28 



Irrigation and Drainage 



crops are capable of utilizing, and, hence, that all methods of till- 

 age which are wasteful of soil moisture detract by so much from 

 the yields per acre. Indeed, what we call good average yields 

 per acre are determined, in a large measure, by the amount of 

 soil moisture which the land is capable of turning over to the 

 crops growing upon it. 



In 1894, work similar to that described was done with pota- 

 toes, eight cylinders being used, two of which were placed in the 



Fig. 2. Potatoes grown in cylinders to determine the amount of water 

 used in producing a crop. 



field, as already described, and six others were kept standing upon 

 the surface of the ground, shaded on the south side from the sun 

 in the manner represented in Fig. 2, which shows the potatoes as 

 they appeared when growing. In the same year, oats were again 

 grown in four other cylinders surrounded by field grain of the 

 same kind, and in pots with their tops flush with the top of the 

 ground. A statement of the results of these several trials is 

 here given. 



We give, in the first place, in illustration of the rate at which 

 potato plants use water in the various stages of their growth, a 



