After a field has been plowed, it still needs to be smoothed out and leveled before it can be planted. With two gangs of individual round disks, a disk harrow chops the sod furrows into smaller pieces. This further damages the original vegetation's root system, and begins to level the field for planting. Depending on the type of sod and plant root system, it may take several passes by a disk harrow before a field is smooth and level enough to be planted.