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排序方式: 共有1523条查询结果,搜索用时 31 毫秒
71.
The application and effects for a series of rare earth (RE) drought resistant materials used in arid, salina,hungriness, wind defending and sand fixing matter, withdraw farming and return to grass and forest in western of China were reported.The important discussion was technological innovation within two years: such as seed clothing agent,RE liquid field film, RE grass and woods transplant living agent, and RE complex pesticide development and application. 相似文献
72.
73.
Can cities become self-reliant in food? 总被引:1,自引:0,他引:1
Sharanbir S. GrewalParwinder S. Grewal 《Cities》2012,29(1):1-11
Modern cities almost exclusively rely on the import of resources to meet their daily basic needs. Food and other essential materials and goods are transported from long-distances, often across continents, which results in the emission of harmful greenhouse gasses. As more people now live in cities than rural areas and all future population growth is expected to occur in cities, the potential for local self-reliance in food for a typical post-industrial North American city was determined. Given current policies and bylaws and available area, crop yields, and human intake, three distinct scenarios were developed to determine the potential level of food self-reliance for the City of Cleveland, which has been plagued with home foreclosures and resulting vacant land, lack of access to healthy food, hunger, and obesity particularly in disadvantaged neighborhoods. Scenario I, which utilizes 80% of every vacant lot, can generate between 22% and 48% of Cleveland’s demand for fresh produce (vegetables and fruits) depending on the vegetable production practice used (conventional gardening, intensive gardening, or hydroponics), 25% of both poultry and shell eggs, and 100% of honey. Scenario II, which uses 80% of every vacant lot and 9% of every occupied residential lot, can generate between 31% and 68% of the needed fresh produce, 94% of both poultry and shell eggs, and 100% of honey. Finally, scenario III, which adds 62% of every industrial and commercial rooftop in addition to the land area used in scenario II, can meet between 46% and 100% of Cleveland’s fresh produce need, and 94% of poultry and shell eggs and 100% of honey. The three scenarios can attain overall levels of self-reliance between 4.2% and 17.7% by weight and 1.8% and 7.3% by expenditure in total food and beverage consumption, compared to the current level of 0.1% self-reliance in total food and beverage by expenditure. The analysis also reveals that the enhanced food self-reliance would result in $29 M to $115 M being retained in Cleveland annually depending upon the scenario employed. This study provides support to the hypothesis that significant levels of local self-reliance in food, the most basic need, is possible in post-industrial North American cities. It is concluded that while high levels of local self-reliance would require an active role of city governments and planners, public commitment, financial investment, and labor, the benefits to human health, the local and global environment, and the local economy and community may outweigh the cost. 相似文献
74.
Priyanka Yadav 《Landscape and urban planning》2012,104(2):238-244
Urban agriculture offers a framework for local self-reliance by provisioning food security, employment opportunities, and other community benefits. However, urban agriculture must rely on the supporting and regulating services of the soil food web. Hence, we quantified belowground biocontrol activity in urban gardens and vacant lots in two post-industrial cities using an in situ insect baiting technique. Due to the differences in habitat structure, we hypothesized that belowground biocontrol services will differ between gardens and vacant lots and the influence of habitat structure would differ with the type of biocontrol organism. Results revealed that biocontrol activity, as assessed by % mortality of baited insects, varied between 51% and 98% with higher activity often recorded in vacant lots than gardens. Major contributions to bait insect mortality were by ants, followed by microbial pathogens and entomopathogenic nematodes, respectively. Ants showed higher (p < 0.0001) % mortality in vacant lots (60% ± 33.4%) than in urban gardens (33.3% ± 22.2%) whereas microbial pathogens exhibited higher (p < 0.0001) mortality in gardens (27.8% ± 15%) than vacant lots (8.3% ± 16.7%). Ants caused higher (p < 0.0001) mortality when larger-mesh size cages were used compared with the smaller-mesh size cages, but mortality by microbial pathogens did not differ with cage type. The high biocontrol activity indicates the resilience of the soil food web in urban ecosystems and the differential effects of habitat structure on biocontrol activity can help guide landscape planning and vegetation management to enhance urban environments and boost local self-reliance. 相似文献
75.
In this paper, we present an overview of several challenges in arable farming that are well suited for research by the control engineering society. We discuss the global needs that these challenges are related to as well as the relation of these challenges to future applications of arable farming. For each of these opportunities we provide several concrete and detailed research questions. Particular attention is paid to the management of resources and sensors in farms. The objective of writing this paper is to further entice control engineers into the domains of agronomy and agricultural technology. 相似文献
76.
Variations in yield and gluten proteins in durum wheat varieties under late‐season foliar versus soil application of nitrogen fertilizer in a northern Mediterranean environment 下载免费PDF全文
77.
ABSTRACT Concern over increasing water scarcity has led to the introduction of the concept of agricultural water productivity and an emphasis on interventions to achieve ‘more crop per drop’. Yet, a strong debate continues on how the concept is to be defined and used. Drawing largely from the irrigation literature, the origins of the concept and its methodological developments are reviewed, and its use in applied work over two decades is discussed. Based on this analysis of conceptual and applied research, key insights into the concept’s contributions and limitations are presented, as well as opportunities for further refinements. 相似文献
78.
Internet of Things for the Future of Smart Agriculture: A Comprehensive Survey of Emerging Technologies 下载免费PDF全文
Othmane Friha Mohamed Amine Ferrag Lei Shu Leandros Maglaras Xiaochan Wang 《IEEE/CAA Journal of Automatica Sinica》2021,8(4):718-752
This paper presents a comprehensive review of emerging technologies for the internet of things (IoT)-based smart agriculture. We begin by summarizing the existing surveys and describing emergent technologies for the agricultural IoT, such as unmanned aerial vehicles, wireless technologies, open-source IoT platforms, software defined networking (SDN), network function virtualization (NFV) technologies, cloud/fog computing, and middleware platforms. We also provide a classification of IoT applications for smart agriculture into seven categories: including smart monitoring, smart water management, agrochemicals applications, disease management, smart harvesting, supply chain management, and smart agricultural practices. Moreover, we provide a taxonomy and a side-by-side comparison of the state-of-the-art methods toward supply chain management based on the blockchain technology for agricultural IoTs. Furthermore, we present real projects that use most of the aforementioned technologies, which demonstrate their great performance in the field of smart agriculture. Finally, we highlight open research challenges and discuss possible future research directions for agricultural IoTs. 相似文献
79.
Application of Hyphenated Chromatography–Mass Spectrometry Techniques to Plant Allelopathy Research 总被引:2,自引:0,他引:2
Terry Haig 《Journal of chemical ecology》2001,27(12):2363-2396
Plant allelopathy offers hope as an additional means of weed control in modern agriculture. Its mechanisms and molecular basis are not yet well understood. Research on the chemical basis for allelopathy has often been hindered by the complexity of plant and soil matrices, making it difficult to track active compounds. Recent improvements in the cost and capabilities of bench-top chromatography–mass spectrometry instruments make these tools more powerful and more widely available to assist with molecular studies conducted in today's expanding field. Such instrumental techniques are herein recommended as economically efficient means of advancing the rigor of allelopathy research and assisting the development of a better understanding of the chemical basis for the allelopathy phenomenon. 相似文献
80.
对山西省城镇化工作中较为突出的"人口半城镇化"问题进行了研究,按照因地制宜、以人为本、科学发展的原则,从人口管理、土地管理、生态环境、行政管理等方面提出了有力的解决措施,以推动城镇化的发展。 相似文献