Steps to reproduce:
1. Select torch.
2. Right click on farmland.
What I expected to happen:
The farmland to turn into dirt and a torch be placed there.
What actually happened:
Nothing.
MC-25152
Torches can't be placed on farmland
Resolved
Works As Intended
0
user-4968d
(Unassigned)
Unconfirmed
Minecraft 1.6.2
Retrieved
Thats cause farm land is considered to be not a full block so the torch can't even atempt to place. (like trying to put a torch on a half slab in the lower position.
Probably best though to add this as a suggestion to Mojang though to make what your expecting happen on the minecraftforums.