Global food demand,productivity growth,and the scarcity of land and water resources: a spatially explicit mathematical programming approach

In the coming decades, an increasing competition for global land and water resources can be expected, due to rising demand for food and bio‐energy production, biodiversity conservation, and changing production conditions due to climate change. The potential of technological change in agriculture to adapt to these trends is subject to considerable uncertainty. In order to simulate these combined effects in a spatially explicit way, we present a model of agricultural production and its impact on the environment (MAgPIE). MAgPIE is a mathematical programming model covering the most important agricultural crop and livestock production types in 10 economic regions worldwide at a spatial resolution of three by three degrees, i.e., approximately 300 by 300 km at the equator. It takes regional economic conditions as well as spatially explicit data on potential crop yields and land and water constraints into account and derives specific land‐use patterns for each grid cell. Shadow prices for binding constraints can be used to valuate resources for which in many places no markets exist, especially irrigation water. In this article, we describe the model structure and validation. We apply the model to possible future scenarios up to 2055 and derive required rates of technological change (i.e., yield increase) in agricultural production in order to meet future food demand.     

新发展格局下虚拟水流动对区域粮食安全的影响

选取2012—2020年中国31个省(自治区、直辖市)的面板数据,基于彭曼公式估算稻谷、小麦、玉米、大豆四大粮食作物的虚拟水含量和贸易流量,通过固定效应回归模型分析虚拟水流动对区域粮食安全的影响。结果表明：粮食作物的虚拟水含量在品种、空间上存在明显的差别,虚拟水从北方流向南且流动量逐年增加;虚拟水净调出量与区域粮食安全呈显著的倒“U”形关系,说明虚拟水在区域间的转移应存在一定限度;播种面积、人均水资源量、农业机械化水平和城镇化水平等因素对区域粮食安全均具有显著的影响。为此,提出了筑牢水利保障、优化种植结构、发展节水农业、提升粮食综合生产能力等保障区域粮食安全的对策建议。     

The impact of water access on short‐term migration in rural India

Migration is an important risk‐reduction strategy for households in developing countries. In this paper, we examine the impact of rainfall variability and irrigation availability on short‐term migration decisions in India. Our results show that both rainfall shocks and the availability of irrigation impact the decisions of households to dispatch migrants. For irrigation, we find that migration responds to costs and that deep fossil‐water wells, which provide a constant source of water, eliminate any benefit of short‐term migration. This suggests that regions with access to more secure and stable sources of water are less likely to rely on migration as an income‐smoothing mechanism, at least in the short run. Whether this holds in the long run will depend on the continued stability and availability of irrigation water.     

The impact of drought and water scarcity on irrigator farm exit intentions in the Murray–Darling Basin

Drought and future water scarcity in the Murray–Darling Basin (MDB) will continue to restructure the irrigation industry in the coming decades. There has been little work conducted in Australia that has modelled farm exit or exit intention. ABARES farm survey data were used to model irrigators’ farm exit intentions across the southern MDB from 2006 to 2013. In particular, we examined the hypotheses that drought and water scarcity positively impacted on farm exit intentions and that it is the poorest performing farms that intend to exit in times of drought. Results revealed that water scarcity impacts varied considerably. There was only weak evidence to suggest that irrigators’ exit intentions were higher in times of drought, but there was stronger evidence to support the influence of a lagged water scarcity impact on farm exit intentions during periods of nondrought (e.g. intending to exit at times when the property market was less depressed). There was also strong evidence that poorer performing farms (measured by rates of return and higher debt over a certain level) were more likely to have exit intentions in drought periods, but not necessarily so in nondrought periods. Older age is the most consistent predictor of farm exit intentions across all industries, though it was most significant in drought periods.     

Impacts of climate change on lower Murray irrigation*

This article evaluates irrigated agriculture sector response and resultant economic impacts of climate change for a part of the Murray Darling Basin in Australia. A water balance model is used to predict reduced basin inflows for mild, moderate and severe climate change scenarios involving 1, 2 and 4°C warming, and predict 13, 38 and 63% reduced inflows. Impact on irrigated agricultural production and profitability are estimated with a mathematical programming model using a two‐stage approach that simultaneously estimates short and long‐run adjustments. The model accounts for a range of adaptive responses including: deficit irrigation, temporarily following of some areas, permanently reducing the irrigated area and changing the mix of crops. The results suggest that relatively low cost adaptation strategies are available for a moderate reduction in water availability and thus costs of such a reduction are likely to be relatively small. In more severe climate change scenarios greater costs are estimated. Adaptations predicted include a reduction in total area irrigated and investments in efficient irrigation. A shift away from perennial to annual crops is also predicted as the latter can be managed more profitably when water allocations in some years are very low.     

The impact of population growth and climate change on food security in Africa: looking ahead to 2050

Providing nutritious and environmentally sustainable food to all people at all times is one of the greatest challenges currently facing society. This problem is particularly acute in Africa where an estimated one in four people still lack adequate food to sustain an active and healthy life. In this study, we consider the potential impact of future population growth and climate change on food security in Africa, looking ahead to 2050. A modelling framework termed FEEDME (Food Estimation and Export for Diet and Malnutrition Evaluation) was used which was characterized to model the impacts of future climate changes (utilizing the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios projections) and projected population growth on food availability and subsequent undernourishment prevalence in 44 African countries. Our results indicate that projected rapid population growth will be the leading cause of food insecurity and widespread undernourishment across Africa. Very little to no difference in undernourishment projections were found when we examined future scenarios with and without the effects of climate change, suggesting population growth is the dominant driver of change. Various adaptation options are discussed, such as closing the yield gap via sustainable intensification and increasing imports through trade and aid agreements. These strategies are likely to be critical in preventing catastrophic future food insecurity.     

Agricultural policies and food systems: Priorities for indicator development

Existing indicators of agricultural protection and support were developed primarily to gauge the market and welfare effects of government policies. They have shed light on a wider range of impacts through their use in economic models and empirical analysis. The rising scale of support to agriculture globally, and continued reliance on market distorting policy instruments, make this work as important as ever. Deeper investments are nonetheless needed to address heightened concerns about the spill-over impacts of agricultural policies on the performance of food systems, in particular with respect to food security and nutrition, rural livelihoods, resource use and the environment, and global emissions. A first area for development is improved measures of policies to correct agriculture's externalities. A priority here is to develop a carbon tax equivalent of sectoral mitigation efforts. A second area is to provide a clearer delineation of government spending on private versus public goods. This would make a valuable contribution to a ‘repurposing’ agenda that seeks to identify how agricultural budgets can be spent more effectively, as well as the scope for transferring resources to wider social priorities, such as public health and climate action.     

The potential impact of markets for irrigation water in Italy and Spain: a comparison of two study areas*

The viability of irrigated systems in Southern Europe is closely linked to efficient institutional settings and water‐allocation mechanisms. A significant, although not widely used, mechanism for water allocation is an intra‐sectorial water market. The objective of this paper is to evaluate to what extent water markets may contribute to the improvement of the efficiency of water allocation and to the profitability of irrigated agriculture. The related issues of water allocation among farm types and farm specialisation are also addressed. The analysis is based on a basin‐level linear programming model, comparing the situation with and without a market. It includes both fixed and variable transaction costs and estimates their combined effects on market performances. The model is applied in two areas in Southern Italy and Spain, and simulates the behaviour of different farm types, derived from cluster analysis on a sample of farms in each area. The paper confirms that water markets could potentially improve the economic efficiency of water use, in terms of higher profit per hectare, given limited water availability. The potential improvements are associated with a more intense specialisation of farms and are strongly differentiated among farmers, particularly where significant restrictions to water availability occur. This corroborates the expectations of institutional difficulties in implementing water markets. However, the exchanges, and consequently the potential effects of water markets, are heavily affected by the actual level of water availability, as well as the size and the structure (fixed vs. proportional) of transaction costs. The paper calls for a more in‐depth analysis of the connections between market performances and institutional settings, as related to the issue of water‐agriculture policy design and coordination.     

气候变化对灌溉井供水可靠性的影响分析*——基于华北井灌区100个村庄的实证调查

[目的]探究气候变化对灌溉井供水可靠性的影响及主要影响因素,以期为政府科学、合理制定相关政策提供实证依据。[方法]基于2010—2012年中国华北5省100个村庄实地调查数据,以作物灌溉面积未受影响比例作为衡量供水可靠性指标,构建村级供水可靠性理论模型,运用多元回归模型,实证分析气候变化对灌溉井供水可靠性的影响及影响因素。[结果](1)长期气候变化显著影响灌溉井供水可靠性,气候变化因素对灌溉井无水和缺水供水可靠性影响方向和作用程度不同;(2)村级灌溉井状况、村级组织灌溉管理状况与极端气候等变量显著影响灌溉井供水可靠性;(3)年份和地区虚拟变量对灌溉井供水可靠性影响存在差异。[结论]提出构建和培育更加完善的农业气象灾害监测预警系统,加强农田灌溉设施建设及维护,推进农业灌溉用水管理制度改革,发展各种形式农民合作组织,是提高中国农业生产适应气候变化能力的重要举措。     

The impact of deforestation,urbanization, public investments,and agriculture on human welfare in the Brazilian Amazonia

The relationship between human welfare and deforestation in the Brazilian Amazonia has traditionally been thought to follow a boom-and-bust pattern. According to this pattern, forest clearing triggers rapid increases in human welfare levels (“the boom”) due to short-term economic gains; these levels then drop to below national or regional averages (“the bust”) after the forest stocks have declined, thus causing the local populations to become deprived of ecosystem services. However, recent studies have questioned the validity of this boom-and-bust pattern. In this paper, we use panel data and simultaneous autoregressive models to evaluate the effects of deforestation, urbanization, public investments, agriculture, and state policies on temporal changes in human welfare that occurred across multiple municipalities in the Brazilian Amazonia from 2005 to 2012, a period during which governments implemented a set of strategies aimed at controlling deforestation across the region. We found that: (a) signals of a boom-and-bust pattern are weak at the regional level, and therefore this pattern cannot be generalized across the entire region; (b) human welfare is increasing more rapidly in low-development municipalities than in high-development cities, and all municipalities are converging on at least one regional average rather than on a national average; (c) urbanization does not lead to positive changes in human welfare, which indicates that the infrastructure available in regional urban centers is limited; (d) public investments are negatively associated with human welfare growth, thus signifying that if public investments are not used to leverage the potential of other sectors of the local economy, human welfare will not improve; (e) agriculture is negatively associated with positive changes in human welfare at the local level, possibly due to the dominance of cattle-ranching as the predominant economic activity of this sector; and (f) state-level policies matter, and future analyses of regional trends in the realm of development and conservation across this region should take such policies into account. Finally, we suggest that although human welfare and deforestation retain a weak statistical relationship, we cannot contend that they have been fully decoupled. Forest loss across the region is still pervasive, and institutions are too weak to sustain the transition from a frontier development model to a conservation-centered model.     

Diversity of Mexican diets and agricultural systems and their impact on the land requirements for food

Mexico is a megadiverse country with large agroclimatic diversity and socioeconomic inequality. These two factors result in strong diversity in diets and agricultural systems within the country. In this paper, we assess the impact of Mexican diets and production systems on the per capita land requirements for food. We estimate it for the extremes: from the very basic diet of the poorest share of the population to the affluent diet of the richest share of the population; and for extensive and intensive systems, with irrigation as the indicator of the intensity of the system. We show that the basic diet produced in rainfed systems requires 1620 m²/cap/yr and produced in irrigate systems requires 700 m²/cap/yr. The affluent diet produced in rainfed systems requires 2540 m²/cap/yr and produced in irrigated systems requires 1230 m²/cap/yr. Hence, differences in diets result in a requirement for 80% or 60% more land for an affluent diet; and differences in production systems result in more than twice the amount of land for extensive than for intensive systems. In 2050, it would be possible to feed the entire population with affluent diets only if all the present area of crop land had the productivity of intensive systems. In contrast, it would be possible to feed all people with a basic diet even if all present crop land area had only the productivity of extensive systems.     

The impact of integrated livestock disease management for food security in Togo

In sub-Saharan Africa, livestock is one of the key channels through which most households meet their food security needs. However, diseases such as the African Animal Trypanosomosis (AAT) constrain productivity. Using data from 445 randomly sampled small-scale cattle farmers, this paper investigates the role of integrated livestock disease control on household food security. Using a novel approach to link different food security measures to cattle productivity, the paper identifies the channels of impact at the household level. Methodologically, the paper estimated the propensity score matching algorithm to net out the effect of adoption. The results show that households who adopt RDU have record livestock productivity and higher consumption per capita expenditures. They tend to be more food secure, experience lower seasonal food supply fluctuations and experience a lower probability of falling below the food poverty line.     

The impact of temporary uses on property prices: the example of food trucks

Food trucks represent a temporary use of vacant or underutilised land. They have been assumed to increase the livability, vibrancy and attractiveness of a neighbourhood. However, no previous study has investigated whether this effect is reflected in property prices within the surrounding neighbourhood. We investigate the impact of a food truck pod on the values of single-family homes nearby. Using a quasi-experimental design, transaction data from Portland, Oregon and a difference-in-difference specification of a spatial regression model, we find that food trucks actually represent a negative externality, and that proximity of a home to food trucks is penalised by homebuyers. The closer a home is to the food trucks, the lower is the sales price. Explanations for this effect include increased parking shortages and trash issues in a neighbourhood due to food truck visitors.     

The impact of climate change on the external cost of pesticide applications in US agriculture

Agricultural pesticides have adverse impacts on the environment and human health. These impacts are sensitive to climate change because pest pressure and optimal pesticide application rates vary with weather and climate conditions. This study uses the Pesticide Environmental Accounting (PEA) tool and statistically estimated relationships between pesticide applications, weather and climate to compute the impacts of climate change on the external cost of pesticide applications. Using data from 32 US states, 56 crops and 325 pesticides, the current average external cost of pesticide use in US agriculture is calculated at US$42 per hectare. Under projected climate change this value increases up to $72 per hectare by 2100.     

中国水权交易的发展及其试点推广效应

水权交易是目前解决水资源稀缺的一项重要政策工具,亦是中国当前水资源管理改革的重要方向之一。基于中国水权交易所2016—2022年的交易数据对中国水权交易的总体概况、不同交易类型的水权交易特征进行统计描述性分析,并讨论其试点推广效应。研究表明:目前中国的水权交易以取水权交易为主,其次为区域水权交易,灌溉用水户水权交易渐趋活跃;区域水权交易主要表现为用水总量指标在区域间的重新配置,取水权交易主要表现为行业间的取水权交易,而灌溉用水户水权交易主要表现为行业内的水权交易;政府在水权交易中发挥了重要作用,随着水权交易的发展,参与主体开始出现多元化,更多的用水户开始进入水市场;中国的水权交易试点具有一定的推广效应,不仅仅表现为“量”的增多,还表现在交易方式上的创新。中国水权交易未来的发展空间在于不断创新水权交易方式并激励更多的用水户参与水权交易,需要因地制宜推进水权改革,加快推动初始水权的分配与确权工作;同时,还需要进一步完善水资源计量与监控体系,并积极推动水权交易法规制度建设,进一步推进水权交易市场的发展。     

Peasant agency in Ghana's oil palm sector: The impact of multiple markets on food sovereignty

This paper contributes to the debate on peasant differentiation and market integration in the food sovereignty literature by examining the smallholder‐oriented oil palm sector in Ghana's eastern region. Against the background of loosening entry barriers in global value chains, and through an analysis of farmers' different positions in palm oil's multiple markets, we witness peasant‐like patterning of production and strategic market participation among well‐situated non‐contract farmers. We propose that such interface settings where commodity relations are present, but do not penetrate fully offer valuable entry points for revisiting the role of global markets in peasant reproduction in the Global South. We consequently argue the need to replace the idealized category of “peasant” with an analytical category that can recognize social differentiation and reproduction through partial engagement with commodity markets.     

关于加快农田水利供给侧改革的几点思考

我国灌溉面积位居世界第一,主要矛盾由总量不足转变为结构性矛盾,深入推进供给侧结构性改革提上议程。针对存在的主要结构性矛盾,研究提出系统解决方案,即调整结构、去除库存、提升品质、降低成本、补齐短板。调整结构重点是严格落实"以水定地",着力以水资源、水生态、水环境承载能力倒逼灌溉面积调整;去除库存重点是依法实施"僵尸"工程降等报废,及时办理注销登记;提升品质重点是大力发展高效节水灌溉,提升灌溉服务质量;降低成本重点是深化国有灌区管理体制改革,创新"最后一公里"管理模式;补齐短板重点是坚持统分结合、重点在统的原则推进农田水利产权改革,深化农业水价综合改革,建立准确补贴机制。     

我国水产品海／淡比重对城镇居民额外消费支出的影响

我国水产品存在“质量”引致城镇居民额外消费支出现象,论文以Deaton理论为依据,利用VECM模型研究了海／淡产品结构对额外“质量”支出的影响。研究结果表明,海／淡比重调整是我国城镇居民“质量”消费支出增长的诱因,二者呈负相关关系,其中海水贝类与淡水甲壳类是导致该现象的重要因素。因此,一方面对水产品未来需要更全面和细分的价格监控,另一方面扩大海水产品比重（特别是贝类）有利于缓解城镇居民购买水产品时的额外支出增长。     

The positive impacts of irrigation schedules on rice yield and water consumption: synergies in Jilin Province,Northeast China

Food and water security in China are inextricably linked to the development of regional economy, especially for regions with temporary or sustained water shortage such as Jilin Province in northeast China. Water-saving irrigation practices are therefore urgently sought to maintain sustainable growth in grain production. To improve knowledge of the effect of irrigation water level on rice yield and water-use efficiency (WUE), we conducted a field experimental study over two growing seasons in central Jilin. The irrigation experiment included four schedules: (1) traditional irrigation (CK), (2) shallow wet irrigation (T1), (3) intermittent irrigation (T2), and (4) controlled irrigation (T3). Soil test pits were used to estimate evapotranspiration and seepage. The study showed that T3 had the highest WUE (1.64?kg/m³). However, the highest rice yield was found in T1 (9867?kg/ha¹) that achieved the second highest WUE (1.63?kg/m³). Compared with CK, T1 and T3 consumed 7.3% and 36.1% less water, respectively. If adopted at the operational scale, these two schedules could help reduce the pressure of local surface water supply and the production costs significantly. The results gained from this study could also have relevant implication in developing an effective irrigation management for other high-latitude regions.