YIELD OF SPRING WHEAT 



113 III 109 107 105 103 101 99 97 95 



MINN, 



29 



ARIZ. 



Mexico 



1 I > i L 



109 107 105 103 101 99 97 



Figure 1. — Sketch map of the Great Plains showing the location of field stations 

 at which the Division of Dry Land Agriculture has conducted experiments. 



