158 



ELEMENTS OF AGRICULTURE 



hottest weather. The "corn-belt" of the United States 

 seems to be the largest area in the world where these 

 climatic features are favorable, and where the land is 

 level enough for economic corn-production. Even here 

 there are probably no seasons when corn does not suffer 

 to some extent from unfavorable weather. 



s 



o 



is 



3414 



3213 



3012 



2811 



2610 



NORM/a 



FIG. 68. Rainfall for June, July and August and yield of corn per acre. 1 



Average yields of corn 1888 to 1902. 



Average rainfall for June, July and August. 



It is, of course, the temperature of the growing season 

 rather than the temperature for the year that limits the 

 corn crop. Nearly nine-tenths of the corn of the United 

 States is grown in regions where the July temperature 

 is between 70 and 80 Fahr. More is grown in the warmer 

 part of this region than in the colder part. 



The amount and intensity of sunshine is also important. 



Yearbook, 1903, pp. 215-224 



