Why doesn't irrigation work on grasslands?

[doben]

When I irrigate a grassland square, I don't seem to get the bonus I'm supposed to -- the food yield stays at 2 instead of going up to 3. Am I missing something, or is this a bug? Anyone else have this problem?

[derk]

You are probably under a Despotism government. Therefore, any square that produces 3 or more food, shields or trade produces one less. To 'fix' this, you have to switch governments.

derk

[doben]

Yup, that's it. Thanks, Derk.