基于LMDI的吉林西部地区粮食产量变化的影响因素解析

吉林西部地区是吉林省粮食生产的增长极,是促进吉林省粮食产能持续稳定增长的重要保障区域。本研究应用LMDI模型系统分析了2000—2019年吉林西部地区粮食产量变化及其影响因素,量化了粮食播种面积、种植结构、粮食单产对粮食产量变化的效应大小,并分析其时空变化特征。结果表明,2000—2019年吉林西部地区粮食产量增加825.02万t,播种面积效应起到明显的正向作用,增产452.33万t,结构效应增产141.38万t,单产效应增产231.32万t,贡献占比分别为54.83%、17.14%和28.04%。从时间变化上看,面积效应2009年出现最高值194.94万t,2017年出现最低值-74.86万t;结构效应2004年出现最高值74.54万t,2002年出现最低值-21.66万t;单产效应在时间上波动强烈,最高值出现在2005年(407.47万t),最低值出现在2009年(-429.69万t)。在空间分布上,面积效应最高值为长岭县,最低值在宁江区;结构效应最高值在扶余市,最低值在通榆县;单产效应最高值在前郭县,最低值在洮北区。受脆弱生态环境约束,未来吉林西部作为资源脆弱地区应谨慎扩大耕地面积,以优化种植结构、提升粮食单产为主,实现粮食长期可持续增产。

农村人口老龄化对我国粮食产量变化的影响——基于粮食主产区面板数据的实证分析

文章基于2001-2015年间我国粮食主产区相关数据,实证分析了农村人口老龄化与粮食产量变化以及投入要素边际效应的关系。结果表明:农村人口老龄化对粮食产量变化产生了显著负向的影响,农村人口老龄化下粮食产量得以保持增长的原因主要是粮食播种面积和化肥使用量的增加;农村老龄劳动与化肥以及机械等要素之间存在替代关系,与正常劳动、粮食播种面积、农药、农用薄膜等要素之间存在互补关系,农村老龄劳动比重的增加减弱了化肥以及机械对粮食产量变化的边际作用,但强化了正常劳动、粮食播种面积、农药、农用薄膜的边际作用。在农村人口老龄化和农业供给侧结构性改革双重背景下,既要保持粮食产量持续增长又要实现绿色粮食生产,需要在保护地力,提升耕地质量,加快培育新型职业农民、加快农业机械化的普及以及培育新型农业服务主体等方面采取合理的政策。

小波理论运用于粮食产量变化的实例分析

小波分析是应用数学的一门分支,在各个领域都有着广泛的运用.对小波变换的方法步骤进行了阐述,并以成都市建国以来粮食产量年际变化为实例,进行了分析实践.实例表明,小波分析的成果能够很好地为区域粮食政策服务.

陕西省耕地数量变化对粮食总产的影响

对1978年以来陕西省粮食总产量、耕地面积的变化以及相关影响因素进行统计分析,结果表明,陕西省耕地资源数量呈持续减少趋势,其主要原因是生态退耕和农业产业结构调整,其次为建设用地、灾毁等;粮食总产量呈波动上升趋势,粮食总量年变化率与粮食播种面积年变化率、耕地面积减少量和因其导致的粮食减产量变化趋势高度一致,说明耕地面积的减少直接导致粮食产量的减少,耕地资源数量是影响陕西省粮食产量的重要因素。因此,保持一定数量的耕地面积的动态平衡是保障粮食安全的先决条件。

吉林省吉林市粮食安全预警研究

中国是世界第一人口大国,人口基数大,增长速度快,所以中国的粮食安全问题尤为重要。综合考虑了自然、社会和经济水平等因素,立足于粮食供给与需求的平衡关系,并结合人口数量、物价变化等因素,提出了粮食产量变化率和粮食安全指数计算方法,并通过WOFOST模型对未来年度的粮食产量进行预测,来判断吉林省吉林市的粮食安全状况,得出了该市暂无粮食危机的结论。

Quantitative Assessment of Impacts of Climate and Economic-technical Factors on Grain Yield in Jilin Province from 1980 to 2008

Climate change is one of the most important challenges threatening agricultural grain yield and food security. Determining the factors influencing grain yield in Jilin Province and the weights of their contribution are a very important task, because Jilin Province is an important agriculture base in China. In this study, the accumulation factor sequence evaluating data method was used to analyze the climate and economic-technical factor contribution weights to grain yield and grain yield changes in each city of Jilin Province. Climate yield was also estimated to study the climate effect on the grain yield, and it was calculated in two ways： an improved algorithm and a traditional quadratic method. The results show that the climate and economicechnical factors have different contribution weights to grain yield in different cities in Jilin Province. The contribution weight of the climate factor to grain yield was 0.212-0.349, while that the economic-technical factor was 0.651-0.788. Furthermore, the changes of the climate factor contributing to grain yield changes accounted for 0.296-0.546, and the changes of the economic-technical factor accounted for 0.454-0.704. The weights of climate and economic-technical factor contributing to grain yield are very different between the eastern and western cities in Jilin Province, but their weights contributing to the grain yield change are similar in these cities. In general, the amount of fertilizer used per hectare （FUPH） is the main factor affecting grain yields and yield changes from 1980 to 2008. It is noted that when the FUPH growth rate stabilized after 1995, the effects of the climate factor on the grain yield become more obvious than before. The improved algorithm is effective for esti- mating climate yield in Jilin Province, and the climate yields were mostly between -500 kg/ha and 500 kg/ha, and showed a slightly rising trend in most cities.

Impact of Climate Change on Rice Water Demand and Food Security： Case of Thailand and Vietnam

Water plays an important role in food production especially rice. Rice productivity depends greatly on sufficient water to meet evaporative demand and soil moisture. It is certain thalL rice, the most important crop of Thailand and Vietnam, is vulnerable to climate change. This paper proposes an analysis on the impact of climate on rice water requirement and food security in Thailand and Vietnam. Water demand, yield and production of rice were computed under the changed surface air temperature for three time slices, namely 2020s, 2050s and 2080s. Food security was analyzed from rice supply （calculated milled-rice product, rice stock, and imports） and demand （domestic uses from population growth, exports to world market, domestic seed and other uses）. The result showed that, under the higher surface air temperature scenario, water requirement office in Thailand and Vietnam could increase by 1.8 times in the end of the 21 st century. Production of rice dropped by declined yield. Thailand and Vietnam which is the world largest rice exporter in last decades will face the rice shortage in 2080s and 2030s respectively.

Two centuries of April-July temperature change in southeastern China and its influence on grain productivity

China is a traditional agriculture based country and one main region for crop production is southeastern China where temperature is a dominant climate variable affecting agriculture. Temperature and social disturbances both influence crop production, yet distinguishing their relative impacts is difficult due to a lack of reliable, high-resolution historical climatic records before the very recent period. Here we present the first tree-ring based warm-season temperature reconstruction for southeastern China, a core region of the East Asian monsoon, for the past 227 years. The reconstruction target was April-July mean temperature, and our model explained 60.6% of the observed temperature variance during 1953–2012.Spatial correlation analysis showed that the reconstruction is representative of April-July temperature change over most of eastern China. The reconstructed temperature series agrees well with China-scale(heavily weighted in eastern China) agricultural production index values quite well at decadal timescales.The impacts of social upheavals on food production, such as those in the period 1920–1949, were confirmed after climatic influences were excluded. Our study should help distinguish the influence of social disturbance and warm-season temperature on grain productivity in the core agricultural region of China during the past two centuries.

Elucidating Variations in Nitrogen Requirement According to Yield, Variety and Cropping System for Chinese Rice Production

Better understanding of the factors that influence crop nitrogen(N) requirement plays an important role in improving regional N recommendations for rice(Oryza sativa L.) production. We collected data from 1 280 plot-level measurements in different reaches of the Yangtze River, China to determine which factors contributed to variability in N requirement in rice. Yield, variety, and cropping system were significantly related to N requirement. The N requirement remained consistent at about 18.6 kg N Mg^(-1)grain as grain yield increased from 7 to 9 Mg ha^(-1), then decreased to 18.1, 16.9, and 15.9 kg N Mg^(-1)grain as yield increased to 9–10, 10–11, and > 11 Mg ha^(-1), respectively. The decreased requirement for N with increasing yield was attributable to declining N concentrations in grain and straw and increased harvest index. Super rice variety had lower N requirement(17.7 kg N Mg^(-1)grain) than ordinary inbred and hybrid varieties(18.5 and 18.3 kg N Mg^(-1)grain, respectively), which was a result of lower grain and straw N concentrations of super rice. The N requirements were 19.2, 17.8, and 17.5 kg N Mg^(-1)grain for early, middle, and late rice cropping systems, respectively. In conclusion, the rice N requirement was affected by multiple factors, including yield, variety, and cropping system, all of which should be considered when planning for optimal N management.