数字农业的福利效应——基于价值再创造与再分配视角的解构

在数字经济时代，传统农业不断向数字农业转型升级，对农业整体的价值创造及各主体间的福利分配产生了重要影响。本文基于已有文献，结合数字农业发展的客观实践，重新梳理了数字农业的定义及特征，在此基础上对数字农业的价值再创造和价值再分配两个过程进行全面剖析。本文发现数字农业通过生产环节、流通环节和销售环节的数字化实现了经济、生态和文化价值的再创造，并通过“农户—市场中介”“市场中介—消费者”“生产性服务商—农户”三个环节商流、资金流的重塑实现了价值再分配。进一步地，本文基于可行能力理论框架对上述过程中的福利效应进行了详细解构，认为数字农业从功能和能力两个维度促进了农户、消费者乃至整个社会福利水平的提升。本文研究结论对于政府出台数字农业相关政策措施，持续激发农业发展潜力具有重要的参考意义。     

水稻种植大户与农业科技溢出效应研究——基于江西省微观调查数据

文章基于经营大户农业科技溢出效应的理论分析与江西省吉安市301户水稻种植户的微观调查数据,将农业大户的科技溢出效应分为雇佣导致的直接效应与模仿生产行为导致的间接效应。通过计量工具探讨影响水稻种植大户农业科技溢出效应的关键影响因素。研究结果表明:大户雇佣经历与村大户雇佣人数影响显著为正,经营大户的农业科技直接溢出效应明显;村大户种植面积、村大户为农业技术指导员及参加农业技术宣传会影响不显著,经营大户的农业科技间接溢出效应不明显。建议政府通过补贴等财税措施进一步鼓励经营大户雇佣当地居民,强化农业科技直接溢出效应;政府通过改变村技术指导员任命方式与提高其经济补贴改善技术指导效果,通过实施经济激励与改变宣传模式强化技术宣传效果,从而激发农业科技间接溢出效应。     

美国农业支持政策效应评估

本文主要运用OECD组织开发的政策矩阵评估模型对美国不同的农业支持政策效应进行定量刻化 ,以确定不同农业支持政策对于生产、消费、贸易、农民收入和经济福利等产生不同的政策效应。对美国小麦不同的政策措施的分析结果表明 ,不同的农业支持政策产生明显不同的政策效应。市场价格支持对产量的增加有比较显著的促进作用 ,而地区支付对农场主的收入有明显的促进作用。从经济影响看 ,市场价格支持对生产、价格、贸易影响比较大 ,产生了较大的价格扭曲 ,引起社会福利损失。而地区支付则相反。比较而言 ,地区支付有更多的收入效应和更小的贸易扭曲效应 ,而市场价格支持有更明显的增产效应和更大的贸易扭曲效应。     

农业投资中政府制度因素效应分析--以山东农业投资为例

本文以农业大省山东农业投资为例，分析了农业投资中，政府制度安排的以“调控效应”和“拓展效应”为基础的“综合制度效应”对农业产出的影响，并得到如下结论：农业投资中的政府制度的综合效应与农业产出呈正相关关系，而总量意义上的农业投资对农业产出并没有绝对的正的影响。因此，各级政府不仅要重视稳定的增加农业投资总额，还要重视通过政府制度安排优化投资结构，充分发挥农业投资中的政府制度因素效应的作用。     

农业外部效应内部化及其路径选择

本文探讨了农业外部经济和农业外部不经济的内部化路径。以农业边际价值和农业外部边际效应为分析指标，分析了外部经济和外部不经济给社会带来的福利和收益的影响。在对农业外部不经济内部化采用征税、协商交易和处罚的手段以外，对农业外部经济也应该进行补偿，使其内部化。尤其是我国的大多数农业经营者还不处于农业经营边际价值递减的阶段，站在一个公正的立场上对待农业的外部效应才能真正使农业外部效应内部化。     

欧美农业支持政策的资本化效应及其启示

欧美国家农业支持政策影响土地租赁价格的资本化效应问题得到了学术界的广泛关注,但鲜有研究涉及发展中国家的农业政策和土地交易市场。对此,本文从理论和实证研究两个维度对欧美国家农业支持政策(包括价格支持和农业补贴)如何影响土地租赁价格进行了文献梳理。研究结果表明:(1)价格支持政策在理论上对土地租赁价格具有正向作用,但实证结果却表明,价格支持政策并不显著影响土地租赁价格。(2)农业补贴在理论上较大程度甚至完全资本化为土地租赁价格,但实证结果却表明,农业补贴的资本化效应在理论预测与经验估计之间存在显著差异。农业补贴的资本化效应不仅在国家或地区之间存在较大差异,而且经验估计值普遍小于理论预期值。(3)在信贷受到约束、农业经营规模较大、土地租约期限较长、采用分成制合约等情境下,农业补贴的资本化程度具有明显的异质性。(4)挂钩补贴转变为脱钩补贴是否强化了资本化效应,在理论与实证研究中出现了完全对立的结论。(5)理论与实证分析一致地表明,农业补贴比价格支持政策具有更高的资本化效应。最后,本文对中国农业支持政策资本化效应问题的未来研究进行了展望。     

非农就业与农户土地利用行为实证分析:配置效应、兼业效应与投资效应——基于2005年江西省农户调研数据

非农就业对农业生产的影响是多方面的,本文将其区分为配置效应、兼业效应、投资效应并分别对其进行了计量检验。研究表明,非农就业显著促进了土地流转,改变了农户的投资结构,特别是增加了雇佣劳动和机械对自家劳动投入的替代,但没有明显提高总土地投入水平,影响土地投入水平的主要因素是土地的经济收益而不是投资能力;促进劳动力转移的政策对农业生产不会产生明显的消极影响,但要释放劳动力转移的土地经营规模化、专业化效应并将非农就业带来的投资能力转变为现实投资,必须在加快劳动力转移的同时配合农产品市场化、农业新技术供给等发展农业的政策。     

农地规模化对农业科研生产率效应的影响研究

文章以农地流转为研究视角,基于中国1988~2012年31个省域面板数据,综合运用固定效应模型与动态门限回归模型,检验农业科技投入对农业生产效率的驱动作用。固定效应模型的分析结果表明,科技投入对农业生产效率提升的效果,受到农地规模的制约;随后的动态面板门限模型显示,以户均农地规模表示的农地流转值存在两个显著的门限。当户均农地规模低于第一个门限值时,科技投入对农业生产效率的影响微弱。随着农地流转的推进,科技促农的效果逐步增强。但当农地面积跨越第二个门限,科技促农系数又降低。因此,在中国农业科技投入有限的常态约束下,应以农地流转政策为契机,协调好农地流转与科技投入的关系而非一味加大科技投入,优化农业科研的区域空间布局,增强科技对中国农业的驱动作用。同时也应采取措施避免农地流转过快带来的负面效应。     

关于当前我国农业科技投入若干问题的思考

加大农业科技投入，提高我国农产品国际市场竞争力，是农业应对入世挑战的重要选择。本文首先在理解农业科技投入含义的基础上，分析了我国农业科技投入的现状和存在问题；接着进行农业科技投资的福利分析，提出农业科技投入的变动对社会福利的变动会造成极大影响；然后对农业科技投入作国际比较，明确我国目前在世界范围内的地位；最后在WTO“绿箱政策”的背景下提出如何进一步加大农业科技投入．更好地适应国际环境。     

农业经济增长与农业环境污染——基于空间效应的分析

本文基于2005～2017年的省际面板数据,运用空间杜宾模型(SDM)分析了农业经济增长对农业环境污染的影响及空间溢出效应。研究结论有:一是农业经济增长因产出规模的扩大,对农业环境污染产生非线性影响,该影响与污染物要素投入指标的选取而异;二是农业机械化水平同污染性要素投入指标正相关,产业结构同污染指标负相关;三是农业经济增长对污染性要素投入具有空间溢出效应,化肥流失量的空间溢出弹性是直接效应弹性的6.46倍,农药流失量的空间溢出弹性同直接效应几乎相当,塑料薄膜残留量的空间溢出弹性仅为直接效应弹性的0.498;四是农业产业内部结构、农业机械化水平具有一定的"外溢"效应,这可能是导致其对农业环境污染产生影响的重要原因。本文的政策意涵:构建更为科学有效的农业环境污染监测指标体系,提高农业环境污染防治方面的技术水平,构建区域农业环境治理的联合机制,开展区域间的诸如品种研发、技术开发、农业机械服务外包等农业生产性服务业,促进地区间的技术共享、新型农业服务经营主体形成和农业产业的规模化经营,提高地区的产业化水平。     

Competition Effects of Supermarket Services

This article investigates the competition effects of supermarket services using fluid milk as a case study. A simultaneous equation model for services and price competition is estimated with scanner data from fifteen supermarket chains using two alternative measures of services, namely store size and principal components of in-store services. Empirical results show that increasing services results in economies of scope, greater supermarket chain-level demand, lower price elasticity of demand, and enhanced market power, leading to higher milk prices and quantity sold. We conclude that, as result of service competition, supermarkets differentiate themselves from competitors and successfully attract less price-sensitive consumers.     

Welfare Effects of Food Safety Recalls

Estimates of the welfare losses associated with food recalls typically assume the announcement causes demand to shift, or the willingness‐to‐pay (WTP) falls for all quantity levels. Several researchers, however, have observed evidence of a rotation as well, where WTP rises for some consumers and falls for others. Preference heterogeneity theory implies that this observation results from an increase in the dispersion of demand. We test this theory using Centers for Disease Control and Prevention announcement data and Nielsen Homescan panel data for the fresh produce category. We find that the rotation effect cannot be disregarded, but is still dominated in welfare calculations by the shift effect of a recall announcement.     

Economic Effects of Mitigating Apple Maggot Spread

Apple maggot is an economically important apple pest that is native to the East Coast of North America, including Canada and the United States. Introduced to the West Coast of the United States in 1979, the pest is spreading rapidly in the region, threatening the major apple production area of Washington State, as well as British Columbia. A dynamic simulation model for perennial fruit production is developed to study the potential economic impact of a pest species, such as apple maggot. The model is designed to provide essential information, including the intertemporal distribution of welfare, to aid the design of effective and efficient policy response to pest outbreaks. This model is used to simulate the economic impact of apple maggot spread in Washington State on apple price, trade flows, and welfare changes. La mouche de la pomme est un ravageur originaire de la côte Est de l'Amérique du Nord (canadienne et étatsunienne) qui cause des pertes économiques considérables. Ce ravageur, qui s'est introduit sur la côte Ouest des États‐Unis en 1979, se propage rapidement et menace les principales zones de production de pomme de l'État de Washington et de la Colombie‐Britannique. Nous avons élaboré un modèle de simulation dynamique pour la production pluriannuelle de fruits afin d'étudier l'incidence économique potentielle d'espèces ravageuses telles que la mouche de la pomme. Le modèle a été conçu pour fournir de l'information essentielle, dont la distribution du bien‐être intertemporel, en vue de contribuer à l'élaboration d'une réaction politique efficace de lutte contre les pullulations de ravageurs. Ce modèle est utilisé pour simuler l'incidence économique de la propagation de la mouche de la pomme dans l'État de Washington sur le prix des pommes, le flux des échanges commerciaux et les changements touchant le bien‐être.     

Effects of subsidies in Russian dairy farming

This study develops a microeconometric model of specialized dairy farms in the Moscow region using panel data over the period 1995–2001. The model is used to analyze the role of subsidies on profit as well as input and output allocation. Theoretical conditions for short‐term profit maximization are not rejected by the data. Differences between farms allow for a fixed‐effect specification. The dairy producers in the region demonstrate a low responsiveness to market signals, but technology change becomes important. Labor, land, and livestock had low shadow prices. Although subsidies have a distorting effect on the input–output mix, this study shows they relieve the credit constraints on dairy farms and have an important positive influence on farm profit.     

The Effects of Pricing Canadian Livestock Emissions

I examine the environmental and economic effects of pricing greenhouse gas emissions from livestock in Canada. Using a partial equilibrium model, I consider three different pricing policies: a consumer level tax, a producer level tax, and a producer subsidy. All policies price emissions at $50 per tonne of carbon dioxide equivalent. The producer level tax generates the greatest reduction in emissions at the lowest social cost per unit of emissions abatement. The producer subsidy results in a smaller reduction in emissions at a higher social cost, relative to the producer tax. However, the subsidy provides a substantial increase in producer surplus, which may make it a politically feasible second‐best policy. The consumer level tax results in a trivial reduction in emissions, at a social cost that is greater than the price placed on emissions. J'examine les effets environnementaux et économiques de l'imposition d'un prix sur les gaz à effets de serre provenant des animaux d'élevage canadiens. Au moyen d'un modèle d'équilibre partiel, je tiens compte de trois différentes politiques d'imposition de prix : taxer le consommateur, taxer le producteur, et subventionner le producteur. Toutes les politiques imposent les émissions au prix de 50$ par tonne en équivalent de dioxyde de carbone. Taxer l'éleveur génère la plus grande réduction des émissions au plus bas coût social par unité de réduction des émissions. Subventionner l'éleveur entraéne une plus petite réduction des émissions à coût social plus élevé, en comparaison û la taxe imposée à l'éleveur. Par contre, le choix de subventionner fournit une augmentation substantielle de surplus pour l'éleveur, faisant de cette option un bon deuxième choix envisageable au niveau politique. Taxer le consommateur ne produit qu'une réduction négligeable des émissions, à coût social plus élevé que le taux imposé sur les émissions.     

Effects of supermarket monopsony pricing on agriculture

Potential effects of alleged monopsony pricing of farm food products by supermarkets on farm product prices, quantities, incomes and land values are assessed relative to competitive behaviour. A long‐run comparative static equilibrium model is used. For export‐competing and import‐competing products, the farm food input supply curve facing the supermarkets is close to perfectly elastic and this limits monopsony behaviour. At the margin, the opportunity to reallocate agricultural land between traded and nontraded farm products means a highly elastic supply function for nontraded food inputs facing supermarkets and very limited monopsony effects.     

Slippage Effects of the Conservation Reserve Program

Each year, billions of dollars of public funds are expended to purchase conservation easements on farmland. One unintended impact of these programs is that they may bring non-cropland into crop production. Such a slippage effect can be caused by increased output prices and by substitution effects. This article shows that for each one hundred acres of cropland retired under the Conservation Reserve Program (CRP) in the central United States, twenty acres of non-cropland were converted to cropland, offsetting 9 and 14% of CRP water and wind erosion reduction benefits, respectively. Implications of these results for the design of conservation programs are discussed.     

植物甾醇清除自由基活性研究

目的:探讨植物甾醇体外清除自由基活性。方法:采用羟基自由基体系、超氧阴离子自由基体系、DPPH体系对植物甾醇的体外抗氧化活性进行研究,并同二丁基羟基甲苯(BHT)和VC进行比较。结果:在试验质量浓度范围内,植物甾醇对羟自由基、超氧阴离子自由基的清除率为53.95%、68.60%,但没有清除DPPH自由基的能力,且其抗氧化活性小于VC和BHT。结论:植物甾醇具有一定的体外抗氧化能力,是一种天然安全有效的自由基清除剂。     

Effects of subsidized crop insurance on crop choices

This study focuses on how subsidized crop insurance affects crop choices. Crop insurance may change farm investments by reducing risks and providing subsidies. First, actuarially fair insurance reduces risks in crop production and marketing, holding the expected return constant. Second, insurance subsidies encourage farms to purchase crop insurance, which increases the expected return to insured risky crops. Farms also have many self‐insurance mechanisms such as crop diversification or working off the farm. We derive conditions under which (1) unsubsidized and actuarially fair crop insurance or (2) insurance premium subsidies lead to more investment in a risky higher return crop. We then examine the role of self‐insurance for these conditions. The impact of premium subsidies is decomposed into a direct profit effect and an indirect coverage effect. These effects are explained by substitutions between market insurance and self‐insurance and between a risky crop and a safe crop. We discuss each effect as a combination of subsidy and risk effects. Numerical illustrations show that an insurance subsidy has a larger impact on risky crop investments compared to that of an input subsidy when farms are more risk‐averse and have high costs of self‐insurance. The framework provides a novel way to evaluate subsidized crop insurance programs.