Abstract: Vented floor structures are described herein. In some embodiments, precast vented floor structures (which can also be referred to as “air floors”) can be used in crop storage facilities, such as potato, onion, and/or other crop storage facilities. Embodiments of the vented floor structures described herein can be manufactured using a form to create air vents in the floor structure that do not require plastic shells or other ancillary structures to define or create the vent openings. Embodiments also include inserts that can be installed (e.g., removably installed) in vent openings to vary the opening size and/or configuration, or complete plug selected vent openings.