A manifold apparatus for an air seeder has output ports spaced around a lower portion of the sidewall A vertically oriented input conduit extends upward through an input port defined in the bottom of the manifold into an upper portion of the manifold interior. A plurality of substantially vertical channels each extend downward from an inner top wall surface to one of the outlet ports and has an entrance opening at a top end thereof. The upper portion of the manifold interior is configured such that an air stream carrying entrained agricultural products passing out an open top end of the input conduit contacts the top wall and is directed outward into the entrance openings, and such that a substantially equal portion of the air stream and agricultural products flows into each entrance opening. Blunt edged pulsating rings can distribute agricultural products evenly across the input conduit.