区域性生态农业建设的作物配置新策略的研究

本文针对现行作物分类法的局限性，运用农业生态经济系统的功能性原理，提出一种新的作物分类法，以作物生产过程所表现的主体功能为依据将作物分成三大类型即社会型、经济型和生态型，并对每一类型作物的基本特性和增产增效对策进行了系统分析。在此基础上，提出了区域性生态农业建设中农田作物的合理配置的新策略。     

The Labor Market as a Smoothing Device: Labor Supply Responses to Crop Loss

The paper studies the way in which labor supply responses enable households to smooth consumption in the face of crop loss. The 1993 Indonesian Family Life Survey is unusual because it contains self-reported information on crop loss and on household responses to crop loss. Of those households that report a crop loss, 41.6% also report that they responded by taking an extra job. Using these self-reported measures, the authors find evidence which suggests that the income associated with this shock-induced labor supply is important in allowing the household to avoid reducing consumption expenditure. Household members, however, do not seem to increase their total hours of work. They appear to just reallocate their time from household farming to other labor market activities.     

我国作物遗传资源保护现状与对策分析

作物遗传资源是生物多样性的重要组成部分,是一个国家最有战略意义的宝贵财富。作物遗传资源多样性保护和可持续利用问题已列为联合国《生物多样性公约》的主要内容。文章从我国作物遗传资源的收集状况、保存状况、相关法规与管理体制现状几个方面梳理出我国作物遗传资源的保护现状,找出我国在此方面存在的主要问题,提出了加强我国作物遗传资源保护的对策建议。     

Crop Genetic Diversity, Productivity and Stability of Agroecosystems. A Theoretical and Empirical Investigation

This paper purports a model of farmers' crop choices in an uncertain environment. The model shows that profit maximizing farmers will choose a crop mix characterised by greater crop diversity if diversity is positively related to productivity and negatively correlated with production and income variability. An application using data from a Vavilov megadiversity spot, southern Italy, from 1970 up to 1993 is provided to test model hypotheses. It is found that interspecies crop genetic diversity is positively related to mean income and negatively related to the variance of income.     

Small and Productive: Kenyan Women and Crop Choice

The question of gender differences in agricultural productivity has received particular attention in the development literature. The stylized fact that women produce less than men, while on average occupying smaller farms, presents a quandary as it is also a stylized fact that smaller farms have higher yields per unit of area. Using data from the 2006 Kenya Integrated Household Budget Survey, this study examines whether there is a gap in output per acre between men and women farmers in Kenya. Using ordinary and two-stage least-squares (OLS and 2SLS) analyses, it shows that when crop choice is taken into account, women are as productive as men. Specifically, the study finds that market-oriented crops are the source of differences. This suggests that further research into what determines crop choice is needed, in addition to policy that ensures that women have the same access as men to support for market-oriented crops.     

长江上游地区退耕还林（草）的紧迫性与对策

本文论述了长江上游地区退耕还林（草）的重大意义及其紧迫性,在此基础上,提出了实施的对策。     

基于非参数核密度法的农作物区域产量保险费率厘定研究

利用湖北省82个县(市、区)1991～2007年县级中稻单产数据,逐县选择相应的ARIMA(p,d,q)模型拟合其中稻历年单产,并计算出单产减产率,然后在此基础上运用非参数核密度估计法算出各县中稻产量保险纯费率,最后考虑到农作物产量损失的空间相依性,根据各县所面临的系统风险状况对纯费率进行调整,得到更为合理的纯费率。     

元代农书中农作物名物词的同实异名现象

农业词语的发展具有一定的阶段性和较强的传承性,经历了新词产生、旧词消亡和新旧词共存的过程,在这个发展过程中,农作物名物词形成了同实异名现象。这种现象的产生,既是多种语言因素共同作用的结果,又体现着人们的认知水平,语言在时空、雅俗上的差异变化以及与社会环境的关系等因素。     

罂粟替代种植的最佳农作物--珠芽魔芋

本文提出，用一种新发现和培育出的农作物——珠芽魔芋替代罂粟种植，以达到消除境外毒源的目的。文章对珠芽魔芋的特点、替代种植的可行性进行了分析和探讨。此外，还与其他替代种植的农作物进行了比较。     

Farm Acreage Shocks and Crop Prices: An SVAR Approach to Understanding the Impacts of Biofuels

The last 10?years have seen tremendous expansion in biofuels production, particularly in corn ethanol in the United States, at the same time that commodity prices (e.g., corn) have experienced significant spikes. While supporters claim that biofuels are renewable and carbon-friendly, concerns have been raised about their impacts on land use and food prices. This paper analyzes how US crop prices have responded to shocks in acreage supply; these shocks can be thought of as a shock to the residual supply of corn for food. Using a structural vector auto-regression framework, we examine shocks to a crop??s own acreage and to total cropland. This allows us to estimate the effect of dedicating cropland or non-crop farmlands to biofuels feedstock production. A negative shock in own acreage leads to an increase in price for soybeans and corn. Our calculations show that increased corn ethanol production during the boom production year 2006/2007 explains approximately 27% of the experienced corn price rise.     

农作物区域产量保险风险区划指标体系研究

划分农作物区域产量保险风险分区的关键是确定区域大小及指标体系,难点是如何尽量将必要却难以量化的指标合理量化。本文以划分湖北中稻县级产量保险风险分区为例,探讨如何在综合考虑气候、农业灾害、地形地貌、水利设施等因素的基础上,建立一个适当的指标体系,其中包括少数量化具有一定难度的重要指标。     

退耕还林工程的环境改善功能对种植业的影响分析

利用因果分析法和面板数据法分析了我国林草地的增减变动对种植业的影响.结果表明,在退耕还林工程实施以前,林草地的减少所引致的环境退化对种植业造成了负面影响;工程实施后,中部、东部地区林草地的增加促进了种植业单产的提高,而西部地区尚未建立起这种关系;通过退耕还林工程来改善农业生态环境,对种植业具有经济功效.     

宁夏平原天然状态下作物水分亏缺研究

本文以宁夏平原为案例,对天然状态下的农田水分平衡状况进行了深入的定量研究,采用长系列(1961～2001年)、短时段(月)和多种作物类型(8种)相匹配的操作方法,建立农田水量平衡模型,计算得到了宁夏平原各个县域单元、各种作物、逐年、逐月的有效降水、盈水量、亏水量值。结果表明:自然降水不能满足作物生长发育的需求,水分亏缺是宁夏平原天然状态下农田水分平衡的主要特征;不同作物水分亏缺程度差异较大;宁夏平原未来农业发展必须推行"以水定产"战略。     

Crop burning and forest fires: Long-term effect on adolescent height in India

This paper examines the effect of biomass burning on adolescent health in India. The biomass burning problem is quite acute especially in North India, with some states experiencing forest fires and few states actively engaging in crop burning practice. We combine remote sensing data on biomass burning events with a pan-India survey on teenage girls (TAG survey). We exploit regional and temporal variation in our data to establish the link between occurrence of extremely high levels of biomass burning during early life and adolescent height for girls in India. Our results indicate that exposure to extremely high level of biomass burning during prenatal and postnatal period is associated with lower height (by 0.7 percent or 1.07 cm) later in life. Girls from North India are found to be especially vulnerable to the harmful effects of exposure to biomass burning.     

Risk Preferences and Environmental Uncertainty: Implications for Crop Diversification Decisions in Ethiopia

To the extent that diversifying income portfolio is used as a strategy for shielding against production risk, both individual risk aversion and weather uncertainty could affect crop diversification decisions. This paper is concerned with empirically assessing the effects of risk aversion and rainfall variability on farm level diversity. Unique panel data from Ethiopia consisting of experimentally generated risk aversion measures combined with rainfall data are employed in the analysis. The major contribution of this study is its explicit treatment of individual risk preferences in the decision to diversify, simultaneously controlling for environmental risk in the form of rainfall variability. Covariate shocks from rainfall variability are found to positively contribute to an increased level of diversity with individual risk aversion having a positive but less significant role. We find that rainfall variability in spring has a greater effect than rainfall variability summer??the major rainy season. This finding is in line with similar agronomic-meteorological studies. These results imply that in situ biodiversity conservation could be effective in areas with high rainfall variability. However, reduction in risk aversion, which is associated with poverty reduction, is likely to reduce in situ conservation.     

Stochastic Dominance Analysis of Soil and Water Conservation in Subsistence Crop Production in the Eastern Ethiopian Highlands: The Case of the Hunde-Lafto Area

The aim of this paper is to analyze whether investment in soil and water conservation results in a higher yield and income and/or mitigate variability in yield and income to subsistence farm households in the Hunde-Lafto area. Net returns from crop production with and without soil and water conservation (SWC) are compared based on stochastic dominance (SD) criteria. A non-parametric first order SD and normalized second order are used for data analysis. Analysis is based on the Soil Conservation Research Program (SCRP) database for the Hunde-Lafto research unit. The results of the analysis suggest that adopting a conservation strategy results in higher grain yield and net return than in not adopting. The normalized second order SD analysis results do not support the hypothesis that conservation strategy is unambiguously better than a noconservation strategy in reducing variability in yield and net return to farmers. However, conservation strategy has shown second order dominance at lower levels of yield and income that often correspond to unfavorable rainfall conditions. This makes it a preferred strategy to cope with the most prevalent risk factor of moisture shortage. Therefore, appropriate policies to help and encourage farmers to adopt SWC structures will contribute to improving the welfare of subsistence farm households in the study area and in other similar settings in the country. Designing and implementing SWC techniques that may result in unambiguous second order SD dominance will further improve the desirability and adoption of conservation measures.     

Examining crop price effects on production decision and resource allocation: an ex-ante approach

This article examines the output price effects on the US crop production, employing an ex-ante approach to the differential systems of input demand and output supply. The estimation results of the differential input demand show that the expansion of crop production leads to an increase in acreage (i.e. extensive margin) and a proportional rise in input usage improving yield per acre (i.e. intensive margin). The substitutable relationship between fertilizer and land supports that crop producers have an option to choose either intensive or extensive margin in response to changes in their relative prices. In addition, the estimation results of the differential output supply highlight that the composition of crop supply can be altered by changes in ex-ante crop prices. The estimation results suggest that crop producers substitute corn supply for the supply of cotton, wheat and soybeans or vice versa. Based on the estimated elasticities, the decompositions of profit-maximizing input demand are conducted, which reveals that a change in ex-ante crop prices is associated closely with resource reallocation.     

Estimating bivariate yield distributions and crop insurance premiums using nonparametric methods

Modelling crop yield distribution is crucial in crop insurance premium setting. The correlation between different crop yields due to rotations or systemic risks requires estimation of joint yield distribution for multiple crops. In this article, we apply a nonparametric method to estimate bivariate yield distributions using farm-level yield data of wheat and corn in Shandong Province in China. Then, the simulated yields are used to evaluate the expected indemnity of one traditional and one hypothetical crop insurance programme. Our results reveal that the nonparametric bivariate method is very flexible in shaping the yield probability density functions to estimate local idiosyncrasies and correlation between two crops. It is also feasible to simulate the nonparametric yield distributions at a satisfying level of accuracy. The simulation results show that the hypothetical two-crop insurance contract can be more affordable to farmers than traditional individual crop insurance contracts.     

Smoothing Income against Crop Flood Losses in Amazonia: Rain Forest or Rivers as a Safety Net?

This article examines the role of ex post labor supply in smoothing income in response to crop losses caused by large floods among riverine households in the Peruvian Amazon, where rich environmental endowments permit a variety of resource extractive activities and coping responses. The paper finds that households respond to crop losses primarily by intensifying fishing effort, not by relying on gathering of nontimber forest products, hunting, or asset liquidation. This ex post labor adjustment helps to smooth total income against small crop losses but less well against large crop losses. Both relatively nonpoor households with better fishing capital and poor young households with a physical labor advantage employ this natural insurance in rivers.     

反刍家畜在农业可持续发展中的作用

本文阐述了反刍家畜在农业可持续发展中的作用。反刍动物牛羊是非耗粮型家畜,它们可以利用人类不能食用的草、秸秆和其它农副产品,转化成生物学效价较高的肉和奶。同时喂养反刍动物可以防止环境污染,其粪便可以肥田,也可以经处理后做饲料用。在不适于种粮食的贫瘠土地上种植饲料作物还可以防止水土流失