It might not be a popular choice but a couple of outside house cats are about the most effective method of controlling mice and rats on a farm or rural property.
I agree with the Lug, since we adopted a pr of fixed cats at our place, very few rodents AND thus, very few snakes looking for a meal.
If you have a lot of feed in barns, like we do, having cats makes great sense. When I bought my farm, I removed all the cats on my property. I had lots of issues with mice, starlings and sparrows eating feed and pooping in my barns and robins building nests in my barns, resulting in rotten babies on the floor and more poop. We had 1 cat show up that one of my dogs started feeding. That one cat saved me money on vermin eaten and soiled feed and time cleaning up poop. We now have slightly to many cats. Get the cats fixed if you go that route.
In areas we don't let the cats in, because of the smaller birds I raise, I use traps and poison. The Tin Cat traps and similar repeating knock offs work well too. I sold thousands of mice I caught in them so far. Jaguar has been the most effective poison I have used in areas the cats can't get into. I change poisons occasionally.
Keith