THE IRRIGATION AGE. 



359 



and two crops of hay are raised. 



Throughout the arid region there are a few localities 

 where subirrigation is quite generally practiced. Perhaps 



of the ground water. Wherever alkali is prevalent the 

 rise of the ground water near the surface is almost cer- 

 tain to be followed by an accumulation of alkali on the 

 surface. Again, the fact that alfalfa 

 fields subirrigate is usually nature's way 

 of giving warning that the ground water 

 is rising dangerously near the surface, 

 and observations should be made to de- 

 termine if the level is above the danger 



limit One of the best ways of making Fig 25 _ Supply Ditch with Bottom width of Four Feet 



such determinations is by means of bored 

 test wells. These are made by boring 



holes from 2 to 4 inches in diameter in different parts of the most notable of these is to be found in the vicinity 

 the field and noting at regular intervals the elevation of of the towns of St. Anthony and Sugar City, in the upper 

 the ground water in each. Where the subsoil is a clay Snake River Valley in Idaho. This subirrigation district 



or a clay loam no lining will be necessary other than a 

 joint of drain tile or a short wooden tube. Where the 

 subsoil is loose it may be necessary to line the wells with 

 thin galvanized iron or with a wooden box. The wells 



P~ "ft J 



Fig. 26 Supply Ditch with Bottom Width of Six Feet. 



may be connected by a line of levels, the elevations being 

 taken on the tops of stakes driven beside the wells. These 

 well records, if. taken at weekly or even monthly inter- 

 vals, for several years, will show at a glance not only the 



comprises an area of about 60,000 acres. A characteristic 

 of the subsoil of this large area is that it is composed of 

 sand and gravel, sometimes mixed with cobble rock to the 

 lava bed rock, which is found at depths varying from a 

 few feet to 90 feet. The surface soil 

 around St. Anthony is a dark-colored 

 gravelly loam 2 to 4 feet deep. On the 

 Elgin Bench it is a dark sandy loam 

 1.5 to 5 feet deep, while around Sugar 

 City it is a clay loam 4 to 6 feet deep. 

 The land slopes to the south and west 

 at the rate of about 10 feet to the mile. 

 At first ordinary ditches were built 

 and for years attempts were made to irrigate the land 

 by the usual methods. These failed, however, since all the 



Fig. 29 Lateral Ditch with Bottom Width of Fourteen Inches. 



water turned into the ditches soon sank into the porous 

 subsoil beneath. In time much of this subsoil filled up 



01.0 **/ 



Fig. 87 "A" Crowder. 



position of the ground water, but also its rise and fall 

 throughout the seasons. Whenever it is found that the 

 water table stands for any considerable time at less than 

 4 feet from the surface there is cause for alarm, and meas- 

 ures should be taken to prevent such an accumulation of 

 seepage waters or to remove the surplus by drainage. 



Alfalfa is subirrigated also from the beds of streams. 

 On bottoms the danger is not so great, because there is 

 less alkali present and the height of 

 the ground water is governed by the 

 condition of the stream. It happens 

 often that when the water table is 

 at its highest point the alfalfa plants 

 are dormant, or nearly so, and as a 

 result are not so readily injured. Two 

 cases of successful subirrigation from 

 stream channels are here cited by 

 way of illustration. 



On the farm of J. A. King, located 

 on the second bottoms about 5 miles 

 northeast of Boulder, Colo., the water 

 table is 10 to 12 feet below the sur- 

 face. An average yield of alfalfa of 

 4 tons per acre has been obtained for 

 the past nine consecutive seasons from 

 this farm without any perceptible de- 

 terioration. The crop was irrigated 

 the first year, but after that the roots 

 had evidently reached water and con- 

 tinued to draw their supply from that 

 source. 



On the Arkansas river south of 

 Cimarron, Kans., John Bull has an 



alfalfa field of over 50 acres which is subirrigated. The 

 water table is found at a depth of 6 to 8 feet, and the yield 

 is usually 1 ton at each cutting. It is cut three to five 

 times each season, and in some years one crop of seed 



Fig. 30 Lateral Ditch with Bottom Width of Sixteen Inches. 



with water, due to an impervious lava bed rock, and the 

 top layers of soil became moistened from below. This 



Fig. 31 Lateral Ditch with Bottom Width of Two Feet. 



condition led the farmers to adopt a new method of ir- 

 rigation, a type of which is shown in figure 32. On a 



Fig. 28 Adjustable "A" Scraper or Crowder. 



farm of 120 acres, the property of C. H. DeCamp, located 

 12 miles south of St. Anthony, Idaho, the main canal 

 passes along the north and west boundaries. From this 

 a supply ditch is run which feeds the smaller laterals. 



