学术前沿 | 一文了解农业、环境政策领域的研究问题
启研学社由知名学者担任学术顾问，高校师生与企研数据科学团队联合组建，以大数据资源及相关技术助力中国学术与智库研究为宗旨的研究组织。团队当前的主要目标是挖掘经济社会大数据资源在学术和智库领域的应用价值，开展学术大数据治理研究，以及探索大数据分析技术融入中国经济社会研究的可行进路。
The Economics of Agricultural and Resource Policies
The Economics of Agricultural and Resource Policies Early agricultural economists like Galbraith and Black (1938) studied the basic properties of agricultural markets. These economists realized that farmers face inelastic demand and that overall agricultural supply is also inelastic. Therefore, small shifts in supply and demand (e.g., drought, especially good climate, change in income) may drastically affect agricultural prices, which then become unstable. Several major scholars continued their work and established basic characteristics of agricultural markets that help explain some of the causes for agricultural crises and provide a guide for agricultural policies. The writings of Schultz (1964), Johnson (1960), Tweeten (1970) and others suggest that inelastic demand and supply, high rates of technological change, low malleability of agricultural labor and capital (asset fixity), and vulnerability to economic and natural shocks resulted in the “farm problem,” with a high degree of price and income instability as well as rural poverty. Like in macroeconomics, these patterns of behavior led to calls for different types of market intervention.Agricultural policies were designed to address several problems, for example the stabilization of prices and food availability. Such topics have probably haunted policymakers since the days of Biblical Joseph and require effective design of inventory. Gustafson (1958) develops a pioneering dynamic framework for optimizing grain management. This led to an important line of research, which focused on efficient and equitable decision rules for inventory management and the allocation of effort between the public and private sectors (Williams and Wright 2005). This research inspired government and international inventory programs around the world and in many cases were quite critical of existing programs and suggested improvements.
Another policy challenge was addressing low farm incomes. In the United States and developed countries, governments tried various policies such as price and income support and deficiency payments (see Houck and Ryan 1972; Gardner 1992; Rausser 1992). Government policies have their limitations, however, and one role of agricultural economists was to assess and suggest possible improvements. Economists realized that each of these policies had an element of slippage, namely they intended to reduce supply, but miscalculated farmers’ behavior and resulted in large surpluses and significant government expenditure. Agricultural economists have developed the concept of decoupled policies that would enhance farmers’ well-being without affecting supply, but the search for such policies continues. While policies in developed countries tend to subsidize the farm sector and have resulted in surpluses, in developing countries agricultural policies have tended to tax the farm sector and thus resulted in under-supply. Schultz (1964) and others recommended to reduce or eliminate taxation of farmers in developing countries, and rather provide technical support to enhance productivity, and thus improve food security. The general prescription of economists is to reduce price distortions by eliminating subsidies as well as the taxation of agricultural products.
A third policy challenge is to develop mechanisms that address price and yield risks faced by farmers. Besides inventory management, agricultural economists have analyzed the implications and gains from the use of futures markets, as well as insurance programs. These may include crop insurance, disaster assistance, price insurance, and revenue assurance as well as weather-based insurance. While research finds fault with most government insurance programs in terms of efficiency and environmental considerations (Smith and Goodwin 2013), we are still challenged to design alternative programs that remain solvent and efficient. Tariffs, as well as non-price trade regulations, were other means through which the government intervened in agriculture. There is a large body of literature on agricultural trade and its impacts (Anderson and Martin 2005). This research suggests that there are global welfare losses from barriers to trade, and much of the loss is accrued by developing countries that were blocked from exporting their products to developed countries. Furthermore, governments developed policies to stabilize their own agricultural prices without recognizing the impact of other countries; the net effect was enhanced instabilities. Economists like D. Gale Johnson (1975) suggest that trade liberalization and market power through inventories would lead to more stable and efficient pricing. But governments didn’t necessarily follow the advice of agricultural economists and pursued policies that didn’t seem to improve economic welfare, which led to another body of literature on political economy in agriculture: the study of the impact of interest groups in agriculture (Rausser, Swinnen, and Zusman 2011).
Nevertheless, over the years there have been change and progress. The late, great Bruce Gardner found that over time, as farms grew in size, the lag in farm income compared to urban sectors declined, and some of the rationale for supporting agricultural income was reduced. International trade and political economy considerations were driving forces behind the transitions in agricultural policies in the last part of the twentieth century. Anderson, Rausser, and Swinnen (2013) find that international trade agreements, including the World Trade Organization (WTO), reduced trade distortions associated with agricultural prices both in developed and developing countries, and prices reflected better basic demand and supply forces with less intervention.
While early research on agricultural policy emphasized agricultural markets, agricultural economists have realized that agriculture has interesting feedback relationships from the rest of the economy, and that it is dependent on macroeconomic forces. Schuh (1974) emphasizes that U.S. farmers suffered when the dollar was overvalued and this spawned a body of literature that suggests that agricultural sectors around the world are more affected by overall macro-level policies than by specific agricultural policies. D. Gale Johnson (1991) emphasizes the important role of discount rates and exchange rates on the agricultural sector, and that instability in the general economy was affecting agriculture and vice versa.
A growing emphasis of agricultural policy research has been on economies in transition. Johnson and others provided realistic assessments of the inefficiencies and challenges of the agricultural sector in Eastern Europe and China in the 1960s and 1970s and suggested strategies for reform. Swinnen (1999) develops an analysis based on principles of political economy to explain the patterns of land and agrarian reform in Eastern Europe, showing the important roles of path dependency, ethnicity considerations, and overall macroeconomic conditions, and assessing the efficiency losses and distributional impacts of these reforms. Rozelle and Swinnen (2004) analyze the relationship between reform transition strategies and economic performance in agriculture in China and Eastern Europe. These authors suggest that agricultural policy reforms consist of changes in prices and reductions in subsidies that might reduce supply during periods of transition. Other important components are land reforms and restructuring of the farm sector and institutions that serve it. They find that reforms that reduce transaction costs and prevent obstacles to trade tend to increase productivity and overall production. Reduction of subsidies may result in a short-term reduction in supply. Reardon and Timmer (2012) review a large body of literature on the transformation of food systems globally, including the diffusion of supermarkets and advanced processing technologies in developing countries. Once technology and financial resources are available and barriers to trade are limited, value chains evolve to modernize food systems around the world. The pace of this ongoing transformation is rapid and its implications are subjects for future research. Because agricultural economists have to address major practical policy problems and assess their impacts on different groups, they have often been pioneers in the application of tools like benefit-cost analysis and, in particular, applied surplus analysis (Just, Hueth, and Schmitz 2008). With the advent of faster computers, agricultural economists have developed computer-based general equilibrium models that analyze the impact of agricultural policies as well as other related policies on the overall economy. With databases like the Global Trade Analysis Project (GTAP) and an increasing number of general equilibrium models—some of them including dynamic features— quantitative agricultural policy analysis can assess the impact of agricultural policies on various sectors of the economy as well as globally (Hertel et al. 2007). Furthermore, understanding these linkages has expanded our understanding of the distributional impact of agricultural policies beyond their impact on certain groups, to include impact on income distribution and issues like poverty and welfare. For example, Hertel et al. (2007) study the distributional impacts of policy reform like the one proposed during the Doha Round. These authors find that the status quo at the beginning of the millennium negatively affected farmers and consumers in developing countries. Adoption of the policies that were part of the Doha Round would only slightly benefit consumers and farmers in developing countries, whereas full liberalization would be very beneficial for developing countries but harm the wealthiest farmers in the United States. The tools of agricultural policy analysis were very useful in the analysis of the economic transition in Eastern Europe and China. The dustbowl and concerns about food safety and pesticide contamination led to government intervention to improve food safety, and to reduce agricultural externalities. This then led to growing emphasis on resource and environmental issues; agricultural economists have been major contributors to the literature on environmental and resource economics (Kling, Segerson, and Shogren 2010; Lichtenberg et al. 2010). Several major research themes have emerged throughout this literature. First is the importance of using cost-benefit analysis to assess large investments in natural resources. Despite political pressure, agricultural economists such as Bill Martin have warned against the inefficiency of large water projects, such as the Central Arizona Project (Bush and Martin 1986). Indeed, these efforts resulted in the introduction of benefit-cost analysis as an important element in project evaluation in the United States, and around the world. Second is to provide producers with the right incentives that take into account the cost of externalities as well as the dynamic cost of resource allocation. For example, pesticides should be regulated so that the effective price facing farmers takes into account environmental costs as well as the cost of resistance (Waterfield and Zilberman 2012). Another important theme is to develop mechanisms for trading rather than allocating resources through direct control. For example, studies have shown that there are substantial gains to be realized from moving to a water trading system (Schoengold and Zilberman 2007). A fourth theme is developing market-like mechanisms to manage and provide environmental amenities. One example is the development of payment for ecosystem services. Indeed, one of the major contributions of the agricultural economics profession is the research that led to the creation of the Conservation Reserve Program in the United States (Babcock et al 1997). Land use and rural development have been crucial elements of agricultural economics. Johann Von Thu¨ nen was an agricultural economist before agricultural economics existed, and he is the father of economic demography (Von Thu¨ nen 2009). His theory of land allocation and valuation over space has been a starting point for the field of rural and regional planning. Research in this area investigated farm real estate pricing, rural pricing and social capital, and the value of rural amenities (Castle 1998). With the availability of geospatial data, agricultural economists contributed to the development of advanced spatial econometric techniques to assess the evolution of land use patterns and its economic and ecological implications (Irwin et al. 2009).
One of the most important contributions of agricultural economics research to our understanding of natural resource issues stems from its multi-disciplinary approach. Applied economics has become an integrating discipline combining data from biology, agronomy, and public health to assess various policies—be it deciding the re-entry period after a field has been sprayed or determining water quality management strategies. The development of agricultural biotechnology has led to a new set of policy questions and opened a new area of economics research. Here the concerns were about intellectual property and ensuring mechanisms to avail the technology to orphan crops and crops of the poor, issues of regulations, as well as issues of labeling (Barrows, Sexton, and Zilberman 2014). While the technology has shown significant economic benefit (Klu¨mper and Qaim 2014), it has been completely or partially banned in many regions of the world, and agricultural economists have developed models of political economy (Herring and Paarlberg 2016) as well as consumer perception to understand this reality (Lusk, Roosen, and Bieberstein 2014).
Another recent area of research lies in the economics of biofuels. As concerns of greenhouse gas emissions and energy supply led to the production of agricultural-based fuels, agricultural economists recognized some of the trade-offs between food and fuels, assessed the winners and losers of policies, and assessed the direct and indirect effect of biofuels on emissions. This is an area where some of the most advanced machinery of agricultural economics has been very effective. For example, Khanna (see Khanna, Swinton, and Messer 2018) has been using GIS data to assess where and when different types of biofuels will be used under different policy scenarios. Moreover, agricultural economists have contributed significantly to research on climate change and its policies. For example, Schlenker and Roberts (2009) develop creative econometric methods to assess the impact of climate change on agricultural yields. McCarl and Schneider (2001) use programming techniques to assess the potential for mitigation of climate change by agriculture. There is a growing body of literature on adaptation to climate change in developed and developing countries (Lipper et al. 2017). The literature has found that the major challenges of climate change are developing mechanisms to: (a) address the challenges of relocation and migration due to climate change; (ii) develop innovations that will allow for accelerated adaptation to changes; and (iii) provide adequate infrastructure that will allow adequate maintenance of supply chains.
农业与资源政策经济学
早期农业经济学家Galbraith and Black（1938）研究了农业市场的基本特征。这些经济学家意识到，农民面临着缺乏弹性的需求，同时整个农业供给也缺乏弹性。因此，供求的微小变化（例如干旱，特别是良好的气候，收入的变化）可能会严重影响农产品价格，从而使农产品价格变得不稳定。几位主要学者继续了他们的工作，并确立了农业市场的基本特征，这些特征有助于解释农业危机的一些原因，并为农业政策提供指导。Schultz（1964），Johnson（1960），Tweeten（1970）等人的研究表明，需求和供给缺乏弹性，技术变化率高，农业劳动力和资本的可延展性低（资产固定性）以及对经济和自然的脆弱性 冲击导致了“农业问题”——价格和收入的高度不稳定以及农村贫困。就像在宏观经济学中一样，这些行为模式导致了对不同类型市场进行干预的呼吁。
农业政策旨在解决几个问题，例如稳定价格和粮食供应。自从《圣经》约瑟夫时代以来，这些话题就困扰着政策制定者，需要制定出有效的库存设计。Gustafson（1958）开发了一种开创性的动态框架来优化粮食管理，这导致了一个重要的研究领域，该研究领域聚焦有效和公平的库存管理决策规则以及公共部门和私营部门之间的工作分配（Williams and Wright， 2005）。这项研究启发了世界各地的政府和国际库存方案，并在许多情况下对现有方案提出了批评和改进建议。
另一个政策挑战是解决农业收入低下的问题。在美国和一些发达国家，政府尝试了各种政策，例如价格和收入支持政策以及差额支付（见Houck and Ryan,1972; Gardner,1992; Rausser 1992）。政府政策有其局限性，但是，农业经济学家的作用之一是评估并提出可能的改进建议。经济学家意识到，这些政策中的每一项都会有失误的要素，即它们旨在减少供应，但对农民的行为进行了错误的计算，导致大量过剩和大量政府支出。农业经济学家提出了脱钩政策的概念，这种政策可以在不影响供应的情况下提高农民的福祉，但对这种政策的研究仍在继续。发达国家的政策往往补贴农业部门，进而导致过剩；而发展中国家的农业政策倾向于对农业部门征税，从而导致供不应求。Schultz（1964）等人建议减少或消除对发展中国家农民的税收，而应提供技术支持以提高生产率，从而改善粮食安全。经济学家的普遍建议是，通过取消补贴以及对农产品的征税来减少价格扭曲。
第三个政策挑战是建立一种机制，这种机制可以应对农民面临的价格和产量风险。除库存管理外，农业经济学家还分析了利用期货市场以及保险项目带来的影响和收益。这些影响和收益可能包括作物保险、灾难援助、价格保险、收入保证以及基于天气的保险。尽管研究发现大多数政府保险项目在效率和环境方面存在缺陷（Smith and Goodwin，2013），但我们仍然面临着需要设计出具有偿付能力和有效率的替代计划的挑战。
关税以及非价格贸易法规，是政府干预农业的其他手段。关于农业贸易及其影响的文献很多（Anderson and Martin 2005），这项研究表明，贸易壁垒给全球福利造成了损失，而且大部分损失是由发展中国家被禁止将其产品出口到发达国家所造成的。此外，各国政府制定了稳定本国农产品价格的政策，而没有认识到这种政策对其他国家的影响，其净效应是增强了价格的不稳定性。像D. Gale Johnson(1975)这样的经济学家认为，贸易自由化和通过库存产生的市场力量将导致更稳定和有效的定价。但政府并不一定会听从农业经济学家的建议，并采取似乎不能改善经济福利的政策，这导致了另一个关于农业政治经济学的文献体系：利益集团对农业影响的研究（Rausser, Swinnen and Zusman, 2011）。
然而，这些年发生了一些变化和进步。已故的伟大经济学家Bruce Gardner发现，随着时间的推移与农场规模的扩大，农场收入相对于城市部门的滞后性下降了，支持农业收入的一些理由也有所减少。国际贸易和政治经济因素是二十世纪下半叶农业政策转变的推动力。Anderson，Rausser和Swinnen（2013）发现，包括世界贸易组织（WTO）在内的国际贸易协定减少了发达国家和发展中国家与农产品价格相关的贸易扭曲，并且在人为干预较少的情况下，价格更好地反映了基本的供需力量。
尽管早期的农业政策研究侧重农业市场，但农业经济学家已经意识到，农业与其他经济主体之间存在着有趣的反馈关系，而且它依赖于宏观经济力量。Schuh（1974）强调，当美元被高估时，美国农民会受到不利影响，这一研究催生了大量的文献，这些文献表明，与特定的农业政策相比，全球农业部门受整体宏观政策的影响要更大。D. Gale Johnson（1991）强调了贴现率和汇率在农业部门中的重要作用，而总体经济的不稳定性正在影响农业，反之亦然。
农业政策研究日益强调转型期的经济。Johnson等人对20世纪60年代和70年代东欧和中国农业部门的低效率和挑战进行了现实评估，并提出了改革策略。Swinnen(1999)以政治经济学原理为基础展开分析，解释了东欧土地和农业改革的模式，说明了路径依赖、民族因素和整体宏观经济条件的重要作用，并评估了这些改革的效率损失和分配影响。Rozelle and Swinnen（2004）分析了中国和东欧的改革转型战略与农业经济绩效之间的关系。这两位学者认为，农业政策改革包括价格的变化和补贴的减少（这可能会在过渡时期减少供应）、土地改革，农业部门和为其服务的机构的结构调整。他们发现，改革能够降低交易成本并防止贸易壁垒，这往往会提高生产率和整体的生产。减少补贴可能会导致短期供应减少。Reardon和Timmer（2012）回顾了有关全球粮食系统转型的大量文献，包括在发展中国家推广超市和先进的加工技术。一旦获得了技术和财政资源，并且贸易壁垒受到限制，价值链就会逐渐使世界各地的粮食系统现代化。目前转变的速度很快，其影响是未来研究的主题。
由于农业经济学家必须解决重大实际政策问题并评估其对不同群体的影响，因此他们往往是采用成本收益分析（特别是采用盈余分析）等工具的先驱者（Just，Hueth and Schmitz 2008）。随着计算机的问世，农业经济学家已经使用基于计算机的一般均衡模型，分析农业政策以及其他相关政策对整体经济的影响。通过使用全球贸易分析（GTAP）等数据库和越来越多的一般均衡模型（其中一些模型包括动态特征），农业政策的定量分析可以评估其对经济各部门以及全球的影响（Hertel等，2007）。此外，了解这些联系能够扩大我们对农业政策分配影响的理解，使其不仅包括农业政策对某些群体的影响，还有对收入分配和诸如贫穷、福利等问题的影响。例如，Hertel等（2007）研究了政策改革（如多哈回合谈判期间提出的政策改革）的分配效应。这些学者发现，从新世纪开始就存在的状况（如发达国家的农业贸易政策）对发展中国家的农民和消费者产生了负面影响。多哈回合谈判的政策对发展中国家消费者和农民的收益增加较少，而充分自由化对发展中国家非常有利，但会损害美国最富有农民的利益。农业政策分析工具在分析东欧和中国的经济转型方面非常有用。
沙尘暴以及对食品安全和农药污染的担忧导致政府采取干预措施，以改善食品安全，减少农业外部性，随后，资源和环境问题日益受到重视；农业经济学家是环境和资源经济学文献的主要贡献者（Kling, Segerson, and Shogren, 2010; Lichtenberg et al. 2010）。这些文献中出现了几个主要的研究主题。
首先是使用成本收益分析来评估自然资源大型投资的重要性。尽管有政治压力，但Bill Martin等农业经济学家还是警告说，大型水利项目（如亚利桑那中部项目）效率低下（Bush和Martin 1986年）。事实上，农业经济学家的这些努力会使成本收益分析成为美国和全世界项目评估的一个重要因素。
第二，向生产者提供适当的激励措施，使其考虑到外部性成本以及资源分配的动态成本。例如，杀虫剂应当受到管制，使农民面临的有效价格包括环境成本以及耐药性成本（Waterfield and Zilberman 2012）。
另一个重要主题是建立交易机制，而不是通过直接控制来分配资源。例如，已有研究表明，采用水资源交易系统可以实现巨大收益（Schoengold and Zilberman 2007）。
第四个主题是发展类似市场的机制以管理和提供环境设施。例如，开发生态系统服务的支付功能。事实上，农业经济学界的主要贡献之一是在美国开展建立自然保护区计划的研究（Babcock等，1997）。
土地利用和农村发展一直是农业经济的重要组成部分。Johann Von Thunen在农业经济学存在之前就是一名农业经济学家，他也是人口经济学之父（Von Thunen，2009）。他的土地分配理论和空间价值理论一直是农村和区域规划领域的起点。该领域的研究考察了农业地产定价、农村定价和社会资本以及农村设施的价值（Castle 1998）。随着地理空间数据的使用，农业经济学家为应用高级空间计量经济学做出了贡献，进而评估土地利用模式的演变及其对经济和生态的影响（Irwin et al. 2009）。
农业经济学对我们了解自然资源问题研究最重要的贡献源于其使用多学科方法。应用经济学已经成为一门综合学科，结合了生物学、农学和公共卫生方面的数据来评估各种政策（无论是决定喷洒田地后的重返期，还是确定水质管理策略）。农业生物技术的发展带来了一系列新的政策问题，开辟了新的经济学研究领域，包括知识产权和确保利用技术来保护孤生作物和穷人作物的机制、法规问题，以及标签问题（Barrows, Sexton, and Zilberman 2014）。虽然该技术已显示出显著的经济效益（Klumper and Qaim 2014），但它在世界许多地区被完全或部分禁止，并且农业经济学家已经开发了政治经济模型（Herring and Paarlberg 2016），以及消费者感知模型以理解现实（Lusk, Roosen, and Bieberstein 2014）。
近期另一个研究领域是生物燃料经济学。对温室气体排放和能源供应的担忧导致了以农业为基础燃料的生产，农业经济学家认识到粮食和燃料之间的替代关系，评估了政策的赢家和输家，以及生物燃料对排放的直接和间接影响，在这一领域，农业经济学的一些最先进的分析技术非常有效。例如，Khanna（参见Khanna, Swinton, and Messer 2018）一直在使用 GIS 数据来评估在不同政策方案下使用不同类型的生物燃料的地点和时间。此外，农业经济学家对气候变化及其政策方面的研究做出了重大贡献。例如，Schlenker and Roberts（2009）使用开创性的的计量经济学方法评估气候变化对农业产量的影响。McCarl and Schneider（2001）使用编程技术来评估农业减缓气候变化的潜力。发达国家和发展中国家关于适应气候变化的文献越来越多（Lipper et al. 2017）。现有文献表明，应对气候变化的主要挑战是建立各种机制，以解决以下问题（i）应对气候变化造成的搬迁和移徙的挑战；（ii）发展能够加速适应变化的创新机制；（iii）提供适当的基础设施，以充分维护供应链。
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