Water Used by Plants 25 



matter per acre are measurably proportional to the amount of 

 water used by the crop in producing it. These relations are 

 expressed in the following table: 



. In the field In cylinders 



Dry matter Water used Dry matter Water used 



LBS. PER ACRE INCHES LBS. PER ACRE INCHES 



Oats in 1891 6,083 13.93 8,861 19.69 



Oats in 1892 8,189 19 



Barley in 1891 4,157 11.27 7,441 13.19 



Barley in 1892 . 14,196 23.52 



Corn in 1891 8,190.5 12.26 19,845 26.39 



Corn in 1892 7,045.3 11.34 19,184 25.09 



Clover in 1892 12,496 29.73 



Peas in 1892 8,017 



Now, here, in the case of the oats, the average yield of dry 

 matter per acre in the cylinders was 4.26 tons, while in the field 

 it was 3.04 tons. But the soil put into the cylinders in the spring 

 was the same as that in the field and contained the same per cent 

 of soil moisture, but there was given to the soil in the cylinders 

 1.39 times the amount of water which fell as rain upon the sur- 

 rounding fields, plus the amount of water by which the soil was 

 dryer at harvest than at seed-time ; and we had a yield 1.4 times 

 as large. 



In the experiment with barley, we had an average yield of 

 5.41 tons of dry matter per acre in the cylinders, but only 2.08 

 tons in the field. There were added to the cylinders 1.63 times 

 the amount of water which fell upon the field, plus the amount 

 of water by which the soil was dryer at harvest than at seed-time, 

 and we realized a yield of dry matter 2.6 times as large. There 

 was in the field a yield of 40 bushels of grain per acre, but in 

 the cylinders 104 bushels, and yet so far as we can see, the only 

 advantage the barley in the cylinders had over that in the field 

 was the increased amount of water added to the soil. 



In the case of corn, the yield of dry matter per acre in the 

 cylinders was nearly 2.6 times as large as that in the field, and 

 there was added to the soil in which this corn grew a little less 



