Abstract: A facility for forcing warm air uniformly through hay layered on a flat surface. Air forced through distribution channels beneath the surface is directed upwardly through a plurality of spaced upright, tubular supply duct formers which controllably distribute the air into the hay. A plurality of tubular, foraminous vent duct formers are distributed throughout the hay at spaced locations intermediate the supply duct formers. The vent duct formers provide low resistance escape paths for some of the drying air with the result that the drying air flows substantially horizontally through the hay from the supply ducts to the vent ducts formed in the hay, assuring uniform drying of the hay. Both the supply duct formers and the vent duct formers may be equipped with valves to control the flow of air therethrough. The supply duct former is adapted to be lifted to an elevated position when a new layer of hay is deposited on an already dried layer.