I06 THE BOOK OF CORN 



value of the crop obtained, which must be observed in 

 the profitable use of materials. Crops are, in respect 

 to fertilizers, divided into two general classes, first, 

 those which possess a high fertility value and a low 

 commercial value, and second, those which possess a 

 low fertility value and a high commercial value. 



To the first class belong the cereals and to the 

 second class vegetables and fruit crops, hence in the 

 application of manures or fertilizers to the first class, 

 greater care must be exercised in order to obtain a 

 profit, because the financial return per unit of applica- 

 tion is much less in the first than in the second class. 

 That it can be done profitably has been shown by many 

 experiments and by practice, provided all the consid- 

 erations underlying are carefully observed, for, as 

 already pointed out, crops differ in respect to their 

 need of added food, due both to their specific require- 

 ments and their period of growth. Hence in a rotation 

 of crops the application may be adjusted in such a way 

 as to reduce the cost of application to a minimum, 

 while at the same time encouraging a maximum 

 growth. 



In any rotation of the first class of crops which 

 may be adopted, whether (i) corn, (2) corn, barley, 

 wheat and hay, (3) corn, beans, wheat and hay, oats, 

 wheat and hay, (4) com, wheat or rye and hay, (5) 

 corn and cotton, (6) tobacco and cotton, or others 

 which are used, a careful observation of the principle 

 that different crops require different kinds and propor- 

 tions of food, because of differences in their power of 

 acquiring food, and their season of growth, should re- 

 sult in the application of those constituents that are 

 specifically needed for the particular crop, which will 

 contribute to its increase and leave a residue for the 

 succeeding crop. By this method there would result 

 from a systematic application of manures and ferti- 



