我国甘蔗燃料乙醇生产潜力与发展策略

由于甘蔗具有抗逆性强、能量效率高、生产成本高等优势,甘蔗制燃料乙醇在世界燃料乙醇生产、贸易中占据重要地位。我国利用甘蔗制燃料乙醇当前已具备充足的原料供应能力,成熟的育种技术、乙醇发酵、蒸馏技术,较好的经济效益,都使甘蔗燃料乙醇生产潜力巨大。因此,我国可以在未来5年内,利用我国现有甘蔗原料资源,打造年产能150万～200万t燃料乙醇、226亿kw·h绿色电力和100万t绿色肥料的新兴甘蔗乙醇产业群。     

What Explains Agricultural Price Movements?

After 2005, commodity prices experienced their longest and broadest boom since World War II. Agricultural prices have now come down considerably since their 2011 peak, but are still 40% higher in real terms than their 2000 lows. This paper briefly addresses the main arguments on the causes of the agricultural price cycle. It broadens the scope of analysis by focusing on six agricultural commodities, and identifies the relative weights of key quantifiable drivers of their prices. It concludes that increases in real income negatively affect real agricultural prices, consistent with the Prebisch–Singer hypothesis and its predecessor, Engel's Law. Energy prices matter most (not surprisingly, given the energy‐intensive nature of agriculture), followed by stock‐to‐use ratios and, to a lesser extent, ex‐change rate movements. The cost of capital affects prices only marginally, probably because it not only influences demand, but also evokes a supply response. The added value of these results lies in that, when examined in tandem and against market fundamentals, they challenge the conclusions from uni‐dimensional approaches that often put disproportionate weight on an individual factor.     

Payment Limitations and Acreage Decisions under Risk Aversion: A Simulation Approach

Payment limits have played an important role in U.S. farm policy deliberations for the last thirty years. Current limits are largely nonbinding. Proposals to strengthen and enforce limits are currently in discussion. We evaluate the likely effects of such proposals on acreage for corn, soybeans, wheat, cotton, and rice in several important producing states. Our results generally indicate that payment limits are unlikely to significantly affect acreage in most cases; exceptions occur for cotton and rice, where the probability that limits would be binding is much greater and thus more likely to affect production.     

国内外水资源价值与价格研究综述

针对学术界在水资源价值与价格方面的理论探索及其实践应用,以及目前水价面临的主要挑战,系统整理并归纳了水资源价值研究进展,水资源定价方法和水资源计价方式的种类、适用范围,以及与价值理论相对应的定价模型。研究结果表明：目前对于水资源多元价值的研究仍处于初级阶段,对水资源多元价值的认识不足;现有定价研究大多从单一角度出发,难以全面涵盖水资源社会价值、市场经济价值以及生态经济综合价值,且单一的计价方式不利于节水目标的实现。未来需要开展多维度评估价值、多角度制定价格以及多种计价方式研究,加强水价改革中市场机制的引入,应特别关注发展较慢的农业水价综合改革,以实现水资源的可持续利用。     

On the Comovement of Commodity Prices

We present strong evidence against the excess-comovement hypothesis—that the prices of commodities move together beyond what can be explained by fundamentals. Prior studies employ broad macroeconomic indicators to explain common price movements, and potentially correlated fundamentals are not controlled for. We use inventory and harvest data to fit a partial equilibrium model that more effectively captures the variation in individual prices. The model explains the majority of the comovements among commodities with high price correlation, and all of the comovements among those with marginal price correlation. Common movements in supply factors appear to play an important role in the observed comovements in commodity prices.     

Optimal Storage by Crop Producers

When post–harvest marketing strategies are restricted by disallowing speculative purchases, sales out of storage becomes an irreversible decision and the dynamic marketing problem becomes analogous to the optimal exercise of a financial option. The optimal marketing strategy is to hold at low prices and to sell at high prices with a cutoff price function marking the boundary between low and high prices. A method for estimating the cut–off price function is developed and applied to Illinois soybean prices. The decision rule is demonstrated to result in substantial gains from storage.     

Commodity Prices and Unit Root Tests

Price theory suggests that commodity prices should be stationary series. Yet, tests for unit roots rather frequently imply that these prices are not stationary. This seeming inconsistency is investigated by applying alternative specifications of unit root tests to prices of corn, soybeans, barrows and gilts, and milk. The preponderance of evidence suggests that nominal prices do not have unit roots, but the results are sensitive to the specification of the test equation. Accounting for a structural change that shifts the mean appears to be an important issue in unit root tests.     

16世纪中至17世纪初我国蔗糖业生产技术的发展及其影响

16世纪中期至17世纪初,我国制糖技术和甘蔗种植技术取得了较大的突破,明嘉靖年间白糖的发明,以及当时人对甘蔗种植技术的总结,均代表了封建社会蔗糖业生产力水平,这种突破性成果给封建社会的经济发展与民众的社会生活带来了较为深远的影响。     

甜菜成品糖浊度影响因素分析

本文详细分析了影响甜菜成品糖浊度的主要因素,探讨了甜菜原料、制糖设备的管理、甜菜制糖工艺过程及制糖检测等因素对成品糖浊度的影响,并提出控制手段和方法,对降低糖厂成品糖浊度有一定的指导和借鉴作用.     

江西省商品林经营现状评价及发展对策

森林资源是产业经济发展与生态环境保护的基础,合理利用森林资源有助于经济环境目标的实现。本文论述了江西商品林资源的现状,对存在的问题进行了分析,并针对这些问题提出了解决问题调整结构的对策措施。     

试论汉代农业领域中的商品生产问题

汉代农业生产是自给生产和商品生产的结合，汉代农业生产的主体包括经营专业户、地主和小农，其生产都不同程度地含有商品生产的因素。汉代小农的生产是自给性生产和商品性生产的统一，在小农生产中商品生产的存在具有必然性，离开商品性生产，自给性生产也将无法维持。     

The Economics of a Blend Mandate for Biofuels

A biofuel blend mandate may increase or decrease consumer fuel prices with endogenous oil prices, depending on relative supply elasticities. Biofuel tax credits always reduce fuel prices. Tax credits result in lower fuel prices than under a mandate for the same level of biofuel production. If tax credits are implemented alongside mandates, then tax credits subsidize fuel consumption instead of biofuels. This contradicts energy policy goals by increasing oil dependency, CO₂ emissions, and traffic congestion, while providing little benefit to either corn or ethanol producers. These social costs will be substantial with tax credits costing taxpayers $28.7 billion annually by 2022.     

The expansion of intensive marine aquaculture in Turkey: The next‐to‐last commodity frontier?

Aquaculture is one of the fastest growing food‐producing sectors, and its share in global seafood production is rising significantly compared with capture fisheries. This transforms seafood production practices while allowing capital to expand to new marine commodity frontiers. Building on the conceptualization of aquaculture as a new frontier for capture fisheries, the article aims to uncover how commodity frontiers expand within the intensive marine aquaculture sector and shape the transformation of seafood production by focusing on its recent growth in Turkey. It analyses this transformation based on 22 in‐depth interviews with key social actors in Turkey, as well as a review of sector and state reports and the relevant legislations of Turkey and the European Union, and argues that the three‐pronged horizontal, vertical, and taxonomic expansion already observed in industrial capture fisheries has similarly taken place in intensive marine aquaculture through the commodity widening, deepening, and marketing strategies employed by aquaculture firms.     

Assessing the Financial Performance of Forestry-Related Investment Vehicles: Capital Asset Pricing Model vs. Arbitrage Pricing Theory

Capital asset pricing model (CAPM) and arbitrage pricing theory (APT) are used to assess the financial performance of eight forestry-related investment vehicles. Although results from APT support previous findings from CAPM about timberland investments, three bodies of evidence show that APT findings are more robust. The major conclusions are (a) institutional timberland investments and timberland limited partnerships have a low risk level and excess returns; (b) forestry industry companies have not earned risk-adjusted returns, and the performance of medium forest industry firms is worse than that of large firms; (c) stumpage price does not resemble the return generation process of timberland investments; and (d) lumber futures have little excess return.     

Block-Rate versus Uniform Water Pricing in Agriculture: An Empirical Analysis

In this article we adapt Burtless and Hausman's (1978) methodology in order to estimate farmers' demand for irrigation water under increasing block-rate tariffs and empirically assess its effect on aggregate demand and inter-farm allocation efficiency. This methodology overcomes the technical challenges raised by increasing block-rate pricing and accounts for both observed and unobserved technological heterogeneity among farmers. Employing micro panel data documenting irrigation levels and prices in 185 Israeli agricultural communities in the period 1992–1997, we estimate water demand elasticity at −0.3 in the short run (the effect of a price change on demand within a year of implementation) and −0.46 in the long run. We also find that, in accordance with common belief, switching from a single to a block-price regime, yields a 7% reduction in average water use while maintaining the same average price. However, based on our simulations we estimate that the switch to block prices will result in a loss of approximately 1% of agricultural output due to inter-farm allocation inefficiencies.     

Generic Advertising and Product Differentiation

This article considers whether generic advertising lowers the differentiation among competing brands of the same good. Analytical results show that if the benefits from generic advertising from increased demand are outweighed by the costs from lower product differentiation then high–quality producers will not benefit from generic promotion. Hypotheses are tested empirically under a conditional–logit approach using retail–market sales and advertising data for the U.S. prune industry. Results from this study provide evidence that generic advertising has a slight differential effect on the perceived qualities of different brands.     

基于排污权交易的再生水定价模型

通过对已有再生水定价方法进行分析,以基于成本的再生水定价模型为基础,建立了再生水供方最低定价模型;引入排污权交易这一重要因素,得出再生水需方最高定价模型,从而得到较为合理的再生水定价区间,并以常州市为例对上述再生水定价模型进行实证研究,最后讨论了基于排污权交易的再生水定价模型的特点与适用条件。