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941.
In this paper, we review the physical characteristics of agricultural non point pollution and discuss the implications for setting appropriate pollution control objectives and designing incentive-based pollution control policies. First, we discuss that policy objectives must be designed carefully to ensure positive economic net benefits can be expected from pollution control. Next, we review several classes of incentives and recommend the use of design-based incentives (i.e., incentives based on variable input use, management practices, and land use) for controlling non point pollution. Cost-effectiveness requires that incentives elicit three types of responses from farmers: (1) use variable inputs at appropriate levels, (2) adopt appropriate management practices, and (3) make appropriate land use decisions at the extensive margin of production. If a set of incentives fails to induce the correct responses, the resulting runoff levels and hence ambient pollution levels and damages will be too large relative to policy goals. A review of existing programs suggests that greater program coordination and improved targeting of incentives are needed for further water quality improvements. Alternatively, properly designed market-based systems may be effective alternatives. These systems would reduce overall pollution control costs by allowing markets to allocate point source and non point source control costs more efficiently.  相似文献   
942.
During the past few years,organic dairy farming has grown dramatically inDenmark. Consequently, an increasing number ofpeople are encountering this method ofproduction for the first time. Amongst these,many veterinarians have suddenly had to dealwith organic herds in their home district, and,meeting examples of poor animal welfare, theyhave recently started to express some concerns.Against this background, a so-called``Synthesis of Knowledge' project was initiatedto examine the health and welfare of dairycattle and the use of medication in thetransition to organic production. The aim ofthe project was to investigate associatedproblems from the point of view of the dairyherd. Based on qualitative research interviewswith vets and agricultural advisors, as well asfocus group interviews with farmers who hadrecently converted from conventional to organicfarming, an expert panel attempted to identifyproblem areas and possible solutions. Theproblems related to (a) the adjustment to newand unknown practices, (b) poor management ingeneral, and (c) inappropriate legislation fororganic farming.One problem area was the rearing of dairycalves, particularly with regard to theestablishment of post partumrelationships between cow and calf, grouphousing, and the grazing of young animals. A``natural life' was identified as beingfundamental to organic animal husbandry. Interms of animal welfare, this concept can beunderstood as a way of living in which the calfis allowed to express its natural behavior andsatisfy its natural needs. Essentially, theconditions needed for good calf welfare requirethe compatibility and interplay of elementsfrom ``nature' (the natural life; includingopportunities to satisfy natural needs) and``culture' (farmer management skills; exerciseof care). These elements should be balanced toensure animal welfare in organic herds.  相似文献   
943.
福建农业发展时段的可持续性分析及其启示   总被引:2,自引:0,他引:2  
本文引入“狭义”可持续发展的概念,对福建近50年(1952-1998年)人口与粮食的动态变化一时序分析,探讨了福建农业发展的可持续性,最后提出几点建议,以期对福建农业发展有所裨益。  相似文献   
944.
During the last 50 years the practising and intensity of agriculture and forestry have differed considerably between Finnish and Russian Karelia. We studied the effects of different land use practices on the landscape composition in the two countries using the road transect sampling along four study routes (99-121 km) between 1997 and 1999. Effective environmental management in Finland has resulted in more distinct agricultural land types, more even distribution of the different age classes of forests, and the higher abundance of coniferous forests. Fields (mean percentage of the landscape: Finland 28%, Russia 13%), clearcuts and sapling stands (15%, 6%), and young forests (23%, 9%) were more typical elements of the Finnish landscape, whereas settlements (9%, 13%), semi-natural grasslands (3%, 7%), and mature forests (20%, 49%) were more characteristic of the Russian landscape. Landscape-level differences between the two countries may have various effects on the diversity of fauna and flora inhabiting Finnish and Russian Karelia.  相似文献   
945.
An energy analysis of sugarcane production in small and large farms was made in Morocco. Total energy expenditures were 64.90 and 47.83 GJ/ha and energy outputs were 100.80 and 85.80 GJ/ha in large and small farms, respectively. The output/input energy ratios were 1.6 and 1.8. The energy intensity lies between 0.7 and 0.8 MJ/kg and is one of the highest among sugarcane producing countries. Irrigation is the most energy consuming operation with about 50% of total energy inputs. Electricity, fertilizers, fuel, and machinery are the main energy inputs. The influence of the different inputs is discussed and practical measures for energy saving and environmental conservation based on energy analysis are discussed.  相似文献   
946.
ABSTRACT: The relation offish community composition to riparian cover at two spatial scales was compared at 18 streams in the agricultural Minnesota River Basin. The two spatial scales were: (1) local riparian zone (a 200 meter wide buffer extending 2 to 3 kilometers upstream of the sampling reach); and (2) the upstream riparian zone (a 200 m wide buffer on the mainstem and all perennial tributaries upstream of the sampling reach). Analysis of variance indicated that streams with wooded‐local riparian zones had greater fish species richness (means = 20 and 15, respectively) and Index of Biotic Integrity (IBI) scores (means = 40 and 26, respectively) than streams with open‐local riparian zones. Streams with wooded‐upstream riparian zones tended (were not statistically significant) to have greater numbers of species (means = 19 and 15, respectively) and IBI scores (means = 33 and 28, respectively) than streams with open‐upstream riparian zones. There was no significant interaction between the riparian zone conditions at the two scales. This study suggests that maintenance of wooded riparian cover along streams could be effective in maintaining or improving fish community composition in streams draining heavily agricultural areas.  相似文献   
947.
1980~1992年对大伙房水库6个站进行了不同季节底栖动物群落特征生态调查。共发现26种底栖动物,隶属于20属,3科。底栖动物密度由1980年的3335个/m2减少到1992年的829个/m2。共发现9种耐污种类,占总数的34.6%,密度占86.5%以上。水质生物学评价结果表明:1、2站动物种类少(10种),多样性指数低(1.2956),属α──中污染;5站动物种类多(16种),多样性指数高(1.4024),属β──中污染;大伙房水库只受到轻度污染。  相似文献   
948.
为了探讨SR菌应用于净化回收电镀废水重金属工艺的安全性,通过11项试验和调查,研究了SR菌的毒力、毒性、致毒性、感染性和致敏性,SR菌在机体内的转归,人接触SR菌的反应,SR菌对植物生长的遗传的影响,结果表明SR菌的毒力,致毒性都在无毒范围;不致传染病;不致皮肤过敏;SR菌对植物的生长和遗传无不良影响,进入胃肠道的SR菌SR菌6h入血液循环,24h由尿,粪排出,体内的SR菌在7d左右被机体解体,通  相似文献   
949.
Conservation science is a morally motivated field, with implicit and explicit values built into its practice. As such, conservationists must engage with conservation ethics to interrogate underlying values. We examine cutting-edge ecological science and contemporary ethics to revisit two conservation norms that have become dogmatic in the field: ecological collectives, but not individual animals, are valuable and anthropomorphism should be staunchly avoided. Emerging studies demonstrate that individuals and their intraspecific variation can be instrumentally valuable for conservation science, and there is an emerging consensus within environmental philosophy around the moral worth of individuals. Thus, we suggest conservation science should explicitly recognize the value of individuals. We also argue that avoiding anthropomorphism is detrimental to conservation because critical anthropomorphism enables a more nuanced scientific approach—allowing conservationists to ask enlightened questions with creativity and compassion. We provide evidence that both dogmatic norms are scientifically and morally outdated and propose new normative values to push conservation towards more robust science and ethical practice.  相似文献   
950.
Abstact More and more lands worldwide are being cultivated for food production while forests are disappearing at an unprecedented rate. This paper aims to make a long-term forecast on land uses worldwide and provide the publics, researchers, and government officials with a clear profile for land uses in the future. Data of land uses since 1961 were used to fit historical trajectories and make the forecast. The results show that trajectories of land areas can be well fitted with univariate linear regressions. The forecasts of land uses during the coming 25 years were given in detail.Areas of agricultural land, arable land, and permanent pasture land worldwide would increase by 6.6%, 7.2%, and 6.3% respectively in the year 2030 as compared to the current areas. Permanent crops land area all over the world is forecasted to increase 0.64% by 2030. By the year 2030 the areas of forests and woodland, nonarable and nonpermanent land worldwide would decrease by 2.4% and 0.9% against the current areas. All other land area in the world would dramatically decline by 6.4% by the year 2030.Overall the land area related to agriculture would tend to decrease in developed countries, industrialized countries, Europe, and North and Central America. The agriculture related land area would considerably increase in developing countries, least developed countries, low-income countries, Asia, Africa, South America, etc.Developing countries hold larger total land area than developed countries. Dramatic and continuous growth in agricultural land area of developing countries would largely contribute to the expected growth of world agricultural land area in the coming years. Population explosion, food shortage and poverty in the world, especially in developing countries, together caused the excessive cultivation of land for agricultural uses in the past years. Increasing agricultural land area exacerbates the climate changes and degradation of environment. How to limit the growth of human population is a key problem for reducing agricultural land expansion. Development and use of high-yielding and high-quality crop and animal varieties, diversification of human food sources, and technical and financial assistance to developing countries from developed countries, should also be implemented and strengthened in the future in order to slow down or even reverse the increase trend of agricultural land area. Sustainable agriculture is the effective way to stabilize the agricultural land area without food shortage. Through various techniques and measures, sustainable agriculture may meet the food production goals with minimum environmental risk. Public awareness and interest in sustainable agriculture will help realize and ease the increasing stress from agricultural land expansion.  相似文献   
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