TILLAGE 



329 



Sod plows (Fig. 138A) have long, slightly curving mold-hoards 

 that do the minimum amount of pulverization in turning the fur- 

 row-slice. They are used principally in 

 the plowing of tough grass sods, since 

 they turn the furrow-slice without 

 breaking it very much, thus leaving a 

 comparatively smooth plowed surface. 

 This has some advantages in the pro- 

 duction of a seed bed, 



A form of the mold-board plow 

 known as the hillside or swivel plow 

 may be reversed so that the soil may 

 all be thrown in one direction. 



The disk plow (Fig. 141) may be 

 used under some conditions to good 

 advantage. If the soil is quite com- 



pact and dry it may be used where it faF-aS *(?] 

 would not be possible for the mold- Company.) 

 board to do any work at all. It has this other advantage, that it 

 does not tend to produce a plowpan, because the furrow-slice is 



FIO. 140. TH.- rombim-d jointer 



Flo. 141. Disk plow. (Molinr Plow Company.) 



broken off rather than cut off. Under some conditions it turns 

 rubbish under better. Disk plows are extensively used in arid and 

 semi-arid regions, but may be used successfully on almost any soil. 



