The role of ‘virtual water’ in efforts to achieve food security and other national goals,with an example from Egypt

The term ‘virtual water’ has been used previously to describe the volume of water embodied in food crops that are traded internationally. This paper describes the economic dimension of the ‘virtual water’ concept as an application of comparative advantage, with particular emphasis on water as the key factor of production. The paper also extends the discussion of ‘virtual water’ by describing a nation’s goals regarding food security within a broader framework that includes other objectives such as providing national security, promoting economic growth, and improving the quality of life for citizens. The analysis suggests that land, labor, and capital must also be considered when evaluating a nation’s production and trade opportunities. In countries where one or more of those resources is limiting, focus on ‘virtual water’ alone will not be sufficient to determine optimal policies for maximizing the social net benefits from limited water resources. In countries where labor is relatively abundant, public policies that promote labor-intensive crop production and processing activities may be desirable. The role of ‘virtual water’ within a broader policy framework is demonstrated using crop production and international trade data from Egypt, where substantial amounts of ‘virtual water’ and ‘virtual land’ are embodied in wheat and maize imports. Policies that promote increased exports of labor-intensive crops will improve rural incomes and enhance food security.     

Irrigation and food security in the 21st century

Global food projections indicate that food prices in the next threedecades will likely be stable or decline, but progress inreducing malnutrition in developing countries will be slow. Smallshortfalls in crop productivity growth would lead to rising foodprices and worsening malnutrition. Increased food production fromirrigation is essential, and will require expansion of irrigatedarea and water supplies, and improved efficiency of use of existingwater supplies. Neither of these growth factors will prove easy, andboth will require complex institutional and policy reforms. Failureto meet food production needs through efficient expansion andintensification of irrigated agriculture would increase pressure onland resources and hasten the process of environmental degradation.Irrigation and water development strategies have been hampered bya lack of understanding of the links between water scarcity, foodproduction, food security, and environmental sustainability.Research to improve this understanding would have high payoffs.     

农业资源利用及粮食生产潜力分析——基于西南中高原地区

从农业自然资源和农业社会资源两个方面论述了西南中高原地区的农业资源利用现状、存在的问题、粮食生产现状和生产潜力,并提出了提升该区域粮食生产潜力的途径:积极发展旱地分带轮作多熟制度,提高复种指数;注重粮食作物种群内在生产力的提高,加大科技创新力度,增强农业科技对粮食生产的支撑作用;控制坡耕地农田径流的非目标性输出;重视耕地质量建设,提高耕地对粮食生产的保障能力。     

Spatial and temporal trends of water productivity in the lower Mekong River Basin

We estimate the physical and economic water productivities of rice and upland crops grown in the Lower Mekong River Basin and we examine their spatial and temporal trends. We discuss the constraints to low productivity, suggest measures for improvement and show the future productivity requirements for food security for increased population. Both the physical and economic water productivities of rice are higher in Vietnam, moderate in Laos, and lower in Thailand and Cambodia. In contrast, the physical water productivities of upland crops such as sugarcane and maize are highest in Thailand. The economic water productivity of upland crops is higher in Laos followed by Vietnam, Cambodia and Thailand, and is much higher than that of rice. However, the economic productivity of all crops is dominated by the productivity of rice, particularly lowland rainfed rice, which is the dominant crop in the Lower Basin. The intra-regional variation (among the provinces within a country) of productivity is not substantial. There is an increasing trend of both physical and economic water productivity in all four riparian countries; however, the increase is more prominent in Laos and Vietnam. The economic productivity of upland crops is much higher than that of rice and therefore cultivation of more upland crops can significantly increase farm-level incomes, with positive impacts on reducing poverty. Increasing upland crops areas is unlikely to have any impact on the food security of the basin. The current rate of increase of both production and productivity of rice is considerably greater than the rate required to feed the expected extra population by 2050, suggesting that food security is not threatened by the population increase. There appears to be considerable scope to increase productivity and maintain the export potential of the basin.     

Role of root and tuber crops in food production strategy for semi-subsistence agriculture

Persistent population pressure on agricultural land in the tropics has led to the evolution of food production strategies heavily weighted towards increasing productivity per unit of land. In many of these same areas, tropical root crops represent a major item in the national food economies. Given this scenario, this paper examines the potential role of tropical root crops in meeting domestic food needs. First, the present contribution of root crops to food production is briefly summarised and used to provide simple guidelines for allocating research resources. These guidelines are somewhat deficient in that they overlook a number of energetic considerations of importance at both the individual producer and national level. To illustrate, a two-goods model of a semi-subsistence agricultural production unit is constructed and some conclusions drawn which lend weight to the opinion that tropical root crop research should receive high priority.     

Co-evolutionary scenarios of intensification and privatization of resource use in rural communities of south-western Niger

Agricultural production in the semi-arid agro-ecosystems of the Sahel centres on cereal staple crops and pastoralism with increasing crop–livestock integration. Animals mobilize soil fertility through manure production, graze crop by-products, and transfer nutrients from distant pastures to cropped areas. Yet in these systems various interacting factors, i.e. climate variability, poor soil fertility, poverty, and institutional constraints limit the capacity of agriculture to keep pace with the growing needs of an increasing human population.The major trends associated with population growth are (1) increasing area cropped at the expense of rangelands; (2) reduced availability of and access to good quality grazing resources, and (3) seasonal migration of labourers and transhumance of herds. These trends lead to co-evolution of farming systems towards increased privatisation of resource use.This study examines the implications of the development processes where farming systems co-evolve with their surroundings. It explores the impact of integrated management of livestock and crops in rural communities on both the livelihoods of differently endowed farms, and on the agro-ecosystem. Different scenarios explored the co-evolution of three sites situated in Western Niger with their environment. The sites differ in relative area cropped. The scenarios simulate the different future outcomes for varying socio-economic and biophysical criteria with either current or more intensive management.Explorative bio-economic models are used to compare a range of farm, livelihood and ecological indicators, and to reveal social and ecological trade-offs.If current agro-ecosystems and their environments co-evolve towards increased privatisation of grazing resources, then soil fertility is likely to deteriorate on the lands managed by the agro-pastoral groups. Soil fertility may improve on lands managed by the livestock-scarce farmers settled in villages, at the cost of declining farm incomes. The agro-pastoral groups are likely to resort to more distant pastures for feed. The village-based, livestock-endowed farms will resort to feeding on on-farm crop residues. Intensification, though associated with relative decreases in real incomes, will enhance food security in these new systems, except for the poorer settled farmers.     

Bases for farm resource allocation in the traditional farming system: A comparative study of productivity of farm resources in abakaliki area of Anambra State,Nigeria

A study was carried out to determine the returns in utilisation of farm-resources in the production of three crop enterprises. These returns determined the productivity of resources in yam-based crop mixture (YBCM), cassava-based crop mixture (CBCM) and rice enterprises.The results show that of the three crop enterprises considered in the survey year, YBCM received special attention in the resources allocated. Prime land, prime labour and a large proportion of household cash were allocated to the production of YBCM relative to other crop enterprises. Cost-return analysis indicated that all scarce resources such as labour, land and capital were more productive in monetary terms in CBCM and rice enterprises than in YBCM.The cultural value of yam in YBCM transcends the monetary and food security values. It includes intangible value such as social status. The special place of yam in the crop production system militates against practical solutions such as the transfer of farm resources from the less productive (YBCM) to the more productive enterprises. Thus it is that improved management techniques such as the use of higher-yielding yam varieties, increase in cropping densities and the use of fertilizers need to be explored as a means of improving the returns of the resources used in the YBCM enterprises.     

改进粒子群算法在农业种植结构优化中的应用

【目的】促进地区农业水资源高效利用,在保证粮食安全的基础上,降低灌溉需水量,推动农业节水、提高产量和效益。【方法】以安阳市为例,以经济、社会、生态和水资源效益最大为综合目标,引入惯性权重衰减和粒子变异策略,建立了基于改进粒子群算法的多目标农业种植结构优化模型。【结果】通过对现状水平年2018年、规划水平年2025年(近期)、2035年(远期)的种植结构调整,在结合现状缺水程度下,压减耗水量大的小麦、玉米等粮食作物种植比例,增加油料、蔬菜及食用菌等经济作物种植比例,经济、社会、生态、水资源目标的综合效益分别提升13.59%、10.90%、9.82%;同时,在满足农作物全生育期需水量的情况下,缺水率分别缩减9.02%、9.56%、9.95%,在一定程度上缓解了农业水资源供需矛盾。【结论】改进粒子群算法使种植结构得到平衡优化,在提高综合效益及产量的同时能够降低灌溉需水量。     

Assessing grain crop water productivity of China using a hydro-model-coupled-statistics approach. Part II: Application in breadbasket basins of China

We assessed the basin-scale crop water productivity (CWP) on staple grain crops, i.e. rice, wheat, maize, soybean, at major breadbasket basins of China over time periods of 1997-2004. The multiple-year average CWP was 1.06 kg m⁻³ for the selected basins (equivalents of 946 m³ water consumption in producing 1 metric ton of crop economic yield), varying from 0.97 kg m⁻³ to 1.18 kg m⁻³. Of all the water consumed in crop production, irrigation water contributes 28-41%, while soil-stored precipitation contributes 59-72%, confirming the crucial yet hitherto under-estimated role played by green water in total crop yield formation. The blue water depletion rate ranges from 0.48 to 0.87, with most of the basins exceeding 0.50, while the green water depletion rate from 0.39 to 0.85, with the majority of basins being beyond 0.60. We conclude that both blue and green water shortage will contribute to water scarcity in grain crop production. The mission of ensuring China's food security will entail multiple trade-offs among water security, ecosystem conservation, environment protection, and human development with increasing challenges in the years to come. However, increasing water productivity through research innovation and technological upgrades at river basin scale is a key to mitigating water stress that may be caused by increasing food production in the coming decades.     

我国农作物秸秆资源量及利用问题研究

我国是世界农业大国,农作物秸秆资源丰富,但长期以来主要农作物秸秆资源的种类、数量及其变化情况不甚明了。为此,在梳理以往秸秆资源量测算及利用文献的基础上,结合我国2013-2019年水稻、玉米、小麦、豆类、薯类等5种主要粮食作物产量数据,科学确定秸秆籽粒折算系数,运用草谷比系数法测算主要粮食作物的秸秆资源量,为我国制定秸秆综合利用政策、规划提供借鉴和决策支持。同时,结合实际找出目前我国秸秆综合利用中存在的问题并提出相应解决对策。     

Exante assessment of dual-purpose sweet potato in the crop–livestock system of western Kenya: A minimum-data approach

Mixed crop–livestock systems have a crucial role to play in meeting the agricultural production challenges of smallholder farmers in sub-Saharan Africa. Sweet potato is seen as a potential remedial crop for these farmers because of its high productivity and low input requirements, while its usefulness for both food and feed (dual-purpose) make it attractive in areas where land availability is declining. In this paper, we develop and apply a ‘minimum-data’ methodology to assess exante the economic viability of adopting dual-purpose sweet potato in Vihiga district, western Kenya. The methodology uses and integrates available socio-economic and bio-physical data on farmers’ land use allocation, production, and input and output use. Spatially heterogeneous characteristics of the current system regarding resources and productivity are analyzed to assess the profitability of substituting dual-purpose sweet potato for other crops currently grown for food and feed. Results indicate that a substantial number of farmers in the study area could benefit economically from adopting dual-purpose sweet potato. Depending on assumptions made, the adoption rate, expressed as the percentage of the total land under adopting farms, is between 55% and 80%. The analysis shows that the adoption rate is likely to vary positively with the average total yield of dual-purpose sweet potato, the harvest index (the ratio between tuber and fodder yields), the price of milk, and the nutritional value of available fodder. This study demonstrates the usefulness of the minimum-data methodology and provides evidence to support the hypothesis that dissemination of the dual-purpose sweet potato could help improve the livelihoods of smallholder farmers operating in mixed crop–livestock systems in east Africa.     

The policy relevance of virtual water can be enhanced by considering comparative advantages

The virtual water metaphor was created originally to gain the attention of public officials responsible for choosing policies that influence the use of water resources in arid regions. Over time, the metaphor has been used in both empirical and conceptual settings, primarily to describe the water used to produce crop and livestock products that are traded in international markets. Several authors have described how water-short countries can enhance their food security by importing water-intensive food crops. Some authors have noted similarities between the virtual water metaphor and the economic theory of comparative advantage. The virtual water metaphor addresses resource endowments, but it does not address production technologies or opportunity costs. Hence, the metaphor is not analogous to the concept of comparative advantage. The metaphor can be helpful in motivating public officials to consider policies that will encourage improvements in the use of scarce resources, but comparative advantages must be evaluated to determine optimal production and trading strategies. The theory of comparative advantage is explained and demonstrated in several scenarios that depict differences in resource endowments and production technologies. Optimal strategies are not always consistent with expectations based only on resource endowments. Policy discussions regarding water resources can be enhanced by considering comparative advantages when evaluating opportunities to import or export agricultural products.     

Bioenergetic and energy constraints in increasing cereal productivity

The grain yield potential of cereal crops such as wheat, rice, barley, oats and sorghum has increased by genetic improvement in the harvest index (grain yield/biological yield). Such alterations in the harvest index were analysed from the point of view of intrinsic energy and nitrogen, phosphorus and potassium requirements. A higher harvest index, without any reduction in biological yield, increases the harvest of: (a) energy (MJ) in the above ground parts of the crop and (b) nitrogen and phosphorus in the grain. In addition, it enhances the fertiliser requirement of the crop. From bioenergetic considerations, higher grain yields, obtained by improving the harvest index, represent a path which demands least increments in photosynthate and nutrient inputs. The other alternatives available for increasing cereal productivity, once the upper limits of the harvest index are reached by breeding, have higher costs in terms of photosynthate and fertiliser requirements (energy inputs). There seems to be no other immediate plant breeding alternative to increase productivity without additional energy (fertiliser) inputs.     

我国马铃薯加工业发展现状及建议

作为我国第4大主粮作物，马铃薯生产对保障国家粮食安全具有重要的战略意义。我国是马铃薯种植大国，却不是马铃薯产业强国，与世界发达国家相比，在品种、加工、产品、装备等方面还存在差距和不足。介绍了我国马铃薯加工业整体情况、目前存在的问题和短板，并从科技创新、产业发展等方面提出了具体建议。      

Land use and land cover classification in the irrigated Indus Basin using growth phenology information from satellite data to support water management analysis

Water resources planning and management is fundamental for food security, environmental conservation, economic development and livelihoods. In complex basins like the Indus Basin, water is utilized by different land cover and land uses. Up to date information about these Land Use and Land Cover (LULC) classes provide essential information on the water flow path. Traditionally, landscapes are described by cover type. For water management analysis, the information on land use is vital. To this end, a classification of LULC in the Indus Basin (covering 116.2 million hectares of Pakistan, India, China and Afghanistan) has been made. Vegetation index images freely available from SPOT-Vegetation satellite were used to describe the phenological cycle of all agro-ecosystems at a spatial resolution of 1 km × 1 km. An unsupervised clustering technique was adapted to classify 27 land use classes. Ground information and expert knowledge on the growing patterns of crops was used to label the resulting LULC classes. This helped to discern specific crops and crop rotations. An error matrix was prepared using ground truthing data to evaluate the classification accuracy. Existing global, regional and local studies were also considered for validation. The results show an overall accuracy of 77%, with the producer's accuracy being 78% and user's accuracy 83%. The Kappa coefficient (0.73) shows moderate agreement between on ground and satellite derived map. This is deemed sufficient for supporting water management analysis. The availability of major crop rotation statistics and types of forests and savanna is key information for the input data in hydrological models and water accounting frameworks.     

Increasing water productivity in crop production—A synthesis

Scarcity of water resources and growing competition for water in many sectors reduce its availability for irrigation. Effective management of water for crop production in water scarce areas requires efficient approaches. Increasing crop water productivity (WP) and drought tolerance by genetic improvement and physiological regulation may be the means to achieve efficient and effective use of water. But only high water productivity values carry little or no interest if they are not associated with high or acceptable yields. Such association of high (or moderate) productivity values with high (or moderate) yields has important implications on the effective use of water. In this paper we discussed the factors affecting water productivity, and the possible techniques to improve water productivity. A single approach would not be able to tackle the forthcoming challenge of producing more food and fiber with limited or even reduced available water. Combining biological water-saving measures with engineering solutions (water saving irrigation method, deficit irrigation, proper deficit sequencing, modernization of irrigation system, etc.), and agronomic and soil manipulation (seed priming, seedling age manipulation, direct- or wet-seeded rice, proper crop choice, integrating agriculture and aquaculture, increasing soil fertility, addition of organic matter, tillage and soil mulching, etc.) may solve the problem to a certain extent. New scientific information is needed to improve the economic gains of WP because the future improvements in WP seem to be limited by economic rather than a lack of technological means.     

Assessing grain crop water productivity of China using a hydro-model-coupled-statistics approach: Part I: Method development and validation

Identifying and quantifying the links between water resources and food production is crucial in addressing the intensified conflicts between water scarcity and food security. We proposed an integrated framework for quantifying relationships between food and water based on the concept of green water (GW), blue water (BW) and crop water productivity (CWP). An estimation method coupling hydrologic model and crop and water statistics was developed and validated to quantify basin-scale GW, BW and CWP in breadbasket basins of China. A basin-scale GW and BW assessment method was developed by using the Soil and Water Assessment Tool (SWAT). Monthly-step calibration and validation were performed at 15 discharge flow stations in seven first-order river basins of the country. The coefficient of determination (r²) and Nash-Sutcliffe Efficiency (NSE) in calibration stage ranged from 0.18 to 0.95, and −4.22 to 0.93, respectively; while in validation period, r² ranged from 0.02 to 0.97 and NSE ranged from −266.7 to 0.96. The simulated available soil water was validated against the observed soil moisture data, and the results showed that the model can reflect the yearly average values of soil water storage. Overall, the modeling performance for river basins with 4.94 million km² of drainage areas in total was acceptable. The simulated hydrologic components were then coupled with crop-and-water-statistics-based estimation method for assessing basin-scale CWP on four staple grain crops, i.e. rice, wheat, maize, and soybean. The results were validated by comparing with the similar investigations in China and around the globe. It was concluded that the overall performance of the estimation method was acceptable, and the method can be applied in assessing basin-scale GW, BW and CWP in China.     

Bio-economic evaluation of farmers’ perceptions of viable farms in western Kenya

Arable land in western Kenya is under considerable pressure from increasing human population. Rural households depend on farming for at least part of their livelihood, and poverty rates are among the highest in Kenya. Land is often depleted of nutrients, and for most farmers, access to inputs and markets is poor. There is a need to identify options that are manageable within the context of the farmer’s resource base and the household’s objectives that could improve farm household well-being. In this study we integrated qualitative informal participatory approaches with quantitative mathematical programming and biophysical simulation modelling. Households in four sub-locations in Vihiga District were clustered and pilot cases identified. Meetings were held with farmers to elicit their perceptions of what their ideal farm would look like, and how its performance might compare with their own farm’s performance. With farmers’ help, a range of scenarios was analysed, relating to changes in current enterprise mixes, changes in current farm sizes, and changes in prices of staples foods and cash crops. A considerable mismatch was found between farmers’ estimates of their own farm’s performance, and what was actually produced. There seems to be a threshold in farm size of 0.4 ha, below which it is very difficult for households to satisfy their income and food security objectives. Even for larger farms whose households are largely dependent on agriculture, the importance of a cash crop in the system is critical. There is a crucial role for extension services in making farmers aware of the potential impacts on farm revenue of modest changes in their farm management systems. We are monitoring nine households in the district, whose farmers have made some changes to their system in an attempt to increase household income and enhance food security.     

Nutrient flows and balances at the field and farm scale: Exploring effects of land-use strategies and access to resources

Nutrient flux and balance studies are valuable tools to assess the sustainability of agro-ecosystems and potential consequences for agricultural productivity. This paper presents results from a study at the field/farm scale representing mixed farming systems typical for the East African Highlands. We selected catchments in the Dega (cool highlands and Woina Dega (warm-to-cool mid-highlands) of the Central Highlands of Ethiopia, to get more insight on how individual land use strategies and access to resources affect the magnitude of nutrient flows and resulting balances and to explore some of reasons of the variability within and between farming systems at different altitudes. Our results show that environmental condition, farming system (e.g. choice of crop), access to resources (e.g. land, livestock and fertilizer) and smallholders’ source of off farm income influence the magnitude of nutrient fluxes and the degree to which nutrient fluxes may be imbalanced.