以农灌为出路的城镇污水管理

针对传统城镇污水管理中存在的下水道管理目标失当、污水处理系统工艺落后、出水管理不严格等缺陷,提出了以农灌作为城镇污水最终出路时应采取的一系列措施,包括调整下水道管理优先目标、加强城镇污水纳网管理和排水许可管理、加强城镇污水处理厂水质管理并制定应急预案、加强出水监测并实行公开制度、明确农灌用水条件等,以保证城镇污水安全、高效、合理的回用于农田灌溉。     

Logistic Regression Analysis on Factors Affecting Adoption of Rice-Fish Farming in North Iran

We evaluated the factors influencing the adoption of rice-fish farming in the Tavalesh region near the Caspian Sea in northern Iran.We conducted a survey with open-ended questions.Data were collected from 184 respondents(61 adopters and 123 non-adopters) randomly sampled from selected villages and analyzed using logistic regression and multi-response analysis.Family size,number of contacts with an extension agent,participation in extension-education activities,membership in social institutions and the presence of farm workers were the most important socio-economic factors for the adoption of rice-fish farming system.In addition,economic problems were the most common issue reported by adopters.Other issues such as lack of access to appropriate fish food,losses of fish,lack of access to high quality fish fingerlings and dehydration and poor water quality were also important to a number of farmers.     

环竺山湾湖小流域种植业面源污染减排潜力研究

农田面源污染一直被认为是竺山湾湖水质恶化的重要因素之一。采用实地调研农户的方法考察了环竺山湾湖小流域粮食作物(水稻、小麦)、蔬菜、果园生产在"十二五"初期养分投入状况,结合太湖流域"十一五"期间已获示范验证、可推广应用的环境友好型种植技术模式或实践,估算了环竺山湾湖小流域种植业生产控污减排能力。结果表明,基于目前的稻麦、蔬菜和果树种植面积,规模化应用稻-麦施肥减量技术和稻-绿肥技术轮作模式可分别实现无机N投入减量132.4、424.3 t·a-1和总N减排20、42.3 t·a-1;蔬菜种植优化技术模式可减少无机N投入993.7 t·a-1和减排总N 181.3 t·a-1;果园优化施肥与三叶草截流控害集成技术模式,至少可实现节省无机N投入1000 t·a-1和减排总N 116.8 t·a-1。综上,环竺山湾湖小流域种植业生产已较"十一五"时期无机N投入水平明显降低,但依然还有减量空间;有机肥施用量逐步提升,但符合竺山湾湖小流域的最适施用水平还有待深入研究。最后给出了环竺山湾湖小流域农田面源污染规模化防控建议,以期为改善竺山湾湖水质进而确保太湖水质安全提供支持。     

益生菌在动物养殖业中应用的研究进展

益生菌作为一类活的微生物制剂,能有效调节动物肠道菌群,其添加到动物饲料中具有提高动物生长性能,增强机体的免疫功能及抗病能力,提高饲料消化率,降低环境污染,既环保又可带来经济效益,目前已被广泛用于动物养殖业。现作者就益生菌在动物养殖业中的应用进行综述。     

Striped catfish (Pangasianodon hypophthalmus,Sauvage, 1878) aquaculture in Bangladesh: an overview

Farming of the striped catfish, Pangasianodon hypophthalmus, is a major aquaculture activity in Bangladesh, particularly in the district of Mymensingh. However, pangasius farm management practices and the socio‐economic impacts of pangasius farming systems in Mymensingh have not yet been adequately described in the literature. This article provides an overview of the present status and characteristics of pangasius culture in Bangladesh based on data from a study conducted in Mymensingh district during 2009. The mean productivity of pangasius was 36.9 MT ha^?1, where 87.9% of the farms produced between 15 and 65 MT ha^?1 of pangasius, with an additional 10–20% Indian major and Chinese carps and Nile tilapia. Pangasius aquaculture in Bangladesh has improved the economic and social status of a variety of stakeholders in communities where the fish is farmed.     

Evaluation of potential feed sources,and technical and economic considerations of small‐scale commercial striped catfish (Pangasius hypothalamus) pond farming systems in the Mekong Delta of Vietnam

A technical and socio‐economic survey was conducted in Dong Thap, Can Tho and An Giang, provinces of Vietnam in 2009. The results showed that most of the small scale farmers of striped catfish (Pangasius hypothalamus) carry out fish pond culture, developed and operated by self‐learned experience and from neighbours knowledge. The mean pond depth varied from 3.5 to 4.0 m, ranging from 2 to 6 m. Most of the fish farms have extremely high stocking density, with an average of about 40 fish m^?2, in some cases up to 70 fish per m². The average yields and net income of small‐scales pond farming is about 21–27 kg per m² crop^?1 and US$ 0.184–0.329 kg^?1 crop^?1 respectively. These figures are not significantly different compared with large‐scale pond farming. About 75%, 86% and 80% of fish farmers in Dong Thap, Can Tho and An Giang province, respectively, received positive net returns. Farm‐made feed is still playing an important role because of higher net profit compared with commercial pellet feeds. Rice bran and trash fish are the main feed ingredients for farm‐made feed formulations. Striped catfish farmers are now actively searching for locally produced plant protein sources as alternatives to marine trash fish or fish meal.     

VOLUNTARY MANAGEMENT IN THAI SHRIMP FARMING

The implementation of the voluntary adoption of the Code of Conduct (CoC) to promote environmental responsibility and sustainable development of Thai shrimp industry is examined. Farmers' perceived benefits, risks and uncertainties associated with the adoption and their perceived extra fixed cost are found to be the critical conditions to the success of the program. Improvement of farmers' perceptions through increased information and knowledge, development of supportive policies and mechanisms (i.e., a “Group CoC” system, insurance program, a combination of environmental policy approaches) and strengthening farmers organizations, as well as establishing networks among and between the players throughout the market chain are suggested to enhance the adoption and implementation of the scheme.     

Transaction costs in contract farming models for mussel and oyster farming in South Africa: Organisational and management implications

Abstract

This study examines transaction costs faced by small mussel and oyster growers to elicit the appropriate organisational design of contract institutions. The theoretical premise is that high transaction costs essentially constrain the participation of small growers in mussel and oyster mariculture. Transaction cost analysis is applied to contract farming models and this approach is first discussed conceptually. Experience with contract farming by small growers in a developing context is synthesised and used in guiding the design of contract farming models. This is followed by a brief overview of the mussel and oyster industries, which is used to gain insight into transaction costs associated with contract institutions. Contracting models and implications are assessed separately for each industry. For mussel mariculture, four farming models are examined and the appropriate model is subsequently selected. For oyster mariculture, the transaction costs of contract fanning are examined to assist in organisational design.     

ECONOMIC RISK ASSESSMENT OF A SEMI-INTENSIVE SHRIMP FARM IN SINALOA,MEXICO

In Mexico shrimp farming is the most important aquaculture activity. However, its sustainable development has been threatened in recent years by the economic risk associated with low yields caused by outbreaks of viral diseases. A stochastic bioeconomic model was developed to analyze the economics of farm management adjustments as a response to disease risks, using pond-level data from a farm operating in the State of Sinaloa, Mexico, during the period 2001–2005. The data base analyzed included different combinations of stocking density (in the range 6–30 PL/m²) and culture time (from 12 to 31 weeks), which allows for wider application of the simulation results, even at the industry level. Results from this study indicate that operating costs would increase by 33% if the farmer would choose to market product directly. Scenarios with lower stocking densities and intermediate culture times generated the highest probabilities 6–9 PL/m² 16–19 weeks (76%/100%/70%), and 10–14 PL/m² 20–24 weeks (72%/99%) of achieving superior economic performance, as demonstrated by achieving the target reference point of 35% operating profit margin ratio. The study reinforces the value of the current trends in Sinaloa to reduce stocking density as a good management practice to decrease the impact of diseases. This study also provides important additional knowledge on the specific economic results and risks associated with the combination of these two management variables at different levels.     

覆膜方式对旱作马铃薯若干生理指标的影响

采用田间小区试验和室内分析相结合的方法,研究了露地平播、平作行上覆膜、双垄全膜覆盖、起垄行上覆膜及起垄覆膜膜侧播种五种不同覆膜方式对旱作马铃薯若干生理指标的影响,旨在探讨适合内蒙古武川县旱作马铃薯栽培的覆膜方式。结果表明,四种覆膜方式均能不同程度提高旱作马铃薯叶片相对含水量、可溶性蛋白含量,并使叶片超氧化物歧化酶活性、丙二醛含量、游离脯氨酸含量处于较低水平,以维持植株正常的生长代谢,其中以起垄覆膜膜侧播种和双垄全膜覆盖两种覆膜方式的效果最好。