The move puts Johnson on the 40-man roster and keeps him from opting out of his contract and possibly leaving the organization. To make room on the 40-man, the Orioles moved lefty Zach Britton to the 60-day disabled list, a transaction which doesn't change his timetable given that Britton was put on the disabled list on March 26 with left shoulder impingement.
The 24-year-old Johnson is 1-3 with a 2.62 ERA (44.2 IP, 13 ER) in eight games (seven starts) for the Tides. He was acquired from the Los Angeles Dodgers on July 30, 2009, in a deal that brought Josh Bell -- who was traded to Arizona earlier this season -- to Baltimore in exchange for George Sherrill.
Britton has made two rehab starts for Double-A Bowie and is scheduled to pitch on Tuesday for Norfolk in Rochester.