This journal article investigates the significance of drought and other water-related constraints in South Asia compared with other limitations to the production of four major food crops — wheat, rice, sorghum and chickpea — in five South Asian farming systems.

The study was based on a survey of 330 'expert informants'. It indicates that water shortages and constraints such as high-cost irrigation or flooding of low-lying fields contribute to no more than 30 per cent of current yield gaps in major food crops. Other constraints contribute the most to yield losses, particularly soil infertility and poor management of fertiliser, weeds, pests and diseases. The respondents suggested interventions to address these constraints and improve food security, which include biotechnology and improvements in soil fertility.

This article, written by scientists in Niger and the United States, assesses the suitability of solar-powered irrigation for improving food security in rural regions of West Africa. The authors describe an irrigation system that combines drip irrigation with a photovoltaic solar-powered water pump, and test its efficacy and impact through household surveys and field data. They find that solar-powered drip irrigation is cost-effective and significantly boosts household incomes and nutritional intake.

This commentary, by South African scientists Thembela Hillie and Mbhuti Hlophe, examines nanoscience's potential to solve the technical challenges associated with removing pollutants from water. The authors describe a range of nano-based water treatment technologies already in the marketplace and discuss how nanofiltration membranes can be used in low-cost methods to produce safe drinking water. They highlight a case study in South Africa where such membranes were used to treat brackish groundwater.

The authors emphasise the importance of technology transfer in getting nano-based solutions to the countries that need them, arguing that direct transfer does not often work. Rather, what developing countries need are approaches that combine technology transfer with technology adaptation and adoption — involving local stakeholders in establishing water treatment devices and developing local capacity to use them.