192 DRY LAND FARMING 



may also differ much in the amount of moisture called 

 for to grow them in their several varieties. Durum 

 wheat, for instance, can better endure dry conditions 

 than fife wheat. Western rye grass can stand more 

 drought than timothy, and common red clover calls for 

 less moisture precipitation than alsike clover. The con- 

 trasts mentioned are not in all instances the outcome of 

 a greater or a less amount of water actually used in 

 growing the crop. It may and does arise in part from 

 the greater power which some crops have to gather 

 moisture from lower depths than others. Thus alfalfa 

 can draw moisture from lower depths tharr clover, and 

 rye from lower depths than oats. Those crops, there- 

 fore, that have proved best adapted to succeed under 

 dry conditions, should be given the preference in semi- 

 arid regions. 



Much that has been said with reference to the ability 

 of plants to grow on a limited rainfall, or to the lack of 

 the same in them, will apply equally to the ability of the 

 same plants, or to the lack of ability in them, to endure 

 dry atmospheric conditions. The crops that do not 

 usually grow at their best in a dry atmosphere include 

 the Canadian field pea, the common vetch, clover in many 

 of its varieties, flax when grown for fiber and such veg- 

 etables as turnips. This does not mean that these crops 

 cannot be grown under dry atmospheric conditions, but 

 that they cannot be so well grown under these condi- 

 tions as under conditions the opposite. The temperature 

 exercises an important influence. Peas and vetches, for 

 instance, will flourish much better in the higher eleva- 

 tions where the temperatures are moderate than in the 

 river basins where they are hot. These differences 

 should all be recognized when growing plants in dry 

 areas, and the farmer should govern himself accordingly. 

 In dry areas crops that mature early rather than late 

 should be given the right of way, so to speak. This will 



