PROCEEDINGS OF THE OHIO ACADEMY OF SCIENCE. 253 



Table o. Thermal Constants for Corn at Wauseon, Ohio, with 



Correlation Coefficient Between the Total Effective Heat 



and the Corn Yield. 1883 to 1912. 



Correlation 

 Coefficient 

 Effective heat for Average. Greatest. Least. (r) 



Ten days before planting 150 318 — 25 — 0.03 



Planting to above ground.... 143 201 36 —0.03 



Above ground to blossom.... 1,599 1,984 1,232 0.18 



Blossom to ripening 1.337 1,607 897 0.08 



Ten days before blossom 296 350 240 —0.003 



Ten days after blossom 286 360 160 —0.28 



In table 5 the oniy value of r that is high enough to receive 

 consideration is for the ten days after blossoming. As this is 

 negative it shows that cool weather is desirable. 



Table 6. Total Rainfall for Corn at Wauseon, Ohio, with the 



Correlation Coefficient Between the Rainfall and the 



Yield of Corn. 1883 to 1912. 



Rainfall, inches and tenths. Average. 



Ten days before planting 0.9 



Planting to above ground 1.0 



Above ground to blossom.... 7.4 



Blossom to ripening 4.6 



Five days before to five days 



after blossoming 0.8 



Ten days before blossom 1.1 



Ten days after blossom 1.1 



Twenty days after blossom... 

 Thirty days after blossom.... 



The results from the correlation in table 6 are very important. 

 It makes plain that there is no relation between the rainfall 

 during the first part of the period of growth of corn and the 

 yield. But it makes equally plain that for the ten days imme- 

 diately following blossoming rainfall is of great importance to 

 the corn crop. The value of r for this item is 15 times the prob- 

 able error. It is considerably higher than for either the 20 or 

 the 30 days following the date of blossoming. 



