I believe the rules in Oregon are that land zoned as agricultural can not have a house built on it unless you can convince the Planning Dept that a home is required in order to manage an agricultural purpose, such as taking care of livestock. When we first purchased our place, (close to 1000 acres) we still lived in Minnesota. We inquired about a building permit when we first arrived, and were told a home was not permitted, because we had the ranch leased to another producer. When his lease was up we bought our own cattle and were able to get a permit based on our contention that we needed to live on the property in order to properly manage the cattle. Perhaps we would have continued taking the easy money from that lease, had the rules been different, but I have never regretted it. I was raised around Dairy cattle and crop farming, so there was a pretty steep learning curve, but 32 years later it is a fairly profitable operation and I wouldn't want any other life.
I am thankful for the strict land use rules here in Oregon. It means I most likely will never have a close neighbor, especially since we built our house over a mile in from the nearest public road.