A distributing tower (10) of an agricultural distributing machine (12) for discharging granular distributing material, such as seeds, fertilizer or the like, comprising a rising tube (22) for supplying a distributing-material volumetric air flow to an annular distributor head (24) adjoining the rising tube, for dividing the distributing-material volumetric air flow into a multiplicity of distributing-material volumetric air flows corresponding to a number of outlets (26) distributed over the circumference of said distributor head. At least one of the outlets is assigned a shut-off device (28) which has a switch (30), by means of which the distributing-material volumetric air flow can be conducted in the direction of a seed line connection (48) assigned to the shut-off device or in the direction of a return region (45) assigned to the shut-off device. The return region is adjoined by a return device (38) which surrounds the rising tube and/or is part thereof. In the region of the return device, the rising tube has openings (40) for receiving the returned distributing material. In order to be able to cut off any number of outlets without a serious change in the transverse distribution occurring, it is provided that the rising tube, the return device and/or the return region and also the seed line connection are permanently pneumatically connected irrespective of the particular position of the switch. The invention furthermore provides a corresponding method for the series cut-off.
