AND AGRICULTURE. 



45 



If in any soil most of these inorganic sub- 

 stances were absent, it would be naturally bar- 

 ren, and no good or productive crops of any kind 

 could be raised from it. There are many large 

 tracts of land, in all countries, which have never 

 been under cultivation, that are naturally fertile 

 and productive, and many other tracts which are 

 naturally barren and unproductive. 



In naturally fertile soils all those inorganic 

 substances are found which are required by our 

 cultivated crops for food ; in barren soils some 

 of these substances are wholly wanting. 



The above table shows the composition of 



Questions. What makes soil barren ? What is the dif- 

 ference between naturally fertile and naturally barren soils ? 



