平衡膳食模式视角下粮食需求预测

[目的]随着时代的进步和社会经济的发展,对粮食安全内涵的理解也在逐步深化,粮食安全内涵不仅包括数量方面,还包括营养健康安全,保障居民营养健康成为粮食安全的新时代内涵。基于营养目标的粮食需求研究,建立营养—消费—生产的粮食生产模式,对引导居民合理健康消费和保障粮食安全具有十分重要的意义。[方法]文章首先分析了我国城乡居民营养消费状况,然后基于平衡膳食模式视角,引入标准人消费系数这一概念对我国未来粮食需求进行了更准确的预测。[结果]城镇居民粮食消费已达到高营养目标,但目前农村居民仅达到低营养目标水平,相当于21世纪初的城镇消费水平;考虑人口结构因素,2020年和2030年粮食需求总量分别为4.8亿t和5.6亿t,比没有考虑人口结构变化时分别减少8700万t和2 600万t。[结论]根据分析结果,提出以下几点政策建议:(1)宣传普及营养健康消费知识,引导居民合理膳食;(2)关注人口结构变动,及时调整粮食安全调控机制;(3)优化食品工业的产业机构升级,提高饲料粮转化率。     

Impact of training on the intensification of rice farming: evidence from rainfed areas in Tanzania

Agricultural development is indispensable for poverty reduction and food security in sub‐Saharan Africa (SSA). This study investigates the impact of rice production training in a modified version of the System of Rice Intensification (SRI) on the performance of small‐scale rice farmers in a rainfed area of Tanzania. Utilizing the plot level variation, we employ propensity score matching (PSM) to assess the impact of training on technology adoption, productivity, and profitability. We also estimate a difference‐in‐differences model with plot fixed effects using recall panel data covering the periods before and after training. We found that trainees achieved an average paddy yield of 4.7 tons per hectare and rice profit of 191.5 USD per hectare on the plots where new technologies were adopted, which is higher by about 1.3–1.8 tons and 119–137 USD per hectare than on the other plots. Our study suggests the high potential of transforming favorable rainfed rice growing areas in SSA so as to achieve a rice Green Revolution through training in modern input use and improved agronomic practices.     

Why projections on China’s future food supply and demand differ

This article analyses the macroeconomic assumptions, demand and supply parameters, and structures of the models used in projecting China's future food supply, demand and trade. Projections vary greatly, from China being self-sufficient in grain to being a net importer of 369 million metric tons of grain in 2030. The differences stem mainly from the approaches chosen to model China's grain production and, in particular, the combined effects of land decline and yield growth. The article also points out improvements needed in future work on modelling China's grain economy, which include accounting for the links between agriculture and other sectors, technical change in the livestock industry and infrastructure constraints on grain imports.     

2035年中国人粮关系情景分析

该文以2035年作为典型年份,研究根据耕地、复种、粮作比例、播面单产、人均消费需求等不同条件组合,讨论不同情景下中国分县的粮食产量和人口承载力,向国家层面汇总,对2035年中国人粮关系的未来前景进行系统分析,探讨不同情景下中国人口-土地-粮食的互动关系,为中国人粮关系协调发展提供决策依据。研究结果表明:在不同耕地、复种指数、粮作比例和播面单产组合下,我国2035年人口承载力在8.79亿人和16.98亿人之间,不同的生产经营和消费方式对中国是否能实现人、粮平衡具有较大的作用。     

1996-2004年中国耕地的粮食生产能力变化研究

研究目的:核算1996-2004年中国耕地资源的粮食总生产能力及其变化,为国家实施耕地保护战略和确保粮食安全提供决策依据。研究方法:以粮食作物审定品种的区域试验产量为基础,在确定充分发挥气候资源潜力的种植制度基础上,计算了各类耕地的粮食单产,乘以全国各县1996年和2004年各类耕地的面积,得到1996年和2004年各县耕地的粮食总生产能力,汇总出各农业生态区以及全国耕地的粮食总生产能力。研究结果:2004年全国耕地的粮食总生产能力为9.20亿t,比1996年的10.81亿t减少1.61亿t。研究结论:虽然与现实产量相比,中国的粮食生产依然有较大的增产潜力,目前粮食安全的耕地资源保障程度较高,但耕地面积大量减少所造成的生产能力损失不容忽视。中国未来粮食安全除了严格耕地保护外,更主要的是靠农业科技进步提高单产能力。     

The Ghana Grains Partnership

A surge in international food prices that began in 2008 led to a variety of responses from African governments, ranging from price controls, trade restrictions and food security stocks, to facilitating longer-term increase in supply-side increases in production. In Ghana, the objectives emphasized broad-based, pro-poor agricultural growth, expansion of high-value cash crops and improved production of food crops. A hybrid of crop rotation plus addition of external inputs of fertilizers in a modern intensified farming regime was seen as a way forward. The Ghana Grains Partnership (GGP) was underpinned by this assumption, addressing a national shortfall in maize through a coordinated and market-led value chain development approach. The Partnership was initially made up of international and national agribusinesses, an agricultural development fund, farmers and farmer associations and a commercial bank and coordinated by Prorustica. The GGP adopted innovative approaches such as the coordination of commercial and non-commercial objectives. The focus on complete agricultural value chains provided a holistic approach to meet the needs of farmers for agricultural inputs and finance and addressed constraints to more effective commodity output markets. The Partnership's basic principles included the setting up of a farmers' grain association with the partners sharing the costs, benefits and risks.     

The grain potential of cultivated lands in Mainland China in 2004

The regional test yields of certificated cultivars of grain crops represent the potential yields for the given region under the current natural and technical conditions. Therefore, it is appropriate to use the regional test yields to estimate the gross grain potential of Mainland China.In this paper, we calculated the grain potential of cultivated lands for each of the 105 agro-ecological regions in China. First, cropping system in each agro-ecological region was assumed to be the best use of the agro-climatic resources. Second, the potential per hectare for each of the crops was calculated for a given agro-ecological region, based on the regional test yields of certificated cultivars of grain crops in a given cropping system. For rain-fed and dry lands, their grain potentials were further modified by water-restricting coefficients. The water-restricting coefficients were calculated by dividing the hydro-thermal potential with the corresponding photosynthesis-thermal potential for different grain crops, which were obtained from Regulations of Farmland Grading. Thereafter, the grain potential per hectare of each agro-ecological region was calculated considering the cropping system and the potentials per hectare of all the crops in the cropping system. The gross grain potential of each county in a given region was then obtained by multiplying the grain potential per hectare and the total area of cultivated lands in the county. Finally, the gross grain potential of each agro-ecological region and the whole Mainland China were obtained by summarizing the grain potentials for all of the counties. The results showed that the gross grain potential of Mainland China was 0.92 billion t in 2004. It should be pointed out that this calculation on the grain potential did not sufficiently consider the crop growth restricting factors of cultivated lands, such as soil fertility, fertilizer input, and so on. Since the grain potential is far above the actual grain yield, it suggests that the cultivated land assurance for grain security in Mainland China is relatively high. The results of each agro-ecological region showed that the highest grain potentials were distributed in Huang-Huai-Hai Plain, Northeast China, Middle and Lower Reaches of Yangtze River and Sichuan Basin, where excellent hydro-thermal condition and flat terrain are ideally suitable for crop growth.     

Climate adaptation imperatives: untapped global maize yield opportunities

Climate change represents an unavoidable and growing challenge to food security, imposing new adaptation imperatives on all farmers. Maize is arguably the world's most productive grain crop, as measured by grain yield. However, maize yields vary dramatically due to many factors, including soils, climate, pests, disease, agronomic practices, and seed quality. The difference between observed yields and those achievable by optimized crop production methods is called the yield gap. In this work we quantified the current yield gap for 44 countries through the use of a large private-sector data set recently made available to the crop modelling community. The yield gap was quantified for three groups of countries, categorized by level of intensification. Observed yield gaps for high, medium, and low levels of intensification are 23%, 46%, and 68%, respectively. If all maize production countries were able to shrink their yield gap to 16.5% (as in the USA) an additional 335?million metric tons (MMT) of maize grain would be produced. This represents a 45% increase over the 741?MMT produced by these countries in 2010. These data demonstrate that a major untapped maize yield opportunity exists, especially in those countries where intensification has not kept pace with the rest of the world.     

产销平衡区粮食安全评价及形势分析——以甘肃省为例

[目的]粮食安全是社会稳定、经济发展的基础和前提，评估粮食安全状况、分析粮食安全形势，可为科学选择新时期粮食安全战略路径、推进乡村振兴战略实施，促进经济持续发展、构建生态屏障提供决策依据。[方法]文章以粮食产销省份甘肃省为区域，选择粮食产消、粮食供需、口粮保障、粮食储备、粮食流通和粮食生产等6个指标，系统评价2010—2020年区域粮食安全状况；运用产销平衡区粮食安全预警模型，评估近10年甘肃省粮食储备、流通和供需等结构体系的安全性；采用GM (1, 1)模型和线性回归组合模型预测粮食生产趋势，评估近10年甘肃省粮食生产的稳定性。[结果]（1）甘肃省粮食自给率高，人均粮食生产占有量达到了FAO要求的安全水准以上，粮食储备充裕并逐步向合理的储备规模调整，省内外粮食购进和外销保持稳定的流通态势，粮食总供求个别年份出现短缺轻警，总体保持紧平衡态势。（2）2021—2030年甘肃省粮食产量趋势增加，变化范围在1 159万～1 335万t，粮食生产实际产量高于趋势产量，但粮食生产波动指数年际间变幅较大，粮食生产的稳定性欠佳，且主要的口粮作物小麦呈隐性减产态势。[结论]（1）政策支持、财政资金扶持...     

Critical issues suggested by trends in food,population, and the environment to the year 2020

This article reviews the emerging trends in global food supply and demand up to 2020, and discusses policy challenges and obstacles to meeting this demand. Data were obtained from the International Food Policy Research Institute's International Model for Policy Analysis of Commodities and Trade (Rosegrant et al.). The country-specific data pertains to 37 countries and regions and 17 food commodities and prices in the world market. Cereal prices are expected to decline by about 11% by 2020; meat prices may decline by 6%. After 2010, cereal prices are expected to dramatically decline. Cereal demand will change with changes in income and urbanization. Maize and coarse grains will be replaced by wheat and rice. Life style changes may lead to a switch from rice to wheat. Growth in food consumption in developed countries will slow. A projected 82% of growth in global cereal consumption and almost 90% of increased global meat demand will occur in developing countries during 1993-2020. Asia alone will account for 48% of increased cereal consumption and 61% of increased meat consumption. 88% of food production growth will occur in developing countries through increased yields and 94% in developed countries. World trade in cereals will increase from an estimated 185 million metric tons annually to 328 million during 1993-2020. Food security for the poor and child malnutrition will remain unimproved. Yield growth is affected by agricultural research, fertilizer and energy use, land degradation, water scarcity, and bad policy. Water scarcity is the most limiting on yield growth. Malnutrition problems present multiple challenges.     

四川省粮食生产变化及供给侧结构性调整——基于1985~2016年统计数据

［目的］对四川省粮食生产变化、供给侧结构进行分析,结合政策提出供给侧结构性调整对策,为四川省粮食供给侧结构改革提供理论依据。［方法］采用数理统计法和比较分析法,应用 Excel软件对1985~2016年四川省粮食总产和主要粮食作物产量、粮食单产和主要粮食作物单位产量、粮食总播种面积和主要粮食作物播种面积、人口数量等数据信息进行系统化整理,统计和比较分析四川省粮食生产的动态变化及其供给侧结构特征。［结果］（1）总产量基本稳定在3000~3500万t之间, 32年间增产23年,减产9年。近11年来单产连续增长,变化幅度范围为4218.9~5397.5kg/hm2,涨幅为21.8%。播种面积近年来基本稳定在640万hm2。（2）玉米的总产量增产贡献最大,中稻在减产中份额最多,小麦的产量连年持续减少,豆类的产量总体持续增加,薯类产量增加多于减少。全年粮食以及中稻和玉米在2016年单产水平达到最高,其中玉米增幅最大,其次为薯类。几种主要的粮食作物播种面积占比为95%~99%。中稻占比最大,其次是小麦,两者占比高达50%左右。其他作物播种面积占比逐渐增加。（3）口粮总消费量总体呈现下降特征,与粮食总产量相比,足以满足口粮需求; 但饲料和酿酒用粮需求缺口较大,需要从省外调入,调入品种主要是玉米、小麦和杂粮; 全省粮食供求形势产不足需、转化用粮缺口较大。居民粮食消费由主要满足量的需求升级为注重满足质的需求。［结论］（1）粮食总产量总体平稳波动增长。总产量变化因素中,单产贡献率大于面积贡献率;（2）粮食单产总体逐步提高,全年粮食以及中稻、玉米单产水平突破了历史水平,单产受中稻单产影响最大;（3）粮食作物播种面积基本稳定。中稻和小麦占比最高。玉米、薯类、豆类播种面积逐年增加;（4）口粮总消费量整体减少,饲料和酿酒用粮缺口较大,全省粮食供求紧张、转化用粮缺口较大。城乡居民粮食消费急需由量到质升级。     

CARBAP and innovation on the plantain banana in Western and Central Africa

Plantain is considered as a major staple food in Central and Western Africa with a production estimated at approximately 8 million tons (Lescot, 2007). But almost all small producers do not have access yet or do not use the innovations from research, and yields are thus very low. CARBAP (African Research Centre on Banana and Plantain) is a novel example of a regional research partnership for plantains and bananas across Western and Central Africa and particularly Cameroon, Democratic Republic of Congo, Côte d'Ivoire, Ghana, Guinea and Nigeria. It links researchers, creates novel platforms, undertakes training and disseminates materials. It encourages mass propagation by farmers—after training, some 10 million new disease-resistant plants were spread to farms over two years.     

The Malawi agricultural input subsidy programme: 2005/06 to 2008/09

Malawi's implementation of a large-scale agricultural input subsidy programme has attracted significant international interest. This paper reviews the programme from 2005/06 to 2008/09. Nationwide disbursement of heavily subsidized fertilizers and seed to large numbers of beneficiaries represents a significant logistical achievement and substantially increased national maize production and productivity, contributing to increased food availability, higher real wages, wider economic growth and poverty reduction. However, the latter years of the programme have been accompanied by high international fertilizer prices and costs and high maize prices, the latter undermining the programme's food security, poverty reduction and growth benefits for many poor Malawian farmers relying on purchased maize for substantial amounts of their staple food requirements. Estimated economic returns to the programme have been satisfactory, given other programme benefits not captured in cost—benefit analysis. With substantial reductions in both prices and subsidized volumes of fertilizers in subsequent years, there is considerable scope for building on achievements to raise programme effectiveness, efficiency and benefits. Any application of Malawi's subsidy experience to other countries should take into account the special characteristics of the Malawian maize economy and measures needed to raise programmes' effectiveness and efficiency and their contribution to sustainable development policies.     

新一轮国际粮食价格上涨：原因及对中国市场的影响

[目的]随着中国粮食进口不断增加,国内外市场联系越来越紧密。2020年下半年以来,国际市场粮食价格快速上涨,对国内粮食市场产生一定影响,分析国际市场价格上涨的原因和影响对确保国内粮食供应稳定、保障国家粮食安全具有重要意义。[方法]文章分析了2019年以来小麦、大米、玉米、大豆4种粮食产品的国内外价格走势,从供需状况、贸易政策、气候变化等因素分析国际市场价格波动的原因,并探讨了国际价格对国内价格的影响。[结果]当前全球主要粮食品种供应充足,库存仍处于较高水平,此轮国际粮食价格上涨主要是受到美国等发达国家宽松的货币政策以及疫情后全球消费逐步回暖的影响;但国际市场价格上涨对中国市场的影响总体有限,国内小麦、大米、玉米价格上涨的主因是国内消费回暖和生猪产能恢复带动的饲用需求快速增长,油用大豆受国际市场的影响较大。[结论]为稳定国内粮食市场,避免国际市场的冲击,中国要进一步提升粮食综合生产能力,强化科技支撑,加强粮食储备管理,健全政策支持体系,并引导居民建立科学的消费观念。     

基于SD模型的诸城市农业结构仿真优化研究

［目的］预测2017—2035年诸城市农业结构的变化趋势,对农业结构进行多情景优化仿真,提出优化调整建议。［方法］文章以山东省诸城市作为研究对象,将农业结构划分为种植、种养结合和加工休闲3个子系统,选取56个指标,运用多元统计回归分析等方法构建41个方程,建立农业结构系统动力学（System Dynamics,简称SD）模型,运用Vensim—PLE软件进行仿真优化分析。［结果］SD模型预测结果表明,到2035年,粮食作物播种面积1105万hm2,总产量8037万t,经济作物播种面积652万hm2,总产量15203万t; 生猪出栏量达到29615万头,家禽出栏量1105 231亿只,畜禽粪污利用率8792%; 农业总产值达到25132亿元,休闲农业产值6134亿元,食品加工业产值1 25263亿元。假设种植业生产中的农业科技投入增加2个百分点, 2035年粮食作物产量较优化前增加576万t; 经济作物产量较优化前增加2814万t; 假设有机肥施用补贴增加3个百分点, 2035年畜禽粪污利用率较优化前提高762个百分点; 假设农产品加工业的研发力度和科技投入增加1个百分点, 2035年食品加工产值较优化前增加73521亿元; 农产品加工业产值占农业总产值比值由优化前的325：1达到41：1。［结论］为进一步推进诸城市农业结构调整,迫切需要加大农业科技投入,完善有机肥扶持政策,培育种养结合新型经营主体,重点扶持培育加工龙头企业,发展现代化休闲农场,促进农业产业融合发展。     

基于光能利用率模型的河南省冬小麦单产估算研究

[目的]快速、准确估算空间尺度上作物产量,对于评价农田生态系统对气候变化的响应、制定科学合理的粮食政策、对外粮食贸易等具有重要意义。河南省冬小麦产量占全国1/4,准确估算河南省冬小麦产量对维护国家粮食安全具有重要作用。单产估算作为农作物估产中的关键技术,也是作物估产的难点之一。[方法]文章首先利用VPM(Vegetation Photosynthesis Model)估算冬小麦NPP(Net Primary Product),结合收获指数、冬小麦收获部分的含水量、含碳量、NPP分配到地上或地下部分比例等一系列符合该研究区的经验指数,进行河南省冬小麦单产估算研究,并分析了引起模拟误差的原因。[结果]模拟单产较实测单产低估4.4%(实测单产为6 810kg/hm~2,模拟单产为6 519kg/hm~2),但两者之间存在显著相关关系,两者相关系数的平方R2=0.70(n=50,p0.01)。通过与MODIS-GPP产品获得的冬小麦单产数据比较,基于VPM模型的模拟结果优于MODIS-GPP产品。[结论]基于VPM可快速、准确估算河南省空间尺度冬小麦单产,该方法具有较好的适用性。     

Forests to fields. Restoring tropical lands to agriculture

In discussing land use in tropical forest regions, there is an emphasis on the following topics: the need for the expansion of cropping areas, the precedent for use of the tropical forest for cropping based on past use patterns, the pressure from conservationists against cropping, debunking the mythology that forests are "natural" and refuting the claims that forest clearance is not reversible, the archeological evidence of past forest use for agricultural purposes, abandonment of tropical land to forest, and rotation of forest and field. The assumption is that the way to stop food importation is to increase crop production in the tropics. Crop production can be increased through 1) land intensification or clearing new land, 2) output per unit of land increases, or 3) reallocation to agriculture land previously cleared and overgrown with tropical forest. "Temporary" reuse of land, which reverted back to tropical forest, is recommended. This reuse would ease population pressure, and benefit bioconservation, while populations stabilize and further progress is made in international plant breeding. The land would eventually be returned to a forest state. Conservation of tropical forest areas should be accomplished, after an assessment has been made of its former uses. Primary forests need to identified and conversion to farming ceased. Research needs to be directed to understanding the process of past forest regeneration, and to devising cropping systems with longterm viability. The green revolution is unsuitable for traditional cropping systems, is contrary to demands of international funding agencies for sustainability, and is not affordable by most poor farmers. Only .48 million sq. km of closed forest loss was in tropical rainforests; 6.53 million sq. km was lost from temperate forests cleared for intensive small-scale peasant farming. The use of tropical forest land for farming has some benefits; crops in the wetter tropics are perennial, which would "reduce seasonal soil tillage, increase nutrient cycling, and remove a lower proportion of biomass." Water availability would not be a problem. Low soil nutrient levels could be increased with cutting and burning or fertilizer. The key is proper and careful management, particularly under intensive cropping systems such as rice production or extensive long fallow shifting cultivation.     

再论耕地总量动态平衡

研究目的:分析中国耕地保护政策和未来发展的极限状态,提出中国耕地保护新的思维框架,为国家制定相关政策提供参考.研究方法:反演思维法.研究结果:当中国人口达到16亿时,全国用于建设占用耕地的极限值大约在3.39×106ha～3.73×106ha左右.耕地总量到2020年将达到极限水平.到2030年人口高峰来临,尚有一定的耕地缺口.研究结论:变"耕地总量动态平衡"为"农用地总量动态平衡",变"粮食安全"为"食物安全",建立农用地总量动态平衡与食物安全监测与预警制度,从提高复种指数、增加草食养殖等途经保证食物安全.做到:总体控制,动态监测,提前预警,分区管理,统筹兼顾,逐步实施,整体发展.     

粮食生产、生态保护与宏观调控政策

[目的]长期以来,粮食生产与生态保护一直是一对矛盾综合体,为了实现粮食安全目标,人们往往忽略对于生态的保护,通过对二者之间的相互影响机理的分析,提出更好的宏观调控政策。[方法]采用因果分析法对粮食安全框架下的粮食生产和生态保护的演进关系、影响形式和内容进行了研究,最终给出了二者协调发展的粮食宏观调控政策设计对策。[结果]首先,不合理粮食生产活动对生态环境造成的严重破坏,主要体现在水土流失、水资源浪费、化学物质的残留和生态环境的污染;其次,被破坏的生态环境反过来影响了粮食生产的数量和质量,进而对粮食安全产生了威胁。[结论]为了保证粮食安全的目标,长期牺牲生态环境的做法已经带来了严重的后果,这种后果不仅仅表现为当前的生态失衡,更严重威胁了未来的粮食安全。因此,要充分发挥粮食宏观调控政策的作用,加强生态功能设计,具体可从建立农业自然资源保护和有效利用的制度机制、加强政府生态农业的主导型地位及投入水平、以技术进步支撑保护农业生态和粮食安全和以法律手段规范保证相应措施的顺利实施4个方面进行设计和完善。