Aquaponics has the potential to be a superior food production method compared to traditional agriculture through its potential for sustainability. This is particularly important in advanced aquaponic systems that integrate waste disposal (e.g., kitchen waste) and involve several steps linking waste decomposition to protein production. In such systems a success of one type of organism propagates down the food chain and may have negative impact on contribution of other organisms, which reduces system efficiency. I hypothesised that a combination of top-down and bottom-up regulations, concepts borrowed from resilient natural ecosystems, would allow to optimize environment for aquaponics systems to avoid such negative impacts. First, I conducted an experiment using simplified systems with two trophic levels only to determine productivity, resistance and resilience of the various combinations of top-down and bottom-up forces. The simple systems contained algae and Daphnia magna and were placed under a light removal disturbance to observe the abilities of these different combinations to resist and recover from a generic negative environmental impact. Next, a similar light disturbance was implemented on a large complex aquaponics system to discover if it would react differently from the smaller ones. The resistance and resilience of algae in the small systems was not found to have any relationship to predation. The resilience of algae was better at low nutrient levels compared to high ones. There was evidence that low nutrient treatments had better resistance and resilience of abiotic factors. The larger systems appeared to have inferior resistance and resilience as compared to the simple, small systems. However, a time series analysis indicates that these large systems, in contrast to the simpler systems, actually improved in the amount of algae after the disturbance. New methods for accounting for this in resilience calculations are needed to eliminate potential statistical artifacts that might lead to some of my observations. / Thesis / Master of Science (MSc) / Aquaponics has the potential to be a superior food production method compared to traditional agriculture through its potential for sustainability. This is particularly important in advanced aquaponic systems that integrate waste disposal (e.g., kitchen waste) and involve several steps linking waste decomposition to protein production. In such systems a success of one type of organism propagates down the food chain and may have negative impact on contribution of other organisms, which reduces system efficiency. I hypothesised that a combination of top-down and bottom-up regulations, concepts borrowed from resilient natural ecosystems, would allow to optimize environment for aquaponics systems to avoid such negative impacts. First, I conducted an experiment using simplified systems with two trophic levels only to determine productivity, resistance and resilience of the various combinations of top-down and bottom-up forces. The simple systems contained algae and Daphnia magna and were placed under a light removal disturbance to observe the abilities of these different combinations to resist and recover from a generic negative environmental impact. Next, a similar light disturbance was implemented on a large complex aquaponics system to discover if it would react differently from the smaller ones. The resistance and resilience of algae in the small systems was not found to have any relationship to predation. The resilience of algae was better at low nutrient levels compared to high ones. There was evidence that low nutrient treatments had better resistance and resilience of abiotic factors. The larger systems appeared to have inferior resistance and resilience as compared to the simple, small systems. However, a time series analysis indicates that these large systems, in contrast to the simpler systems, actually improved in the amount of algae after the disturbance. New methods for accounting for this in resilience calculations are needed to eliminate potential statistical artifacts that might lead to some of my observations.

Tang Chi Wai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 104-121) and index. / Abstracts in English and Chinese. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgements --- p.v / Table of Contents --- p.vii / List of Tables --- p.x / List of Figures --- p.xi / List of Plates --- p.xii / Chapter Chapter One --- Introduction / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Conceptual Framework --- p.3 / Chapter 1.3 --- Objectives and Significance --- p.5 / Chapter 1.4 --- Structure of the Thesis --- p.7 / Chapter Chapter Two --- Literature Review / Chapter 2.1 --- Impacts of Soil Erosion on Agriculture --- p.8 / Chapter 2.2 --- Farmland Shortage Problems in the Reservoir Region --- p.10 / Chapter 2.3 --- Terracing Systems in China --- p.11 / Chapter 2.4 --- Contour Hedgerows --- p.13 / Chapter 2.5 --- Sustainable Agriculture and its Development in China --- p.18 / Chapter Chapter Three --- Study Area / Chapter 3.1 --- The Three Gorges Reservoir Region --- p.22 / Chapter 3.2 --- Geographical Settings of Zigui County --- p.23 / Chapter 3.2.1 --- Geographical and Administrative Location --- p.23 / Chapter 3.2.2 --- Geology and Geomorphology --- p.24 / Chapter 3.2.3 --- Soils --- p.25 / Chapter 3.2.4 --- Climate --- p.25 / Chapter 3.2.5 --- Hydrology --- p.26 / Chapter 3.3 --- Socioeconomic Conditions of Zigui County --- p.26 / Chapter 3.3.1 --- Demography --- p.26 / Chapter 3.3.2 --- Educational Attainments --- p.27 / Chapter 3.3.3 --- Economic and Social Development --- p.27 / Chapter 3.4 --- Environmental Problems in Zigui and the Reservoir Region --- p.28 / Chapter Chapter Four --- Cost-benefit Analysis of Contour Hedgerows / Chapter 4.1 --- Introduction --- p.30 / Chapter 4.2 --- Methodology --- p.32 / Chapter 4.2.1 --- Trial Plot Design --- p.32 / Chapter 4.2.2 --- Cost-benefit Analysis --- p.35 / Chapter 4.2.3 --- Identification and Valuation of Costs --- p.35 / Chapter 4.2.4 --- Identification and Valuation of Benefits --- p.37 / Chapter 4.2.5 --- Discount Rate --- p.37 / Chapter 4.2.6 --- Time Horizon --- p.37 / Chapter 4.2.7 --- Cost-benefit Criterion --- p.38 / Chapter 4.3 --- Results and Discussion --- p.38 / Chapter 4.3.1 --- Investment Costs and Operating Costs --- p.38 / Chapter 4.3.2 --- Replacement Costs --- p.39 / Chapter 4.3.3 --- Benefits --- p.42 / Chapter 4.3.4 --- Net Present Values (NPVs) --- p.44 / Chapter 4.3.5 --- Sensitivity Analysis --- p.47 / Chapter 4.4 --- Conclusion --- p.48 / Chapter Chapter Five --- A Questionnaire Survey of the Comparative Performance of Various Farming Systems / Chapter 5.1 --- Introduction --- p.50 / Chapter 5.2 --- Methodology --- p.52 / Chapter 5.2.1. --- Sampling Method --- p.52 / Chapter 5.2.2. --- Questionnaire --- p.52 / Chapter 5.2.3. --- Analytical Technique --- p.53 / Chapter 5.3 --- Results and Discussion --- p.54 / Chapter 5.3.1. --- Background of Households and Farming Systems --- p.54 / Chapter 5.3.2. --- Net Returns --- p.57 / Chapter 5.3.3. --- Inputs of Inorganic Fertilizers and Organic Manure --- p.61 / Chapter 5.3.4. --- Labour Inputs --- p.64 / Chapter 5.3.5. --- Characteristics of Hedgerow Management --- p.65 / Chapter 5.4 --- Conclusion --- p.66 / Chapter Chapter Six --- An Interview Study of the Perception of Contour Hedgerows / Chapter 6.1 --- Introduction --- p.68 / Chapter 6.2 --- Methodology --- p.70 / Chapter 6.3 --- Results and Discussion --- p.72 / Chapter 6.3.1 --- Familiarity with Hedgerows --- p.72 / Chapter 6.3.2 --- Hedgerow Acceptance in Usage --- p.74 / Chapter 6.3.3 --- Factors of Hedgerow Implementation --- p.79 / Chapter 6.3.4 --- Variation of Agricultural Inputs and Outputs --- p.83 / Chapter 6.3.5 --- Values of Indigenous Knowledge --- p.86 / Chapter 6.3.6 --- Implications for Hedgerow Extension --- p.88 / Chapter 6.4 --- Conclusion --- p.90 / Chapter Chapter Seven --- Conclusion / Chapter 7.1 --- Summary of Findings --- p.92 / Chapter 7.2 --- Synthesis of the Study --- p.95 / Chapter 7.3 --- Limitations of the Study --- p.100 / Chapter 7.4 --- Suggestions for Further Studies --- p.101 / Bibliography --- p.104 / Appendix I: Structured Questionnaire --- p.122 / Appendix II: Interview Guide for Hedgerow Users --- p.131 / Appendix III: Interview Guide for Non-hedgerow Users --- p.134 / Appendix IV: Interview Guide for Government Officials --- p.137 / Appendix V: Index --- p.140 / "Appendix VI: Publication-Cost-benefit Analysis of Contour Hedgerow in the Three Gorges Region (Published in ´ب´بResources Science´ح，Vol26 Supplement,pp. 132-136)" --- p.145

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Doctor of Philosophy / Department of Agronomy / P. V. Vara Prasad / Leguminous cover crops systems have been envisaged as a critical component of sustainable agriculture due to their potential to increase soil productivity through cycling of carbon (C) and nitrogen (N) in agricultural systems. The objectives of this study were to evaluate the performance of leguminous summer cover crops; cowpea [Vigna unguiculata (L.) Walp.], pigeon pea [Cajanus cajan (L.) Millsp], sunn hemp (Crotalaria juncea L.) and double-cropped grain crops; grain sorghum [Sorghum bicolor (L.) Moench] and soybean [Glycine max (L.) Merr.] after winter wheat (Triticum aestivum L.) and to determine the effects of these crops and varying N rates in the cropping system on nitrous oxide (N[subscript]2O) emissions, growth and yield of succeeding grain sorghum and maize (Zea mays L.) crop, soil aggregation, aggregate-associated C, and N. Field and laboratory studies were conducted for two years. The cover crops and double-cropped grain crops were planted immediately after winter wheat harvest. The cover crops were terminated at the beginning of flowering. Nitrogen fertilizer (urea 46% N) rates of 0, 45, 90, 135, and 180 kg N ha[superscript]-1 were applied to grain sorghum or maize in fallow plots. Pigeon pea and grain sorghum had more C accumulation than cowpea, sunn hemp and double-cropped soybean. Pigeon pea and cowpea had more N uptake than sunn hemp and the double-cropped grain crops. Fallow with N fertilizer application produced significantly greater N[subscript]2O emissions than all the cover crops systems. Nitrous oxide emissions were relatively similar in the various cover crop systems and fallow with 0 kg N ha[superscript]-1. Grain yield of sorghum and maize in all the cover crop and double cropped soybean systems was similar to that in the fallow with 45 kg N ha[superscript]-1. Both grain sorghum and maize in the double-cropped soybean system and fallow with 90 kg N ha[superscript]-1 or 135 kg N ha[superscript]-1 gave profitable economic net returns over the years. The double-cropped grain sorghum system increased aggregate-associated C and whole soil total C, and all the cover crop and the double-cropped soybean systems increased aggregate-associated N and soil N pools. Inclusion of leguminous cover crops without N fertilizer application reduced N[subscript]2O emissions and provided additional C accumulation and N uptake, contributing to increased grain yield of the following cereal grain crop.

Locavore is a restaurant centered around the principles of sustainable agriculture: foodthat is organically, humanely, and sustainably raised from farms and cooperatives nofurther than 150 miles from Richmond - thus the "local" in Locavore. Like all restaurants,certain programmatic requirements were standard such as providing places to store,prepare, and eat the food, and restrooms. Yet the design of the space also helps answerthe following questions: How does sustainable differ from organic? Is local necessarily better than foreign? How does a restaurant embody community?

M.Sc. / Different agricultural practices of field melon cropping in the Vhembe Distrinct, north of the Soutpansberg mountain range in the Limpopo Province, South Africa are investigated in this study. To achieve sustainable agriculture, farm management practices must be optimised and it is essential to understand the microbiological aspects and how they interact. An initial fungal survey was undertaken in melon fields, of the fungal species present in these soils and how the different management practices affect the filamentous fungal population. Soil samples were also analysed for bacterial pathogens. Physical and chemical soil properties were analysed. Farm management practices are discussed in terms of conservation tillage, controlled traffic, permanent beds, versus conventional tillage. Aspects that may assist in optimising processes towards becoming a biological farmer are discussed, with the goal of encouraging farming to be more biological, by working with nature, to promote sustainable agriculture for present and future generations.

The impact of grazers on the primary production of marine ecosystems has largely been explored in tropical environments. A number of studies support theories on the functional importance of grazers in the community structure of coral reefs. However, large-bodied grazers, like juvenile green turtles, co-occur with herbivorous fishes in subtropical and tropical regions throughout the world and we know little about their combined impact on macroalgal communities and whether they compete for macroalgal resources. My dissertation research was composed of four studies that were conducted simultaneously to further our understanding of plant/herbivore interactions in marine ecosystems. Studies were conducted at the Trident Basin, a non-public military facility within the Port Canaveral Inlet at Cape Canaveral, Florida, USA. The macroalgal study (Chapter 1), determined the spatial and temporal distribution of the macroalgal community. The foraging habits of juvenile green turtles were compared with the macroalgal abundance within the Basin and over time (Chapter 2). Selection ‘for’ specific macroalgal species (based on their availability in the macroalgae study) was used to determine the level of overlap and/or partitioning of resources among herbivorous fishes and juvenile green turtles (Chapter 3). The final empirical study (Chapter 4) measured the impact on thallus height, diameter and/or branching of macroalgae as well as the macroalgal community composition from caging experiments that excluded herbivorous fishes and juvenile green turtles. The algal community was predominantly composed of nine red and green macroalgal species that were persistent year-round. Grazer-resistant macroalgae were rarely observed. Green turtles foraged on many of these same macroalgae but also opportunistically foraged on flotsam, including anthropogenic debris (e.g., plastic). The gut content of the major herbivorous fishes in the community (Abudefduf saxatilis, Archosargus probatocephalus, Diplodus holbrooki, and Lagodon rhomboides) foraged as omnivores depending on where they were captured within the Basin area or their size. All herbivores showed selection for less abundant green algae (i.e., Ulva spp.). Results of the exclusion of juvenile green turtles and large herbivorous fishes in caging experiments suggest that grazing by these large-bodied herbivores had no impact on the composition of the macroalgal community and little impact on the morphological structure of the macroalgal species that were examined. Collectively these four studies contribute to a better understanding of how multiple grazers have evolved to forage in macroalgal communities without detrimental effects on their food resources. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

Doctor of Philosophy / Department of Plant Pathology / Ari Jumpponen / Megan Kennelly / Soil microbial communities play fundamental and complex roles in the productivity of agriculture. However, we still have a limited understanding of the response of microbial communities to different farming systems, such as organic and conventional fertility management regimens. We applied high-throughput sequencing to develop a better understanding of how soil microbial communities (bacteria and fungi) in vegetable production respond to organic or conventional soil fertility management. Specifically, my three studies examined the following questions: 1. How do soil microbial communities from cDNA and DNA samples compare in organic and conventional fertility treatments? 2. How do soil microbial communities in a tomato cropping season respond to long-term organic vs. conventional soil fertility treatments? 3. How do soil bacterial and fungal communities respond to high tunnels, plastic mulch and organic amendments across a tomato cropping season? The first two questions were addressed at the Kansas State University Horticulture and Extension Center in Olathe, KS, using organic and conventional field plots with three levels of fertilizer. We sampled the plots during the development of a tomato crop. The third question was addressed at a commercial farm in Lawrence, KS, during its transition to organic vegetable production, during a tomato crop. The Lawrence experiment included as treatments field plots versus high tunnels, and three organic nutrient amendments. We used 454-pyrosequencing of bacterial and fungal ribosomal markers to compare total resident (DNA) and active microbial communities (cDNA, which is DNA synthesized from a single stranded RNA template) for our first question. We used Illumina MiSeq metabarcoding of bacterial and fungal ribosomal markers for our second and third questions. In all three studies we evaluated bacterial and fungal community responses using Simpson´s diversity index, Simpson´s evenness and richness for each experiment. For the first question, when we compared DNA and cDNA, bacterial diversity was higher in cDNA samples from organic compared to conventional management. In addition, fungal diversity from cDNA samples was higher than from DNA samples. In contrast, in the second question, bacterial and fungal diversity indices did not differ in the tomato crop under organic and conventional management systems. For our third question, high tunnels did not affect bacterial or fungal diversity. Use of plastic mulch for a tomato crop in open field plots did not affect bacterial richness, but decreased fungal richness compared to open field plots without plastic mulch. High-throughput sequencing provides a new perspective on the structure and dynamics of these communities. Information from this approach will ultimately improve our ability to manage soil for sustainable productivity by promoting beneficial microorganisms and suppressing pathogenic ones.

Orientador: Filipe Pereira Giardini Bonfim / Banca: Vânia Christina Nascimento Porto / Banca: Nathalia de Souza Parreiras / Resumo: Os diferentes e inúmeros agroecossistemas do território nacional, onde as hortaliças são produzidas majoritariamente pelo sistema de cultivo convencional, têm-se modificado ao longo dos últimos anos, apresentando crescimento significativo de cultivos diferenciados com destaque para aqueles em ambiente protegido e sob sistema orgânico. O setor de hortaliças é um ramo do agronegócio em pleno crescimento e que movimenta em torno de 55 milhões de reais anualmente, em toda a sua cadeia, do campo ao varejo. Dentre os Estados da região Sudeste, São Paulo é o que possui o maior mercado de alimentos da América Latina, podendo-se inferir que o mesmo possa ocorrer com os orgânicos. Assim, objetivou-se neste estudo analisar a sustentabilidade de sistemas de produção de hortaliças em propriedades rurais de Botucatu e região, bem como caracterizar as unidades produtivas quanto aspectos econômicos, ecológicos e sociais. Os procedimentos metodológicos para elaboração da pesquisa durante todo o seu desenvolvimento até a sua concretização foi com base na pesquisa qualitativa, do tipo descritiva analítica, a qual possibilita a observação, o registro, a análise e correlaciona fatos ou fenômenos sem manipula-los. Para coleta de dados foi utilizado o método "bola de neve". O grupo amostral abrangido foi de 10 agricultores-produtores de hortaliças no município de Botucatu e região pela aplicação do formulário de manejo sustentável que consiste na classificação de quatro níveis distintos de sustenta... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The different and numerous agroecosystems of the national territory, where the vegetables are produced mainly by the system of conventional cultivation, have been modified during the last years, presenting significant growth of differentiated crops with highlight to those in protected environment and under organic system. The vegetable sector is a growing branch of agribusiness, which moves around 55 million reais annually, throughout its chain, from the field to the retail. Among the states of the Southeast, São Paulo has the largest food market in Latin America, and it can be inferred that the same may occur with organic foods. Thus, the objective of this study was to analyze the sustainability of vegetable production systems in rural properties of Botucatu and region, as well as to characterize the productive units as economic, ecological and social aspects. The methodological procedures for the elaboration of the research throughout its development until its implementation was based on the qualitative research, of the descriptive analytical type, which makes it possible to observe, record, analyze and correlate facts or phenomena without manipulating them. The "snowball" method was used for data collection. The sampled group consisted of 10 farmers-producers of vegetables in the city of Botucatu and region by the application of the sustainable management form that consists of 4 different levels of sustainability, being: a) from 0 to 20 unsustainable; b) 20 to 40 weak sustainability; c) 40 to 60 average sustainability and d) 60 to 80 strong sustainability. The data obtained showed that all the farmers visited are family-based and have a good diversity of plants in the field, which allows a good staggering of production and harvesting, facilitating the commercialization of the products presenting as a fundamental strategy for the permanence of work in the field. Another point that can be ... / Mestre

The concept of sustainable diets has received increasing attention as it is recognised that several global challenges, such as malnutrition and mitigating pressures on global land resources, might be tackled together through changes in diets. This thesis has used the UK as a case study to analyse the implications of achieving healthy and environmentally sustainable diets for future land use. This thesis shows the total agricultural footprint of UK's food supply has decreased slightly over the last decades due to a lower ruminant livestock product supply. However, the total cropland footprint and its associated greenhouse gas emissions have increased, and these impacts are increasingly displaced overseas. Land use efficiency of the food supply was evaluated by combining agricultural and nutritional data. While a focus on calories and protein reflects favourably on cereals and oil crops, assessing a wider range of nutrients shows that roots & tubers and vegetables are important to “feed the UK” efficiently. Reducing land use associated with UK's food supply is possible while still meeting dietary requirements and this generally also lowers greenhouse gas emissions. Discretionary foods, such as coffee, tea and wine, and animal products should be reduced for a lower impact, but trade-offs were also identified. Four insights relevant for the wider literature were identified: a) the complexity of international trade complicates the assessment of sustainability due to difficulties linking production and consumption, b) there are different types of agricultural land, each with their own opportunity costs, c) new metrics for agricultural yield are needed, moving from “tonnes per hectare” to “people fed per hectare”, and d) the trade-offs between different environmental indicators are important. With an uncertain policy environment and a lack of willing among the population to make significant changes in their diets, the future of UK land use and diets is unclear.