ABSTRACT
Millions of small-scale farmers around the world irrigate with marginal-quality water, often because they have no alternative. There are two major types of marginal-quality water: waste-water from urban and peri-urban areas, and saline and sodic agricultural drainage water and groundwater. Around cities in developing countries, farmers use wastewater from residential, commercial, and industrial sources, sometimes diluted but often without treatment. Sometimes farmers in deltaic areas and tailend sections of large-scale irrigation schemes irrigate with a blend of canal water, saline drainage water, and wastewater. Still others irrigate with saline or sodic groundwater, either exclusively or in conjunction with higher quality surface water. Many of those farmers cannot control the volume or quality of water they receive.
