I don't think this is a bug, but I am confused. Apparantly you need Civil service to build a farm on an adjacent tile that does not have access to water. Well I built one on some corn. I'm 90% sure that I have overlooked or misread something - maybe corn is an exception, for example. But I'm posting here just to get this cleared up anyway.
http://www.civfanatics.net/uploads10/MPC4_00.gif

Because you're claiming a resource. Its a design thing. :)

Because you're claiming a resource. Its a design thing. :)Cool, that's what I figured.

Because you're claiming a resource. Its a design thing. :)

But why can't he build the other one?


/me notes that farm threads will make a frequent appearance.:mischief:;)

Because you're claiming a resource. Its a design thing. :)

hmmm, what exactly do you mean 'claiming a resource', and how does this allow you to build where normally you couldn't?

In civ 4 you have to build farms beside fresh waster no another farm.
And if u want to build a farm in those kinda places you have to resherch civil servies. It stumped me too but now you now.

That looks to me like corn or sugar. Farms can be built on resources so you can claim them, even without access to water.

I think that farm on itself is not irrigated. Though you can build it over corn or suggar or wheat, it does not make it irriagated. Lakes and rivers do.

Also, later biology research will allow you to build farms anywhere (by the time all "unused" land is all covered with hard-to-get towns).

I think that according to the rules you can build farm anywhere you want, however if you don't have biology and the farm is not adjustent to the fresh water, it wouldn't give you any benefits and UI doesn't allow to build improvement that does nothing. In the case of resource, such as corn, farm gives you benefit so UI allows to construct it (could you check if you've actually got food bonus from irrigation or not in your case?). And after you've researched Civil Services, other irrigated farms start to count as "source" of fresh water.

According to civilopedia and tooltips over tiles, a farm produces +1 food on its own. Irrigiation adds +1 food more, so it's not unnecessary improvement. Also I might want to build it beforehand in case biology comes in a few turns. They could just highlight it in gray as they do for preferable action (mine usually differs :) ), but not completely disable it.