2 THE PRINCIPLES OF AGRICULTURE 



is the production of wood or timber, used 

 in building and in the various wood -working 

 trades. Other contributions are the production 

 of materials used in medicine and in various 

 secondary and incidental arts and manufactures. 



4. The ideal agriculture maintains itself. 

 That is, it is able to thrive forever on the same 

 land and from its own resources. Tiie land 

 becomes more productive with time, and this 

 even without the aid of fertilizing materials 

 from the outside. This state is possible only 

 with a mixed husbandry, in which rotations of 

 crops and the raising of animals are necessary 

 features. The more specialized any agricultural 

 industry becomes, the more must it depend upon 

 outside and artificial aids for the enrichment of 

 the land and for its continued support. 



5. Agriculture may be roughly divided into 

 four general branches or departments : agricul- 

 ture in its restricted sense, animal industry, for- 

 estry, horticulture. 



6. Agriculture in its restricted sense — some- 

 times, but erroneously, called agriculture proper — 

 is a term applied to the general management 

 of lands and farms, and to the growing of the 

 staple grain and fiber crops. In North America, 

 the use of the term agriculture has been restricted 

 to the above application largely through the in- 

 fluence of agricultural colleges and experiment 



