66 THE PRINCIPLES OP AGRICULTURE 



3. How Tillage Is Performed 

 3a. By deep -working tools 



90. Plowing. We plow (a) to get the land 

 in fit condition for planting, (b) to pulverize the 

 soil, (c) to turn under manures, green-crops, 

 and trash, (d) to deepen the soil, and thereby 

 increase its storage capacity for water and ex- 

 tend the root pasturage, (e) to break up or to 

 form a hard-pan, (/) to warm and dry the land, 

 (g) to allow the weather to act on the soil. 

 Passing over the first subject (a), we may ex- 

 plain the remaining objects of plowing. 



91. (b) Plowing is the most efficient means 

 of pulverizing the soil. That is, it is not enough 

 that the soil be inverted : it must be ground 

 and broken. For purposes of pulverization, 

 the shape of the plow should be such as to 

 twist the furrow -slice, causing it to break and 

 crumble as it falls. The moldboard, therefore, 

 should have a sharp, bold outward curve at its 

 upper extremity ; and the furrow-slice should be 

 left in an inclined, or even nearly perpendicular 

 position, rather than turned over flat. 



92. (c) Since it is important that organic 

 matter, as manures, shall quickly decay when 

 turned under, the plowing should be done when 

 the season is moist, as in early spring or in fall. 



