34 ARID AGRICULTUEE. 



this basis, twelve and one-half tons per acre could 

 be produced with ten inches of moisture, pro- 

 vided it is all saved and made available to the 

 plants. 



Several years ago, the author made the fol- 

 lowing statement: The amount of water found 

 to be necessary to produce one pound of dry crop 

 of grains in the humid region is approximately 

 five hundred pounds, which is used by the plant 

 and evaporated from the soil during growth. An 

 annual rainfall of twelve inches would bring to 

 each acre of land 2,722,500 pounds of water. 

 If all this water could be made available for the 

 crop during the growing season, and assuming 

 that 500 pounds of water is sufficient to produce 

 one pound of dry crop, twelve inches of rain 

 would produce 5,445 pounds, or approximately 

 2% tons of vegetable matter. If one-half the 

 rainfall of a single year could be saved to the 

 groMdng plant, it would support more crop than 

 the average native hay production of our irri- 

 gated meadows. 



Such speculations are useful as indicating 

 certain possibilities, but it is unquestionably triie 

 that some plants require more moisture than 

 others, and there are many things to consider 

 outside of the actual amount of moisture used. 

 There are drouth-resistant crops which will ap- 

 proximately stand still in time of drouth until 

 more moisture renews their growth. Other 

 drouth-resistant crops have so adapted them- 



