A distribution tower comprising an upright conduit for pneumatically conveying particulate material in a primary stream. The tower additionally includes a distribution head at the upper end of the conduit, with the distribution head comprising a plenum chamber for receiving the primary stream of particulate material from the conduit. The distribution head further comprises a plurality of discharge outlets for directing particulate material out of the plenum chamber by splitting the primary stream into a plurality of secondary streams. Each of the secondary streams is discharged from the distribution head via one of the discharge outlets. The tower additionally includes a flow adjustment system configured to adjust a distribution of particulate material between the secondary streams without completely restricting the flow of any of the secondary streams through their respective discharge outlet. The tower further includes a control system for controlling operation of said flow adjustment system.