PROCEEDINGS OF THE OHIO ACADEMY OF SCIENCE. 269 



24 times during the past 54 years, and that in those years 21 

 have had a wheat yield above the normal and only 3 a yield below 

 the normal. 



On the Other hand a cool March usually means a poor wheat 

 yield although the unfavorable effect is not quite so marked as 

 is the favorable effect of a warm March. 



If we consider only those years when the departure of the 

 mean temperature has been two degrees a day from the normal 

 then with a warm March the probability of the wheat yield being 

 above the normal is 94% and with a cold March the probability 

 of a poor wheat yield is 75%. 



EFFECT OF SXOW' COVERING ON W^INTER W'HEAT 



It is common to credit a good snow covering in the winter 

 time with a good yield of wheat, or to say that the lack of a 

 snow blanket is sure to cause a poor yield of wheat. But care- 

 ful correlations made in Ohio seem to show no beneficial result 

 from snow covering or damage from the lack of it. At least 

 the snow covering does not have a dominating influence. On 

 the other hand the studies seem to show that bare ground with 

 freezing and thawing weather during January is beneficial. 



SNOWFALL AND YIELD OF WINTER WHEAT 



Further, while a snowfall in January appears to be favorable, 

 it is found, contrary to the usual opinion, that a snowfall in 

 March is decidedly detrimental to winter wheat. 



In figure 6 a chart is reproduced showing by one curve the 

 departure of the wheat yield from the normal in Fulton County, 

 Ohio, and by the other the departure of the snowfall from the 

 normal at Wauseon. It will be at once seen that with two or 

 three exceptions the wheat yield is always poor when the snow- 

 fall is above the normal and the wheat yield is always good when 

 the snowfall is below the normal. 



This curve is substantiated by a correlation between these 

 factors in this and several other counties in Ohio, so that the 

 truth seems to be well established. In fact the correlation co- 

 efficients show that this is the most important weather factor in 



