我国农产品价格形成机制及波动效应分析

在市场机制下,基于不同的市场交易,形成农产品集市价格、批发价格和期货价格,三者共同调节农产品市场供求关系。我国粮食价格波动轨迹符合蛛网模型现象,表明农产品供求弹性较小,无论源于供给还是需求方的变化,都会引起农产品价格较大幅度的变化。农产品价格的不稳定性,实质上反映着农业收益的不稳定性。建立农业共生组织,通过市场主体间的共生与协作,形成农业产前、产中和产后各环节的互补性和资源依存性,是稳定农产品价格的一种准市场性的资源配置方式。     

福建省尤溪县粮食作物比较优势分析与发展对策研究

该文针对粮食高产创建整乡制推进的需求,运用综合比较优势指数法,对尤溪县的主要粮食作物进行比较优势分析研究,得出各乡域间粮食生产比较优势差异.并根据分析结果,提出加快尤溪县粮食作物优化布局与产业发展的思路与对策.     

Mobilizing Against GM Crops in India, South Africa and Brazil

This paper explores the national and transnational character of mobilization against GM crops in India, South Africa and Brazil in the ten-year period to 2005. By examining the contexts and practices of mobilization across the three countries, and in particular the complex, often fraught, local and global connections, the paper examines the diverse mobilizations that have occurred. The paper argues that to understand these processes, particular national political and economic contexts must be appreciated, alongside how the GM debates articulate with other foci for activism and the complex and often fragile nature of alliances that make up activist networks. The paper shows how the debate about GM crops has become a much wider one: about the future of agriculture and small-scale farmers, about corporate control and property rights and about the rules of global trade. In sum, a debate not just about the pros and cons of a particular set of technologies, but about politics and values and the future of agrarian society.     

Rejecting New Technology: The Case of Genetically Modified Wheat

Canada has stringent regulations covering the release of new wheat varieties, but the United States has virtually no regulations in this area. Monsanto Co. developed genetically modified (GM) spring wheat for North America, and made a commitment to the U.S. industry to release this new technology simultaneously in both Canada and the United States, or not at all. The Canadian regulatory bias against new varieties acted as a veto against GM wheat and caused Monsanto to shelve the technology in both countries in 2004. Substantial economic rents were foregone in North America due to the rejection of this new technology.     

陕西省粮食产量预测及其影响因素的灰色关联分析

根据1988—2007年粮食生产相关指标的统计数据，借助灰色关联理论对影响陕西省粮食生产的粮食单位面积产量，农业劳动力，机械总动力，化肥施用量，受灾面积，粮食播种面积，农田有效灌溉面积，农村用电量等8项指标进行了灰色关联度的定量分析，总结出不同时间段主要影响因素，并根据关联度的大小排序，，结合该省实际情况，提出了针对性，可行性的建议；将灰色关联分析结果中关联度比较高的指标作为神将网络的输入层单元，借助基于动量法的BP神经网络的MOBP模型预测出未来2015年和2020年的粮食产量，经检验该模型的平均相对误差达到2．5％，为陕西省可持续发展战略的制定和规划提供可靠的数据和参考价值。     

Farmers' Subjective Valuation of Subsistence Crops: The Case of Traditional Maize in Mexico

Shadow prices guide farmers' resource allocations, but for subsistence farmers who grow traditional crops they may bear little relationship with market prices. We theoretically derive shadow prices for a subsistence crop with nonmarket value, then estimate shadow prices of maize using data from a nationally representative survey of rural households in Mexico. Shadow prices are significantly higher than market prices for traditional but not improved maize varieties. They are particularly high in the indigenous areas of southern and southeastern Mexico, indicating large  de facto  incentives to maintain traditional varieties there.     

EU Food Safety Standards,Pesticide Use and Farm‐level Productivity: The Case of High‐value Crops in Kenya

This article provides an empirical analysis of the impact of European Union (EU) private food safety standards on pesticide use and farm‐level productivity among small‐scale vegetable producers in Kenya. We apply an extended three‐stage damage control production framework, accounting for multiple endogeneity problems, to farm‐level data collected from a random cross‐sectional sample of 539 small‐scale producers. Estimation results show that farmers producing vegetables for the domestic market use significantly lower quantities of pesticides than do export farmers. However, contrary to findings elsewhere, the econometric evidence here shows that both domestic and export‐oriented vegetable farmers in Kenya use pesticides at levels below the economic optimum. The results also show that the adoption of standards by export farmers does not have any significant impact on total pesticide use. However, adopter categories are distinguishable in terms of types of pesticide used, i.e. adopters use safer pesticides based on World Health Organization (WHO) classification. The third‐stage structural revenue model results demonstrate that adoption of standards has a positive and significant impact on revenue raised in vegetable production. Nevertheless, farmers producing for the export market are indistinguishable from those producing for the domestic farmers in terms of the total revenue earned from producing vegetables during the rainy season, on a ‘per acre’ basis. Although standards can potentially prevent resource‐poor smallholders from maintaining their position in the lucrative export markets, they can also result in positive changes in the production systems of those small‐scale farmers who adopt it, as shown by these results.     

The grain potential of cultivated lands in Mainland China in 2004

The regional test yields of certificated cultivars of grain crops represent the potential yields for the given region under the current natural and technical conditions. Therefore, it is appropriate to use the regional test yields to estimate the gross grain potential of Mainland China.In this paper, we calculated the grain potential of cultivated lands for each of the 105 agro-ecological regions in China. First, cropping system in each agro-ecological region was assumed to be the best use of the agro-climatic resources. Second, the potential per hectare for each of the crops was calculated for a given agro-ecological region, based on the regional test yields of certificated cultivars of grain crops in a given cropping system. For rain-fed and dry lands, their grain potentials were further modified by water-restricting coefficients. The water-restricting coefficients were calculated by dividing the hydro-thermal potential with the corresponding photosynthesis-thermal potential for different grain crops, which were obtained from Regulations of Farmland Grading. Thereafter, the grain potential per hectare of each agro-ecological region was calculated considering the cropping system and the potentials per hectare of all the crops in the cropping system. The gross grain potential of each county in a given region was then obtained by multiplying the grain potential per hectare and the total area of cultivated lands in the county. Finally, the gross grain potential of each agro-ecological region and the whole Mainland China were obtained by summarizing the grain potentials for all of the counties. The results showed that the gross grain potential of Mainland China was 0.92 billion t in 2004. It should be pointed out that this calculation on the grain potential did not sufficiently consider the crop growth restricting factors of cultivated lands, such as soil fertility, fertilizer input, and so on. Since the grain potential is far above the actual grain yield, it suggests that the cultivated land assurance for grain security in Mainland China is relatively high. The results of each agro-ecological region showed that the highest grain potentials were distributed in Huang-Huai-Hai Plain, Northeast China, Middle and Lower Reaches of Yangtze River and Sichuan Basin, where excellent hydro-thermal condition and flat terrain are ideally suitable for crop growth.     

Bridging the Gap between Partial and Total Factor Productivity Measures Using Directional Distance Functions

Technical dependencies as well as data constraints limit our ability to allocate inputs across sectors and hence our ability to measure sectoral productivity. We adapt a directional measure of efficiency to the measurement of sector-specific productivity that does not require allocating all inputs across sectors. Applied to the agricultural sector of a group of countries, the results show important differences in livestock and crops productivity growth. Commonly used partial factor productivity measures for livestock and crops tend to overestimate productivity growth in most developing countries while underestimating it in European countries.     

Regulating coexistence in Europe: Beware of the domino-effect!

In the literature spatial coexistence of genetically modified (GM) and non-GM crops is often regarded as a technical challenge, depending on spatial pollen dispersal and cross-pollination, temporal and spatial distribution and interaction of crops, separation distances and practical measures, but the interaction between economic incentives and costs of coexistence is poorly studied. Europe is currently struggling to implement coherent coexistence regulations in all EU Member States. Since the publication of the European Commission's guidelines in 2003, some Member States have developed, and others are still developing, a diversity of ex ante regulations and ex post liability rules on the coexistence of GM and non-GM crops. In this article, our attention is drawn to ex ante regulations. More specifically, we polarize two alternative ways of regulating spatial coexistence, i.e. rigid minimum distance rules, imposed on GM crop production, versus flexible segregation measures such as buffer zones, leaving more freedom of negotiation between neighboring farmers. We conduct simulations with the software ArcView® on a GIS dataset of a hypothetical case of GM herbicide tolerant oilseed rape cultivation in Central France. Our findings show that rigid coexistence rules, such as large distance requirements, may impose a severe burden on GM crop production in Europe. These rules are not proportional to the farmers' basic economic incentives for coexistence and hence not consistent with the objectives of the European Commission. More alarming, we show that in densely planted areas a domino-effect may occur, a theoretical possibility ignored in the literature. This effect raises coexistence costs and even adds to the non-proportionality of rigid coexistence regulations. Instead, we show that flexible measures would be preferable since they are proportional to the economic incentives for coexistence and, hence, less counterproductive for European agriculture.