Farming without fresh water

[Will9]

It's the middle ages. Recently Xian defected. Two grassland squares north of Xian have no fresh water sorce, but strangly I can farm them. Here is the terrain surronding one square:

South: Desert, Xian
Southwest: Grassland, Hill, Jungle
West: Grassland (farmable)
Northwest: Grassland, Jungle
North: Grassland, Forest
Northeast: Grassland
East: Plain, Hill
Southeast: Desert

I do have Civil Service. My best Guesses to why I could farm the square are: Xian was settled on an Oasis, but it went away when it settled, but I was under the impresion you couldn't settle on an Oasis. Or that Irrigation is being carried through Xian (there is a farm South of Xian). Are there anyother guesses?

If you want a screenshot you'll have to tell me how to take them. Whenever I press printscreen the curser just starts blinking.

[Kuciwalker]

Irrigation is carried through cities.

[Will9]

Okay, I didn't expect that would be it.

[Blake]

Oasis provides fresh water to adjacant tiles (it only matters when it's oasis next to non-desert).

Cities do propagate irrigation, but only if the tile can normally be farmed - a city on desert or hill will not.

[playshogi]

Isn't it odd that you can irrigate from an oasis, but you can't irrigate the oasis itself?

[Blake]

It is odd. I think it's mostly to give the city founded next to an oasis fresh water.

[Martinus]

Originally posted by playshogi
Isn't it odd that you can irrigate from an oasis, but you can't irrigate the oasis itself?

Well, realistically, oasis is a water hole in the desert - there is nothing really to irrigate/farm there, but it is a water source with some trees etc. around it.

[phooey73]

Originally posted by Blake
Cities do propagate irrigation, but only if the tile can normally be farmed - a city on desert or hill will not.

So that's it! I had wondered about this. I had expected cities to ALWAYS propagate irrigation, and I've been confused a couple times when they didn't -- so I started suspecting that maybe they never do, and tested it a few times to see they did -- so I just resigned myself to the uncertainty.

But that's got to be it.