Double-A Somerset placed Jackson on its 7-day injured list Sunday due to an unspecified injury.
Jackson presumably sustained an injury Saturday, when he went 2-for-3 with two walks, two stolen bases, two runs and an RBI. The 22-year-old shortstop prospect has gone 5-for-17 with four walks, four steals, five RBI and four runs in five games for Somerset since receiving a promotion from High-A Hudson Valley on Tuesday.