The highest yields that can be obtained from irrigation are more than double the highest yields that can be obtained from rainfed agriculture. But irrigation is expensive and beyond the means of small-scale farmers in many developing countries. Irrigation can also lead to waterlogging or salinization, after which the land produces less rather than more food.

In spite of these drawbacks, irrigations holds the most promise for increasing food productivity and security, provided it is managed efficiently and combined with other inputs such as fertilizers and improved seed varieties.