中国粮食储备行为变化的机理和应对措施：基于农户储备和国家储备的研究

Establishing and maintaining moderate scale of grain reserve is an important means to achieve food security. With annual growth of grain output in recent years, China is trapped in a dilemma of high grain imports and national grains tocks over the same period. Huge changes have taken place in how grain is been produced, sold, and reserved in the context of rising proportion of non-farm income and changing population structure and employment structure. This generates challenges and opportunities to clearly understand the mechanism of micro and macro grain stocks and its impact, so as to maintain food security under rapid transformation. To address this issue, which has largely been overlooked in previous literatures, four main issues would be discussed in this project. First, a household model will be constructed to model how rapid transformation will affect micro farmers making grain sales and storage decisions. Second, this study attempts to quantify how heterogeneous farmers choose grain sales timing and amount by adopting along panel data set with Poisson and GLM (Logit) estimation. Third, this project will perform pioneer research by conducting the estimation of the level and determinants of Chinese farmers’ grain stock, including and comparing both carry-over stocks and stocks at the end of the calendar year. In particular, adult male equivalent scales (AMES) index will be constructed to take into consideration of physical and demographic factors. We will also consider the actual days staying at home of each individual within a household in the context of labor out-migration, to standardize grain consumption needs in order to verify the motivation of food security concerns established. Finally, national level grain stocks will be observed and its effects on domestic and international grain markets will be simulated. With these scientific methodologies, this research is innovative both in theory and practice, and the recommendations put forward will be much more targeted and applicable.

建立和维持适度规模的粮食储备是实现粮食安全的重要手段。近年来随着粮食产量的逐年增长，中国陷于粮食进口数量和粮食库存同期上扬的困局。同时，随着人口和就业结构的变化，非农收入比重的上升，粮食的生产方式和储备行为发生了很大变化。研究转型时期农户和国家粮食储备行为变化的作用机理并提出针对性的措施具有现实紧迫性。本项目将从理论和实践两个层面、宏观和微观两个视角全面探究转型时期粮食储备行为变化的作用机理。通过建立农户模型，应用粮食结转储备和日历年末储备两个衡量标准，定量研究异质化农户粮食销售数量和销售时机选择的变化原因；运用等成人消费权数对人口结构进行标准化，结合家庭成员实际在家居住时间，定量研究农户粮食储备水平的影响因素和储备动机的变化过程；应用宏观数据，研究国家粮食安全储备最优规模，及其变动对粮食市场和农户储备的影响。这些方法的系统应用具有理论研究上的创新性，提出的相应政策建议具有实践意义。

近年来随着粮食产量的逐年增长，中国陷于粮食进口数量和粮食库存同期上扬的困局。同时，随着人口和就业结构的变化，非农收入比重的上升，粮食的生产方式和储备行为发生了很大变化。本项目依据粮食主产省、RCRE、水稻产业研究中心固定观察点等农户调研数据和东亚、南亚和东南亚等主要水稻生产和出口国稻米价值链参与主体微观调查数据，在农户模型理论的指导下，从不同视角对转型时期农户粮食生产方式调整与生产效率、粮食储备动机和水平进行了系统分析和实证考察，开展了如下内容的研究：①宏观层面中国粮食产业竞争力分析；②农户模型理论与应用研究进展综述；③转型时期农户粮食生产行为变化需求驱动与决策研究；④转型时期农户粮食生产环节外包对生产成本和单产影响效应研究；⑤转型时期农业经营规模变化对粮食单产和生产成本影响研究；⑥转型时期农户粮食销售时机选择和粮食储备水平及动机研究；⑦中国与全球粮食安全关系战略研究。研究表明，第一，中国稻米价值链总成本最高，农户和零售商环节成本高是造成成本竞争力差的主要原因，在加工和经销环节有微弱成本优势。第二，劳动力成本上升从需求端驱动农业社会化服务市场发育，增加非农就业机会和非农收入水平会促进生产环节外包，降低价格有助于外包比例的提高。第三，生产环节外包对水稻单产是否存在显著正向影响取决于家庭生产要素投入的机会成本，农业社会化服务可以提高成本效率。第四，耕地经营规模对粮食单产有显著负向影响，但随时间推移持续减弱。耕地经营规模对粮食生产成本也有显著负向影响，但成本优势随时间推移逐渐降低。第五，农户粮食销售时机选择受农户偏好、流动性约束、仓储条件、经营规模等因素影响。价格投机和保障口粮消费安全是农户粮食储备的重要动机。规模种植农户粮食储备的主要动机是价格投机；小规模尤其是老龄农户粮食储备的动机主要是保障口粮消费安全。研究成果在管理世界、CAER等期刊发表6篇论文、专著1部、获奖1项。