AGRICULTURE. 



|CH. 



draw their inorganic matter and also some of their 

 organic matter from the soil. If this demand on the 

 soil is continued without some return being made to 

 the soil, it is clear that the land will become 

 exhausted, and will not be able to supply the re- 

 quirements of the crops. It will, therefore, not only 

 become exhausted, but as a consequence will be- 

 come less productive. The soil being the only 

 source from which a crop can obtain its inorganic 

 matter, exhaustion arising from any deficiency of this 

 portion of the plants' food is quickly observable. It 

 is desirable that you should realize what crops remove 

 from the land, and this is shown in the following 

 table. 



41. Inorganic Matter removed from an acre of 

 land, by average crops of the following kinds. (Play- 

 fair.) 



42. These numbers may be taken as fairly repre- 

 senting the inorganic matters generally re- 

 moved by these crops, but they will vary according 

 to the weight of the crop, and the character of 

 the soil. These figures must therefore be looked 

 upon as giving only a general idea of the materials 



