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831.
循环型农业是一种新的农业经济发展模式,宝应县是全国唯一的国家有机食品基地示范县。文中介绍了循环型农业的内涵和特征,概述了宝应县有机农业循环经济的现状,通过对已实施的三种有机农业循环产业链模式的研究,结果表明,宝应县有机农业循环产业链模式能使农业废弃物资源化,并能有效地控制宝应县的农业面源污染,实现经济与环境持续发展。 相似文献
832.
Christopher J. Woltemade Jinnieth Woodward 《Journal of the American Water Resources Association》2008,44(1):222-234
ABSTRACT: In 2001, the 1.04‐ha Hornbaker wetland in south‐central Pennsylvania was restored by blocking an artificial drainage ditch to increase water storage and hydraulic retention time (HRT). A primary goal was to diminish downstream delivery of nitrate that enters the wetland from a limestone spring, its main source of inflow. Wetland inflow and outflow were monitored weekly for two years to assess nitrate flux, water temperature, pH, and specific conductivity. In Year 2, spring discharge was measured weekly to allow calculation of nitrate loads and hydraulic retention time. Surface runoff was confirmed to be a small fraction of wetland inflows via rainfall‐runoff modeling with TR‐55. The full dataset (n = 102) was screened to remove 13 weeks in which spring discharge constituted < 85% of total inflows because of high precipitation and surface runoff. Over two years (n = 89), mean nitrate‐nitrogen concentrations were 7.89 mg/l in inflow and 3.68 mg/l in outflow, with a mean nitrate removal of 4.19 mg/l. During Year 2 (n = 47), for which nitrate load data were available, the wetland removed an average of 2.32 kg N/day, 65% of the load. Nitrate removal was significantly correlated with HRT, water temperature, and the concentration of nitrate in inflow and was significantly greater during the growing season (5.36 mg/l, 64%) than during the non‐growing season (3.23 mg/l, 43%). This study indicates that hydrologic restoration of formerly drained wetlands can provide substantial water quality benefits and that the hydrologic characteristics of spring‐fed wetlands, in particular, support effective nitrogen removal. 相似文献
833.
Terry Sohl Jordan Dornbierer Steve Wika Kristi Sayler Rob Quenzer 《Journal of Land Use Science》2017,12(4):197-217
Land use and land cover (LULC) change occurs at a local level within contiguous ownership and management units (parcels), yet LULC models primarily use pixel-based spatial frameworks. The few parcel-based models being used overwhelmingly focus on small geographic areas, limiting the ability to assess LULC change impacts at regional to national scales. We developed a modified version of the Forecasting Scenarios of land use change model to project parcel-based agricultural change across a large region in the United States Great Plains. A scenario representing an agricultural biofuel scenario was modeled from 2012 to 2030, using real parcel boundaries based on contiguous ownership and land management units. The resulting LULC projection provides a vastly improved representation of landscape pattern over existing pixel-based models, while simultaneously providing an unprecedented combination of thematic detail and broad geographic extent. The conceptual approach is practical and scalable, with potential use for national-scale projections. 相似文献
834.
农业规模经营是实现农业现代化的重要路径。为了探讨丘陵山区农业规模化发展对于水土流失的影响机理。通过文献综述法梳理相关研究,分析现有研究存在的不足,并提出研究展望。综观前人的研究可以得知:(1)农业规模经营的效益、政策与推动机制等状况;(2)丘陵山区水土流失的影响因素乃为自然因素与人为因素交互作用的结果,以及农业活动对水土流失的影响;(3)水土流失的调查、监测与影响因素的评估方法及仿真模拟。最后,提出5点研究展望:(1)构建丘陵山区水土流失驱动力模型;(2)建立丘陵山区农业规模化对水土流失的影响评估指标体系;(3)甄别影响程度及其时空差异;(4)丘陵山区农业规模化的水土流失效应模拟反演;(5)提出丘陵山区水土资源可持续利用的农业规模化政策建议。以期对我国丘陵山区发展适度农业规模化与可持续发展研究提供科学参考。 相似文献
835.
836.
Michael White Marilyn Gambone Haw Yen Prasad Daggupati Katrin Bieger Debjani Deb Jeff Arnold 《Journal of the American Water Resources Association》2016,52(1):269-274
The Soil and Water Assessment Tool (SWAT) is widely used in the United States (U.S.) to simulate hydrology and water quality simulation. Process‐based models like SWAT require a great deal of data to accurately represent the natural world, including topography, land use, soils, weather, and management. With the exception of management, all these data are available nationally from multiple sources. To date, credible SWAT studies in the U.S. have assembled suitable management data (operation scheduling, fertilization application rates, and plant growth parameterization). In this research, we develop a national management database for SWAT using existing U.S. Department of Agriculture data sources. These data are compatible with existing SWAT interfaces and are relatively easy to use. Although management data from local sources is preferred, these data are not always available. This work is intended to fill this void with more reasonable management data than the existing defaults. This national database covers all major cultivated crops and should facilitate improved SWAT applications in the U.S. These data were tested in two case studies and found to produce satisfactory SWAT predictions. The database developed in this research is freely available on the web. 相似文献
837.
Community-based urban aquaponics enterprises represent a new model for how to blend local agency with scientific innovation to deliver food sovereignty (FS) in cities, re-engaging and giving urban communities more control over their food production and distribution. Little is known, however, about the factors and outcomes that determine the success or failure of these enterprises. This paper explores stakeholder experiences of building community-based urban aquaponics enterprises to understand the internal and external factors that impact on their success or failure. We draw upon existing FS, social enterprise and aquaponics literature, to identify factors in the related area of community-based urban agriculture. For exploring these factors, we use a comparative case study methodology for two cases in Milwaukee and Melbourne, conducting in-depth interviews with key stakeholders, exploring their relative contexts, objectives and structure. Based on these findings, we highlight the challenges and suggest relevant indicators for establishing an urban aquaponics enterprise. 相似文献
838.
Sandra Schwindenhammer 《Journal of Environmental Policy & Planning》2016,18(1):102-120
A key characteristic of global organic agriculture governance through standards is the coexistence of regulatory fragmentation and regional integration. To reduce barriers to organic trade, especially for market participants from developing countries, international and transnational entrepreneurs increasingly promote the setting of organic agriculture standards (OAS) in different world regions, for example, in East Africa, the Pacific, or Asia. Although scholars from different disciplines have done a lot of research on the role of standards in global governance, we still know little about why and how regional standard-setting processes evolve. Applying findings from regime analysis, entrepreneurship, and political authority, the article introduces the concept of authority pooling. It argues that legal, moral, and technical authority sources interact in a blurred functional division of labour between the public and the private sector in standard-setting. The article presents results from a within-case study of the development of the East African Organic Products Standard using the process-tracing method. It detects the underlying causal mechanism by which international and transnational entrepreneurs pooled different authority sources and, thus, significantly influenced political actors in East Africa to set the first regional OAS in the developing world. 相似文献
839.
Maryam Mirhadi Fard Charles J. Kibert Abdol R. Chini 《International Journal of Sustainable Engineering》2016,9(2):76-92
Site selection is a typical strategic decision for many industries that deals with specifying the most appropriate location for a facility. In the context of sustainable development, site selection decisions need to be improved by adopting environmental, economic and social requirements. This study aims to frame sustainable location decisions by conducting a case study of siting a new cement plant in the state of Florida. As a part of the study, a wide range of technical and sustainability criteria has developed. These criteria can help decision-makers in the cement industry evaluate the selection of a location with the requirements of sustainable development. The sustainability characteristics of alternative sites in the state of Florida are evaluated based on the criteria to identify the most appropriate ones. The analytical hierarchy processand geographic information system techniques are utilized to weight the criteria and evaluate the characteristics of site candidates. 相似文献
840.
我国的经济发达地区普遍存在着人地关系紧张、环境质量恶化和农产品质量下降等问题,发展生态农业是缓解这些矛盾的重要途径。本文以江阴市为例,分析了经济发达地区农业发展中存在的主要制约因素,强调了区内发展生态农业的迫切性和优势条件,根据区域社会经济发展特点,指出该市应以为中心城市服务的都市生态农业为发展方向,借鉴发达国家生态农业建设的先进经验,将生态农业建设与农业现代化建设有机地结合起来,探索和推广适合本地特点的精准设施农业技术,达到节约水、肥资源,提高农产品产量和品质的目的。 相似文献