Wheat stocks and the cointegration of wheat prices

We examine the effect of wheat stocks on the relationship between port and inland wheat prices in western Canada after the dissolution of the Canadian Wheat Board in 2012. Standard statistical tests find no evidence that the port price is cointegrated with inland prices. We argue that large harvests in 2013–2014 and 2014–2015 are responsible for this lack of cointegration. A simple theoretical model demonstrates how wheat stocks drive a wedge between inland and port prices. After including wheat stocks in the cointegrating vector, we find the expected cointegrating relationships between the port and inland prices. Using an error correction model, we show that a 10% increase in the wheat stocks reduces producer prices in Alberta and Manitoba by 6% and 4%, respectively. We conclude by discussing policy options for reducing the size of wheat stocks on the prairies.     

结合植被指数与作物高度反演冬小麦叶面积指数

[目的]叶面积指数LAI(Leaf Area Index)是反映作物长势的关键参数之一。目前,基于无人机影像进行LAI反演多注重影像光谱信息的应用,但是由于高分影像存在强烈的光谱异质性以及无法区分高密闭度植被垂直方向枝叶的光谱特征等不足,在反演作物LAI时,需要探讨作物高度等结构参数对LAI反演的影响。[方法]文章以冬小麦为例,将无人机影像的光谱信息与点云数据相结合,共同构建LAI反演模型,并与单利用光谱信息的一元线性LAI回归模型进行对比,探讨作物高度信息对LAI反演精度的影响。[结果](1)无人机影像获取的点云数据能有效反演作物高度,其决定系数R~2=0.61,均方根误差RMSE=0.02;(2)基于作物高度和植被指数Ⅵ(Vegetation Index)反演LAI的二元模型(Adjust R~2=0.38,Adjust RMSE=0.55)优于单用植被指数反演LAI的一元模型(Adjust R~2=0.29,Adjust RMSE=0.59),[结论]研究表明作物高度和光谱信息结合的反演模型能够提高作物LAI的反演精度,同时表明作物高度因子在LAI反演中具有重要的应用价值。     

我国小麦生产、消费和贸易的现状分析

[目的]小麦是在全球范围内广泛种植的一种非常重要的粮食作物,在三大粮食作物中保持着收获面积第一的地位。中国既是世界上最大的小麦生产、消费国,也是世界小麦贸易大国。全面多角度地分析我国小麦的供需现状,找出小麦产业发展面临的难题,提供科学合理政策建议,对于优化小麦生产和促进小麦贸易都具有积极意义。[方法]利用2007-2016年的统计数据,采用对比分析法对近年来我国小麦的生产、消费和进出口贸易情况进行研究,通过国际竞争力指标分析法测算了10年间我国小麦国际贸易竞争力水平,并与小麦主要出口国进行比较。[结果](1)我国小麦总体生产能力稳步提升,2016年小麦产量已达到1.29亿t,小麦的生产区域主要集中于河南、山东等省份,大部分省份仅少量种植小麦,小麦的成本收益率相对较低,净利润不断走低。(2)小麦消费量平稳增加,我国小麦的消费量达到1.16亿t,口粮消费占比80%,消费量较大的省份也多分布在小麦主产区,中部地区省份消费缺口相对较大。(3)小麦的贸易量趋向合理,进口量达453万t,我国小麦的供需总体上保持了平衡,但小麦国际贸易逆差较大,小麦的国际竞争力较弱,小麦进口来源过于集中在加拿大、美国等小麦生产大国的状况并未改善,好在哈萨克斯坦和俄罗斯等新兴小麦大国的兴起为我国小麦的多元化贸易提供了契机。[结论]我国要坚持小麦生产以我为主的战略,做好政府服务和市场导向的有机结合,增加农业投入促进小麦高效优质生产,加大科技进步对小麦生产的贡献,合理利用国际市场等措施来保障小麦充分供给,确保国家粮食安全。     

仓储小麦品质变化监控检测研究现状及进展

小麦仓储过程中品质会发生一系列的变化,保持其品质新鲜,控制和减缓粮食品质劣变,不用或少用化学熏蒸药剂,为消费者提供绿色放心粮食,是中国粮食仓储行业目前面临的一项紧迫任务。文章对气调储粮、温湿调控、智能监控、害虫检测、菌群检测等储粮检测方法方式进行了系统阐述分析,综述了仓储小麦品质劣变监控检测的研究进展,并结合当前存在的问题,展望了粮食仓储技术的未来发展趋势。     

Are multiple labels on food products beneficial or simply ignored?

This study examines consumer preferences and willingness to pay (WTP) for organic wheat products exhibiting single labels, as well as multiple labels, including organic. The additional labels considered are related to the organic label (non-genetically modified organism [non-GMO]) or perceived as health-promoting (gluten-free, low-carb, sugar-free). Study data were collected using a consumer survey conducted online in 2017 across 16 U.S. western states and analyzed using random parameter logit models. Findings show that organic-labeled wheat products with additional claims were valued equally or less than the organic only version. Overall, consumer higher objective and subjective knowledge of organic standards, as well as preferences for gluten-free products, increased their WTP for organic wheat products. Consumers unfamiliar with organic standards valued the non-GMO label over the organic label. Additionally, consumer WTP for health-related claims on hedonistic products was low or even negative. Hence, multiple labels on organic products generally provide no additional consumer benefit and are likely ignored. Study findings suggest that using the claim that most distinguishes the product, or is most salient, may improve product pricing. Also, non-GMO certification rather than organic certification should be considered for some markets. Finally, consumers with preferences for gluten-free products represent a potential market for organic wheat products.     

金银花饮片—标准汤剂量质传递研究

为了阐明金银花饮片—标准汤剂量质变化及其分布规律,采用UPLC建立金银花饮片—标准汤剂特征图谱方法,并根据质谱分析进行化合物推断;利用新公式-K值分析化合物传递过程中的规律。结果表明,UPLC特征图谱方法重复性、精密度、稳定性良好;对11个特征峰进行结构推断,确定了9个特征峰：新绿原酸（峰1）、绿原酸（峰2）、断氧化马钱苷酸（峰3）、隐绿原酸（峰4）、獐牙菜苷（峰5）、断氧化马钱子苷（峰6）、异绿原酸B（峰8）、异绿原酸A（峰9）、异绿原酸C（峰11）;由K值分析可知,15批金银花饮片—标准汤剂过程各峰都进行了传递,新绿原酸和隐绿原酸K值大于1,绿原酸K值小于1,与绿原酸异构化生成新绿原酸和隐绿原酸有关;异绿原酸B和异绿原酸C的K值大于1,异绿原酸A的K值小于1,与异绿原酸A异构化生成异绿原酸B和异绿原酸C有关。由此,通过K值可分析金银花标准汤剂中量质传递规律,且符合有机酸类化学成分特性。建立的特征图谱方法准确、稳定、可靠,金银花饮片—标准汤剂新公式-K值能够辅助分析饮片—标准汤剂的量质传递规律,可为后续以标准汤剂为基准的配方颗粒或经典方制剂质量控制提供依据。     

Financialization and commodity prices – an empirical analysis for coffee,cotton, wheat and oil

Commodity prices have crucial implications for developing countries. The question whether the financialization of commodity derivative markets has contributed to high and volatile commodity prices has been controversially debated. Building on limitations in the empirical literature, we estimate a multivariate Vector Autoregressive (VAR) model to assess the effect of different groups of financial investors (index investors and money managers) as well as fundamental and macroeconomic variables on the prices of coffee, cotton, wheat and oil. We find that, in contrast to index investors, money managers’ net long positions have a large statistically significant effect on commodity prices. This calls for policy interventions as commodity derivative markets may cease to perform their fundamental developmental roles.     

Soil CO2 emission and carbon budget of a wheat/maize annual double-cropped system in response to tillage and residue management in the North China Plain

To investigate the impacts of tillage and crop residue managements on soil CO₂ emission and C budget in a wheat (Triticum aestivum L.)/maize (Zea mays L.) double-cropped system in the North China Plain (NCP), a field experiment was conducted consisting of four treatments: tillage with crop residues retention (CT+), tillage with crop residues removal (CT?), no-till with crop residues retention (NT+), and no-till with crop residues removal (NT?). Daily soil CO₂ fluxes changed with crop growing stage and peaked during the most vigorous growth of period, fluxes in maize season were higher than those in wheat season. Compared to the tilled soils, cumulative CO₂ emissions were significantly lower under no-till treatments. The largest cumulative CO₂ emission occurred under CT+ (65?g CO₂-C m^?2 y^?1) and the smallest was under NT+ (39?g CO₂-C m^?2 y^?1). After 5 years of the experiment, soil organic carbon (SOC) sequestration were greater with crop residues retention (CT+ and NT+) than with crop residues removal (CT? and NT?), the maximum SOC stock was in NT+ (5940?g C m^?2) while the minimum was in CT? (3635?g C m^?2). NT+ could help to mitigate CO₂ emission in the annual wheat/maize double-cropping system of the area.     

农机社会化服务对小麦生产技术效率的影响

目的 在中国土地规模经营和服务规模经营并重推进粮食作物效率提升背景下,进一步探讨农机社会化服务对小麦生产技术效率提升效应的规模异质性具有现实意义。方法 文章使用随机前沿分析和门限回归分析,利用2018年全国6省区小麦种植户经营情况,对农机社会化服务影响小麦生产技术效率及影响效果规模异质性进行研究。结果 农机社会化服务的采用有助于提升小麦生产技术效率;农机社会化服务对小麦生产技术效率存在门限效应,当农户经营规模低于门限值（0.293hm²）时,农机社会化服务对小麦生产技术效率不具有显著影响,跨越门限值后,农机社会化服务对小麦生产技术效率则具有正向影响效应。基于农户适度规模经营的情况下,农机社会化服务对中等规模（0.293hm²＜Area＜3.333hm²）农户的小麦生产技术效率具有显著正向影响。结论 农机社会化服务有助于提升中国小麦种植户技术效率,但受限于农户规模,推进农机社会化服务发展的同时仍然需要推动土地的适度规模经营。