66 AGRICULTURE ON THE PACIFIC SLOPE 



Subsoil plows. When a plowsole has been made by 

 plowing to the same depth too often, or when there is 

 naturally a hard, close subsoil, -we may use a plow shaped 

 somewhat like a chisel, which is made to follow the turning 

 plow in the same furrow, but which merely loosens the sub- 

 soil without turning it up; so that it will be covered up the 

 next time the turning plow passes. The water, air, and roots 

 will then be able to penetrate into the subsoil and so give 

 the plant a better chance for moisture and food. A great 

 many different shapes have been given to these subsoil plows, 

 and sometimes a "subsoiler" has been attached to the lower 

 end (crossbar) of the turning plow. 



FIG. 37. Disk plow. 



Shovel, scooter, or bull-tongue plows. Instead of the turn- 

 ing plowshare, these plows have merely a straight or slightly 

 curved blade of varying widths pointing forward and shov- 

 ing the earth to the two sides. In the arid region they are 

 used chiefly in drawing light furrows for seeding, and in cul- 

 tivation. 



Cultivators. When crops grown in rows are weedy, or 

 the surface is hard or crusted, we run between the rows the 

 horse hoe or cultivator, a frame set with a number of little 



