Irrigation

Financing water projects
Pay dirt
Aug 31st 2006
From The Economist print edition

Buckets, not big irrigation systems, can prevent the world running dry

"It takes roughly 3,000 litres to grow enough food for one person for one day, or about one litre for each calorie."

"A recent study of vegetable farmers in Ghana, for example, found that those irrigating their fields with wastewater carried by buckets earned a 230% return on their investment, versus 30% for big state-sponsored schemes."

I think the article was referring to this study:

Irrigated Urban Vegetable Production in Ghana
Characteristics, Benefits, and Risks

More than 200,000 urban dwellers eat exotic vegetables daily on Accra's streets and in canteens and restaurants. Most of the perishable vegetables are produced on open spaces in the cities or its fringes due to insufficient cold transport and storage. This activity is highly profitable and can lift vulnerable groups out of poverty. It can also contribute to flood control, land reclamation and city greening. However, poor farmers have increasing problems finding in and around the cities unpolluted water sources for irrigation. This book gives a comprehensive overview of urban and peri-urban vegetable farming in Ghana's major cities with a special focus on 'wastewater' use. It ends with recommendations on how in a low- income country like Ghana health risks for consumers could be effectively reduced, while simultaneously supporting the important contribution of open-space urban and peri-urban agriculture.