50 



The Ohio Naturalist. 



[Vol. VII, No. 3, 



By a comparison of these curves it is comparatively easy 

 to see the relation between the weather and crop yield, insofar 

 as the average temperature and total rainfall of ivhole months 

 affect the yield. It is apparent, however, that for some of the 

 crops the period of usually favorable or unfavorable weather are 

 less than one month in length and are not shown in the monthly 

 data. 



It is probable that wheat, for example, is affected by alter- 

 nate freezing and thawing, short periods of severe cold, snow 

 covering, etc., more than by monthly temperature of precipita- 

 tion conditions. The February preceding the lowest wheat yield 

 of the period gave the coldest week ever experienced in many 

 sections of the State. The low yield of 1875 was preceded by 

 the coldest winter on record, that of 1896 was preceded by a very 

 cold January and that of 1900 by a cold February and March. 

 The good yields of 1891, 1984 and 1898 were preceded by mild 

 winters. 



FiCx. 1. Precipitation for July and yield of corn per acre. 



The relation between the yield of corn and the rainfall in 

 July is not so well marked in a small district as in a large one, 

 yet nearly every year with a large corn yield in this county had 

 a^julyj rain fall above the normal, and nearly every year with 

 a^ small yield of corn had a small July rainfall. One exception, 

 however, was the year 1883 which had a July rainfall above the 



