You can't keep other candidates from 'poaching on your turf'. [=from trying to get voters who usually vote for you or your party to vote for them]
In chapter two, the author is on unfamiliar 'turf'. [=is dealing with an unfamiliar subject]
Synthetic 'turf' was installed in the playing field instead of grass.
(..) to New York and now he's back. And I don't know what to do. So I'm not so sure if it's a better plan to fight him on our turf or his... but you saw what they did, what they can do. At least on his turf, he's not expecting it. So I say we take (..)2018 Avengers: Infinity War
(..) Have Birch and Rasmussen seen this? Not yet. I wanted you to be the first to have a look. I'll schedule a time for you to fill in the president. Oh, no, no, no. That is your turf, Linda. You should do that. - Thank you, Frank. - My pleasure. Thank you. - I so apologize for everything-- (..)2013 TvShow: House of Cards Title: Chapter 2 Season: 1 Episode 2
(..) -that's headed for Sector . -Wait a minute. No, Buzz! This way. -There's a special ship. I just saw it. -You mean it has hyperdrive? Hyperactive hyperdrive. And Astro... turf! -Where is it? I don't see the... -Come on. That's it. Spaceship! All right, Buzz, get ready. And... (..)1995 Toy Story