96 



Nnber of irrigations. Total Water Yield per acre 



4 6.35 feet 3.78 



6 6.92 3.65 



7 9.40 5.2 



The greatest yield was obtained from the greatest amount of water. In 

 this case also water was flooded much too far and the loss by deep percola- 

 tion is no doubt very great. The waste could be very much lessened by 

 using frequent light irrigations and shortening the distance the water has 

 to travel. Because of the waste in both of the above gravelly soils, these 

 results do not represent the correct quantity of water to use. 



On a very sandy loam of fine texture down to a depth of 6 feet or more, 

 the yields obtained for four year old alfalfa were as follows: 



The field was well prepared for irrigation. The yields were nearly the 

 same for the different depths of water applied. 



For a clay soil 6 feet or more deep with a thin layer of hardpan 2 or 3 

 feet below the surface, the yields of an alfalfa field 5 years old were: 



Number of irrgations. Total ' Water Yield per acre. 



8 1.89 feet 4.00 



8 2.85 3.66 



_ 9 3.45 4.37 



While the yield was greatest for the largest quantity of water used, it 

 was not much greater than that obtained where the smallest quantity of 

 water was used. 



On a clay loam of the same character as the above clay soil the yields 

 from a one year old alfalfa field were: 



Number of irrigations. Total depth of water ~ Yield per acre. 



applied. 



7 1.43 feet 2.85 



7 2.11 4.93 



7 2.25 4.35 



The re&ults obtained from these experiments show that on gravelly soil 

 a much larger quantity of water may be used than on more retentive soil. 

 But the quantities used do not represent the amount of water required 

 for they include large losses due to deep percolation which can be very 

 much reduced by running the water shorter distances and using light irri- 

 gation applied more frequently. As a rule the yield seems to increase with 

 the quantity of water applied, but the increase in yield in most cases is 

 slight for a considerable increase in quantity of water and in some cases a 

 greater yield was obtained with the smaller quantity. 



The U. S. Department of Agriculture has made experiments on thirty 

 plats of alfalfa at the University Farm at Davis, California, to determine 

 the best use of water on alfalfa. The yields obtained for varying amounts 

 of water are as follows: 



