312 DRY-FARMING 
spring the land is thoroughly disked and reduced to a 
fine condition. Following this the smoothing harrow 
is occasionally used to form a more perfect mulch. 
When seeding is to be done immediately after plow- 
ing, the plow is followed by the disk harrow, and that 
in turn is followed by the smoothing harrow. The 
ground is then ready for seeding. The disk harrow 
Fig. 81. Disk harrow. 
is also used extensively throughout the summer in 
maintaining a proper mulch. It does its work more 
effectively than the ordinary smoothing harrow and 
is, therefore, rapidly displacing all other forms of 
harrows for the purpose of maintaining a layer of 
loose soil over the dry-farm. There are several kinds 
of disk harrows used by dry-farmers. The full disk 
