New FAO publication aims to bring small-scale irrigation to farmers in sub-Saharan Africa

Irrigation is a key tool for agricultural intensification. Although only 16 percent of the world's fields are irrigated, they yield 36 percent of global harvests. In developing countries, irrigation increases yields of most crops by 100 to 400 percent. Despite this, some of the world's most needy farmers are still unable to water their land effectively

The use of porous jars buried up to the neck is one of the oldest irrigation methods and is practised by traditional farmers throughout North Africa and the Near East

Professor Daniel Hillel, expert in soil/water relations, was asked by FAO Director-General Jacques Diouf to write an irrigation book specifically for one major group of vulnerable agriculturists - the small-scale farmers of sub-Saharan Africa. Hillel is irrigation advisor to the Oversight Committee for FAO's Special Programme on Food Security, spearhead of the Organization's work to promote food self-sufficiency in the world's poorest countries. As a retiree, he was contracted under FAO's Programme for the use of retired experts

"Small-scale irrigation for arid zones: Principles and options" promotes HELPFUL (High-frequency, Efficient, Low-volume, Partial-area, Farm-Unit, Low-cost) irrigation techniques. Hillel, who has a lifetime's experience of irrigation, points out that "Elaborate and expensive systems ... imported and installed in the grand hope of achieving instant modernization, typically fail for lack of expert maintenance and spare parts. Such installations can quickly become white elephants - idle monuments to hasty 'progress' relying on ill-adapted technology."

When they do work, poorly managed irrigation systems cause a range of environmental problems. Rising water tables, caused by excessive applications, leakage from drainage channels and inadequate drainage, lead to salinization and waterlogging, which reduces crop yields. Conversely, overpumping of groundwater depletes supplies and threatens long-term viability of the irrigation schemes and the crop yields they support