PROBLEM OF CROP PRODUCTION 355 



(1) The factors that are essential to the growth of 

 crops ; 



(2) The factors that affect the profit of crop produc- 

 tion; and 



(3) The factors that affect the permanence of a profit- 

 able agriculture. 



And they must not only know, but they must also put 

 into practice, the means at their disposal for controlling 

 or influencing the factors of growth, profit and perman- 

 ence. 



A statement and brief discussion of the fundamental 

 principles underlying crop production, has seemed to us 

 essential to a proper appreciation of the subject, both by 

 the producer and the student of agricultural affairs. In 

 this chapter we have, therefore endeavored to bring to- 

 gether the various phases of the question in such a way 

 that the reader may get a general view, even though a 

 brief one, of the relationship of its different parts to 

 each other and to the problem as a whole. 



311. The First Part of the Problem That of Growing 

 Crops. As previously mentioned* the factors that must 

 be provided before plants can grow are : 



(1) The seed which contains the life principle, the 

 reproductive part. 



(2) Plant food materials the chemical elements of 

 soil, water and air that are available to plants and that 

 are necessary for growth. 



(3) Water a plant food itself and also a carrier of 

 elements of plant food from the soil to the plant. 



(4) Heat without which the life process of the plant, 

 germination and growth, cannot go on. 



*In Chapter III. 



