Jan., 1907.] Weather and Crop Yield. 49 



The normal corn yield for these states is 28 bushels per acre, 

 and the normal rainfall for July is 4 inches. Whenever the rain- 

 fall has approximated 5 inches, the corn yield has been over 

 32 bushels per acre. On the other hand whenever the rainfall 

 has been less than 3 inches the yield has been less than 23 bushels 

 per acre. 



By taking the June and July rainfall together the rainfall 

 curve and the yield curves agree even more closely than the July 

 rainfall and yield curve. 



The normal rainfall for June and July is 8 inches, while as 

 stated above, the normal corn yield is 28 bushels per acre. 

 Whenever the rainfall for these two months has averaged over 

 9 inches the corn yield has been 32 bushels or more, and when the 

 rainfall has been less than 7 inches the yield has been below 25 

 bushels. 



The best yield was 34 bushels an acre in 1902, when the June 

 and July rainfall was over 11 inches. In 1896 the yeild was 33 

 bushels and the rainfall was almost 11 inches. 



The lowest yield was less than 18 bushels per acre in 1901. 

 The rainfall in June and July of that year was less than 6 inches 

 and for July alone it was about 2 inches. 



Other charts prepared for individual states show that by 

 not including western Nebraska and Kansas, and eastern Ohio 

 and Kentucky, and by considering carefully the rate of rainfall, 

 and the length of periods with little or no rainfall, one can give 

 a very close estimate of the yield of corn per acre in the United 

 States, by the latter part of July ; long before the crop is ready for 

 harvesting. 



We believe that a closer analysis of the daily data will show 

 that the period during which a good corn yield is assured by good 

 rains or seriously lessened by the lack of rain, is less than one 

 month. 



In 1904 the writer made a very exhaustive study of the weath- 

 er and the yield of various corps in Fulton County, Ohio, from 

 1874 to 1903 inclusive. 



The data showing the yield of corps were obtained from the 

 records of the Secretary of State, but the weather records, as well 

 as many valuable records of farm operations, the advance of 

 vegetation, the flight of birds, the blossoming, leafing, etc., ot 

 trees, shrubs and plants, were obtained of Hon. Thomas Mikesell 

 of Wauseon. This gentleman has a most remarkable record of 

 phenological observations since 1869 — I know of no more com- 

 plete and exact record in this country than these. 



Charts were made showing the departure of the average tem- 

 perature and total rainfall from the normals, by months from 

 January 1876 to 1904, and the departure of the different crop 

 yields from the normal for the same period. 



