126 



ELEMENTS OF AGRICULTURE 



same effect as covering the soil with a layer of dry 

 earth. 



Crop cultivation also serves to open up the soil to 

 a freer circulation of the air which supplies oxygen, to 

 the growing roots. 



123. Terracing. — There are two methods of treating 

 soils to prevent excessive surface washing that are 

 especially applicable to steep hillsides. Terracing 

 means that the hillside is so cultivated as to form a 

 series of large steps or terraces, and the slope between 



Fig. 21.— Terraced hillside, with* ditches for irrigating; 

 fruit trees planted on the terraces. 



the terraces planted in grass or some thick-growing 

 crop to prevent .washing. Fig. 21 shows how a hillside 

 may be terraced and planted in trees. This is of course 

 an expensive method of protecting hills, and a simpler 

 and equally as applicable method is to construct a suc- 

 cession of smaller terraces about the hill — two good 

 furrows forming a terrace a foot or two wide are suffi- 

 cient. These are allowed to grow up in grass and serve 

 to check the formation of gullies. 



Questions 



1. What is meant by surface cultivation of soils? 2. What 

 is the most common method of surface cultivation? 



