IMBIGATION AND BRT-FARMIlsf G 717 



to the acre. The crop will stool out strongly and adjust 

 itself to the moisture supply. Under dry-land and irri- 

 gation farming, crops as a rule root much deeper than in 

 humid soils. 



616. Extent of dry-faiming. — In the United States 

 many thousands of acres in the Great Plains region, in 

 the semiarid northwestern valleys, and in the Pacific 

 Coast States, are now being cropped under systems of 

 dry-farming (see Fig. 82). Further, the practice is be- 

 ginning to be followed somewhat more definitely in all 

 parts of the world where similar conditions prevail. The 

 large open areas of land and the dry climate in such 

 regions have encouraged the employment of larger power 

 equipment in planting and harvesting the crops^ especially 

 wheat. In parts of California machines are used which 

 cut, thresh, and sack the grain in one operation. 



The study of the principles on which dry-farming is 

 based, together with the extension of their practice, 

 may be expected to bring large areas of land, now sub- 

 stantially worthless, to a measurable degree of productive- 

 ness. The tendency in the practice of both dry-farming 

 and irrigation is toward the more eSicient use of water 

 for purposes of crop production, and to approach the 

 actual requirements of the plant in the utilization of water. 

 In both cases the fundamental principles in the storage, 

 conservation, and use of water by plants must be observed, 

 as well as care regarding the application of these prin- 

 ciples according to the soil, the crop, and the nature of the 

 water supply. 



