Biodiversity Conservation and Productivity in Intensive Agricultural Systems

This paper explores the economic effects of biodiversity loss on marketable agricultural output for intensive agricultural systems, which require an increasing level of artificial capital inputs. A theoretical bio‐economic model is used to derive a hypothesis about the effect of the state of biodiversity on the optimal crop output both in the longer run and in the transitional path towards the steady‐state equilibrium. The hypothesised positive relationship between biodiversity stock and optimal levels of crop output is empirically tested using a stochastic production frontier approach, based on data from a panel of UK specialised cereal farms for the period 1989–2000. The results support the theoretical hypothesis. Increases in biodiversity can lead to a continual outward shift in the output frontier (although at a decreasing rate), controlling for the relevant set of labour and capital inputs. Agricultural transition towards biodiversity conservation may be consistent with an increase in crop output in already biodiversity‐poor modern agricultural landscapes.     

农田污染对粮食生产的影响研究——以四川为例

作为农业生产的根本,农田质量对于粮食生产而言至关重要,因此农田污染的相关防治已经成为我国农业可持续发展、农产品安全以及我国生态环境保护的重要措施。目前我国农田污染主要特征为农田污染物成分复杂,农田污染程度不断扩大。同时由于农田污染导致土壤肥力下降进而导致相关农作物的产量以及品质不断下降。文章以四川省为例,探究农田污染对粮食生产的影响,结果发现,目前四川省农田污染主要来源于农药化肥的不合理使用,水体以及土壤受工业废水污染严重,畜牧业废弃物污染等。农田污染导致可耕种土地面积不断减少,粮食生产受到严重影响。基于此,该文针对四川省农田污染现状提出农田污染综合立体防控策略,并在此基础上通过合理规划农业生产,减少农药化肥使用量,提高生物防治在病虫害防治当中的比例等措施减少农田污染对粮食生产的影响,以期为我国农田保护以及粮食生产提供一定的理论以及政策依据。     

离子型稀土矿开采的环境影响及治理措施

离子型稀土是国家稀缺的战略性资源,其开发产生的环境问题对人民生产和生活产生了重大影响。本文主要阐述了离子型稀土开采从池浸、堆浸到原地浸矿的发展历程,分别从大气污染、水资源污染、土壤环境损伤和地质损害四个方面分析稀土开采对环境产生的破坏,并提出相应的治理措施,建议企业研究开发新的工艺,提高资源利用率,国家加强对稀土开采的监管措施,共同促进稀土行业的可持续发展。     

农户减少化肥用量和采用有机肥的意愿研究——基于洱海流域上游面源污染防控的视角

[目的]过量施用化肥导致水体富营养化是造成洱海流域上游面源污染的主要原因之一,调查分析农户减少化肥用量和采用有机肥的意愿有助于了解其调整施肥结构的行为。当前研究忽视了农户减少化肥施用强度和采用有机肥的意愿间的替代性,未能开展联立研究。[方法]基于洱海流域上游397个水稻种植户的问卷调查数据,通过Bivariate-Probit模型对农户减少化肥用量和采用有机肥两种意愿进行分析。[结果]年龄负向影响农户减少化肥量的意愿,农户对有机肥好处的认知正向影响其减少化肥量的意愿,农户参加农业社会化服务对其减少化肥用量和采用有机肥的意愿均产生正向影响,相比之下,对农户采用有机肥意愿的促进作用更大。[结论]引导农户参加农业社会化服务以及加强宣传和培训,提高农户对有机肥作用的认知可能是加强其减少化肥用量和增加有机肥施用量意愿的有效途径。     

西藏农业面源TN、TP排放的空间差异与分布特征

[目的]农业面源污染已经成为西藏构建国家生态安全屏障的重要制约因素,揭示西藏农业面源污染的现状,探明其主要污染源和分布特征,能够为西藏农业面源污染防治政策的制定提供参考和依据。[方法]利用单元调查法,以西藏不同地区农田化肥、畜禽养殖和农村生活为污染单元,对2000—2016年西藏农业面源排放的总氮(TN)和总磷(TP)排放总量、构成及强度进行核算,并分析其空间差异与分布特征,反映西藏农业面源污染现状并把握其动态演变。[结果]西藏农业面源污染的TN、TP排放量基本呈现有增有减的平稳态势,畜禽养殖贡献率最大,占TN、TP排放总量的96. 3%和94. 5%,畜禽养殖是西藏农业面源污染防治的重点领域。西藏不同地区TN、TP排放量和强度差异明显,那曲市、昌都市、日喀则市的TN和TP排放总量位居前3位,拉萨市和昌都市的TN和TP排放强度位居前2位,阿里地区TN和TP排放总量和排放强度均最低。[结论]综合考虑到农业面源污染总量和负荷强度,拉萨市、昌都市、日喀则市、那曲市应当作为西藏农业面源污染治理的重点区域。     

棉区农户过量施肥风险认知的影响因素分析——基于新疆446个棉农的问卷调查

化肥过量施用在提高棉花产量的同时也带来了严重的农业环境污染问题,并威胁到棉花产业的可持续发展。文章利用新疆重点植棉区的446农户实地问卷调查所得数据,对农户过量施肥风险认知进行评价,并采用二元logit模型,对植棉农户减少化肥施用量的影响因素进行实证分析。分析结果显示,主要影响因素中的户主年龄、植棉经验、土地质量、土地产权、接受科学施肥技术培训、棉花收入的满意度、棉花收入在总收入中的比例等因素对农户减量施肥有显著影响;农户认为科学施肥是否重要的认知因素和农户家庭人口对农户减量施肥没有显著影响。     

R&D policies for desalination technologies

In many arid and semi‐arid regions whether or not to desalinate seawater has long been a non‐issue and policy debates are focused on the timing and extent of the desalination activities. We analyze how water scarcity and demand structure, on the one hand, and cost reduction via R&D programs, on the other hand, affect the desirable development of desalination technologies and the time profiles of fresh and desalinated water supplies. We show that the optimal R&D policy is of a non‐standard most rapid approach path (NSMRAP) type, under which the state of desalination technology — the accumulated learning from R&D efforts — should approach a pre‐specified target process as rapidly as possible and proceed along it thereafter. The NSMRAP property enables a complete characterization of the optimal water policy. The renewable nature of the fresh water stock permits a non‐monotonic behavior of the optimal stock process: under certain conditions, the stock is depleted, to be fully or partly) refilled at a later date.     

农村劳动力转移对化肥面源污染的影响研究——以冀鲁豫3省为例

[目的]以冀鲁豫3省45个地市为研究对象,分析农村劳动力转移对化肥面源污染的影响,为实现农村劳动力转移与绿色农业的协调发展提供对策建议。[方法]文章选取2004—2016年冀鲁豫3省地市数据,厘清了农村劳动力转移的动态演进轨迹和化肥面源污染的时空分布格局,采用空间杜宾模型分析了农村劳动力转移对化肥面源污染的直接影响和空间溢出。[结果] 2004—2016年冀鲁豫3省农村劳动力转移率总体表现为提升趋势,但增速有所放缓,区域差异不断增强;化肥面源污染排放强度具有明显的空间集聚特征,从高到低依次为山东、河北、河南,总体排放强度略有下降,表现出由东北向西南转移的演进趋势;农村劳动力转移对化肥面源污染具有正向的直接影响和空间溢出,且间接溢出大于对该市造成的直接影响,农村劳动力转移的快速推进会把化肥面源污染"转嫁"给邻近地市。[结论]不同地区应合理引导农村劳动力流动,缓解农村劳动力转移过快带来的污染"转嫁",统筹协调、协同治理化肥面源污染。     

An optimal phased replanting approach for cocoa trees with application to Ghana

This study solves for the optimum replacement rate (ORR) and initial replacement year (IRY) of cocoa trees (Theobroma cacao) in Ghana to maximize net present value and achieve steady state by employing a phased replanting approach. The annual ORR is 5%–7% across the three production systems studied: Low Input, Landrace Cocoa, High Input, No Shade Amazon Cocoa, and High Input, Medium Shade Cocoa. The optimal IRY ranges from year 5 to year 9 as a function of cocoa prices, fertilizer prices, labor prices, and percentage yield loss due to disease outbreaks. Deterministic results project economic gains that exceed currently practiced replacement approaches by 5.57%–14.67% across production systems with reduced, annual income volatility. The method applied in this study can be used to increase cocoa yields and stabilize income over time, and facilitate substantial quality of life improvements for many subsistence cocoa farmers in Ghana and around the world.     

Adding value to spatially managed inputs by understanding site-specific yield response

Many mechanized crop producers and agribusinesses are fascinated with precision agriculture technology, but adoption has lagged behind the expectations. Among the reasons for slow adoption of precision agriculture technology is that initial users focused excessively on in‐field benefits from variable‐rate fertilizer application using regional average fertilizer recommendations. This article illustrates how greater use of site‐specific crop response information can improve variable rate input application recommendations. Precision agriculture is spatial information technology applied to agriculture. The technologies include global position systems (GPS), geographic information systems (GIS), yield monitoring sensors, and computer controlled within‐field variable rate application (VRA) equipment. Experimentation with these technologies is occurring everywhere there is large scale mechanized agriculture. Commercial use has been greatest in the US, where 43% of farm retailers offered VRA services in 2001. Except for certain high‐value crops like sugar beet, farmer adoption of VRA has been modest. The farm level profitability of VRA continues to be questionable for bulk commodity crops. The theoretical model and illustration presented here suggest that VRA fertilization has not yet reached its profitability potential. Most VKA field trials to date have relied upon existing state‐wide or regional input rate recommendations. Unobserved soil characteristics can potentially interact with an input to make its effect on yield vary site‐specifically within fields. Failure to use site‐specific response functions for VRA applications may lead to a misallocation of inputs just as great as that which results from using uniform applications instead of VRA. Agricultural economists have a long history of estimating output response to input applications. Several have started to develop tools to estimate site‐specific responses from yield monitor and other precision agriculture data. Likewise, agricultural economists have developed an important body of research results on information value based on managing variability—typically in temporal settings. With these tools, a major potential exists to develop further benefits from precision agriculture technologies that permit truly spatially tailored input applications.     

国外农业面源污染控制政策的研究进展及启示

我国水污染严重,富营养化问题突出,农业面源污染已成为水体富营养化的主要原因。该文对国外农业面源污染控制政策领域中的主要研究进行了疏理,简要回顾与评论了基于投入的政策和基于水质的政策,认为农业面源污染排放的分散性和随机性决定了其控制政策不能以排放量为设计基础。由于设计与执行政策的信息成本过高,基于水质的政策只停留在理论研究层面。基于投入的政策具有更强的现实可行性。     

油气田开发的环境成本计量方法选择及其应用

油气资源不仅在国民经济发展中占有举足轻重的地位,而且油气资源开发还是环境污染的过程,因此,有必要核算油气田开发的环境成本。油气田开发活动中环境成本的确认、计量及相关计算方法,与一般产品成本核算存在一定的差异,因此,环境成本计量方法的适当选择,可以更好地揭示因环境问题引起的财务影响,并如实反映油气田开发的环境绩效。     

地区重点企业水污染减排复合政策模拟研究

在水污染排放税和排放权交易市场并行的现实政策情景下,模拟复合政策对地区重点企业的排放权配置结构、产量、利润和社会福利的影响,并探索实现社会福利和企业创新减排利润同时最优的政策区间。研究发现:相比于排放税,企业利润对排放权价格变化更为敏感;企业最优的从市场取得的排放权相对于超排量的比例与利润之间呈倒U形关系;在排放税税率与排放权单价的价差较小,且排放税率略低于排放权价格时,可实现经济与环境的双赢。为了使复合政策的效率最大化,建议减排政策中应避免排放税和排放权同低或同高的情形。     

Optimal Regulation of Eutrophying Lakes, Fjords, and Rivers in the Presence of Threshold Effects

Eutrophication is a biological process that has an unfavorable economic impact on the economic value of the water basins it affects. Eutrophication depends on thresholds effects, and optimal policies for the regulation of eutrophication must take this into account. Such optimal policies are derived in the present article by utilizing a novel technique in optimal control theory. This technique facilitates a proper analysis of deterministic stock pollutants with thresholds effects, a topic it is argued has been poorly understood in the literature.     

Size matters: Optimal management of dynamic systems with varying size

Many natural and economic systems are managed to deliver the highest benefits to society but are subject to regime shifts. We specifically consider the variability of the size of the system itself as a key driver of a regime shift. We address the question of how the optimal management of these systems should vary with its size. Put simply, certain management options might work when the system is of a given size, while others might be preferred when the system has grown or shrunk. In this paper, we develop a model that allows us to analyse the effect of the size of the system on its optimal management. We apply this model to a case of water pollution in a reservoir/lake that varies in size over time: sometimes the lake is deep and sometimes it is shallow. Numerical simulations were conducted to compare optimal management of the reservoir with and without explicitly modelling its size variation. The findings show that the overall social costs of optimally managing pollution are significantly smaller when the variability in size is taken into account. This is due to differences in the timing and magnitude of the optimal control. The key implication is that the variability of the size of a system should be explicitly considered in this type of management problems.     

Unawareness in environmental protection: The case of light pollution from traffic

New information is often emphasized as a basis of effective and scientifically sound environmental policy and management. However, outdated or incorrect information is not automatically nor instantly replaced by new insights. This article focuses on the various ways environmental information can be unintentionally left with insufficient attention or purposefully neglected. Energy-related emissions caused by road traffic in Finland are used as an illustrative example and light pollution caused by artificial lighting is identified as an emerging issue that has gained especially low recognition in the environmental agenda. Four different reasons for this lack of recognition are discussed: recognized unawareness, false awareness, deliberate unawareness and concealed awareness. Paying attention to light pollution is important because of various ecological, socio-cultural and economic effects but also because implementing measures aimed for reducing light pollution create possibilities for alleviating other social and environmental problems in transport and land use policies.     

The economic impacts of technology and climate change: New evidence from U.S. corn yields

Over the past century, U.S. farmers have been offered a steady stream of new agricultural technologies, and more recently, experienced climate change. Because these two events have been occurring simultaneously, identifying their separate effects is difficult, and misimputation is easy. This article explicitly examines the economics of technical change and the interaction between weather and technology as revealed in a half century of panel data on U.S. Midwest rainfed state‐average corn yields. Observed yields reflect two components: yield potential and damage to the potential caused by weather and pests. Yield potential is modeled as a stochastic production frontier where nitrogen fertilization, public corn research, and introduction and adoption of biotech corn seeds impact yield potential and excess heat impacts nitrogen productivity. The yield‐damage/damage‐control function permits biotech corn plants to abate adverse effects of weather and pest events. Results include the following: nitrogen use, public corn research, and biotech seed‐corn adoption increase yield potential; soil moisture stress reduces yield potential, and excess heat severely reduces nitrogen productivity. Biotech corn plants abate yield damage caused by soil moisture stress but not excess heat.     

Projecting future crop productivity for global economic modeling

Assessments of climate change impacts on agricultural markets and land‐use patterns rely on quantification of climate change impacts on the spatial patterns of land productivity. We supply a set of climate impact scenarios on agricultural land productivity derived from two climate models and two biophysical crop growth models to account for some of the uncertainty inherent in climate and impact models. Aggregation in space and time leads to information losses that can determine climate change impacts on agricultural markets and land‐use patterns because often aggregation is across steep gradients from low to high impacts or from increases to decreases. The four climate change impact scenarios supplied here were designed to represent the most significant impacts (high emission scenario only, assumed ineffectiveness of carbon dioxide fertilization on agricultural yields, no adjustments in management) but are consistent with the assumption that changes in agricultural practices are covered in the economic models. Globally, production of individual crops decrease by 10–38% under these climate change scenarios, with large uncertainties in spatial patterns that are determined by both the uncertainty in climate projections and the choice of impact model. This uncertainty in climate impact on crop productivity needs to be considered by economic assessments of climate change.     

What drives stock market integration? An analysis using agribusiness stocks

This article explores the drivers of regional stock market integration with a focus on the agribusiness sector across relevant regional trade blocs around the world. We implement panel cointegration models to analyze the stock indices of agribusiness firms in the Southern Common Market (MERCOSUR), European Union (EU), Asia‐Pacific Economic Cooperation (APEC), and North American Free Trade Agreement (NAFTA). Based on the literature on market integration and stock return pricing, we identify nine possible determinants of stock market integration, which we separate into three categories: individual market performance, macroeconomic conditions, and agricultural trade. In our analysis, we account for agriculture‐specific factors to control for possible structural shifts in financial markets regimes by including the two main commodity price bubbles during last 20 years. Our results show that most of the variables included in our categories have been important factors in promoting regional stock market integration. Moreover, integration among regional stock markets was strengthened by the implementation of trade agreements. This effect is stronger in trade blocs with fewer members, such as NAFTA and MERCOSUR, compared with larger and more heterogeneous blocs, such as the EU and APEC.     

Incentive-Compatible Pollution Control Policies under Asymmetric Information on Both Risk Preferences and Technology

This article proposes a method to accommodate asymmetric information on farmers' risk preferences in designing voluntary environmental policies. By incorporating stochastic efficiency rules in a mechanism design problem, the government can find incentive-compatible policies by knowing only the general class of risk preferences among farmers. The model also accounts for hidden information on technology types and input use. The method is applied empirically to simulate a pollution control program in New York. Results suggest that participation incentives would be inadequate for many risk-averse producers if the government does not account for the diversity in risk preferences.