Well you prolly already know by the quest that was datamined. Blizzard even sad that they will not have it in the PTR ?
Still I try it today, and it work. And Farm is now officially Mine !!!
When you Reach Exalted with Tillers, you will get the quest from Nana Mudclaw - Inherit the Earth, which send you to Farmer Yoon to speak with him to take over Nana duties. He will take the job and left Sunsong Ranch you to care.
Well the basterd will left you work orders that will give you gold and reputation with faction you chose from quest. One more interesting thing this place works like Inn. I wish Blizzard work more on this place so we have something like Housing ^^