How about one field for pipe-weed and one field for the things you actually grow, because they have a purpose in the game?
How farms work in real life is a ridiculous argument for the different fields concepts. I'm pretty sure that in real life, you can't just bang on a rock a few times with a pick-axe and get any useful amount of minerals out of it. You can't skin a bear in 3 seconds. Ancient texts found in ruins don't just respawn every minute. And so on.
The process of making anything with farming is slow as hell, but worse, it requires constant attention and input from the player. Any other crafting class can simply gather materials while questing or buy them on AH and leave the computer for half an hour while their character auto-crafts, or smelts or whatever. This isn't possible for a farmer. Imagine every time you smelted 5-10 pieces of ore, the ingots dropped to the ground and you had to pick them up manually or they'd disappear after a while. Sound fun?