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.
(..) -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