The machine for drying field crops includes lower and upper conveyors, the space between the two serving as a drying chamber. The upper conveyor is powered and drives the lower conveyor through a plurality of lateral flights that engage one another to keep the two conveyors in registry. A heating system is provided beneath the lower conveyor. Heat is delivered to a plenum between the two runs of the lower conveyor. The two conveyors are porous to allow heated air and light to pass therethrough. Heated air from the lower plenum passes through the lower belt and the drying chamber between the two conveyors, and into a collector plenum between the two runs of the upper conveyor, where it is exhausted to the atmosphere. Infrared or other lighting may also be provided in the two plenums. Alternatively, the machine embodiments may have multiple laterally situated conveyor runs.