规模经营能否提高种植大户的经营效率*——以甘肃玉米种植大户为例

[目的]适度规模经营是提高农户经营效率、实现农民增收的重要途径,对解决目前我国土地利用效率低下问题和保障粮食安全具有重要意义。[方法]文章基于甘肃省280份玉米种植大户和普通农户的微观数据,利用DEA模型,在对玉米种植大户和普通农户的综合效率、纯技术效率和规模效率进行测算的基础上,对比玉米种植大户和普通农户经营效率的差异,探究规模经营能否真正提高玉米种植大户的经营效率。[结果](1)甘肃省经营效率实现最优的玉米种植大户占比较低,大多数玉米种植大户生产效率有待提高;(2)玉米种植大户的综合效率和纯技术效率明显高于普通农户。[结论]绝大部分玉米种植大户经营效率有较大的提升和优化空间,可采取一定的措施提高种植大户的经营效率,使之不断逼近最优经营效率;种植大户的生产力水平高于普通农户,规模经营能够提高玉米种植大户的经营效率。     

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.     

中国燃料乙醇政策演变

迫在眉睫的能源危机促使中国努力寻找替代方案,其中生物燃料乙醇受到最为广泛的关注,并得到迅速发展。然而,中国大多数生物燃料乙醇以玉米为原料,其迅速发展造成原材料玉米价格猛涨,以及饲料价格飚升引发猪肉价格上涨,加上国际粮价上扬的影响,对中国的粮食安全形成威胁。在能源安全与粮食安全的角力中,中央政府选择了以粮食安全为重,连续下发文件对玉米燃料乙醇紧急刹车,要求严格控制玉米燃料乙醇生产,转而开发非粮乙醇。     

玉米的常规储存与管理探讨

为玉米安全度过保管期,保持原有物理性质,延缓玉米的卫生品质指标的下降.根据玉米的储藏特点以及每段时期的保管方法和玉米入库时期的操作情况,总结出玉米的周期保管经验,提出了玉米质量管理的基本要求,包括:把好入库质量关、选择入库时机、粮情检查及粮堆发热诊断等.管理措施的实施有效地减少了玉米的保管损耗,起到了降本增效的目的.     

Policy reform and farmers' coping strategies: The case of corn price shocks in Heilongjiang Province of China

A substantial decrease in corn prices caused by the policy reform in 2016 in China led to heterogeneous supply responses of corn producers: decreasing corn acreage, making no change in corn acreage, and expanding corn acreage. We investigate the causes and consequences of cropland allocation of the supply responses using the balanced panel data on corn-producing households from 2015 through 2016 in Heilongjiang Province. We find that the corn producers largely acted in accordance with their own household resource endowments to make their choice decisions in response to the corn price shocks. Our results show that the decrease in corn prices led to a small decline in total corn acreage and a considerable increase in total acreage for soybeans and rice in 2016 and that the increase in total soybean acreage was more through area expansion rather than through substitution. Our results also show that crop structure for large-scale producers was more responsive to corn price than for medium- and small-scale producers. Given that continuous corn rotation prevails currently in Heilongjiang, our major finding suggests that the acreages planted to corn and soybeans cannot be easily adjusted by the market.     

Risk effects of GM corn: Evidence from crop insurance outcomes and high-dimensional methods

This study evaluates whether genetically modified (GM) corn hybrids with rootworm resistant traits (GM-RW) have lower yield risk. A crop insurance actuarial performance measure, the loss cost ratio (LCR), is used to represent yield risk. High-dimensional methods are utilized in this study to maintain parsimony in the empirical specification, and facilitate estimation. Specifically, we employ the Cluster-Lasso (cluster-least absolute shrinkage and selection operator) procedure. This method produces uniformly valid inference on the main variable of interest (i.e., the GM-RW variable) in a high-dimensional panel data setting even in the presence of heteroskedastic, non-Gaussian, and clustered error structures. After controlling for a large set of potential weather confounders using Cluster-Lasso, we find consistent evidence that GM corn hybrids with rootworm resistant traits have lower yield risk.     

提高农民收入的玉米生产技术选择途径分析

在黄祖辉、刘进宝等人研究的基础上,从理论和实证两个方面分析了玉米技术进步与农民收入之间的负相关关系,采用计量经济模型计算出玉米供给弹性与需求弹性之差约为0.27,充分证明了技术进步对农民收入增长产生了负面影响。在实证分析基础上,对这一现象进行了理论分析,认为玉米为缺乏弹性的农产品,应从减少玉米供给曲线右移幅度和推动玉米需求曲线右移两个方面提出既能够增加玉米产量又能够增加农民收入的措施。     

防止玉米成为“第二个大豆”的战略研究——从产业之囿到破局之策

目的 2020年以来，中国玉米市场发生深刻变化，呈现进口首次突破配额、进口市场更加集中、进口规模增长间隔短和价格创记录4个特点；从长期看，中国玉米供应偏紧、价格倒挂，以及进口量增加难以逆转，玉米正在呈现大豆的苗头性迹象。文章旨在宏观研判玉米发展成为“第二个大豆”的可能性，并从战略布局予以防止。方法 从多方面对比了中国玉米产业和大豆产业特征的异同，为回答玉米是否会成为“第二个大豆”这一问题提供了多角度证据。结果 玉米产业形势相对乐观，不会成为“第二个大豆”，但玉米产业自身的发展特性和中国玉米产业现存的困境不容忽视。结论 科学把控，系统谋划，综合施策，从种植结构调整、良种攻关、全程机械化、优势玉米带建设、烘干设施、“走出去”六大工程着手，解决玉米产业技术装备相对落后、竞争力弱、需求增速快等难题，从战略上防止玉米成为第二个大豆。