A discharge system for an agricultural harvester provides an air curtain that shields straw, chaff and other crop residue from the wind. The system includes a blower adapted for mounting to an agricultural harvester and having an intake side and a discharge side and a plenum fluidly connected to the discharge side of the blower. The plenum is arranged and disposed to distribute air exiting the discharge side of the blower to form an air curtain according to a predetermined profile at a location adjacent discharge that exits a rear door of the agricultural harvester as a windrow.