and the resulting soybean yields, was higher in the seedling area than in the rhizome area. There were no differences among rates of herbicides. Good seedling johnsongrass control was obtained with all treatments although there were differences among herbicides. In 1980 there were differences between BAS 9052 applied early and late postemergence, but there were no differences in 1981. BAS 9052 might be used as a late postemergence application for best seedling johnsongrass control. There were no differences among herbicides on soybean yields. In both years good rhizome johnsongrass control was obtained with BAS 9052 applied early or late postemergence. Poor rhizome johnsongrass control was obtained with S-734, trifluralin, and fluchloralin. High soybean yields were obtained with BAS 9052.
65

The Use of Hyphenated Spectrometric Techniques for the Environmental Forensic Assessment of Non-Traditional Pollutants and Degradates in the Greater Florida Everglades

Arroyo-Mora, Luis E. 24 February 2009 (has links)
A comprehensive investigation of sensitive ecosystems in South Florida with the main goal of determining the identity, spatial distribution, and sources of both organic biocides and trace elements in different environmental compartments is reported. This study presents the development and validation of a fractionation and isolation method of twelve polar acidic herbicides commonly applied in the vicinity of the study areas, including e.g. 2,4-D, MCPA, dichlorprop, mecroprop, picloram in surface water. Solid phase extraction (SPE) was used to isolate the analytes from abiotic matrices containing large amounts of dissolved organic material. Atmospheric-pressure ionization (API) with electrospray ionization in negative mode (ESP-) in a Quadrupole Ion Trap mass spectrometer was used to perform the characterization of the herbicides of interest. The application of Laser Ablation-ICP-MS methodology in the analysis of soils and sediments is reported in this study. The analytical performance of the method was evaluated on certified standards and real soil and sediment samples. Residential soils were analyzed to evaluate feasibility of using the powerful technique as a routine and rapid method to monitor potential contaminated sites. Forty eight sediments were also collected from semi pristine areas in South Florida to conduct screening of baseline levels of bioavailable elements in support of risk evaluation. The LA-ICP-MS data were used to perform a statistical evaluation of the elemental composition as a tool for environmental forensics. A LA-ICP-MS protocol was also developed and optimized for the elemental analysis of a wide range of elements in polymeric filters containing atmospheric dust. A quantitative strategy based on internal and external standards allowed for a rapid determination of airborne trace elements in filters containing both contemporary African dust and local dust emissions. These distributions were used to qualitative and quantitative assess differences of composition and to establish provenance and fluxes to protected regional ecosystems such as coral reefs and national parks.
66

Ekens historia och förekomst i Elleholm socken, Blekinge : en kvantitativ jämförelse över tid utifrån ekinventeringsprotokoll från åren 1819, 1830–31 samt nyinventering 2019

Malm, Patrik, Balaj, Liridon January 2020 (has links)
I århundraden har eken varit betydelsefull i Sverige. Kronans syfte var att kontrollera och lagstifta eken för tillgången på skeppsvirke. Det hårda lagstiftandet och kontrollerna bidrog till att avverkning av eken förbjöds på krono- och skattejord. På 1800-talet upplöstes dispositionsrätten vilket ledde till att ekbestånden minskade. Idag är äldre ekar med höga naturvärden viktiga miljöer då de hyser olika mikrohabitater som gynnar den biologiska mångfalden. Syftet med studien har varit att med hjälp av historiskt material jämföra antalet ekar med dagens invertering. I området Elleholm, i Blekinge, har en sådan inventering inte genomförts på över 200 år. Studien undersöker historiska källmaterial som ekinventeringsprotokoll över Elleholm socken för åren 1819, 1830–1831. Insamlade data har sedan jämförts med nutida inventering. Ute i fält har även ekens hålighet, vitalitet och omkrets noterats för att se över ekens kondition. Det framtagna resultatet visar att antalet ekar har minskat drastiskt sedan protokollen skrevs. Data som samlades in efter inventeringen kring ekens kondition gällande överlevnad är positiva. Nedgången på antalet ekar kan bero på att dispositionsrätten upphörde att gälla under 1830-talet. Vidare kan även den ökade befolkningstillväxten lett till att jordägarna avverkade eken illegalt och legalt. Resultatet visar att ekarna i området Elleholm är i bra kondition, vilket kan bero på gallring och öppenhet i landskapet. På grund av nedgången av ekbestånden skyddas ekarna genom de lagar som reglerar skyddandet av ädellövskog samt ”jätteträd”.
67

Impact of Oyster Mushroom Mycelium on the Growth of Kale and Forage Radish

Lilly, Levi 09 July 2018 (has links)
Saprophytic fungi can be paired with companion crops in interplant systems to increase production efficiency. However, fungal species/strain, substrate, and inoculation rate can affect the growth of companion crops. This project investigated the viability of open-field mushroom production by interplanting three strains of Pleurotus ostreatus (Elm A, Elm B, and 8801) with kale (B. oleracea var. acephala) and forage radish (Raphanus raphanistrub sub. sativus), and measured the effect of interplanting on plant yield over two field seasons. In the field, Elm A showed an increase in plant yield at a low inoculation rate and decrease in plant yield at a high inoculation rate, compared to the untreated. Conversely, 8801 showed a reduction in plant yield at high and low inoculation rates in the field. Elm B at a high rate showed a reduction in plant yield both in the field and greenhouse. Kale was grown in hydroponics with fungal secretions added at a range of concentrations (10, 100, 1,000 and 10,000 ppm). Elm A showed an overall increase in plant yield in hydroponics, and Elm B showed an overall decrease in plant yield, compared to the untreated. Mushroom production was low in field plots and was not a commercially viable option. Pleurotus ostreatus interplanting methods with companion crops need improvement to make this a commercially viable practice.
68

Processes, Patterns, and Predictions of Soil Moisture Variation in Upland and Peatland Cranberry Farms in Massachusetts

Brennan, Rebecca 15 July 2020 (has links)
The American Cranberry (Vaccinium macrocarpon Ait.) represents a vital sector of the economy of southeastern Massachusetts. Due to the hydrogeological and edaphic characteristics of peatlands, variations in soil drainage and soil moisture represent major management challenges for growers in Massachusetts. An emerging trend of upland (mineral soil) cranberry farms planted with new hybrid cultivars has the potential to enhance the profitability and long-term viability of cranberry production in Massachusetts. However, sparse data exist on soil moisture characteristics of peatland and upland cranberry farms. The purpose of this research was to elucidate the differences in soil moisture between upland and peatland cranberry farms, to evaluate the soil temperature-moisture relationship and its use for inferring soil moisture, and to explore the use of unmanned aircraft systems (UAS) as a soil moisture management tool in cranberry agriculture.In this thesis, we found that volumetric soil water content (qv) in upland farms ranged from 5-15%, contrasting with values of 10-40% for peatland farms. In general, soil moisture in upland farms was two times drier and four times more uniform than peatlands farms. Our results suggest that open ditches should be dredged to at least 50 cm to obtain irrigation setpoints of -5 to -2 kPa for Massachusetts cranberry farms. We found that soil temperature and near-surface temperature were accurate predictors of soil moisture but were also strongly dependent on the magnitude of differences between air and water temperature. Soil and near-surface temperatures were also better predictors of moisture in soils with lower vegetation coverage and organic matter content. Near-surface temperature collected with a UAS was consistent with field measurements of qv, suggesting that UAS could be used to assist Massachusetts cranberry farmers by predicting large-scale variation in q v and offering management insights.
69

Comparison and Fusion of space borne L-, C- and X- Band SAR Images for Damage Identification in the 2008 Sichuan Earthquake

LAU, SIN WAI January 2011 (has links)
Remote sensing has been widely used in disaster management. However, application of optical imageries in damage detection is not always feasible for immediate damage assessment. In the case of the Sichuan earthquake in 2008, the damaged areas were covered by cloud and fog for most of the time. The all weather SAR imageries could instead provide information of the damaged area. Therefore, more efforts are needed to explore the usability of SAR data. In regards to this purpose, this research focuses on studying the ability of using various SAR data in damage identification through image classification, and furthermore the effectiveness of fusion of various sensors in classification is evaluated.   Three different types of SAR imagery were acquired over the heavily damaged zone Qushan town in the Sichuan earthquake. The 3 types of SAR data are ALOS PALSAR L-band, RADARSAT-1 C-band and the TerraSAR-X X- band imageries.   Maximum likelihood classification method is applied on the imageries.  Four classes: Water, collapsed area, built-up area and landslide area are defined in the study area. The ability of each band in identifying these four classes is studied and the overall classification accuracy is analysed. Furthermore, fusion of these 3 types of imageries is performed and the effectiveness and accuracy of image fusion classification are evaluated.   The results show that classification accuracy from individual SAR imagery is not ideal. The overall accuracy which PALSAR gives is 30.383%, RADARSAT-1 is 31.268% while TerraSAR-X only achieves 37.168%. Accuracy statistics demonstrate that TerraSAR-X performs the best in classifying these four classes.   SAR image fusion shows a better classification result. Double image fusion of PALSAR and RADARSAT-1, PALSAR and TerraSAR-X, and RADARSAT-1 and TerraSAR-X give an overall classification accuracy of 41.88%, 42.478% and 37.758% respectively. The result from triple image fusion even reaches 52.507%. They are all higher than the result given by the individual images.   The study illustrates that the VHR TerraSAR X band SAR data has a higher ability in classification of damages, and fusion of different band can improve the classification accuracy.
70

Precision Drought Stress in Orchards: Rootstock Evaluation, Trunk Hydration and Canopy Temperature

Scott, Lance V. 01 May 2017 (has links)
In many areas, over half of all diverted water is used for irrigation. Tree fruit crops use a lot of water, but water productivity can be increased using properly-timed precision water stress. In addition to water conservation, increases in water productivity arise from better fruit quality, increased storage life and reductions in pruning and maintenance. One major hurdle to applying precision water stress in orchards is the lack of a reliable, automated method of determining tree water status. However, the influence of physiological characteristics such as rootstock vigor on water productivity are also important. Selecting the most appropriate rootstocks and accurately determining the water status of orchard trees can increase water productivity. Research has shown that some rootstocks can more effectively extract water from soil. In this research, the response to water stress of three different Gisela tart cherry dwarfing rootstocks was compared using a weighing lysimeter system. Gisela 12 and Gisela 3 rootstocks recovered from drought stress more quickly and had higher trunk diameter growth rates than drought-stressed Gisela 5 rootstocks. Two potential methods of determining tree water status were also evaluated. Trunk hydration was measured using electromagnetic sensors and canopy temperature changes were detected using infrared radiometry. Electromagnetic techniques, including time domain reflectometry, can be used to determine the water content of wood. Until recently, the cost of this technology has inhibited its widespread use, but new affordable commercial electromagnetic soil moisture sensors have created renewed interest in this technique. In this research five different types of electromagnetic soil moisture sensors were inserted into the trunks of fruit trees and were monitored over two growing seasons. Maximizing exposure of waveguides to the sapwood increased the response of these sensors to changes in stem water potential. Infrared measurements of canopy temperature have successfully been used with field crops. However, the heterogeneity of orchard canopies makes this technique more difficult in orchards. Here, the efficacy of aiming radiometers at single trees versus at entire orchards was compared over multiple growing seasons. Neither single tree measurements nor whole orchard techniques produced a sufficiently robust signal to recommend them for general use.

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