PLOWS FOR DRY-FARMING 309 



the subsoil plow is simply a vertical piece of cutting 

 iron, down to a depth of ten to eighteen inches, at the 

 bottom of which is fastened a triangular piece of iron 

 like a shovel, which, when pulled through the ground, 

 tends to loosen the soil to the full depth of the plow. 



Fig. 78. Subsoil plow. 



The subsoil plow does not turn the soil ; it simply 

 loosens the soil so that the air and plant roots can 

 penetrate to greater depths. (See Fig. 78.) 



In the choice of plows and their proper use the dry- 

 farmer must be guided wholly by the conditions under 

 which he is working. It is impossible at the present 

 time to lay down definite laws stating what plows are 

 best for certain soils. The soils of the arid region are 

 not well enough known, nor has the relationship 

 between the plow and the soil been sufficiently well 

 established. As above remarked, here is one of the 

 great fields for investigation for both scientific and 

 practical men for years to come. 



