118 



THE PRINCIPLES OF SOIL MANAGEMENT 



Carbonates of the alkalies, which are present in 

 many alkali soils, tend to produce a compact soil struc- 

 ture. The remedy lies in a conversion of the carbonate 

 into some other form, or in the removal of the alkali. 



Fig. 37. A portion of a Meeker harrow, showing its effect on lumpy, 

 clay soil. (See page 481.) 



(See page 314.) Hall has shown that the continued 

 and extensive use of nitrate of soda on the land may, 

 even in humid regions, deflocculate the soil. 



50. Animal life. Many forms of animal life affect 

 the soil structure. Earth-worms, in passing soil through 

 their bodies, leave it in a granulated condition in the 



