Twenty-nine-year-old Turnbull has made twenty-five appearances for the Blues this season, with twenty of those being starts.
He arrived at the Swansway Chester Stadium in June 2017 – initially on a two-year deal from league rivals Barrow AFC.
Formerly with Tranmere Rovers and Burscough, Davies (pictured) - the older brother of Everton starlet Tom - signed a new six-month contract in May.
He made seven appearances for the Blues since his arrival at the Swansway Chester Stadium in March 2017 after impressing on trial.
His initial contract was extended to a one-year deal and the 21-year-old made two league appearances this campaign and has also spent time out on loan with Evo-Stik League South outfit Leek Town.