The A's have signed first baseman Daric Barton to a one-year contract, avoiding arbitration with their longest-tenured player. That means Barton's deal stays intact only if he makes the team out of camp. A source has told MLB.com that it's the second straight non-guaranteed contract for Barton, as first reported by the San Francisco Chronicle. Barton has been in the A's organization for nine years, having landed in Oakland in December 2004 with Dan Haren and Kiko Calero as part of the Mark Mulder trade with St. Louis. He batted .269 with three home runs and 16 RBIs in 37 games this year, while spending most of the season with Triple-A Sacramento.