78 IRRIGATION PRACTICE 





the drainage water were not much higher than in many of 

 the streams and rivers used for irrigation. The lime and 

 magnesia were not washed out to any great extent, but 

 the potash, phosphoric acid and nitric acid, the three 

 most important constituents of the soil, were propor- 

 tionally much more abundant in the drainage water than 

 in the original irrigation water. Analyses of drainage 

 waters in various countries lead to similar results. Hil- 

 gard, in a collection of analyses of drainage water from 

 European countries, has shown that the parts of total 

 solids in 1,000,000 parts of water range from 140 to 721, 

 with an average of 352.6, which is somewhat higher than 

 the 242 found in the above Utah experiment. 



54. Composition of drainage water. It may be said 

 safely that the concentration of drainage water under 

 normal conditions is not extraordinarily high, but hovers 

 in the neighborhood of 200 to 400 parts of total solids 

 in 1,000,000 parts of water. Under abnormal conditions, 

 these figures may be much larger. If, for instance, the 

 soil is rich in organic matter, as after heavy manuring, 

 the drainage water may show a high proportion of organic 

 matter; if the soil is of an alkali nature, the drainage 

 water frequently contains tremendously large quantities 

 of soluble matter. In one of the reclamation experiments 

 of the United States Bureau of Soils at Billings, Mon- 

 tana, the drainage water from an alkali tract, which had 

 been under drained for the purpose of removing the alkali, 

 contained from 250 to 9,000 parts of dissolved matter in 

 1,000,000 parts of water; in the drainage water from a 

 similar tract located near Salt Lake City, were found 

 10,710 to 20,346 parts of dissolved matter in 1,000,000 

 parts of water. These are extraordinary concentrations 

 of drainage water which occur only when the soils are 



