340 



SOIL PHYSICS AND MANAGEMENT- 



The weeder (Fig. 159) consists of a large number of narrow 

 spring teeth well adapted for shallow cultivation of such crops as 

 corn, cowpeas and beans in humid sections and for most of the 

 crops in semi-arid regions. For this implement to do its best work 



Fia. 159. Weeder. 



the soil should be mellow and in good tilth and the weeds small, 

 but if the soil is compact or the weeds quite large it is of little value. 



PLOWING 



Plowing is an art. It is one of the most important as well as 

 the most common methods of preparing the soil for the crop. From 



Fio. 160. An early form of plow. 



the beginning of agriculture- some form of plow has been in use. 

 Even at the present time in some countries the plow is a very primi- 

 tive implement, as shown in Fig. 160, and does very inefficient work. 

 In North America we find the two extremes. In parts of Mexico 

 the people are still using the most primitive form of plows. In the 



