This post is being created for Anonymous who posted a comment and asked for advice on bringing a horse onto their one and a half acres. This is simply what I've learned over the years by starting from scratch. I invite all to comment with your advice too!
1) Zoning. Are you zoned Agriculture
2) Shelter. Your horse will need some shelter. I have just two acres and I chose a fairly large lean-to in which I'm able to convert to two box stalls if needed. I also eventually evened the floor and put down heavy rubber stall mats for easier cleaning.
3) Fence. I've used a combo of electric tape, PVC rail fence, wire horse fence with capped t-post and an electric braid wire around the top of the wire horse fence. Keeping in mind that electric tape does periodically need replacing as the sun and elements wear it down. I've also used corral panels for combined training pen and paddock. I've separated the largest area for pasture and kept my shelter in the smaller paddock area with two gates to paddock area and gate to pasture and gate to training and riding area. You have lots of fence choices out there, just NO barbed wire!
4) Pasture. My pasture is not enough to support two horses so I must supplement with hay. Keep mindful of what plants and weeds and trees are growing out there as there are some that are quite toxic to horses, certain things they should not eat and may. Things that can kill them in a short period and things that cause liver toxicity and can take more time.
5) Drainage. I learned early on that I needed better drainage in my paddock, so I rented a bobcat and cleared it one spring of a foot of mud and crap and layed a lime gravel. I haven't had much problem since as long as I keep up with poop removal.
6) Manure Removal. It is important to remove manure. And have a place to use it or dispose of it. My neighbor is a farmer and I can spread it on his field. I've also hired people to remove it at about $100 a truck load.
7) Keep in mind the importance of vet and farrier. Spring and Autumn vaccinations and hoof trims every 6 to 8 weeks. And any emergencies.
8) Law. Depending on the state in which you live, the laws vary on protecting yourself from suit. I have an equine property sign posted for all to see. Stating the state statute and warning others of their risk and that they've been warned.
9) Horse Buddy. They are herd animals and often get lonely and bored by themselves. I have two horses and also goats. It seems to work well. I've got a neighbor with one horse and they keep two large goats out with him and it appears to be a nice marriage.
I'm sure there are many things I'm forgetting, but I think this is a good start. Please all give your advice and examples of things you've learned. Many of these things I've learned through trial and error and many through my friend Jess.