26 Irrigation and Drainage 



than 2.2 times the amount of water which was available for the 

 field crop. 



In 1893, oats used water at the rate of 595 pounds per pound of 

 dry matter on a sandy soil where the yield was 1.196 pounds on 

 7.069 sq. ft., making a yield of 7,370 pounds of dry matter per acre. 

 But in this case the pot was a galvanized iron cylinder 6 feet deep, 

 standing above the ground, so that the evaporation would neces- 

 sarily be large, as the figures show it was. Expressed in inches, 

 the water used was equal to 19.37 inches of rain. 



Clover, too, was grown in the usual form of cylinder in the 

 ground in the field, and two crops cut from each of two cylinders, 

 producing the yield and using the amounts of water stated below: 



/ First crop > < Second crop N 



No. 1 No. 2 No. 1 No. 2 



LBS. LBS. LBS. LBS. 



Dry matter per acre 7,000 9,353 5,734 7,886 



Water per pound of dry matter 423.14 370.92 983.7 730.9 



It will be seen that in these cases the first crops, which were 

 cut July 1, were much more economical of water used than were 

 the second crops, when measured by the standard of the number 

 of pounds of water per pound of dry matter produced. Express- 

 ing the water used in inches over the surface covered by the 



crop, the results stand : 



First crop /Second crop-^ 



No. 1 No. 2 No. 1 No. 2 



INCHES INCHES INCHES INCHES 



Inches of water used 13.06 15.28 24.89 25.44 



It is thus seen that the two crops of clover, averaging for 

 the four cases a yield of 7.493 tons of dry matter per acre, and 

 equivalent to 8.815 tons of hay containing 15 per cent of water, 

 used for the season a mean of 39.33 inches of water, an amount 

 which considerably exceeds the total annual rainfall of the year 

 for this locality. 



Side by side with the clover trials of 1893, four cylinders were 

 treated in the same manner for corn, all of them growing a flint 

 variety. In these cases, too, one cylinder of each pair had its 



