Abstract: Rotor shaft for use in an aerating device for a ground, wherein the rotor shaft comprises at least one connecting disc which extends transversely of the axis of the rotor shaft and on which at least two knives are arranged, wherein each knife is provided with two knife connecting holes and is connected between the connecting disc and a connecting ring, wherein the connecting disc and the connecting ring are provided with knife connecting holes which coincide with the knife connecting holes of the knives, wherein bolts are arranged through the coinciding knife connecting holes in order to connect the connecting disc, the knives and the connecting ring, wherein the connecting ring is constructed from at least two ring sectors which together form the connecting ring.