6o4 



POPULAR SCIENCE MONTHLY. 



partial, or entire crop failures are to be looked for. The regular- 

 ity of production, of course, results from command of tlie water 

 supply as such ; the high production has usually been ascribed 



_3 



Fir 



st '^Foot Second Vjbo? 



Depth of Soil Column 



'i4 A 27 30 33 30 A 8'J ., , 



Thiid^Foot FouvthyFoot 



largely to the plant food brought to the land by the stream 

 waters used in irrigation, whether in the form of suspended mud 

 or in actual solution. Especially has the never-failing fertility 



