PLOWS FOR DRY-FARMING - 807 
The disk plow has recently come into prominent 
use throughout the land. It consists, as is well 
known, of one or more large disks which are believed 
Fic. 75. Plow bottoms. 
to cause a smaller draft, as they cut into the ground, 
than the draft due to the sliding friction upon the 
moldboard. Davidson and Chase say, however, 
that the draft of a disk plow is often heavier in propor- 
tion to the work done and the plow itself is more 
Fic. 76. Plow with inter.hangeable moldboard and share. 
clumsy than the moldboard plow. For ordinary dry- 
farm purposes the disk plow has no advantage over 
the modern moldboard plow. Many of the dry-farm 
soils are of a heavy clay and become very sticky dur- 
ing certain seasons of the year. In such soils the disk 
plow is very useful. It is also true that dry-farm 
