ROTATION IN DRY AREAS 403 



from the advantage that comes to the grain crops that 

 follow the alfalfa through the supply of plant food and 

 humus which it brings to the land. To this rule, how- 

 ever, there may be many exceptions. The wisdom of 

 growing small-grain crops as a rule only after cultivated 

 crops, or fallow, has been amply justified by experience. 

 To this, however, there are some exceptions. Flax, as 

 has been shown, may come after grass with reasonable 

 certainty in the results when properly grown. Should 

 the autumn rains be heavy, an occurrence that may hap- 

 pen, although it is rare in the semi-arid country, in some 

 areas but not in all, it would be legitimate to follow 

 small grain with small grain. 



