CROP DEVELOPMENT UNDER IRRIGATION 167 



plant as the water applied increases throughout the 

 season. 



This correlation has been demonstrated by a great 

 number of investigators, although in few cases only 

 under true irrigated conditions. Hellriegel was one of 

 the first to investigate this subject and to announce the 

 law that the proportion of seed to the straw in all ordi- 

 nary crops becomes smaller as the available water in the 

 soil during the growing season increases. Mayer, working 

 in Holland, investigated rye, wheat, barley and oats, 

 and found invariably that the more water he offered the 

 plants, the smaller became the proportion of the grain 

 yielded by the crops. French and English investigators 

 have confirmed this conclusion. At the Utah Station, in 

 a long series of experiments under irrigated conditions, the 

 percentage of seed in the harvests of wheat, oats, barley 

 and corn was very carefully determined. In the following 

 table some of the results obtained are shown: 



In the first column is given the depth, in inches, of 

 the water applied throughout the growing season; in the 

 following columns, for each crop, the percentage of grain 

 in the total harvest. The smallest quantity of water 

 applied was 5 inches, and the largest 50 inches. The small- 

 est quantity used should meet, fairly, ordinary crop needs, 

 and the largest quantity used is not very far above that 



