54 FOOD FOR PLANTS 



naturally well drained and located in those regions 

 where the average temperatures during the growing 

 months of May to September, inclusive, reach from 

 75 degrees to 80 degrees Fahr. That is, the best cli- 

 matic conditions do not depend upon average annual 

 temperature, but upon the high temperature main- 

 tained during these growing months. The growing 

 season will, however, vary also in different sections 

 of the country, ranging from 90 to 160 days, and 

 varieties exist which are adapted to these different 

 growing periods. The yield is also, of course, in- 

 fluenced by moisture, depending again not altogether 

 upon the total rainfall, but upon the requisite 

 amounts that may be depended upon from May to 

 September, the growing months. The plants need 

 high temperatures and maximum rainfalls through- 

 out July and August, with clear, sunshiny weather 

 between rains. 



The variety also has a direct influence upon the 

 yield of the crop, and work done recently in the mat- 

 ter of corn breeding and selection has very consider- 

 ably broadened the area of profitable culture. The 

 Flint varieties are more suitable for the northern sec- 

 tions, and the Dent varieties for the central and 

 southern sections of the United States. 



The Object of Growth — Grain. 



Corn is grown mainly for its grain, and for this 

 reason the greatest attention has been given to the 

 development of varieties that will yield the largest 



