When we first got our goats, the small pasture was enough for the three of them. Then our boy, Mr. Bill had to be separated, since, being the horn dog he is, he would not leave the girls alone. Goats can be bred very young but most times it isn't successful and can actually hurt the moms if they are too young or too small. Bill went to a smaller pen. We have since enlarged Bill's pasture as well but there is an area outside of the pasture that is full of sweet clover and grass. We normally would mow it down but decided that it would be so much better if we let the goats graze there.
We run an electric fence that operates off of a solar unit around the pasture as well as a wire around the bottom of the fence that goes around the garden. I found this fence on Amazon that works off of the same unit and encircles the clover/grass area. It is mobile so if there are other areas that need to be cleaned up, you can move it. You just have to have electrical power to it. The thing I like most is that it is complete. There are no extra posts to buy, to extra stakes. The only thing you have to furnish is the power.
I know it is kind of difficult to see, but it does a great job of keeping these babies in and helps get some of the property cleaned. We were lucky, as you can see in the pic with the guinea, we were able to open the gate and just run the power around it. That way they can go into the barn if they want and have access to water. Our goats have always been pretty easy to keep contained. If you have little escape artists, you may want a taller fence.