152 



THE IRRIGATION AGE. 



Fig. 3 Drainage system under construction. Note depth of trench. 



tract was then planted to alfalfa, which gave 

 satisfactory yields for a few years, but the 

 water table continued to rise until the alfalfa 

 became unprofitable and the entire tract was 

 used for grain up to the time that the recla- 

 mation work was started. In 1912 the entire 

 quarter section produced only about 30 tons 

 of barley hay and this largely from the 

 sandy ridge in the northwest corner of the 

 tract. In 1913 the tract was uncultivated, 

 some parts being entirely barren of vegeta- 

 tion, while a rank growth of alkali weeds 

 and foxtail covered most of it. 

 Preliminary Survey 



During the summer of 1913 detailed 

 topographical, soil and alkali surveys were 

 made of the area. The topography is some- 

 what irregular, the general slope is about 

 2J4 feet from north to south. A sandy ridge 

 runs through the northwest part of the field, 

 with a deep depression just to the west. A 

 shallower depression lies just east of the 

 ridge, and a broad, flat area extends from 

 this through the middle of the field. With 

 the exception of the one deep depression, 

 the local differences in elevation are less 

 than two feet. 



The soil is mapped by the Bureau of 



Soils as "Fresno sandy loam," whereas the more 

 detailed survey mentioned separated it into the 

 sandy loam and fine sandy loam types, each occupy- 

 ing irregular shaped areas over the tract. Prac- 

 tically the entire area is underlain by hardpan at 

 depths ranging from a few inches to several feet, of 

 a thickness ranging from a few inches to four feet. 

 Sometimes several layers of hardpan were encoun- 

 tered within a six-foot soil column. Hardpan 

 conditions varied considerably within short dis- 

 tances, and, as was found later, offered little resist- 

 ance to the downward movement of water. 



The detailed survey showed that the alkali 

 varied in the surface foot from less than .2 per cent 

 over most of the tract to 3.0 per cent over small 

 areas. It was found that the principal salts were 

 sodium chloride and sodium carbonate, with a pre- 

 dominance of the former. Observations taken dur- 

 ing 1912 and the early part of 1913 showed that at 

 no time during the year was the water table more 

 than seven and one-half feet below the surface, and 

 during June it stood within two feet of the surface. 

 During the entire growing season the water was 

 less than six feet from the surface, and for four and 

 one-half months was less than four feet below the 

 surface. 



Plan of Drainage 



The system of drainage installed during No- 

 vember and December, 1913, consists of a main 

 drain, beginning near the center of the north line 

 of the tract, running south to within, about 600 feet 

 of the south line, thence southeastward 750 feet and 

 thence east to a sump at the southeast corner. The 

 main drain has a fall of 1 in 1,000 and an average 

 depth of about seven feet. As originally constructed, 

 the upper 300 feet were 6-inch tile, followed by 1,588 

 feet of 8-inch tile and 1,400 feet of 12-inch tile. The 



W. FTeld Operations of Bureau of Soils, 1912 Fresno Area. 



Fig, 4 The tract was flooded in order to wash the alkali down. 



