Hmm, seems more difficult to start farming underground in the new version. Muddy floor is needed.
I have a brook just nearby but it is 1 z-level below my planned farming area.
I guess I'll have to build some pumps to flood that area to make it muddy.
A mini-project: A short aqueduct, 2 waterwheels, 2 pumps, channels to power the waterwheels.
I have a nice little hill just on the other side of the brook that will serve as a pump station.