Varies state to state. You owe the three types of "people" that might be on your property different levels of protection. The utility people, invitees, and tresspassers from most to least. Meaning that if a tresspassers breaks his leg while riding his quad on your land that is posted as "no tresspassing" then you owe him very little compared to a power meter reader that falls into a hole and breaks his leg, he can sue your pants off.
You can't keep people off your land, you have some liability out there. My homeowner's extends to the land I own with certain conditions such as if I am making money off of it or if there is a residence type structure (cabin) out there. Without the homeowner's benefit, I would recommend an umbrella liability policy to protect yourself. The benefit is that this type of policy is pretty cheap and will extend to all areas of your life. Should you cause a traffic wreck and your auto liability coverage be exceeded, then the umbrella policy will kick in.
That umbrella policy is like saying you are a smart guy, won't do anything wrong in your life, but if the unexpected happens then you won't likely lose everything.