I have struggled with Yellow Nutsedge in my lawn for over 5 years. Professional lawn treatment services could control it, but when I switched to taking care of my lawn all by myself, this weed became established in my lawn and got worse with each year. A few years ago I tried a herbicide containing methanearsonate, but it yellowed my yard considerably for a few weeks, and the nutsedge came back. Two years ago I paid TruGreen for a single application to treat it, but the nutsedge came back.
I bought a bottle of Ortho Nutsedge Killer at WalMart last year and used it on my worst patch of nutgrass. It worked great, killing the nutgrass, and not damaging the lawn. I went back for more and it was sold out for the year. This year I bought 8 bottles, and have used 5 of them so far. During mid summer, I have to walk the yard a couple of times a week with a bottle, spraying all the nutsedges I see, but it then kills them.