by Jazzuu
Well, you are spot on 100% correct. You MUST have the technology to farm a "fallow field" and get the corn.What we are suggesting is that you can not do that (or take the corn tile) if there is a forest tile on top of the corn tile. The forest tile must go first, either by being harvested itself (for timber resources) or being burned (and angering the gods!) to get to the corn grown as a result of the clearing of the forest (done in the blink of an eye, but hey, that's those wild, wacky and generally crazy game designers for you! :D)
Naturally, if there is a (valid!) empty or follow field, then you CAN take the corn without removing the forest on any remaining space..