The invention relates to a Kelly bar arrangement for a drilling apparatus and a method for working the ground with a drilling apparatus. Provision is made for a tubular outer Kelly bar and an inner Kelly bar which is displaceably supported inside the outer Kelly bar and has a rope suspension, wherein the drilling torque can be transmitted between the outer Kelly bar and the inner Kelly bar. According to the invention provision is made in that on the inner Kelly bar at least one line is arranged, in that in a lower or upper end region of the inner Kelly bar a rotary feedthrough with a first attachment section and a second attachment section is arranged and in that on the rotary feedthrough a rotary means is arranged for actively rotating the two attachment sections relative to each other.