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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

Management of Ultra Narrow Row Cotton

Delaney, Dennis Patrick, Monks, C. Dale. January 2006 (has links) (PDF)
Dissertation (Ph.D.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.
62

Energetics of low-input corn production /

Ess, Daniel R., January 1990 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 101-105). Also available via the Internet.
63

Evaluating constraints and opportunities in managing weed populations with cover crops

Mirsky, Steven B. January 2008 (has links) (PDF)
These (Ph.D.)--Pennsylvania State University, 2008. / Title from PDF title page. Available through UMI ProQuest Digital Dissertations. Includes bibliographical references (leaves 164-171). Also issued in print.
64

Overseeding annual ryegrass and cereal rye into soybean for winter forage and as a cover crop for weed control and soil conservation

Smith, Luke B. January 2005 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 14, 2006) Includes bibliographical references.
65

Cover crop residue effects on machine-induced soil compaction /

Ess, Daniel R., January 1994 (has links)
Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 177-186). Also available via the Internet.
66

Energy Management in Solar Powered Wireless Sensor Networks

January 2012 (has links)
abstract: The use of energy-harvesting in a wireless sensor network (WSN) is essential for situations where it is either difficult or not cost effective to access the network's nodes to replace the batteries. In this paper, the problems involved in controlling an active sensor network that is powered both by batteries and solar energy are investigated. The objective is to develop control strategies to maximize the quality of coverage (QoC), which is defined as the minimum number of targets that must be covered and reported over a 24 hour period. Assuming a time varying solar profile, the problem is to optimally control the sensing range of each sensor so as to maximize the QoC while maintaining connectivity throughout the network. Implicit in the solution is the dynamic allocation of solar energy during the day to sensing and to recharging the battery so that a minimum coverage is guaranteed even during the night, when only the batteries can supply energy to the sensors. This problem turns out to be a non-linear optimal control problem of high complexity. Based on novel and useful observations, a method is presented to solve it as a series of quasiconvex (unimodal) optimization problems which not only ensures a maximum QoC, but also maintains connectivity throughout the network. The runtime of the proposed solution is 60X less than a naive but optimal method which is based on dynamic programming, while the peak error of the solution is less than 8%. Unlike the dynamic programming method, the proposed method is scalable to large networks consisting of hundreds of sensors and targets. The solution method enables a designer to explore the optimal configuration of network design. This paper offers many insights in the design of energy-harvesting networks, which result in minimum network setup cost through determination of optimal configuration of number of sensors, sensing beam width, and the sampling time. / Dissertation/Thesis / M.S. Computer Science 2012
67

EFFECTS OF AGRICULTURAL LAND COVER ON WATER QUALITY AT THE WATERSHED SCALE IN THE LOWER KASKASKIA RIVER WATERSHED

Friedmann, Julia Dawn 01 May 2010 (has links)
Agriculture is currently the leading cause of stream impairment in the United States. As the population continues to grow as well as the demand for biofuels, more pressure is being exerted on land to produce greater quantities of food. To satisfy the need for increased production marginal forest and grasslands have been converted to agriculture, fertilizers and equipment have rapidly evolved, and land has been taken out of conservation programs. Unfortunately, water quality impairment often accompanies these efforts to increase crop production. To reduce the impacts of agriculture on water quality, best management practices (BMPs) have been developed and tested at the field scale, with fewer studies focusing on the effects of agricultural land cover and BMPs (e.g., riparian buffers) on water quality at the watershed scale. Thus, a study was designed to assess the effects of riparian buffers and agricultural land cover on water quality at the watershed scale. Within Richland and Silver Creek watersheds, tributaries of the Lower Kaskaskia River Watershed in Illinois, forty-three catchments ranging from 12 to 50 km2 were selected across an agricultural to urban land cover gradient. Between January 18, 2008 and August 3, 2009, grab samples were collected twice a month during the wet portion of the year and once a month during the dry portion of the year and analyzed for nutrients (ammonium, nitrate, and orthophosphate), bacteria (total coliform, fecal coliform, and E. coli), and total suspended solids (TSS). Correlation analyses were performed on the data to determine relationships between the water quality variables, whole-catchment land cover (agriculture, forest, and urban), and percent forest canopy cover within 50 m of the stream using two different stream layers (National Hydrologic Dataset (NHD), and Flow Accumulation Boundaries (FAB)). Also, riparian buffer characteristics were quantified in headwater streams to determine if they were more highly correlated with water quality variables than in larger order streams. The percent of agricultural land cover within a watershed was significantly correlated with TSS (r = 0.4556, p = 0.0021) and ammonium-N (r = 0.3043, p = 0.0473) during baseflow, and TSS (r = 0.2837, p = 0.0652), ammonium-N (r = 0.5306, p = 0.0003), nitrate-N (r = 0.2654, p = 0.0854), and orthophosphate (r = 0.3783, p = 0.0124) during stormflow. Total amount of enrolled Conservation Reserve Program (CRP) land within Richland Creek and Silver Creek watersheds were found not to be correlated with water quality. A possible reason for these results could be because only a very small percent of lands in Richland Creek and Silver Creek were enrolled in CRP. Whole-catchment land cover in most cases explained more variance than percent forest canopy cover within 50 m of streams for the water quality parameters analyzed. There were only slight differences between the two stream layers (NHD and FAB). However, the headwater streams of the FAB stream layer explained more variance in critical water quality parameters, ammonium-N (r = -0.5309, p = 0.002) during baseflow and ammonium-N (r = -0.6107 p <0.0001), and orthophosphate (r = -0.5273 p = 0.0003) during stormflow. Having an understanding of the impacts that riparian buffers and headwater streams have on water quality is key for watershed managers to focus restoration efforts in the most critical areas for maintaining stream quality.
68

THE EFFECTS OF COVER CROPS ON THE SOIL MICROBIOME: A METAGENOMICS STUDY

Hackman, Jacob James 01 August 2018 (has links)
To our knowledge, this metagenomics study is the first of its kind to determine how cover crops and tillage management practices affect the soil microbiome in southern Illinois. Seven different cover crops were used over the course of two years from 2014 to 2015, and two different forms of tillage were used: Conventional Tillage (CT) and No-Tillage (NT). Four barcodes were used to generate libraries for the phylogenetic identification of fungi, bacteria, oomycetes, and fusaria: the ITS1, EF1a (Elongation Factor 1-a), and the V4 region of the 16s rRNA subunit. Targeted amplicon sequencing using 250 base pair Paired End (PE) reads yielded 14 x 106 base pair reads in total. Using these amplicons, we successfully unveiled the fungal and bacterial constituents of the studied field plots (database limitations considered) using the QIIME and NCBI Blast protocols. Specifically, this study had three goals 1) to determine if cover crops or tillage had a significant impact on the overall microbial diversity found in bulk soil samples taken from cover crop plots; 2) to determine if the incidence and abundance of individual bacterial or fungal taxa were affected by the cover crop or tillage treatment; 3) perform a bioinformatics methodology comparison for fungal identification using the ITS1 region between Qiime, and MEGAN protocols. Our results indicate many instances of cover crop or tillage interacting with one or more groupings of taxa. Significant whole community differences could be detected to the species (P=0.0335) and family (P=0.0001) taxonomic ranks of fungi using with the three most abundant families based on assigned reads being Mortierellaceae, Trichocomaceae, and Botryosphaeriaceae. Significant whole community interactions between tillage types and year at the level of phylum were observed between bacteria and archaea. Three main phyla constituting bacterial reads were Proteobacteria, Actinobacteria, and Acidobacteria. The primary driver in individual differences in bacterial populations appeared to be the year in which samples were taken either 2014 or 2015 (P=0.0001). This was attributed in part due to drastic fluctuations in weather from November 2014 to November 2015. Whole community differences and shifts could be observed based on cover crop down to the species level using both QIIME and NCBI BLAST protocols. The different dispersions and taxa found between cover crops imply that there is a relationship between certain organisms and the type of plant matter present. Tillage type, year, and cover crop were all found to have some degree of clustering based on reads taken from the four amplicons used. For comparison between NCBI and QIIME methodologies using the ITS1 region, the NCBI BLAST protocol provided the most overlap between taxa at the Order and Class taxonomic rankings. An upwards of 70% complementarity of taxa was found comparing the results after using the NCBI or the QIIME protocols. Whole community analysis using PERMANOVA revealed complementarity shifts based on treatment types when comparing both QIIME and NCBI protocols for taxonomic assignments visualized using PCoA plots. This comparison between the two methods for fungal community analysis using the ITS region, highlights the significant discrepancies as well as the complementarity of the two methodologies when analyzing fungal microbiomes.
69

Coberturas vegetais e doses de nitrogênio, associadas à inoculação com Azospirillum brasilense, no cultivo do milho na região de Cerrado

Portugal, José Roberto [UNESP] 24 February 2015 (has links) (PDF)
Made available in DSpace on 2015-08-20T17:09:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-24. Added 1 bitstream(s) on 2015-08-20T17:26:26Z : No. of bitstreams: 1 000843763.pdf: 3771507 bytes, checksum: 95075b8d207831c0a64fbf7c2f3c81e0 (MD5) / No Brasil e no mundo, a cultura do milho é uma das mais importantes, por ser a base da alimentação animal e utilizado também na alimentação humana. Técnicas sustentáveis de manejo na cultura do milho são necessárias, visando aumento de produtividade, minimizando custos e impactos ambientais. O objetivo deste trabalho foi avaliar diferentes coberturas vegetais (milheto, crotalária, guandu, milheto + crotalária, milheto + guandu e pousio), doses de N (0, 40, 80 e 120 kg ha -1 ) com e sem a inoculação de sementes com Azospirillum brasilense na cultura do milho, cultivado em sistema plantio direto no crescimento e produtividade na região do Cerrado. Foi utilizado delineamento experimental em blocos casualizados em esquema fatorial 6x4x2, constituindo 48 tratamentos, com 4 repetições. O estudo foi realizado na Fazenda Experimental pertencente à Faculdade de Engenharia - UNESP - Campus de Ilha Solteira, localizada no município de Selvíria - MS. O solo do local é do tipo LATOSSOLO VERMELHO Distrófico típico argiloso. A precipitação média anual é de 1.330 mm, a temperatura média anual é de 25 oC e a umidade relativa do ar entre 70 e 80%. Durante a condução do experimento, foram realizadas as seguintes avaliações: massa seca, teores e quantidades acumuladas de N, P e K nas plantas de cobertura; no milho: população inicial e final de plantas, produção de massa seca da parte aérea das plantas, teor de N foliar, índice de clorofila foliar, teores e valores acumulados de N, P e K na planta, altura de plantas e de inserção de espiga, diâmetro de colmo, comprimento de espiga, diâmetro de espiga, massa de mil grãos e produtividade de grãos. As coberturas vegetais, exceto o guandu no primeiro ano e pousio no segundo, produziram quantidade adequada de resíduo para manter o sistema plantio direto na região de Cerrado de baixa altitude. O consórcio milheto + crotalária possibilita quantidades acumuladas de N e K.. / In Brazil and in the world, maize crop is one of the most important because it is the basis of animal feed and also used in human feed. Sustainable techniques of management in maize crop are needed, aiming at increasing yield, reducing costs and environmental impacts. The objective of this study was to evaluate different cover crops (millet, sunn hemp, pigeonpea, millet + sunn hemp, millet + pigeonpea and fallow), N rates (0, 40, 80 and 120 kg ha -1 ) with and without inoculation of seeds with Azospirillum brasilense in maize crop, cultivated in no- tillage system on growth and yield in the Cerrado region. The experimental design was complete randomized blocks in a factorial scheme 6x4x2, constituting 48 treatments, with 4 replications. The study was conducted at the Experimental Farm belonging to the Faculty of Engineering - UNESP (Ilha Solteira), located in Selviria - MS. The soil of the place is a Typical Dystrophic Red Latosol clayey texture. The average annual rainfall is 1.330 mm, the average annual temperature is 25°C and the relative humidity between 70 and 80%. During the experiment, the following evaluations were performed: dry matter, content and accumulated values of N, P and K in cover crops; in maize: initial and final population of plants, production of dry matter of the shoots, leaf nitrogen content, leaf chlorophyll index, content and accumulated values of N, P and K in the whole plant, plant height and of ear insertion, stem diameter, ear length, ear diameter, thousand grain weight and grain yield. The cover crops except the pigeonpea in 2012/13 and fallow in 2013/14 produced adequate amount of residue to keep the no-tillage system in the Cerrado region. The consortium of millet + sunn hemp provided the greater accumulated amount of N and K for both years of cultivation. The great yield of maize grains under pigeonpea residue was due to increase in ear diameter and thousand-grain weight. Thus, the great maize yield ...
70

Coberturas vegetais e doses de nitrogênio, associadas à inoculação com Azospirillum brasilense, no cultivo do milho na região de Cerrado /

Portugal, José Roberto. January 2015 (has links)
Orientador: Orivaldo Arf / Banca: Salatier Buzetti / Banca: Domingos Fornasieri Filho / Resumo: No Brasil e no mundo, a cultura do milho é uma das mais importantes, por ser a base da alimentação animal e utilizado também na alimentação humana. Técnicas sustentáveis de manejo na cultura do milho são necessárias, visando aumento de produtividade, minimizando custos e impactos ambientais. O objetivo deste trabalho foi avaliar diferentes coberturas vegetais (milheto, crotalária, guandu, milheto + crotalária, milheto + guandu e pousio), doses de N (0, 40, 80 e 120 kg ha -1 ) com e sem a inoculação de sementes com Azospirillum brasilense na cultura do milho, cultivado em sistema plantio direto no crescimento e produtividade na região do Cerrado. Foi utilizado delineamento experimental em blocos casualizados em esquema fatorial 6x4x2, constituindo 48 tratamentos, com 4 repetições. O estudo foi realizado na Fazenda Experimental pertencente à Faculdade de Engenharia - UNESP - Campus de Ilha Solteira, localizada no município de Selvíria - MS. O solo do local é do tipo LATOSSOLO VERMELHO Distrófico típico argiloso. A precipitação média anual é de 1.330 mm, a temperatura média anual é de 25 oC e a umidade relativa do ar entre 70 e 80%. Durante a condução do experimento, foram realizadas as seguintes avaliações: massa seca, teores e quantidades acumuladas de N, P e K nas plantas de cobertura; no milho: população inicial e final de plantas, produção de massa seca da parte aérea das plantas, teor de N foliar, índice de clorofila foliar, teores e valores acumulados de N, P e K na planta, altura de plantas e de inserção de espiga, diâmetro de colmo, comprimento de espiga, diâmetro de espiga, massa de mil grãos e produtividade de grãos. As coberturas vegetais, exceto o guandu no primeiro ano e pousio no segundo, produziram quantidade adequada de resíduo para manter o sistema plantio direto na região de Cerrado de baixa altitude. O consórcio milheto + crotalária possibilita quantidades acumuladas de N e K.. / Abstract: In Brazil and in the world, maize crop is one of the most important because it is the basis of animal feed and also used in human feed. Sustainable techniques of management in maize crop are needed, aiming at increasing yield, reducing costs and environmental impacts. The objective of this study was to evaluate different cover crops (millet, sunn hemp, pigeonpea, millet + sunn hemp, millet + pigeonpea and fallow), N rates (0, 40, 80 and 120 kg ha -1 ) with and without inoculation of seeds with Azospirillum brasilense in maize crop, cultivated in no- tillage system on growth and yield in the Cerrado region. The experimental design was complete randomized blocks in a factorial scheme 6x4x2, constituting 48 treatments, with 4 replications. The study was conducted at the Experimental Farm belonging to the Faculty of Engineering - UNESP (Ilha Solteira), located in Selviria - MS. The soil of the place is a Typical Dystrophic Red Latosol clayey texture. The average annual rainfall is 1.330 mm, the average annual temperature is 25°C and the relative humidity between 70 and 80%. During the experiment, the following evaluations were performed: dry matter, content and accumulated values of N, P and K in cover crops; in maize: initial and final population of plants, production of dry matter of the shoots, leaf nitrogen content, leaf chlorophyll index, content and accumulated values of N, P and K in the whole plant, plant height and of ear insertion, stem diameter, ear length, ear diameter, thousand grain weight and grain yield. The cover crops except the pigeonpea in 2012/13 and fallow in 2013/14 produced adequate amount of residue to keep the no-tillage system in the Cerrado region. The consortium of millet + sunn hemp provided the greater accumulated amount of N and K for both years of cultivation. The great yield of maize grains under pigeonpea residue was due to increase in ear diameter and thousand-grain weight. Thus, the great maize yield ... / Mestre

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