628 



EXPEEIMENT STATION KECOED. 



with similar analyses of the water of the Columbia and Snake rivers, indicate that 

 the water used for irrigating is not the source of the alkali which is found to greater 

 or less extent in the valley, especially where irrigation has been practiced longest. 

 The analyses of the river waters are as follows : 



Analyses of sediment in river ivaters. 

 [Grains per imperial gallon.] 



Yakima 

 River. 



Columbia 

 River. 



Snake 

 River. 



Sand and silica 



Calcium oxid 



Magnesium oxid 



Ferric and aluminum oxid 



Potassium oxid 



Sodium oxid 



Sulphur trioxid 



Chlorin 



Organic solids and carbonates. 

 Undetermined 



Total . 



4.59 



2.45 



.82 



3.23 



.45 



3.51 



3.59 



Trace. 



13.65 



0.72 



3.20 



.68 



.09 



.08 



.36 



.28 



Trace. 



3.41 



.18 



1.5b 

 2.08 

 .66 

 .12 

 .14 

 .67 

 .86 

 .23 

 2.37 

 .29 



9.00 



The analj^ses of the soluble salts in 56 samples of soil from the region under con- 

 sideration, generally from fields where alkali is noticeably present, indicate that "the 

 alkali areas in every case have been brought into existence through the action of the 

 soil water on the soluble salts naturally existing in the soil and distributed generally 

 throughout all parts of it; and the position of these areas has been determined by 

 the natural drainage of the land previous to the advent of irrigation, and also largely 

 since irrigation has been introduced." The alkali of the valley is largely of the black 

 variety (sodium carbonate). All of the soils show some alkali, but the smallest 

 amounts are found in the uncultivated and unirrigated soils, and where irrigation 

 was limited there was less surface alkali than where an unlimited amount of irriga- 

 tion water was obtainable. 



"Throughout the whole iriigated section of this valley, and ranging from a few 

 inches to several feet below the surface, is a well-defined layer of hardpan, varying 

 from about 3 in. to 1 ft. in thickness. This hardpan consists of a calcareous layer 

 quite impervious to water, and has much to do with permitting the soil near the 

 surface to become clogged with alkali." The hardpan layer "may be found also 

 above the irrigated sections and the lower bench lands surrounding the valley proper. 

 Below in the valley the stratum is dark gray in color, due perhaps tc) organic matter 

 and an excessive amount of soil Ijeing mixed with it. Those samples found at greater 

 elevations were lighter in color and nearly free from organic matter." 



Analyses of hardpan from the valley are given in the following table: 



Composition of hardpan from Kittitas Valley. 



a From unirrigated land. 



These analyses do not prove the hardpan to be the source of the alkali in the valley, 

 as many suppose. In fact, the water-soluble material from this calcareous stratum 

 is seldom in excess of what is fomid in the soil overlying it. 



