Disc harrows are used to incorporate plant material into the soil. They are easy to use but require multiple passes to make a field ready to plant. You also will need another piece of equipment to make beds that are flat and ready to plant such as a Perfecta harrow.
Perfecta harrows are used to make beds that are ready to either transplant or direct seed. We use them also to incorporate cover crop seed.
Spading machines are a state-of-the-art tool that does what a disc harrow and Perfecta do in one pass. Added bonuses are that less fuel is used and it is kinder to the soil organic matter and organisms.