THE IRRIGATION AGE. 129 



effective rains I have taken as those where less than .2 inches fell 

 during any 24 hours, and have used the man, observed at Madison, 

 during the period 1887 to 1897. 



The average rainfall during the barley, oats and corn periods in 

 the 13 states named is 11.616, 13.375; and 14.779 inches. These 

 amounts are diminished by drainage and ineffective showers so as to 

 leave the mean effective rainfall for barley 8.625 inches: for oats 10.19 

 inches; and for corn 12.01 inches. For eastern Kansas the effective 

 rains for these crops are not far from 9.04 inches for barley; 10.44 

 inches for oats and 12.49 inches for corn. 



These effective rains, could they be used with the same economy 

 as we used water in our experiments, should produce yields of 40.2 bu. 

 of barley, 64.97 bu. of oats and 71.51 bu. of shelled corn per acre. 



It will be seen that these computed yields, although much larger 

 than average yields, are, nevertheless, very close to what is expected 

 from well managed lands in our best seasons, when there has been an 

 average rainfall, well distributed during the growing season. The 

 average yields for the thirteen states in question, as given in the 10th 

 Census Reports, is 22.08 bu. per acre for barley, 30.17 bu. for oats and 

 34.38 bushels for corn, amounts only about one half of the 40, 64 and 

 72 bushels expected in the best years, and computed from our observa- 

 tions and experiments as possible. 



The small average yields reported from so many states, and 

 agreeing so closely as they do, must be looked upon as expressing 

 conditions naturally unfavorable to large yields and conditions which 

 the best of management cannot hope wholly to counteract without the 

 aid of irrigation. 



The facts are we are here confronted with results which are, in a 

 very large measure, due to the long intervals between effective rains. 

 This uneven distribution of rain is so general that when the yields 

 over wide areas are compared the small yields due to faulty distribu- 

 tion of rain so far outweigh those from areas where the amount and 

 distribution is just right that small averages are inevitable. Nor is 

 this condition of things strange: for, since the rainfall is in no way 

 controlled by any factor operating to cause precipitation, either when 

 it is needed or in the amount which the particular crop at the time de- 

 mands, it cannot be expected that such a regime of chance could, no 

 the average, develop the conditions favorable to large yields. 



The average yield of hay per acre in the thirteen states named 

 was in 1879 only 1.156 tons per acre. Nearly all of this hay is made 

 during the months of May and June, when the mean effective rain is 

 5. 14 inches, which, according to our studies, should produce a yield of 

 -1.188 tons of hay. If the second crop of hay were included in the 10th 

 Census average it could hardly carry the yield up to 1.5 tons per acre 

 and yet we have, during four consecutive years, on the same piece of 

 ground, in rotation with other crops, by supplementing the rainfall at 



