THE USE OF ALKALINE AND SALINE 

 WATERS FOR IRRIGATION. 



BY 



THOMAS H. MEANS, 



ENGINEER OF SOILS, V. S. RECLAMATION SERVICE. 



THE greater part of the water easily 

 available for irrigation in the arid 

 regions of the United States has been ap- 

 propriated, and in many cases appropri- 

 ation has gone so far beyond the easily 

 available as to require extensive and 

 costly irrigation works to biing the 

 water to the land. As time goes on, the 

 scarcity of water becomes more evident, 

 and we are now confronted by large 

 areas of excellent land, lying in a posi- 

 tion very favorable for irrigation, with 

 little or no water in the streams for the 

 accomplishment of this irrigation. 



In the effort to extend the area of irri- 

 gated land so as to include these unoc- 

 cupied tracts, sources of water more or 

 less contaminated with salt and alkali 

 have been developed, and the application 

 of these waters to the land has produced 

 a new set of conditions worthy of our 

 careful consideration. The fact that 

 water contains much or little soluble 

 matter seldom enters into the calcula- 

 tions of the farmer or engineer, and seri- 

 ous mistakes, involving heavy loss, have 

 been made by the use of water containing 

 excess of salt or alkali mistakes often 

 the result of lack of knowledge concern- 

 ing the effect of salt and alkali upon 

 plant grow r th. Cases, however, are on 

 record where water has been condemned 

 by chemists, but its use persisted in by 

 canal companies or individuals to their 

 serious loss. Again, on the other hand, 

 well-meaning chemists have been prone 

 to condemn sources of water as detri- 

 mental to plant growth, and in that way 

 have seriously hampered the develop- 

 ment of agriculture, when by proper 

 methods of cultivation and irrigation 

 this water might be used successfully 

 and profitably. A number of cases have 

 recently come to notice where pumping 

 plants have been closed down by the ad- 

 vice of chemists, on account of the salt 

 and alkali in the water, when such 

 waters could be used a thousand years 

 without detriment to the soil or grow- 



ing plants if the farmer understood 

 the proper methods of handling alkali 

 waters, and in southern California and 

 Arizona orange and lemon trees have 

 been killed by the use of a slightly alka- 

 line water when , by a very simple change 

 in methods of irrigation, the trees could 

 have been made to flourish. All this 

 points to the fact that information upon 

 the best methods of using saline and 

 alkali waters is needed. 



Chemists have made serious attempts 

 to define the limits of the amount of va- 

 rious chemical salts allowable in a water 

 to be used for irrigation. At the pres- 

 ent time the statements seen in print are 

 greatly at variance. Many statements 

 are made largely from the result of labo- 

 ratory studies, while others are made 

 from studies over a very limited field. 

 In work of this sort it is very difficult to 

 determine from laboratory investiga- 

 tions how much alkali a plant will 

 stand, and it is only by very wide obser- 

 vation of field conditions where alkali 

 waters are in use that definite informa- 

 tion can be gathered as to the limits of 

 endurance of ordinary crops. For ex- 

 ample, water is used on large areas of 

 land in New Mexico and Arizona, and 

 has been used successfully from ten to 

 twenty years, which would be regarded 

 with suspicion or condemned in Cali- 

 fornia. 



Studies carried on in the Department 

 of Agriculture, Bureau of Soils, over 

 the entire western irrigated area, led to 

 the publication in 1899 of the following 

 statement: "Five hundred parts of 

 soluble matter may be taken as the ex- 

 treme limit of endurance for plants, 

 while 250 or 300 parts mark the dan- 

 ger point, at which the results of the 

 use of the water are very uncertain." 



At this same time other writers on 

 the subject place the limit at 30 parts 

 sodium chloride and from 173 to 300 

 parts of the less harmful salts per 

 100,000 of water. Thus it will be seen 



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