John Thompson works on power, policy and sustainability issues in food and agriculture, water resource management and rural development. He is a STEPS Centre member, IDS Fellow and joint Co-ordinator of the Future Agricultures Consortium. He presents two crucial agricultural water issues to take priority on World Water Day.

Upgrading rainfed areas has high potential both for food production and for poverty alleviation, for this reason we at the STEPS Centre believe the international community should make it a priority. 

Today, 55 per cent of total gross value of our food is produced under rainfed conditions on 70 per cent of the world's cropland, much of which is located in developing countries. 

Traditionally most investments in water management went into large-scale irrigation development while neglecting rainfed areas. Thus, there are compelling reasons to shift investments to improving the productivity of water and land in rainfed areas:

• There is a large unmet potential to increase productivity in areas where yields are low - through small-scale water harvesting and supplemental irrigation, combined with better land management.
• More poor rural people depend on rainfed agriculture than on irrigated agriculture, so targeting the poor implies focusing on smallholders in rainfed areas.
• Investment costs to upgrade rainfed systems are typically lower than those of large-scale irrigation. The systems can be quickly implemented and can yield fast and high marginal returns.
• Water-driven environmental degradation can be held in check because there is likely (but not necessarily) less pressure on blue water resources and less competition with wetlands.
• Large-scale irrigation development has high environmental (river and groundwater depletion and salinisation) and social costs (people displaced by large reservoirs).
• At the global level, the potential of rainfed agriculture is great enough to meet additional food requirements, through increased productivity. Upgrading rainfed agriculture involves adding irrigation on a smaller scale.

The second issue that needs prioritising is the improvement of water management through the System of Rice Intensification. Rice is a thirsty crop, whether it is grown in paddies or on dry land, and requires a great amount of water compared to other food crops. 

Almost 90 per cent of global rice is produced under inundated conditions (i.e. in fields with a standing water layer of 5 to 15 cm during the major part of the growing season). In some of the most intensively cropped areas in China and India, the world's first and second largest rice producing countries, where groundwater is used for irrigation, water tables have been falling at an alarming rate, sometimes one metre per year or more. Finding ways to reduce the agricultural (and particularly rice) demand for irrigation water will be crucial for the sustainability of production in the future.

System of Rice Intensification

The System of Rice Intensification (SRI) is a methodology developed in Madagascar for increasing the productivity of irrigated rice by changing the management of plants, soil, nutrients – and water. These practices contribute to both healthier soil and plants supported by greater root growth and the nurturing of soil microbial abundance and diversity. SRI concepts and practices have been successfully adapted to upland rice and the approach is now being tested in over 20 countries, mainly in Asia and Africa.

With SRI there can be water savings of around 50 percent, thus it is likely to become more attractive as water scarcity becomes a more pervasive agricultural constraint and the effects of climate change are becoming more pronounced (e.g., El Niño effects and monsoon failures). By inducing rice plants to grow much larger and deeper root systems SRI gives rice plants more resistance to water stress conditions. Better root systems also enable farmers to reduce their irrigation requirements.

Some eminent rice agronomists have dismissed such achievements as the result of poor record keeping and unscientific thinking. Moreover, despite these promising results, few would dispute that SRI requires skilful management of the factors of production and, at least initially, additional labour input – between 25 and 50 per cent, particularly for transplanting and weeding.

The international community should fund rigorous research into SRI in a variety of locations to determine the conditions under which it can contribute to improving water conservation, increasing productivity and enhancing future food security.