中国水稻加工环节成本结构及影响因素分析

［目的］“产业兴旺”是乡村振兴战略中的重要内容,探究中国水稻加工环节成本结构及影响因素,对促进我国农业一、二、三产业的融合,实现农业价值链转型升级,提升我国农产价值链竞争力具有重要的意义。［方法］通过微观调研数据,构建超越对数成本函数和要素需求函数,采用似不相关回归法（Seemingly Unrelated Regression）实证分析我国水稻加工厂的成本及要素投入的影响因素。［结果］（1）稻米加工厂存在规模报酬经济,扩大规模可以降低稻米加工平均成本。（2）建立品牌、与农户形成合同关系、鼓励多元主体经营、公司成立时间、企业能够获得政府支持对降低加工厂的平均加工成本具有正向显著影响。（3）建立品牌、与稻农签订合同、企业负责人的年龄、受教育年限越高对提高加工厂资本投入,促进结构升级具有显著影响。［结论］应采取相关政策措施鼓励稻米加工产扩大加工规模,与上下游形成更为紧密的利益共同体,加强稻米加工企业的品牌意识进而提高我国稻米加工产业的成本竞争力,并鼓励具有更为丰富管理经验、接受更高教育水平的管理者担任企业负责人,在促进我国稻米加工行业的升级转型的同时,提高我国稻米副产品的深度开发利用。     

Is Exchange Rate Pass-Through in Pork Meat Export Prices Constrained by the Supply of Live Hogs?

The impact of lags in the production and marketing of agricultural products on the degree of exchange rate pass-through in export prices is investigated. The predictions of the theoretical model are tested by investigating Canadian pork export prices in the United States and Japan. The empirical methodology accounts for unit root and cointegration using the dynamic seemingly unrelated regression framework and a minimum distance estimator. Predetermined hog supplies have a statistically significant impact on export prices of two out of three Canadian provinces. The degree of misspecification involved with standard pass-through models that do not account for production lags is also illustrated.     

2000~2015年新疆粮食生产时空演替与驱动因素分析

［目的］分析2000~2015年新疆粮食生产的时空演化特征及驱动因素。［方法］文章采用了重心迁移、聚类分析和似无关方程组模型。［结果］（1）2000~2015年间,粮食总产呈波动上升趋势,播种面积呈现“减少—增加”态势,小麦和玉米是新疆最主要的粮食作物,小麦优势地位略有下降,玉米增势明显,水稻、豆类、薯类亦呈下降趋势;（2）“北牧南耕”传统农业格局已被打破,形成天山南北坡两个粮食主产区,人均粮食占有量区域差异增大,未来“北粮南运”趋势可能进一步增强;（3）新疆粮食主产区相邻单元空间趋同性增强,部分粮食作物空间集聚特征逐渐凸显,玉米最显著,小麦、水稻次之,豆类、薯类不明显;（4）似无关方程组回归结果显示,要素投入、社会经济、资源环境、技术水平和市场要素是影响新疆粮食作物生产空间格局变化的主要因素。［结论］为优化粮食生产布局,需要调整不同作物种植结构,适度发展规模经营,加强技术推广应用,同时加强支农政策力度和政策引导。     

保护性耕作技术的农户增收效应与作用机制

目的 探索保护性耕作技术采纳对农户收入的影响机制,评估保护性耕作技术的农户增收效应对促进保护性耕作高质量发展、推动中国农业发展方式转变具有十分重要的理论价值和现实意义。方法 文章基于粮食种植户调研数据,采用工具变量法、分位数回归以及内生处理效应模型考察保护性耕作技术的农户增收效应及其作用机制。结果 保护性耕作技术采纳对农户增收具有显著的促进作用,但这种增收效应在不同收入群体之间存在差异,其中低收入农户从保护性耕作技术采纳中的获益多于中、高收入农户。此外,保护性耕作技术采纳主要通过增加粮食产出来促进农户增收,尚不具有通过促进非农就业来提高农户收入的作用机制。结论 健全保护性耕作农机作业服务对低收入农户的倾斜扶持,瞄准保护性耕作机具补贴和投入力度,完善适用于当地农业生产实际的保护性耕作技术路线。     

1978~2014年间中国玉米生产的时空特征变化研究

［目的］厘清中国玉米生产的时空变化特征,有助于保障玉米的持续、稳定供应。［方法］文章采用经验模态分解等方法,基于玉米总产、播种面积及单产3个指标,从全国和省域两个尺度系统分析1978~2014年中国玉米生产的时空特征。［结果］（1）研究期间,全国玉米产量增加了1.60亿t,其波动量呈现先增大后减小的趋势,波动指数的变化幅度不大; 玉米播种面积增加了1716万hm2,其变化趋势与玉米总产量的变化趋势基本一致;玉米单产从1978年的2802.7kg/hm2波动性增至2014年的5809.1kg/hm2,总体波动幅度大于玉米播种面积和总产量的波动幅度。（2）研究期间,省域玉米增加量呈现出“北高南低”的特征,中国玉米生产重心进一步北移;省域玉米播种面积增加量呈现出“北高南低”“西高东低”的特征,东北区和华北区的玉米播种面积进一步扩大;省域玉米单产增加量呈现出“西高东低”“北高南低”的特征,省域单产以趋势增长为主,但年际间的波动较剧烈。［结论］1978~2014年,省域间玉米生产分异特征明显,建议制定差别化的玉米生产策略。     

The spread of Conservation Agriculture: justification,sustainability and uptake

Conservation Agriculture (CA) has been practised for three decades and has spread widely. We estimate that there are now some 106 million ha of arable and permanent crops grown without tillage in CA systems, corresponding to an annual rate of increase globally since 1990 of 5.3 million ha. Wherever CA has been adopted it appears to have had both agricultural and environmental benefits. Yet CA represents a fundamental change in production system thinking. It has counterintuitive and often unrecognized elements that promote soil health, productive capacity and ecosystem services. The practice of CA thus requires a deeper understanding of its ecological underpinnings in order to manage its various elements for sustainable intensification, where the aim is to optimize resource use and protect or enhance ecosystem processes in space and time over the long term. For these reasons CA is knowledge-intensive. CA constitutes principles and practices that can make a major contribution to sustainable production intensification. This, the first of two papers, presents the justification for CA as a system capable of building sustainability into agricultural production systems. It discusses some of CA's major achievable benefits, and presents an overview of the uptake of CA worldwide to 2009. The related paper elaborates the necessary conditions for the spread of CA.     

Efficient Estimation of Hedonic Inverse Input Demand Systems

This article is concerned with efficient estimation of characteristics demand. We derive and estimate an inverse input demand system for quality characteristics by using 172,946 observations over 881 trading days in the Icelandic fish auctions. An improved estimation method based on an expanded random coefficient model is suggested as an alternative to the currently used two-stage method of Brown and Rosen . The estimates demonstrate the improved efficiency of the suggested method. A number of empirical results emerge, including a general increase in the demand for quality.     

我国玉米主产区生产成本效率分析*——基于吉林、河北和四川3省调研数据

［目的］通过实证分析2017年吉林、河北和四川3个玉米主产省份的玉米生产成本效率,及其与生产要素的相关性,为提高玉米生产成本效率,降低生产成本,研究提出有效的政策建议。［方法］文章采用2017年吉林、河北和四川3省的玉米生产投入情况的调研数据,运用数据包络分析法测算3省的玉米生产成本效率,通过最小二乘法测度要素投入与成本效率的相关性。［结果］吉林省（070）的成本效率远高于河北（039）和四川（035）,3省的种子、化肥和机械投入对成本效率的影响存在较大地区差异。河北省和四川省的劳动力对成本效率的影响较大,吉林省的土地机会成本对成本效率的影响较大。［结论］建议调整种植结构,改善种植方式,整合资源,以增强农业生产能力。     

Agricultural mechanization and reduced tillage: antagonism or synergy?

This paper reviews agricultural mechanization and reduced tillage use in the context of sustainable intensification in developing country agriculture. The scoping review includes selected and contrasting cases – including Zimbabwe (manual systems), Bangladesh (2-wheel – single axle tractor systems), India (4-wheel – i.e. 2 axles tractor systems), Kazakhstan (mechanized systems) and Brazil (diverse systems). The expansion of reduced tillage appears strongly associated with the level of agricultural mechanization – facilitated by a number of common drivers and contextualized by the prevailing farm power and intensity of tillage. Soil conservation, timely planting and farm power savings in crop establishment are important drivers for the expansion of reduced tillage across the world, facilitated by conducive markets, institutional and policy environments and the integration of diverse actors to introduce, adapt and promote the necessary components.     

基于ARIMA模型的中国玉米单产潜力分析

在中国玉米单产的AEZ(农业生态区划)模型潜力基础上,运用ARIMA(自回归单整移动平均)模型,基于1949—2018年数据预测2023年前中国玉米单产.结果表明:2019、2020、2021、2022和2023年中国玉米单产分别为6293、6458、6627、6801和6979 kg/hm2,分别是AEZ模型潜力上限...     

旱作农区土壤风蚀过程、影响因素及其防治技术措施

我国北方旱作农业区土壤风蚀问题十分严重,不仅对当地形成生态灾难,而且风蚀的细粒物质可随风榆移到很远的地方,对广大地区的环境造成影响,尤其在沙尘暴期间,这种影响更为突出;加强北方早作农田土壤风蚀防治工作十分重要,应根据土壤风蚀发生的过程。针对影响风蚀的因素,采取有效的防治技术措施,加强土壤风蚀的防治;在查阅文献的基础上,对土壤风蚀的过程、影响闲素、防治的主要技术措施进行了较全面的分析和阐述。     

吉林省西部半干旱区玉米节水高产高效研究

吉林省西部半干旱区在乾安和前郭县选用15hm2耕地采用滴灌灌溉、地膜覆盖、大垄双行、高产品种、合理施肥等一系列综合配套技术,变雨养农业为雨养农业和设施农业相结合的现代农业,达到了节水、高产、高效的目的。     

Smallholder Demand for Maize Hybrids in Zambia: How Far do Seed Subsidies Reach?

We add to an emerging body of literature on input subsidies in Africa south of the Sahara. Our analysis focuses on demand for seed, characterising smallholders with a high predicted demand for hybrid seed who were not reached by the subsidy programme. We use cross‐sectional data from the 2010 agricultural season and an instrumented control function approach to test the hypothesis that the subsidy on hybrid maize seed in Zambia is selectively biased. Consistent with other literature, we find that the subsidy is a recursive determinant of seed demand, but in 2010, its recipients had more land, more assets, and lower poverty rates. Findings illustrate the social costs of the programme as currently designed and highlight the need to build alternative supply channels if poorer maize growers are to grow hybrid seed.     

河北省夏玉米需水量变化特征及未来可能趋势

基于1963—2015年近50年间河北省夏玉米主产区8个气象站点气象资料,采用联合国粮食与农业组织(FAO)推荐的Penman-Monteith模型和作物系数法计算夏玉米需水量,再结合《IPCC排放情景特别报告》中的两种排放情景RCP2.6(低排放情景)和RCP8.5(持续排放情景)预估的未来气候情景,探讨气候变化下未来河北省夏玉米需水量的时空演变规律。结果表明:1963—2015年河北省夏玉米需水量呈现下降趋势,在空间上大致以黄骅为高值中心,由东北向西南逐渐递减,并在邢台形成低值中心的分布特征;从未来气候变化情景来看,相对于基准时段(2015年),RCP2.6和RCP8.5情景下,在2020年、2030年、2050年、2070年未来4个典型年份夏玉米的需水量均表现出增加的特征。     

逐步回归分析在经济林产品需求预测中的应用

详细分析了逐步回归模型的基本原理,以五种水果为例,利用1991～2007年数据,论述逐步回归在经济林产品需求预测的应用过程,最后依据所建模型对2008～2012年各种水果需求进行预测及分析。