THE IRRIGATION AGE. 



157 



Taking May 22, 1916, as a representative date, 

 the average of the eight wells on this tract shows 

 the water table to be 4.8 feet below the surface, 

 while on the same date, as shown by an average of 

 eighteen wells, the water stood one foot higher on 

 other parts of the Kearney Vineyard property. On 



Fig. 10 Barley hay on east half of drained tract, May, 1916. 



the same date the average depth to water was 2.6 

 feet in three wells on the tract immediately south 

 of the drained area. 



Removal of Alkali 



The soil and alkali survey made in the summer 

 of 1913 showed, as has been stated, that the surface 

 foot, over a considerable portion of the tract, con- 

 tained less than .20 per cent of combined salts, al- 

 though there were areas where there was 3.0 per 

 cent or over. The most alkaline portions were in 

 the depressions, which have been described as being 

 on either side of the ridge near the northwest cor- 

 ner of the tract. An area containing as high as 1.0 

 per cent was found covering about the center third 

 of the east eighty acres. 



In the fall of 1913 a series of analyses were 

 made of soil samples taken from holes fifty feet 

 apart on two parallel lines fifty feet apart running 

 from the southeast to the northwest corner of the 

 tract. The results of these analyses were com- 

 pared with analyses made from soil samples taken 

 from the same places in July, 1914, and July, 1915. 

 In 1913 and 1914, samples were taken of each foot 

 of soil from the surface- to hardpan. During 19L5 

 samules were taken for each foot from the surface 

 to six feet. 



Local variations in the alkali content of the soil 

 make individual tests rather misleading and in 

 order to reach any conclusions, all the tests in both 

 lines were taken collectively. The following table 

 gives the results of this method of handling the 

 data: 



Sodium Salts in Surface Foot 



No. of Per cent Per cent 



tests NaCl Na,CO 3 Total 



122 .0972 .0401 .1373 



119 .0276 .0406 .0682 



138 .0208 .0338 .0546 



1914 decrease in NaCl, 71.6 per cent; increase 



in Na 2 CO 3 , 1.2 per cent; decrease in total alkali, 



50.3 per cent. 



1915 decrease in NaCl, 78.6 per cent; decrease 



in NaXOg, 15.7 per cent; decrease in total alkali, 



60.3 per cent. 



Fig. 8 shows the same results graphically. It 



will be noted from the above table 



that of the total, .1373 per cent of 

 salt in the surface foot in 1913, 70.8 

 per cent was NaCl, or common salt, 

 and 29.2 per cent Na 2 CO 3 , or black 

 alkali. In 1914 there was a decrease 

 of 71.6 per cent in the.NaCl and an 

 increase of 1.2 per cent in the Na 2 CO 3 , 

 making a total decrease of 50.3 per 

 cent. In 1915 the decrease in NaCl 

 was 78.6 per cent of the amount pres- 

 ent in 1913 and there was also a de- 

 crease of 15.7 per cent in the Na,CO 3 

 for the same period, making a total 

 decrease in two years of 60.3 per cent. 

 The proportion of the two salts mak- 

 ing up the remaining total of .0546 

 per cent of the soil had changed from 

 a predominance of NaCl to a pre- 

 dominance of Na 2 CO 3 . 



The following table shows the 

 distribution of sodium salts through 



soil column in 1915 : 



No. of Per cent Per Cent 



Year 



139 

 138 



NaCl 

 .0208 

 .0161 

 .0145 

 .0125 

 .0104 

 .0039 

 .0139 



Na,CO 3 

 .0338 

 .0263 

 .0222 

 .0196 

 .0174 

 .0163 

 .0226 



Total 

 .0546 

 .0424 

 .0367 

 .0321 

 .0278 

 .0256 

 .0365 



Year 



1913 .. 



1914 .. 



1915 . 



tests 



First foot 138 



Second foot 138 



Third foot .... 

 Fourth foot . . . 



Fifth foot 139 



Sixth foot 137 



Average 138 



Fig. 9 shows graphically the same results as 

 found in the above table. This diagram shows that 

 both salts decrease quite regularly with the depth. 

 Unfortunately, we have no data for making a simi- 

 lar diagram for 1913 and 1914, consequently it is 

 not known whether the salts that have been re- 

 moved from the surface foot have been redistrib- 

 uted through the six-foot soil column, or partially 

 redistributed through this column and partially re- 

 moved ; or as is more likely the case, together with 

 the salts originally between the second and sixth 

 foot, they may have been partially removed and 

 partially redistributed below six feet. 



Assuming 92 pounds to be the weight of a 

 cubic foot of soil, there would be 320,600 tons of 

 soil in the surface foot on 160 acres. The soil 

 analyses show that NaCl and Na 2 CO 3 to the amount 

 of .0827 per cent, or 265.13 tons, have been removed 

 from the surface foot in two years. The drainage 

 water analyses show that for the same period 285.4 

 tons of these salts have been removed from the tract. 



At frequent intervals in 1914, and each week 

 during 1915, samples of the drainage water were 

 taken and analyzed for alkali. An average of these 

 samples shows that in 1914, 151.5 tons of alkali were 

 removed in the drainage water, of which 51.6 per 

 cent was NaCl, 34.5 per cent Na,CO 3 , and 13.9 per 

 cent Na 2 SO 4 . In 1915, 183 tons of alkali were re- 

 moved, of which 36.6 per cent was NaCl, 48.4 per 

 cent Na 2 CO 3 , and 15 per cent Na 2 SO 4 . 



