Perennial crops under stochastic water supply

Perennial crops require substantial initial investment in groundwork and planting, as well as a multiyear gestation period without commercial yield. Therefore, a crop's cycle (from planting to felling) should be long enough in order to cover the fixed cost and become profitable. The problem becomes involved when the cycle's duration is stochastic due to occurrence of uncertain event that terminates the cycle prematurely. Studying orchard management under stochastic drought events, we show that to each perennial crop that is profitable without drought hazard, there exists a critical drought hazard above which the crop turns loss making. We refer to this critical drought hazard as the crop's drought vulnerability index and show that it increases with the length of the gestation period, the ratio of fixed cost to average annual profit and the interest rate, and decreases with the natural (uninterrupted) cycle length. We then investigate the economic value of a stable water source, such as recycled water, that stabilizes the water supply and diminishes the drought hazard. An empirical application in northern Israel reveals that the stabilization value of recycled water due to its role in eliminating the drought hazard far exceeds its supply cost.     

Agricultural commercialization and nutrition revisited: Empirical evidence from three African countries

The transition from subsistence to commercial agriculture is key for economic growth. But what are the consequences for nutritional outcomes? The evidence to date has been scant and inconclusive. This study contributes to the debate by revisiting two prevailing wisdoms: (a) market participation by African smallholders remains low; and (b) the impact of commercialization on nutritional outcomes is generally positive. Using nationally representative data from three African countries, the analysis reveals high levels of commercialization by even the poorest and smallest landholders, with rates of market participation as high as 90%. Female farmers participate less, but tend to sell larger shares of their production, conditional on participation. Second, we find little evidence of a positive relationship between commercialization and nutritional status. As countries and international agencies prioritize the importance of nutrition-sensitive agriculture, better understanding of the transmission channels between crop choices and nutritional outcomes should remain a research priority.     

山东省粮经作物播种比例演变及结构优化研究——基于1986～2015统计数据

[目的]目前我国农业主要矛盾是结构性失衡,作为种植业大省的山东省的农业结构性矛盾更为突出,种植业供给侧结构性改革势在必行。[方法]选取山东省1987~2016年农业统计年鉴中有关1986~2015年粮食作物和经济作物以及同类作物不同品种的播种面积的统计数据,运用统计分析法、图表法和对比分析法,分析山东省粮经作物播种面积比例演变特点,以及粮食作物和经济作物各自内部播种面积比例演变特点。[结果]30年间,山东省粮食作物播种面积及占比呈缓慢下降趋势,而经济作物播种面积和占比则持续上升,但大豆、棉花等经济作物国际市场依存度持续走高。从粮食作物和经济作物具体品种来看,玉米、蔬菜、瓜果播种面积持续大幅度上升,而大豆、棉花播种面积连年下降。[结论]山东省应在遵循国家发展粮经饲统筹的"三元"种植结构的政策导向基础上,兼顾种植户的经济利益,顺应消费者需求变化,从种植制度与生产方式安排、农作物品种选择、农作物品质提升3个方面进一步优化种植业结构。     

近地层臭氧对农作物产量影响的风险评估模型研究进展

近地层臭氧污染及其对农作物产量和粮食安全的负面效应已成为国内外广泛关注的焦点之一,建立适宜且更为精确的模型开展臭氧影响下的农作物产量损失评估对于粮食安全保障及臭氧污染控制具有重要的意义。综述了浓度响应、剂量响应和通量响应等统计模型的发展及其在产量损失评估中的应用,评述了其优缺点和通量响应模型的不确定性,同时,通过臭氧干沉降模型的研究进展及其与通量响应模型的优势比较,提出了基于观测和臭氧干沉降模型开展臭氧影响下的自然农田作物产量损失评估技术新的研究方向。     

Mobile Phones and Radios: Effects on Transactions Costs and Market Participation for Households in Northern Ghana

The literature on agricultural markets suggests that transactions costs are the main obstacles preventing households from participating in agricultural markets. We examine the impact of the recent massive penetration of information communication technologies (ICTs), particularly mobile phones and radios, in developing countries to investigate the role of information in economic transactions and participation in food crop markets. To fully capture market participation behaviours, the current theoretical framework on market participation and transactions costs is extended to include those households that sell and buy in the same time period. We correct for endogeneity and selectivity throughout our models. We used a novel dataset of 393 households in northern Ghana with detailed information on market transactions and ICTs usage. Results show that receiving market information via mobile phones has a positive and significant impact on market participation, with a greater impact for households with a surplus of food crops. We find that radios have a larger impact on the quantity traded. This may reflect the nature of mobile phones in reducing searching costs, whereas radios provide an updated and regular flow of information which affects the pattern of crops consumed and sold. We also emphasise that the most significant factor is how ICTs are used, rather than their ownership.     

Do stronger intellectual property rights promote seed exchange: evidence from U.S. seed exports?

With increased private investment in crop breeding research in the developed world, intellectual property rights have gained importance in seed sector. Trade Related Aspects of Intellectual Property Rights (TRIPS)‐plus provisions included in recent free trade agreements between the developed and developing countries show a tendency of the developed world to impose their high standards for protection of plant intellectual property on the developing world. While stronger intellectual property rights can increase international exchange in seed, market power effect can lead to a reduction in exports of seed to foreign markets. This article estimates the impact of intellectual property rights on U.S. seed exports. The estimation is performed at a crop level using Heckman selection model. The results reveal that the impact of intellectual property rights varies across different types of crops—open‐pollinated, genetically modified, and hybrid crops. While TRIPS provisions are important to facilitate transfer of genetically modified crops, they play a minor role for open‐pollinated and hybrid crops. The results also show that plant breeders’ rights envisioned by the UPOV system can be important to promote seed exchange when proper mechanisms are put in place to enforce these rights.     

Using participatory rural appraisal and participatory research and extension in a post-independence environment: a case from East Timor

A participatory rural appraisal (PRA) conducted in East Timor in 2004 as part of an agricultural development project provided the basis for a number of community-based participatory extension initiatives. The PRA involved several communities throughout a watershed and also served as a training exercise for local agriculture ministry staff. Despite the poverty of many of the communities involved, and in contrast to published literature on the local agricultural situation, farmers clearly expressed their need for more marketable crops and alternative sources of livelihoods. Their desires contrasted with the project's initial assumption that the major need was for increased production of staple crops to alleviate food scarcity. The project consequently branched out from concentrating on basic agronomy of staple crops into developing marketable crops, improving livestock production and facilitating development of a local business. Farmers' groups were set up to allow farmers to develop their own agricultural enterprises. Some ministry staff who participated in the project welcomed the opportunity to move from the traditional authoritarian extension system set up under Indonesian colonial rule to a more collegial and educational system. The breakdown of institutions and lines of authority following independence may create new opportunities for participatory development in newly independent states.     

On the Segregation of Genetically Modified,Conventional and Organic Products in European Agriculture: A Multi‐market Equilibrium Analysis

Evaluating the possible benefits of the introduction of genetically modified (GM) crops must address the issue of consumer resistance as well as the complex regulation that has ensued. In the European Union (EU), this regulation envisions the co‐existence of GM food with conventional and quality‐enhanced products, mandates the labelling and traceability of GM products and allows only a stringent adventitious presence of GM content in other products. All these elements are brought together within a partial equilibrium model of the EU agricultural food sector. The model comprises conventional, GM and organic food. Demand is modelled in a novel fashion, whereby organic and conventional products are treated as horizontally differentiated but GM products are vertically differentiated (weakly inferior) relative to conventional ones. Supply accounts explicitly for the land constraint at the sector level and for the need for additional resources to produce organic food. Model calibration and simulation allow insights into the qualitative and quantitative effects of the large‐scale introduction of GM products in the EU market. We find that the introduction of GM food reduces overall EU welfare, mostly because of the associated need for costly segregation of non‐GM products, but the producers of quality‐enhanced products actually benefit.     

On the asynchronous approvals of GM crops: Potential market impacts of a trade disruption of EU soy imports

Due to their high protein content, soybeans are important feedstuffs in the European Union (EU). However, the cultivation of soybeans using genetically modified (GM) varieties in non-EU countries is increasing and the EU authorization of GM products takes longer than in other countries, leading to an asynchronous approval between the EU and non-EU countries that might induce soybean trade disruptions. This paper uses an integrated modelling system to simulate Argentina, Brazil and the United States ending soybean exports to the EU. The impact on world trade and on the EU import prices of soy products is analysed with a computable general equilibrium model. EU soy imports are shown to decline, and the import price of soybeans in the EU increases. The effects on EU agricultural markets are analysed based on a partial equilibrium model. Feed costs in the EU are found to increase with poultry and pork the most affected: production and exports decline and imports increase. However, the effects of a trade ban are found to be less profound than in many other studies due to compensating substitution effects at various market levels: increasing imports from third countries, increasing domestic oilseed production and the use of other protein feeds.     

全球转基因大豆发展概况

自1996年以来,全球转基因大豆得到迅速发展。从1996年至2004年,转基因大豆的种植面积从50万hm 2增至4840万hm 2,增长了约96倍;转基因大豆种植率从0.8%升至52.6%,增长了约63倍;转基因大豆分布国家从2个增至9个。在2004年,转基因大豆主产国依次是美国、阿根廷、巴西和巴拉圭。转基因大豆是全球最重要的转基因作物。虽然转基因大豆安全性存在很大争论,但是,全球转基因大豆预计仍将得到进一步发展,而中国仍将禁止商业化种植转基因大豆。