Check the cutting knives on your disc mower. If any appear dull or damaged, snap them off and replace them. You can purchase replacement knives from the manufacturer at little cost.
Attach the disc mower to your tractor. The tractor provides the power for the mower. Because rocks and sticks can fly up from the knives, the tractor you use should have a cab for safety purposes.
Move your tractor to the edge of the hay field in the direction that you want the hay to be cut in.
Start moving. As you move over the hay field, the knives on the disc mower will spin, allowing them to cut neatly through the hay.