Q: How do you get rid of broom sedge in the pasture?
A: Broomsedge is a perennial grass that self-seeds rapidly when it finds open soil in a pasture. This plant doesn’t invade a pasture, it just takes advantage of opportunities that are presented. There are no selective herbicides that do a good job in controlling it.The best you can do is make sure your desired pasture grass is limed and fertilized as it should be. Don’t let animals over-graze the pasture, as this leaves bare patches ripe for broomsedge seeds to germinate. Take some long walks across the pasture in early summer when you can easily see the green tufts and spray each one with glyphosate (Roundup, etc). If you are patient and manage the pasture correctly, broomsedge will disappear.
Read more here.