Publish Articles Online
Besides farming, you could also write articles about your farming activities. It is easy to get published online in a variety of places for free. HubPages is free to join, and if you keep with it, you might be able to start earning money from articles about a wide variety of topics that you choose.
Writing online isn't a get rich quick scheme, though. Like anything, the more you put into it, the more you get out of it. For me, it fits in nicely with my lifestyle here on the farm and provides an additional stream of passive income.