DRY FARM CROPPING PRACTICES 91 



grown. What we are about to say in this chapter should 

 not be interpreted as suggesting that radical changes 

 should be made in the crops now used in those portions 

 of the West that enjoy a rainfall of sixteen inches or 

 more, or that are outside the prairie area. The sug- 

 gestions that follow are meant rather as a guide to those 

 men in the dry belt who have found that the commonly 

 grown crops have not given satisfactory returns. 



58. Drought Resistant Crops. — The dry farmer should 

 keep in mind that some plants are better able to with- 

 stand drought than others. The factors that constitute 

 drought resistance are not all well understood but sev- 

 eral are now quite well appreciated by dry farming in- 

 vestigators. For instance, it is now well known (1) that 

 different crops require different amounts of moisture to 

 produce a unit of dry matter, (2) that certain types of 

 crops are able to withstand more drought than others, 

 (3) that the growth of some classes of crops so parallels 

 the monthly distribution of rainfall that they produce 

 larger yields than others, the growth habits of which are 

 different — in other words they avoid drought — and (4) 

 that crops which permit of intertillage may develop bet- 

 ter under similar precipitation than those not adapted 

 to this method of culture. 



Recent investigations have shown that among our 

 commonly grown crops millet, sorghum and corn re- 

 quire the least moisture per unit of dry matter produced ; 

 that the legume crops, like alfalfa, peas and clovers re- 

 quire the most — and that the grain crops — wheat, oats, 

 barley and rye and flax — are intermediate in moisture 

 requirements. 



