38 



Irrigation, and Drainage 



Here, again, if we figure the yield of dry matter per acre on 

 the basis of the amount of ground occupied, we shall have the 

 large crop of 8.67 tons of dry matter per acre, using in its pro- 

 duction 22.67 inches of water. 



In twenty other 18-inch cylinders in the plant-house, a variety 

 of white dent corn was grown, four plants in a cylinder. These 



Fig. 4. Crop of potatoes using from 272-347 pounds of water for 1 

 pound of dry matter. 



were planted May 22 and harvested Aug. 23, and on the twenty 

 cylinders, aggregating 35.34 square feet of soil, 18.1 pounds of 

 dry matter were produced, which used 5,685 pounds of Water in 

 coming to maturity, or at the rate of 314.1 pounds of water for 

 one pound of dry matter, and a depth of water, when expressed 

 as rainfall, of 30.93 inches, the yield per acre being 22,310 pounds 

 of water -free matter. 



