PEOPORTION OP GRAIN TO STRAW 261 



of heads to leaves and stems is highest in dry-farm 

 crops. In fact, it is a general law that the proportion 

 of heads to straw in grain crops increases as the water 

 supply decreases. This is shown very well even 

 under humid or irrigation conditions when different 

 seasons or different applications of irrigation water 

 are compared. For instance, Hall quotes from the 

 Rothamsted experiments to the effect that in 1879, 

 which was a wet year (41 inches), the wheat crop 

 yielded 38 pounds of grain for every 100 pounds of 

 straw; whereas, in 1893, which was a dry year (23 

 inches), the wheat crop yielded 95 pounds of grain to 

 every 100 pounds of straw. The Utah station like- 

 wise has established the same law under arid condi- 

 tions. In one series of experiments it was shown as 

 an average of three years' trial that a field which had 

 received 22.5 inches of irrigation water produced a 

 wheat crop that gave 67 pounds of grain to every 

 100 pounds of straw ; while another field which re- 

 ceived only 7.5 inches of irrigation water produced a 

 crop that gave 100 pounds of grain for every 100 

 pounds of straw. Since wheat is grown essentially 

 for the grain, such a variation is of tremendous impor- 

 tance. The amount of available water affects every 

 part of the plant. Thus, as an illustration, Carleton 

 states that the per cent of meat in oats grown in Wis- 

 consin under humid conditions was 67.24, while in 

 North Dakota, Kansas, and Montana, under arid and 

 semiarid conditions, it was 71.51. Similar varia- 



