56 



Journal of Agricultural Research 



Vol. III. No. I 



included in the measurements of both 1912 and 1913. The ratios of 

 the water requirement of these crops in 191 2 to that in 191 3 are given 

 in Table XXXIII. Similar ratios are also given for crops grown in 

 191 1 and 1913. It will be seen that the mean 1913-1911 ratio approxi- 

 mates unity; in other words, the mean water requirement of the crops 

 under investigation was practically the same for both 3-ears. The 

 water requirement in 191 2 is seen to be far below the 1913 value, the 

 mean ratio being 0.75 ±0.01. The mean ratio of the monthly evapora- 

 tion for June, July, and August, 1912, compared with i9i3,is o.8o± 

 0.02, which is in approximate agreement with the ratio of the water 

 requirement of crops grown during the two years. 



The crops at Akron as influenced by climatic conditions in 1911, 191 2, 

 and 1913 may then be summarized as follows: 



Table XXXIII. — Comparison of the -water requirement of the same crops at Akron, 

 Colo., 1911, 1912, and IQI3 



The conditions during 1911 and 191 3 were such as to give rise to prac- 

 tically the same water requirement. The water requirement of crops 

 grown in 1912 was on the average only 79±2 per cent of crops grown in 

 1911 and 75±2 per cent of crops grown in 1913. Therefore, in order to 

 determine the relative water requirement of the different crops, it appears 

 justifiable to increase the 191 2 water requirement ratios by the reciprocal 

 of 0.77 — namely, 1.3. This procedure has been followed in the summary 



