THE MAXIMUM DUTY OF WATER. 



THE EXTENT TO WHICH TILLAGE MAY TAKE 

 THE PLACE OF IRRIGATION. 



(Read Before The New Farmers Club Topeka, Kansas, Dec. 29, 1899.) 



BYF. H. KING. 



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

 able of producing, 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 like reason, it is very important to know what 

 is the minimum amount of water which, under stated climatic condi- 

 tions, 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 realizing the largest profits which are possible to the 

 business. 



Much effort has been given at the Wisconsin Station determining 

 by rigid methods how much water must be used by certain crops in 

 coming to maturity, when placed under the best 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-hujnid districts agricultural operations maybe 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 tillage, to dispense with irri- 

 gation, and avert disastrous results during seasons of drought. 



Our studies indicate that the minimum amount of water which can 

 produce a ton of water-free dry matter in corn is 2.4 acre inches; 

 potatoes 3.4; barley 4.1; peas 4.2; oats 4.4 and medium clover 5 acre 

 inches. These estimates include the nece sary losses of water from 

 the soil and from the plant, and the dry matter is that produced above 

 ground, not including the roots or stubble left in the field. 



Calculating from the data of our trials, and a normal ratio of grain 

 to straw, 20 bushels of wheat per acre would require 6 acre-inches of 

 water and 12 inches should produce 40 bushels. 



To secure 40 bushels of barley per acre 8.56 acre-inches of water 

 are needed; 60 bushels of oats would demand 9.4 acre-inches and 11.75 



