In a method of operating a seed cart, a compartment is provided defining a volume for receiving a commodity. A distribution manifold is provided including two sets of passages, the distribution manifold being associated with the compartment to selectively receive a commodity in one or both of the two sets of passages. A fan is operated to create an air stream. The air stream from the fan is divided into a plurality of primary tubes. An inlet divider plenum is provided having two outlets in communication with each one of the primary tubes. The flow of air from each of the plurality of primary tubes is divided amongst the two corresponding outlets with a corresponding movable vane within the inlet divider plenum such that an airflow ratio between the two sets of passages is controlled in response to the position of the vane.
