SOIL IMPROVEMENT 



71 



making it fine. As the furrow slice slides along the curved 

 surface of a polished mouldboard, the particles are caused to 

 sHde upon each other. Take the leaves of a book between 

 your thumb and finger when the edges are nearly even. 

 Bend them, and see that they all slide a little and the edges 

 are no longer even. Thus, in plowing, the particles of soil 

 tend to sUde upon each other 

 and the crumbling is accom- 

 phshed. Other objects of 

 plowing include: 



1. The covering of wild 

 plants and burying of stub- 

 ble, stalks, vines, and other 

 wastes. 



2. The unlocking of plant- 

 food in the soil by exposing 

 the particles to new condi- 

 tions of heat, light, moisture, 

 and air. 



3. The deepening of the 

 water reservoir and making 

 the moistiure conditions more 

 perfect. 



4. Loosening of the soil to 

 allow of better shallow tillage. 



Plowing not only pulverizes and loosens the soil; it may 

 also warm and dry wet soil; it may deepen the surface soil 

 and increase the feeding area for roots; it admits air and 

 increases the weathering; it deepens the water reservoir. 



Plows. — ^Walking plows are best for rough and stony 

 fields. Riding plows have wheels, and are called sulky 

 plows. These are much more common in sections where 

 the fields are large, level, and free from stones and stumps. 



Gang plows are those which have two or more plows 

 attached to the same frame and turn several furrows at a 



Fig. 42. — Cultivating young peach 

 trees. Frequent tillage makes the soil 

 yield its fertility to growing plants. 

 (Experiment Station, N. J.) 



