What are the weeds?
Why do you need to kill the weeds? Are they in the way of something?

If they are Johnsongrass, horses will nearly jump out of their stalls to eat it. You should protect them from the weeds. Letting the horses graze on Johnsongrass is not recommended because the long grass blades can wrap up in the intestines. Instead you can feed Johnson grass to the horses root first from your hand. Only let them bite a few inches at a time.

You can mow them down or bring in a cow. Once they are mowed down, they might look okay. But if you are asking how to keep a spot free of green stuff growing in it, short of continuous traffic on it, there isn't any.