国内外关于农机需求的理论与实证研究综述

本文从理论和实证研究两个角度回顾了国内外关于农机需求研究的重点文献，归纳了宏观和微观农机需求研究的共同理论基础，探讨了国内外对农机需求研究的进展，最后指出：农机需求的微观研究是目前国内农机需求研究的空白领域和值得进一步研究的、具有理论创新意义的发展方向。     

Ambient Taxes Under m-Dimensional Choice Sets, Heterogeneous Expectations, and Risk-Aversion

We consider the design of ambient taxes forrisk-neutral and risk-averse polluters whenpolluters and the regulatory agency haveasymmetric information about environmentalrelationships and probabilities associatedwith random events. Unlike prior work, we showthat under these conditions, optimal ambienttaxes must be firm-specific, and accompaniedby additional incentives to influencepolluters' choices of abatement techniques.     

领导干部在农业结构调整中应强化十种意识

新阶段的农业结构调整,必须适应变化了的新形势.为此,要进一步深化对农业结构调整的认识,牢固树立大农业意识、市场意识、规则意识、品牌意识、科技意识、信息意识、产业意识、工业意识、城镇意识和服务意识.     

辽宁东部水源涵养林计量指标体系及其效益评估

对辽东山区水源涵养林产生的各种效益进行计量评价研究,制定了水源涵养林计量效益评价指标体系,包括3级结构、16项指标、49项因子;依各功能因子的重要性并经测算,对各项指标赋予权重和排序,森林的蓄水、减少径流、改善水质功能的权重值较高;采用条件价值法,估算辽东山区水源涵养林的各种功能价值,森林的林副产品和木材收益的功能价值较高。辽东山区水源涵养林按整体处在一般经营状态下计算,年均创造功能价值约为30.2亿元。     

Domestic Support and Border Measures for Processed Horticultural Products

In horticultural markets, trade barriers often apply to the processed products whereas domestic support applies to farm-produced raw commodities. Here we assess the effects of such trade barriers and domestic support by simulating the effects of policy reform on global processing tomato markets, which are faced with modest processed product tariffs and high domestic support in the European Union (EU). Both protection and EU subsidy drive down world welfare, but we find that reducing import tariffs for tomato products would yield greater effects on markets and larger welfare impacts outside Europe than would reductions in EU domestic support.     

基于引力模型的中美农产品贸易边境效应研究

针对中美两国在农产品贸易上的新变化,应用引力模型的派生模型——边境效应引力模型对中美两国农产品贸易的流量和流向进行理论和实证研究。首先介绍了边境效应引力模型基本模型的推导过程,并引入了调整模型。然后采用1987至2005年其中5年的截面数据进行计算,结果发现:中美农产品贸易的边境效应显著存在,且呈逐年下降趋势;两国之间的农产品贸易边境效应存在流向和区域上的差异;距离的平方并不影响模型的可靠性。     

农村合作运动与农业技术的植入——以民国时期江苏省为例(1927-1937)

农村合作运动是国民政府为发展农业生产、复兴农村经济、改善农民生活而实施的有关社会经济建设的行动。农村合作运动中组建的各种合作社,在改良品种、改进耕作技术、推广农业知识等方面发挥了重要的作用,扮演了引进和扩散现代农业生产要素的角色,丰富了作物的品种,提高了农业生产的效率,增加了农民收入。     

Prevention versus Treatment under Precautionary Regulation: A Case Study of Groundwater Contamination under Uncertainty

Policy discussions on agricultural pollution problems characterize prevention as more cost effective and precautionary than ex post treatment. We derive conditions under which treatment alone is more cost effective in situations involving multiple sources of emissions, multiple sites affected, and a commonly used precautionary approach to uncertainty. We also show that a greater degree of precaution can result in less reliance on prevention. An empirical case study indicates that treatment alone is the most cost-effective means of dealing with nitrate in most Maryland community water system wells. The use of leaching prevention measures is restricted to the most intensive poultry producing areas. The incremental cost of precaution is substantial.     

Stop and Go Agricultural Policies with a Land Market

This article studies the design of farm policy in the presence of asymmetric information about farmers' productivity, a government objective to insure farmers a minimum "parity" income, an endogenous land rent, and diminishing returns on alternative (nonprogram crop) land uses. In this setting, acreage set asides are never part of an optimal farm policy, although compensated acreage limits are. When there are new farmer entrants who cannot be excluded from farm programs, optimal policy takes the form of a pure voluntary acreage limitation—or "buyout"—program in which high-cost producers participate and low-cost producers do not.     

Estimating Willingness to Pay for Improved Water Quality in the Presence of Item Nonresponse Bias

This article deals with the problem of item nonresponse in contingent valuation surveys using a payment-card method, by applying a grouped-data sample-selection estimation technique that is capable of imputing the missing values conditional upon a respondent's decision to answer a willingness-to-pay question. The advantage of the technique lies in its ability to utilize all of the information in the sample, permitting a more efficient estimation in the presence of item nonresponse bias. The major determinants of willingness to pay appear to be household income, number of children, education, perception of existing water quality, and identification with environmental issues.