Adverse Shocks in Agriculture: The Assessment and Management of Downside Risk

This paper investigates the assessment and effects of adverse shocks on agricultural production, with an application to corn yield. Adverse shocks are assessed by the probability of facing low yields, i.e. by the probability of being exposed to downside risk. Defined in terms of willingness‐to‐pay to eliminate risk, the ex‐ante cost of facing adverse events is evaluated under prospect theory. Prospect theory is relevant in the evaluation of adverse shocks as it identifies a role for both loss aversion and oversensitivity to low probability events. The analysis is applied to experimental data on corn yield in the US Corn Belt. Estimates show how the distribution of corn yield is affected by management and technology. Implications for the cost of adverse shocks are examined. The results show how management and technology can reduce exposure to adverse shocks and lower the cost of risk in agriculture.     

贵州省雷电灾害风险评价与区划研究

[目的]从致灾因子、孕灾环境、承灾体和防雷减灾能力4个方面确定13个评价指标开展雷电灾害风险评价与区划研究,实现定量化的雷电灾害风险评价。[方法]应用闪电监测资料、土壤数据库资料、GTOP30数据集以及社会经济统计和相关地理信息数据,基于目标、准则、指标层建立雷电灾害风险评价模型,采用投影寻踪方法获取指标权重,定量化分析致灾因子危险性、孕灾环境敏感性、承灾体易损性以及防雷减灾能力强弱,研究综合雷电灾害风险并完成等级划分。[结果]贵州省雷电灾害风险西部高于东部,整体呈现由西南部向东北部递减。其中西部的水城、六枝、普定、晴隆以及贵阳的云岩区、南明区、白云区中北部为高风险区,次低及低风险区主要分布在威宁及赫章西部区域、开阳东北部、平塘中东部、独山、荔波、万山、玉屏、碧江、思南、石阡、沿河的部分区域。[结论]通过灾前风险识别,可针对性的制定综合对策,为提高贵州省雷电灾害防御能力提供科学决策参考。     

Feasibility of risk‐based inspections in organic farming: results from a probabilistic model

A risk‐based inspection system might improve the efficiency of the organic farming certification system and ultimately provide a basis for increased competitiveness of this sector. This requires the definition of an effective inspection procedure that allows statistical evaluation of critical risk factors for noncompliance. In this article, we present a study based on data from selected control bodies in five European countries that is aimed at determining the feasibility of risk‐based inspections in the organic sector according to the data that are currently routinely recorded. Bayesian networks are used for identification of the factors that can affect the risk of noncompliance. The results show that previous/concurrent noncompliant behavior explains most of the risk, and that the risk increases with farm size and the complexity of their operations. The data currently recorded by control bodies appear to be insufficient to establish an effective risk‐based approach to these inspections.     

内蒙古玉米干旱风险区划方法研究

针对目前内蒙古地区农业保险业的现实需求,特别是农业可持续发展、农业防灾减灾等的重大科技需求,急需开展农业气象灾害影响评估技术服务,实现对农业气象灾害风险的定量分析和动态评估。为了填补内蒙古干旱风险区划研究的空白,文章针对内蒙古玉米的作物特性进行研究,利用119个气象站点1960~2013年的温度、降水、日照、相对湿度、风速等观测资料,综合考虑了致灾因子和承载体的地域特性,建立了内蒙古玉米气候区划、气象干旱、农业干旱、气候生产潜力、气候适宜性5个方面的干旱风险评估指标。利用GIS的空间分析功能,对各指标进行重分类和叠置分析,确定内蒙古玉米干旱风险动态评估分级指标体系,对内蒙古2011~2013年玉米干旱进行了风险评估模拟。评估结果与内蒙古2011~2013年玉米实际年景十分相符,证明了该风险区划方法在内蒙古地区的可行性,可以为有关部门控制农业气象灾害的发生、防御或减轻灾害对农业生产的危害、制定救灾措施、农业灾害保险政策、进行风险转移提供科学依据,进而最大限度地减轻灾害造成的不利影响。     

PREMIUM RATEMAKING IN AN ALL RISK CROP INSURANCE PROGRAM1

Fluctuation in farm incomes resulting from variation in crop yield is one of the most significant features in agriculture. Crop insurance is a feasible method by which the farmer can protect his income and his investment from the disastrous effects of crop losses due to natural hazards. This study has attempted to cover two parts. First, it has examined the most important-factors influencing crop yields in connection with the premium rate scheme (i.e. the long-run average yield and the level of coverage). These factors include resource inputs, technology, weather, and stochastic variable. Second, it has developed a refined method of approximating the premium rate. The data used in testing normality were based on the Manitoba Crop Insurance Corporation's annual yield survey covering the years 1916 to 1964. The test shows that none of the annual yield distributions within the area surveyed was normally distributed, revealing that a cartful and exact delineation of a crop risk area is necessary. The findings also show that the cyclical pattern of weather and the upward trend in crop production due to technology were evidently important for the adjustment of the level of coverage and premium rate over time. Additional research relating the effects of weather and technology on crop yields would help to establish a more realistic insurance program. Other aspects should not be overlooked. These include (a) other possible levels besides the existing level of coverage and (b) a livestock or a combined crop-livestock insurance program along with the crop insurance program. The purpose of these additional aspects is to provide farmers with a fuller measure of protection.     

STABILISATION AND RISK REDUCTION IN AUSTRALIAN AGRICULTURE*

Agricultural producers typically are faced with risk about the yields they will experience and the prices they will receive. Stabilisation schemes can spread risk and thereby reduce the risk faced by individual producers. The risk-reducing capacity of a scheme and the cost of risk reduction depend upon the design of the scheme. In particular, it is important to distinguish between risk and instability. A classification of scheme designs is presented to bring out the effects of various design types. Schemes for the wheat industry are given most attention.     

基于随机森林算法的洪水灾害风险评估研究

根据流域灾害系统理论,在考虑致灾因子、孕灾环境和承灾体的基础上,选取9个风险评价指标,运用样本数据进行人工识别风险并得到训练样本,采用随机森林算法构建基于随机森林的洪水灾害风险评估模型。然后采用随机森林自评估工具,分析建立的洪水灾害风险评估模型的误差和指标,同时构建支持向量机模型作为对比方案,并采用五折交叉验证方法对基于随机森林算法的洪水灾害风险评估模型和支持向量机模型进行验证。最后以海河流域邱庄段为研究对象,分别运用基于随机森林算法的洪水灾害风险评估模型和基于支持向量机模型对相同的数据集进行评估和对比,结果显示,12 h内降雨总量、洪水持续时间和土壤含水量是引发洪水的主要因素,而基于随机森林算法的洪水灾害风险评估的训练精度及测试精度均高于支持向量机模型。     

河北省冬小麦—夏玉米干旱灾害风险评估

目的 通过分析河北省冬小麦和夏玉米的干旱灾害风险的时空分布格局,从致灾因子危险性、承灾体暴露性、环境敏感性、防灾减灾能力4个因子出发确定10个指标,为河北省农业防旱抗灾工作提供科学支持。方法 文章基于自然灾害理论,利用2000—2018年河北省气象站点数据,计算水分亏缺指数,并通过建立农作物减产率和水分亏缺指数的关系来确定不同干旱等级的临界阈值,建立基于信息扩散理论的干旱危险性评估模型。利用遥感数据以及统计年鉴数据,建立承灾体暴露性模型、环境敏感性模型和防灾减灾能力模型,在此基础上,对河北省冬小麦和夏玉米不同生育阶段进行干旱灾害综合风险评估。结果 （1）将信息扩散模型应用于小样本事件中,弥补资料不足带来的缺陷,可对不同级别的干旱进行风险评估;（2）干旱发生程度以轻度干旱和中度干旱为主,发生严重干旱的概率极低,致灾因子是影响旱灾程度的关键因素;（3）冬小麦和夏玉米在不同生育阶段风险的空间分布是不均的,高风险区和中高风险区呈现零星点状分布,冀中和冀南综合风险比较高,防灾减灾能力在一定程度上缓解了旱灾对该区的影响力度,而对于冀东地区来说,承灾体的暴露性以及防灾减灾能力决定了旱灾对该区的影响力度。结论 因此,建立的冬小麦和夏玉米不同生育期干旱灾害风险评估模型可有效地识别农业旱灾高风险区,服务于农业生产实践,可为防灾减灾提供支持。     

巴中市农田土壤重金属分布及生态风险评价

[目的]通过测定秦巴山区巴中市农田土壤中镉(Cd)、铅(Pb)、锌(Zn)3种重金属元素的含量及分布特征,为农田重金属防治科学决策的制定提供数据支撑。[方法]文章采用内梅罗指数和潜在生态风险指数来综合评价巴中市土壤重金属污染状况。[结果]巴中市农田土壤锌平均含量比四川省丘陵地区背景值高6.78%,而镉和铅含量均未超出其背景值,总体评价良好,但各检测点之间差异较大,镉含量最多超出背景值5.7倍。内梅罗指数评价结果显示,全市平均综合污染指数为1.10,接近清洁状态。潜在生态风险指数评价结果显示,其最小值为15.94,最大值为177.74,平均值为35.38。[结论]巴中市农田土壤重金属污染状况基本处于低度风险级别,但各地块污染程度不尽一致,应因地制宜,采取适当措施治理土壤污染。     

Early evacuation is the best bushfire risk mitigation strategy for south‐eastern Australia

Given the large and increasing bushfire threat to lives and property in Australia, there is a need for economic evaluation of risk mitigation policies that can be implemented by governments and homeowners. Three broad policies applicable for existing at‐risk communities are evaluated: expanded use of landscape‐scale prescribed fire; home ignition zone treatment (bushfire defence sprinklers); and early evacuation when a bushfire is burning on extreme or catastrophic fire danger days. Early evacuation is the only option that yields net economic benefits relative to existing policy.     

森林资源资产评估风险识别与防范

森林资源资产评估是资产评估领域细分化、专业化分工的结果,其评估风险具有一般资产评估的共性,又有其特殊性。基于非系统性风险视觉研究发现,当前评估机构、评估人员、评估基础数据,评估业务委托方、评估技术体系、评估结果使用等都有可能形成森林资源资产评估风险。通过培育高质量评估机构、加强评估人员职业培训教育等措施可以有效防范这些风险。     

RELATIVE VARIABILITY IN WHEAT YIELDS ACROSS COUNTRIES AND OVER TIME

Wheat yield variability is analysed in light of recent concern that rapid technological change has caused increased instability in world cereal production. The coefficient of variation of wheat yields is estimated for 57 countries from detrended data for various periods between 1951 and 1986. The coefficient of variation in wheat yields is shown to be determined by country size, moisture regime and temperature. Technological variables, such as level of adoption of high-yielding varieties and fertiliser dose, had no effect on differences in yield variability across countries. Analysis of yield variability for the same set of countries for three periods from 1951 to 1986 shows a general decline in yield variability since 1975 in developing countries. Analysis of wheat yield variability in India at the state and district levels confirms the analysis of country level data. The coefficient of variability of wheat yields in India in the period 1976-85 has fallen to less than half the level in the 1950s and this decline is statistically significant.     

Improving recommendations resulting from on-farm research: agroforestry,risk, profitability and vulnerability in southern Malawi

Leguminous agroforestry (AF) species have been investigated and promoted in Malawi as a means to improve soil quality and maize (Zea mays) yields. Our objective was to determine whether AF systems' recommendations that solely consider impacts on average maize yields differ from those that include an analysis of production risk, profitability among different wealth groups and socioeconomic vulnerability. Employing participatory quantitative and qualitative on-farm research techniques, we investigated three AF-based maize/legume relay-cropping practices in southern Malawi. The perennial legumes included Sesbania sesban, Tephrosia vogelii and Cajanus cajan (pigeonpea). We found that AF species recommendations did diverge from those based solely on maximizing maize yields when incorporating risk, profitability and socioeconomic vulnerability as additional variables. For instance, the highest yielding system (the S. sesban/maize relay crop) was never recommended for the most vulnerable farmers based on the vulnerability analysis, and the cropping systems were often more profitable for the least vulnerable farmers than they were for the most vulnerable farmers. Cropping system recommendations based solely on obtaining the highest average maize yields would also have generally overlooked the economic and nutritional importance of pigeonpea, and the difficulty for the most vulnerable farmers to profit from fertilizers, potentially placing these farmers at greater risk.     

广西石漠化地区土地利用空间变化的生态风险研究

[目的]利用2000年、2005年、2010年、2015年广西轻度及以上石漠化的69个区/县土地利用数据,分析其土地利用时空变化特点,揭示其变化对该区域土地生态风险的影响。[方法]基于GIS支持,采用土地利用动态变化度、土地转移流、土地生态风险指数(RSI)等对研究区土地生态风险的异质性特征进行定量分析。[结果](1)2000—2015年广西石漠化地区土地利用动态度呈逐渐增大趋势,土地利用动态度变化,反映出研究区土地利用变化较频繁。(2)耕地、林地、草地、建设用地4类用地转移的数量与方向决定着广西石漠化地区土地利用变化的特征。(3)2000—2015年广西石漠化各区/县土地生态风险程度略微增大,南部的贵港、南宁是生态重警区,研究区的土地生态安全有待进一步改善。(4)土地生态风险指数与土地利用类型变化的活跃程度呈正相关。[结论]研究区未来土地利用,应进一步优化土地资源配置,加强生态环境保护,提高土地利用综合效益。     

Evaluating the Potential of Index Insurance Schemes to Reduce Crop Yield Risk in an Arid Region

We evaluate yield risk reduction through weather index, area yield index and farm yield insurance contracts for wheat farms in Kazakhstan by employing data from 1980 to 2002. We use the usual mean variance (MV) approach and also a second‐degree stochastic dominance (SSD) criterion. While MV is not necessarily consistent with the expected utility (EU) theory, SSD results only in a minimum but EU‐consistent benefit from insuring. Differences in the estimation results for both approaches underline the advantage of applying both criteria to analyse the risk‐reducing potential of crop insurance. Bootstrapping results show that none of the analysed insurance schemes provides statistically significant risk reduction for every single farm. In addition, weather‐based index insurance is found to provide less risk reduction than area yield insurance based on the rayon (county) yield. Moreover, rayon yield index insurance can reduce yield risk more effectively for Kazakhstan's wheat producers than farm yield insurance with a low strike yield.     

重金属污染农用地风险分区与管控研究

[目的]评价重金属污染农用地的风险等级,对重金属污染农用地的风险分区进行划定,建立农用地重金属污染风险分区分级以及风险控制区划方法,提出不同风险分区的管控对策。[方法]采用单因子指数法对重金属污染农用地土壤与农作物污染等级进行评价,构建农用地重金属风险控制区划方法体系。[结果]利用目前已有的土壤和农作物重金属污染评价标准,可以将土壤与农作物污染等级划分为清洁、尚清洁、轻度污染、中度污染和重度污染5种类型,根据其污染风险等级,按照安全与基本安全保护区、低风险监控区、中风险预警区和高风险限制区对其进行管控利用。[结论]将农用地土壤与农作物重金属污染评价有机结合,确定土壤与农作物不同污染程度下农用地的风险等级,可以对重金属污染农用地实现有效安全利用分区与管控,为国家分级分类管控治理农用地提供理论依据。     

陕西省主要粮食作物生产成本收益研究——以小麦、玉米为例

陕西省是我国的农业大省,粮食作物的生产成本和收益与农民收入直接相关,对农村经济的可持续发展具有重要影响。文章分析了陕西省主要粮食作物的种植现状,以小麦、玉米为例探究了主要粮食作物的生产成本收益,并对生产中存在的问题及潜力进行了详细分析,结果表明,尽管实施了多项惠农政策,粮食作物生产仍表现为成本高,收益低,农民播种积极性不高;粮食生产面临形势严峻,但陕西省粮食生产有很大的潜力可以挖掘。该文还提出了提高农民耕种积极性、提高粮食作物单产水平、实现农业产业化等对策建议,以期为提高粮食作物产量和品质,提高生产成本收益提供一定依据。     

Climate Smart Agriculture? Assessing the Adaptation Implications in Zambia

We examine a set of potentially climate smart agricultural practices, including reduced tillage, crop rotation and legume intercropping, combined with the use of improved seeds and inorganic fertiliser, for their effects on maize yields in Zambia. We use panel data from the Rural Incomes and Livelihoods Surveys merged with a novel set of climatic variables based on geo‐referenced historical rainfall and temperature data to explore the changing effects of these practices with climatic conditions. We estimate the impacts on maize yields, and also on the exhibition of very low yields and yield shortfalls from average levels, as indicators of resilience, while controlling for household characteristics. We find that minimum soil disturbance and crop rotation have no significant impact on these yield outcomes, but that legume intercropping significantly increases yields and reduces the probability of low yields even under critical weather stress during the growing season. We also find that the average positive impacts of modern input use (seeds and fertilisers) are significantly conditioned by climatic variables. Timely access to fertiliser emerges as one of the most robust determinants of yields and their resilience. These results have policy implications for targeted interventions to improve the productivity and the resilience of smallholder agriculture in Zambia in the face of climate change.     

An institutional evaluation of sustainable forest management in Flanders

The aim of this paper is to evaluate the existing Flemish institutional framework of sustainable forest management (SFM). The evaluation was performed using criteria and indicators that were based on the four-dimensional structure (discourse, rules, power and actors) of the policy arrangement approach. The data collection and analysis were done using a single representative case. The conclusions of the evaluation are mixed. The introduction of sustainable forest management is hampered by different perspectives on SFM and a fragmented network of many different owners with a clear asymmetrical distribution of trust and power. It is, however, enabled by the way that the most powerful and trusted actors in the network – the forest group and the forest service – have the same perspective on SFM perspective as the government. We expect that SFM can be achieved in the near future, although it remains a vulnerable situation.     

基于支持向量机的小型水库风险等级模型研究

根据小型水库现状,研究得到小型水库安全风险的主要影响因子。在此基础上,利用机器学习方法,建立小型水库安全风险等级评价模型。通过实例分析,验证了模型的正确性和适用性。研究表明,基于支持向量机的小型水库安全风险等级评估在小水库安全风险识别上具有一定的适用性,能够有效解决小型水库安全风险等级评价中存在的数据样本较少的问题,该研究成果可以为小型水库下游区域山洪预警提供新的思路。