Alfalfa in Kansas. 



23 



FIG. 6. The average length of the growing season, in days, from the records of the 

 United States Weather Bureau. 



The length of the growing season gradually diminishes as one pro- 

 gresses from the southeast corner of the state diagonally toward the 

 northwest corner. The range is from 199 days down to 147 days, de- 

 pending on the dates of the last killing frost in the spring and the first 

 killing frost in the fall, and representing a difference of 52 days, or 

 about 1V 2 weeks. This difference is occasioned by altitude as well as 

 longitude. The altitude gradually increases from 1000 feet on the east 

 line to more than 3500 feet on the west line. 



Another factor that has considerable bearing on the yield is the number 

 of clear days. The average number of clear days in a year in the east- 

 ern third of the state is 174, in the central third 185, and in the western 

 third 196. Clear days mean sunshine, and alfalfa likes sunshine. 



FTO. 7. The altitude of Kansas, in feet. 

 [After Borman, in "Sorghums Sure Money Crops."] 



