DRAINAGE 



57 



The area of the land in the United States which may be 

 improved by drainage is still large. It is estimated by Mr. 

 C. G. Elliott, formerly Chief of Drainage Investigation, 

 United States Department of Agriculture, that there are 

 yet 70,000,000 acres of land in the United States to be 

 reclaimed by drainage. In addition to this there are large 

 areas of land which could be made more productive and more 

 valuable by drainage. 



Water in the Soil. The water in the soil may be classified 

 as capillary water and hydrostatic water. Capillary water 



Fig. 41. 



Land needing drainage. Typical conditions in northern Iowa 

 and southern Minnesota. 



is that which covers the surface of the soil particles or grains 

 as a film. It is the water in the soil which moves toward the 

 surface by capillarity as the water at the surface evaporates. 

 Hydrostatic water, or ground water, is that which fills the 

 open spaces between the soil particles and which obeys gravity 

 to the extent that it may be drawn off at the bottom 



