FACTORS IN WHEAT PRODUCTION 101 



Dakota. Here the winds in sweeping over the 

 open plains country blow the snow into drifts, 

 and the fields, deprived of the protecting snow 

 mantle, are exposed to the extreme cold. The 

 value of the snow cover is shown by the fact that 

 winter wheat is grown in some parts of north- 





FIG. 58. A snow cover on the ground serves to protect winter wheat. 



central Wisconsin, a region of heavy snowfall, 

 while in the southeastern part of the state, with a 

 milder winter temperature but a lighter snowfall, 

 spring wheat is raised. 



Where the normal rainfall is insufficient to 

 make wheat crops reasonably certain, irrigation 

 is practiced. This is available only for restricted 

 areas because of water supply or of unfavorable 



