Forecasts on population growth and economic development indicate that there will be substantial increases in food demand for the forthcoming decades. We focus here on the water requirements of food production, on the issue of whether there would be enough water to produce sufficient food in the future, and we offer options to face this challenge based on recent trends observed in some agricultural systems. Given the competition for water faced by the agricultural sector, and the uncertainties associated with climate change, improving the efficiency of water use in both rain-fed and irrigated systems is the main avenue to face the challenge. In rain-fed agriculture, managing the risk associated with rainfall variability is a promising option to increase productivity. In irrigated systems, a case study on the improvements in water productivity in Andalusia, Spain, is used to illustrate some of the opportunities to make progress. Progress in reducing irrigation water use in recent decades has been substantial, but decreasing the consumptive use of crops is a much more difficult challenge. The need for more research and technology transfer on improving water-limited crop production is highlighted, and emphasis is placed on interdisciplinary approaches to gain the insight needed to achieve new breakthroughs that would help in tackling this complex problem.

For the first time, alginate polymer has been applied to prevent dyes from leaching out of colorimetric oxygen indicator films, which enable people to notice the presence of oxygen in the package in an economic and simple manner. The dye-based oxygen indicator film suffers from dye leaching upon contact with water. In this work, UV-activated visual oxygen indicator films were fabricated using thionine, glycerol, P25 TiO2, and zein as a redox dye, a sacrificial electron donor, UV-absorbing semiconducting photocatalyst, and an encapsulation polymer, respectively. When this zein-coated film was immersed in water for 24h, the dye leakage was as high as 80.80±0.45%. However, introduction of alginate (1.25%) as the coating polymer considerably diminished the dye leaching to only 5.80±0.06%. This is because the ion-binding ability of alginate could prevent the cation dye from leaching into water. This novel water-resistant UV-activated oxygen indicator was also successfully photo-bleached and regained colour fast in the presence of oxygen.

There have been calls for an overhaul of regulatory and governance frameworks to incorporate the implications of the water-energy-food nexus. We map one small component of the regulatory space of the nexus and highlight its immense complexity. We draw on insights from the economics and socio-legal literatures to show that a decentralised approach to regulation based upon procedural justice can enable the trade-offs of the nexus to be considered and addressed. We use a nexus case study of micro hydro-electricity generation in Dartmoor National Park in England to show that when we take into account interactions between state and non-state regulation, the economic concepts of interdependencies and transaction costs, and a recognition that regulation of the nexus is a process involving decisions of procedural justice, some existing regulatory frameworks are already well-equipped to deal with the implications of nexus analysis.

CGIAR Research Program on Policies, Institutions, and Markets (PIM); CGIAR Research Program on Water, Land and Ecosystems (WLE) | Al-Riffai Perrihan et al., 'Linking the economics of water, energy, and food: A nexus modeling approach', , IFPRI, 2017

BACKGROUND: Poor quality irrigation water is a major cause of disease transmission for urban inhabitants consuming fresh produce in many developing countries. Irradiation of food is an alternative approach to reducing health risks for consumers, but its implementation depends heavily on consumer acceptance.RESULTS: In this pilot study, we show that most respondents consider the water quality of Mexico City to be poor and a health risk, and would be willing to pay for irradiated food as a means of pasteurizing fresh iceberg lettuce.CONCLUSION: Irradiated food could, potentially, be accepted in developing countries that have problems with water quality. Such acceptance would presumably be due to the perception that such a novel technology would (1) alleviate water impairment, and (2) lead to economic improvement. It is then possible that the public considers that water quality is a more pressing concern than any potential side effects of food irradiation.

This publication is a product of an ongoing collaborative research project between the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and the International Food Policy Research Institute (IFPRI). The project aims to introduce dryland crops into the updated IMPACT model and undertake strategic analysis of future opportunities and challenges for SAT agriculture. We would like to extend our sincere thanks to Mark Rosegrant, for providing the necessary background material for the training workshop from which this technical manual has been developed. Special thanks are to Siet Meijer for sharing her experience and offering the training at ICRISAT Patancheru (India), which was very useful in introducing the different variants of the IMPACT model to ICRISAT staff. We also appreciate the coordination and cooperation rendered by our staff to make the training program a success. We thank the Learning System Unit for providing us the necessary logistical support for the training.

Raised-bed plasticulture, an intensive production system used around the world for growing high-value crops (e.g., fresh market vegetables), faces a water-food nexus that is actually a food-water-energy-land-economic nexus. Plasticulture represents a multibillion dollar facet of the United States crop production value annually and must become more efficient to be able to produce more on less land, reduce water demands, decrease impacts on surrounding environments, and be economically-competitive. Taller and narrower futuristic beds were designed with the goal of making plasticulture more sustainable by reducing input requirements and associated wastes (e.g., water, nutrients, pesticides, costs, plastics, energy), facilitating usage of modern technologies (e.g., drip-based fumigation), improving adaptability to a changing climate (e.g., flood protection), and increasing yield per unit area.Compact low-input beds were analyzed against conventional beds for the plasticulture production of tomato (Solanum lycopersicum), an economically-important crop, using a systems approach involving field measurements, vadose-zone modeling (HYDRUS), and production analysis. Three compact bed geometries, 61cm (width)× 25cm (height), 45cm× 30cm, 41cm× 30cm, were designed and evaluated against a conventional 76cm× 20cm bed. A two-season field study was conducted for tomato in the ecologically-sensitive and productive Everglades region of Florida. Compact beds did not statistically impact yield and were found to reduce: 1) production costs by $150–$450/ha; 2) leaching losses by up to 5% (1cm/ha water, 0.33kg/ha total nitrogen, 0.05kg/ha total phosphorus); 3) fumigant by up to 47% (48kg/ha); 4) plasticulture's carbon footprint by up to 10% (1711kg CO2-eq/ha) and plastic waste stream by up to 13% (27kg/ha); 5) flood risks and disease pressure by increasing field's soil water storage capacity by up to 33% (≈1cm); and 6) field runoff by 0.48–1.40cm (51–76%) based on HYDRUS model simulations of 10-year, 2-h storm events in other major tomato production regions of California and Virginia.Re-designing the bed geometries in plasticulture production systems to be more compact is an example of win-win production optimization not only for traditional farms in rural areas but also for urban and peri-urban farms which are located closer to city centers. Compact beds could enable more plants per unit area, thus requiring less land area for the same production. Needing less area facilitates urban and peri-urban farming where land values can be high. Urban and peri-urban farming has several benefits, including reductions in transportation energy as production is closer to market and the ability for city wastewater to be reused for irrigation instead of freshwater withdrawals. Compact beds allow plasticulture to have smaller water, chemical, energy, carbon, waste, and economic footprints without impacting production. Improving agricultural systems in this way could enhance economic and environmental viability, which is essential for a sustainable food-water-energy-land-economic nexus.

A water footprint assessment is not an appropriate guide for allocating water efficiently in water-scarce regions such as Morocco. Water footprints contain too little information to identify policies or investments that will achieve public goals regarding agriculture, natural resources and livelihoods. In fact, they would impair efforts to enhance food security and sustain economic growth. The better way forward for Morocco and other countries is to analyze the full range of economic, social and environmental issues pertaining to water use in agriculture and other sectors.

This paper presents an exhaustive review of global croplands and their water use, for the end of last millennium, mapped using remote sensing and non-remote sensing approaches by world’s leading researchers on the subject. A comparison at country scale of global cropland area estimated by these studies had a high R2-value of 0.89–0.94. The global cropland area estimates amongst different studies are quite close and range between 1.47–1.53 billion hectares. However, significant uncertainties exist in determining irrigated areas which, globally, consume nearly 80% of all human water use. The estimates show that the total water use by global croplands varies between 6,685 to 7,500 km3 yr−1 and of this around 4,586 km3 yr−1 is by rainfed croplands (green water use) and the rest by irrigated croplands (blue water use). Irrigated areas use about 2,099 km3 yr−1 (1,180 km3 yr−1 of blue water and the rest from rain that falls over irrigated croplands). However, 1.6 to 2.5 times the blue water required by irrigated croplands is actually withdrawn from reservoirs or pumping of ground water, suggesting an irrigation efficiency of only between 40–62 percent. The weaknesses, trends, and future directions to precisely estimate the global croplands are examined. Finally, the paper links global croplands and their water use to a paradigm for ensuring future food security.