Cy xi A JL 1 xLix -X_X.i V 



FARMING IN REGIONS OF LIMITED RAINFALL 



Dry-Farming.— Dry-land farimng, or dry-farming, is com- 

 monly understood to mean the profitable production of crops 

 without irrigation on lands receiving less than thirty and at least 

 fifteen inches of rainfall annually. In reality there is no such 

 thing as dry-farming. No crops can be produced on dry land. So- 

 called dry-farming has for its object the reclamation of vast areas 

 of unirrigable lands which were formerly thought to be of no agri- 

 cultural value. It is a striking fact that about sixty-three per cent 

 of the whole area of the United States receives less than thirty 

 inches of rainfall annually. Eighteen Western states are included 

 in this area. About twenty per cent of this area, or about 240,- 

 000,000 acres, receive less than fifteen inches. There are, therefore, 

 more than a billion acres that may be called dry-farming lands 

 in Western United States. 



Information Has Been Meager. — In the past only meager 

 and unreliable information could be secured concerning dry-land 

 farming. Within recent years, however, experimental data have 

 been secured which will greatly aid in solving many of the problems 

 confronting the dry-land farmer. 



It is to be understood that the climate in the dry-farming 

 region is not uniform, but variable. One season taay have almost 

 humid, and another almost arid conditions. The distribution of 

 the rainfall, likewise, is variable. It is not an unusual occur- 

 rence to have a single torrential downpour of rain which exceeds 

 in the amount the normal rainfall for the month in which it 

 occurs. At other times a monthly precipitation of 1.9 inches 

 may come in nine light showers and prove of no practical value 

 because all the moisture evaporates before it can penetrate the 

 soil mulch. 



The Water Problem. — ^The main problem thus far in growing 

 crops without irrigation in regions of limited rainfall concerns the 

 conservation of the rainfall for crop use (Chapter VIII). It has 

 been demonstrated that by proper methods there need be no com- 

 plete crop failure on suitable soils wherever the annual rainfall is 



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