转基因抗虫棉推广应用与次要害虫危害的关系——基于微观农户调查的实证研究

近年来棉花生产中次要害虫危害的上升引起了人们对农业转基因生物技术经济影响可持续的争论,一些人认为次要害虫的危害将会逐渐抵消转基因生物技术所带来的收益。本文以Bt转基因抗虫棉技术为例,利用长期农户调查数据,考察了Bt抗虫棉商业化种植10年来农户防治次要害虫的农药施用量的变化,并建立了相应的计量经济模型,对次要害虫用药量与Bt抗虫棉采用之间的关系进行了检验。研究发现,过去10年,农户用于控制次要害虫的农药施用量确实在增加;但是,次要害虫用药量的增加主要原因并不是由于采用Bt抗虫棉防治棉铃虫所致,气候因素是次要害虫用药量上升的重要原因。     

Bt抗虫棉的种植对农药施用的影响

虽然Bt抗虫棉在我国得到迅速推广，但人们对其发展有不同的看法。本文旨在分析Bt抗虫棉在大田上的种植对棉农农药施用的影响。通过对主要棉花生产省份连续三年（1999-2001年）1055年农户棉花生产情况数据的调查分析后得出结论，各植Bt抗虫棉比种植非Bt棉每公顷平均减少农药施用35公斤，并由此推算出1997-2001年由于抗虫棉推广使全国棉花生产的农药施用量减少了近15万吨以上。在此基础上本文对结论的政策含义进行了讨论。     

浙江农户农药施用效率的调查与分析

施用农药有利于减少因病虫害和划害所引起的农作物产量的损失,然而,施用农药存在明显的负外部性,尤其对生态环境起破坏作用。本文通过对农户用药行为、农药生产流通的调查,分析了农户用药缺乏效率的原因,提出了改变这种状况的对策。     

农户安全施用农药的意愿及其影响因素研究——对四川省广汉市214户农户的调查与分析

本文利用实证研究的方法,以四川省广汉市214户农户的调查数据为依据,对影响农户安全施用农药意愿的主要因素进行计量经济分析。研究表明,农户安全施用农药的意愿受到农户个人特征、农户对农药的认知以及已经存在的施用农药行为等多种因素的影响,并随着这些因素的变化而不断变化。     

影响农药施用行为的农户特征研究

本文基于江苏省三个不同地区的237户分散农户的调研数据,运用偏最小二乘法分析了分散农户农药施用的主要行为特征。研究发现,分散农户的受教育年限、是否参加政府培训和农户家庭总收入等因素显著地影响其在农药施用各阶段的行为,而农户的家庭种植面积、家庭人口、农户自身性别和年龄等因素在其农药施用不同阶段的影响各不相同。因此,在农户受教育层次和收入水平难以在短期内提高的背景下,当务之急是政府建立、健全公益性的农业技术推广体系,覆盖主要农产品产区,加大政府培训力度,提高农户对农药残留的认知水平,这在江苏省等工业化发达地区已显得非常迫切。     

农药施用五种新技术

低量喷雾技术。指单位面积施药量不变，将农药原液稍微稀释，用水量相当于常规喷雾的1／10至1／5。     

转基因抗虫棉不抗虫的原因及对策

近年来,常听到人们反映转基因抗虫棉抗性下降了,不怎么抗虫了。是抗虫棉真的不抗虫了吗?回答是:不见得!我国的棉花研究专家认为,抗虫棉对棉花棉铃虫的抗性并没有严重下降,生产上出现的所谓抗虫棉不抗虫了,首先要确定所用的品种是否     

冬季如何施用农药

冬季气温低，病虫害的活动与危害大都处于隐蔽与静止状态。在冬季施甩化学农药，除了选择对路农药外，还要注意如下六点。 一是选择晴天高温时段用药。因为害虫在冬季温度高时，其取食量与呼吸强度大于阴冷天气，药液喷洒到虫体上，     

牢记农药使用禁忌安全高效施用农药

科学有效的施用农药,才能在达到防治效果的同时,避免发生药害,因此,施用农药应注意十忌。一、忌用活水配制农药。活水中杂质多,用其配药易堵塞喷雾器的喷头,同时会破坏药液的悬浮性,产生沉淀。     

劳动力成本上升对经济作物农药施用强度的影响研究——基于苹果主产区的省际面板数据分析

经济作物的农药过量施用问题一直是生态环境保护和食品质量安全的重要议题。文章基于2004-017年省际面板数据,探究了劳动力成本上升对中国苹果主产区农药施用强度的影响。结果表明:(1)劳动力成本与中国苹果主产区亩均农药施用成本呈倒"U"型关系,且随着劳动力成本不断增加,施药强度呈先上升后下降的趋势。一方面,随着劳动力成本上升,果农出于保证收益和降低风险的考虑会增加施药强度,而劳动力成本进一步上升,会使得劳动力要素投入减少,传统的基于精耕细作和打"放心药"的过量施药行为得到改善;另一方面,生产者出于节约成本的考量,倾向于按需施药和科学合理施药,减少了施药次数,有利于降低苹果果品的总体施药强度。(2)劳动成本上升与实现农药减施的政策目标具有较大协同性,这对进一步实施农药减施增效政策以及提升农产品质量安全具有重要的政策意义。     

Adoption of Bt Cotton and Impact Variability: Insights from India

There is a growing body of literature about the impacts of Bacillus thuringiensis (Bt) cotton in developing countries. While many studies show remarkable benefits for farmers, there are also reports that question these results. Most previous studies consider impacts in deterministic terms, neglecting existing variability. Here we explain the main factors influencing the agronomic and economic outcomes. Apart from differences in pest pressure and patterns of pesticide use, germplasm effects can play an important role. Theoretical arguments are supported by empirical evidence from India. Better understanding of impact variability can help explain some of the paradoxes in the recent controversy over genetically modified crops.     

The Adoption of Genetically Modified Cotton and Poverty Reduction in Pakistan

This article employs a propensity score‐matching approach to examine the direct effects of adoption of Bacillus thuringiensis (Bt) cotton on yields, pesticide demand, household income and poverty, using cross‐sectional data from a survey of farmers in the Punjab province of Pakistan. Generally, the findings reveal that adoption of the new technology exerts a positive and significant impact on cotton yields, household income and poverty reduction, and a negative effect on the use of pesticides. The positive and significant impact of the technology on yields and household income is consistent with the potential role of new agricultural technology in directly reducing rural poverty through increased farm household income.     

Adoption of new tobacco varieties in Greece: Impacts of empirical findings on policy design

Greece is a major international tobacco producer. Flue-cured tobacco varieties constituted the major alternative crop to Greek farmers growing certain oriental tobacco varieties. Diffusion of flue-cured tobacco was rapid due to its high yields and the depressed market for certain oriental tobacco varieties. Currently, the common organisation of the tobacco market is undergoing substantial changes, and the farmers' response will be a vital factor of success. A portfolio selection model reveals that the major factors influencing the adoption decision of tobacco growers are the size of the farm measured in annual work units, the farm's proximity to urban centres, the farm's diversification and the farmer's age. The number of contacts with institutions is, surprisingly, inversely related to adoption. Future tobacco policies impinging on factors influencing decisions to adopt new varieties or production practices may be more cost-effective.     

Adoption and Ex-post Impacts of Improved Cowpea Varieties on Productivity and Net Returns in Nigeria

Cowpea covers the largest area of any grain legume in Africa and is especially important in West Africa where Nigeria and Niger alone account for over 75% of the total cowpea production in the world. Despite successes of international and national cowpea improvement research in the development and release of several improved varieties, there is limited empirical evidence of adoption and ex-post impacts of improved cowpea. Using a nationally representative survey data from a sample of 1,525 cowpea-growing households in northern Nigeria cultivating over 2,500 cowpea plots, we assess the adoption and impacts of improved cowpea varieties on cowpea yields, net returns and production costs. We apply a control function approach and propensity score matching models to estimate the causal effects of adoption of improved cowpea varieties . Our results show that 38% of the cowpea plots were planted with improved varieties, and cowpea yields, net returns and production costs increase significantly with the adoption of improved cowpea varieties. Adoption of improved cowpea varieties is associated on average with 26% yield gains, 61% increase in net returns and 14% increase in production costs. We also show that farmers who have a lower propensity to adopt improved cowpea varieties also face higher costs of production.     

Adoption and Impacts of Sustainable Agricultural Practices on Maize Yields and Incomes: Evidence from Rural Zambia

This paper uses a multinomial endogenous treatment effects model and data from a sample of over 800 households and 3,000 plots to assess the determinants and impacts of adoption of sustainable agricultural practices (SAPs) on maize yields and household incomes in rural Zambia. Results show that adoption decisions are driven by household and plot level characteristics and that the adoption of a combination of SAPs raises both maize yields and incomes of smallholder farmers. Adoption of improved maize alone has greater impacts on maize yields, but given the high cost of inorganic fertiliser that limits the profitability of adoption of improved maize, greater household incomes are associated rather with a package involving SAPs such as maize–legume rotation and residue retention.     

A Question of Integrity: Variants of Bt Cotton,Pesticides and Productivity in Pakistan

Bt cotton remains one of the most widely grown biotech crops among smallholder farmers in lower income countries, and numerous studies attest to its advantages. However, the effectiveness of Bt toxin, which depends on many technical constraints, is heterogeneous. In Pakistan, the diffusion of Bt cotton occurred despite a weak regulatory system and without seed quality control; whether or not many varieties sold as Bt are in fact Bt is also questionable. We utilise nationally representative sample data to test the effects of Bt cotton use on productivity. Unlike previous studies, we invoke several indicators of Bt identity: variety name, official approval status, farmer belief, laboratory tests of Bt presence in plant tissue, and biophysical assays measuring Bt effectiveness. Only farmer belief affects cotton productivity in the standard production model, which does not treat Bt appropriately as damage‐abating. In the damage control framework, all Bt indicators reduce damage from pests. Biophysical indicators have the largest effect and official approval has the weakest. Findings have implications for impact measurement. For policy‐makers, they suggest the need, on ethical and productivity grounds, to improve variety information and monitor variety integrity closer to point of sale.     

中国棉花国际贸易对国际市场棉花价格影响的实证分析——对中国棉花“贱卖贵买”现象的质疑

本文运用葛兰杰因果关系检验法对中国棉花国际贸易对国际市场棉花价格的影响进行了实证分析。分析表明，在棉花进口方面，中国呈现出典型的“大国贸易”模式，而在棉花出口方面，中国却呈现出“小国贸易”模式，此结论纠正了以往人们通常认为的中国棉花国际贸易存在“贱卖贵买”特征的观点和认识。     

人格特质对茶农有机茶技术采纳的影响

根据福建省安溪县656份的问卷调查数据,基于大五人格特质理论,运用结构方程模型分析人格特质对茶农的有机茶技术采纳行为的影响。结果表明:安溪县茶农的经营特征与其所处的技术环境对有机茶技术采纳行为不存在显著直接效应,但都通过技术采纳态度对技术采纳的行为产生正向影响作用,其中有机茶技术采纳态度起完全中介作用;人格特质对有机茶技术采纳行为既存在直接正向预测作用,又通过有机茶技术采纳态度对技术采纳行为产生间接正向预测作用,并且间接效应大于直接效应,起中介变量的作用。因此,运用人格测评工具来发挥技术采纳者的性格优势在技术采纳过程中的作用,释放有机茶技术的生态溢出效应,将为有机茶技术推广研究提供新思路。     

Genetically Modified Crops, Corporate Pricing Strategies, and Farmers' Adoption: The Case of Bt Cotton in Argentina

This article analyzes adoption and impacts of Bt cotton in Argentina against the background of monopoly pricing. Based on survey data, it is shown that the technology significantly reduces insecticide applications and increases yields; however, these advantages are curbed by the high price charged for genetically modified seeds. Using the contingent valuation method, it is shown that farmers' average willingness to pay is less than half the actual technology price. A lower price would not only increase benefits for growers, but could also multiply company profits, thus, resulting in a Pareto improvement. Implications of the sub-optimal pricing strategy are discussed.