Irrigation increases food production. Only squares adjacent to fresh water (river or lake) or to another irrigated square may be irrigated. After the discovery of Electricity, you can irrigate a tile without proximity to fresh water.
| Terrain | Produces |
|---|---|
| Flood Plain | 3 food, 4 if irrigated |
| Grassland | 2 food, 3 if irrigated |
| Plains | 1 food, 2 if irrigated |
Workers are ordered to irrigate by pressing [I] or the "Irrigate" button.