Terrain-Tech Question

[jim panse]

I want to know what enables the possibility for double irrigation ('farmland'). Is this only the Refrigeration advance?
And: If I give the Refrigeration advance only to one civ will the other civs be able to irrigate twice once getting engineers? Is double irrigation possible without Refrigeration (I suppose not)?

Thanks in advance.

[N35t0r]

It's only the Refrigeration tech slot that allows this, it doesn't have to do with engineers (settlers can build farmland, though at half the speed engineers do, as with all things)

Only the civs which have 'refrigeration' will be able to double-irrigate, however remember that you need the supermarket improvement in order to get the bonus...

[jim panse]

Thank you very much for that quick answer!