Water Needed for a Paying Crop 95 



THE LEAST AMOUNT OF WATER WHICH CAN PRODUCE 

 A PAYING CROP 



In the manufacture of butter from milk, it is a mat- 

 ter of prime commercial importance to know just how 

 much butter -fat that milk contains, and what is the 

 maximum amount of butter that fat is capable of pro- 

 ducing ; for only this knowledge can show how closely 

 the manufacturer is working to his possible .limit of 

 profit, and how great his losses may be. For a like rea- 

 son, it is very important to know what is the minimum 

 amount of water which, under stated climatic conditions, 

 can meet the needs of a given crop, producing a paying 

 yield. It is important, because only such knowledge as 

 this can show how economical or how wasteful our 

 methods of tillage may be, and how nearly we are realiz- 

 ing the largest profits which are possible to the business. 



In the Introduction, much pains has been taken 

 to give in detail the evidence, and the methods of pro- 

 curing it, which shows how much water must be used 

 by a given crop in coming to maturity when placed 

 under the best of conditions. This has been done, 

 because it is a part of the knowledge which is needed 

 to show under what climatic conditions irrigation may, 

 and under what it may not, be practiced ; because it 

 is needed to show how far into the* sub -humid districts 

 agricultural operations may be pushed without the aid 

 of irrigation ; because it will help to teach how far we 

 may hope, by the practice of the best methods of till- 

 age, to dispense with irrigation, and avert disastrous 

 results during seasons of drought. 



